Venus is Earth’s twin in size and radiogenic heat budget, yet it remains
unclear how Venus loses its heat absent plate tectonics. Most Venusian
stagnant-lid models predict a thick lithosphere with heat fow about half
that of Earth’s mobile-lid regime. Here we estimate elastic lithospheric
thickness at 75 locations on Venus using topographic fexure at 65 coronae—
quasi-circular volcano-tectonic features—determined from Magellan
altimetry data. We fnd an average thickness at coronae of 11 ± 7 km. This
implies an average heat fow of 101 ± 88 mW m−2, higher than Earth’ s
average but similar to terrestrial values in actively extending areas. For
some locations, such as the Parga Chasma rift zone, we estimate heat fow
exceeding 75 mW m−2. Combined with a low-resolution map of global elastic
thickness, this suggests that coronae typically form on thin lithosphere,
instead of locally thinning the lithosphere via plume heating, and that most
regions of low elastic thickness are best explained by high heat fow rather
than crustal compensation. Our analysis identifes likely areas of active
extension and suggests that Venus has Earth-like lithospheric thickness
and global heat fow ranges. Together with the planet’s geologic history,
our fndings support a squishy-lid convective regime that relies on plumes,
intrusive magmatism and delamination to increase heat fow.
The Sun’s differential rotation is controlled by high- latitude baroclinicall...Sérgio Sacani
Rapidly rotating fluids have a rotation profile that depends only on the distance from the rotation axis, in accor-dance with the Taylor- Proudman theorem. Although the Sun was expected to be such a body, helioseismology showed that the rotation rate in the convection zone is closer to constant on radii. It has been postulated that this deviation is due to the poles being warmer than the equator by a few degrees. Using numerical simulations, we show that the pole- to-equator temperature difference cannot exceed 7 kelvin as a result of the back- reaction of the high- latitude baroclinically unstable inertial modes. The observed amplitudes of the modes further indicate that this maximum temperature difference is reached in the Sun. We conclude that the Sun’s latitudinal differential rotation reaches its maximum allowed value
Artigo que descreve o trabalho feito com o Chandra nos aglomerados de galáxias de Perseus e Virgo sobre a descoberta de uma turbulência cósmica que impede a formação de novas estrelas.
Magma oceans and enhanced volcanism on TRAPPIST-1 planets due to induction he...Sérgio Sacani
Low-mass M stars are plentiful in the Universe and often host small, rocky planets detectable with current instrumentation.
These stars host magnetic fields, some of which have been observed to exceed a few hundred gauss. Recently, seven small
planets have been discovered orbiting the ultra-cool M dwarf TRAPPIST-1, which has an observed magnetic field of 600 G. We
suggest electromagnetic induction heating as an energy source inside these planets. If the stellar rotation and magnetic dipole
axes are inclined with respect to each other, induction heating can melt the upper mantle and enormously increase volcanic
activity, sometimes producing a magma ocean below the planetary surface. We show that induction heating leads the four
innermost TRAPPIST-1 planets, one of which is in the habitable zone, either to evolve towards a molten mantle planet, or to
experience increased outgassing and volcanic activity, while the three outermost planets remain mostly unaffected.
Long-lived volcanic resurfacing of Venus driven by early collisionsSérgio Sacani
The geodynamics of Earth and Venus operate in strikingly distinct ways,
in spite of their similar size and bulk density, resulting in Venus’s absence
of plate tectonics and young surface age (0.2–1 billion years). Venus’s
geophysical models have sought to explain these observations by invoking
either stagnant lid tectonics and protracted volcanic resurfacing, or by
a late episode of catastrophic mantle overturn. These scenarios, however,
are sensitive to poorly understood internal initial conditions and rheological
properties, and their ability to explain Venus’s young surface age remains
unclear. Here we show that long-lived volcanism, driven by early, energetic
collisions on Venus, ofers an explanation of its young surface age with
stagnant lid tectonics. This volcanic activity is fuelled by a superheated
core, resulting in vigorous internal melting regardless of initial conditions.
Furthermore, we fnd that energetic impacts stir Venus’s core, suggesting
that its low magnetic feld is not likely to be caused by a compositionally
stratifed core, as previously proposed.
Characterization of Quasi-Keplerian, Differentially Rotating, Free-Boundary L...Sérgio Sacani
We present results from pulsed-power driven differentially rotating plasma experiments designed to
simulate physics relevant to astrophysical disks and jets. In these experiments, angular momentum is injected
by the ram pressure of the ablation flows from a wire array Z pinch. In contrast to previous liquid metal and
plasma experiments, rotation is not driven by boundary forces. Axial pressure gradients launch a rotating
plasma jet upward, which is confined by a combination of ram, thermal, and magnetic pressure of a
surrounding plasma halo. The jet has subsonic rotation, with a maximum rotation velocity 23 3 km=s. The
rotational velocity profile is quasi-Keplerian with a positive Rayleigh discriminant κ2 ∝ r−2.80.8 rad2=s2.
The plasma completes 0.5–2 full rotations in the experimental time frame (∼150 ns).
The Sun’s differential rotation is controlled by high- latitude baroclinicall...Sérgio Sacani
Rapidly rotating fluids have a rotation profile that depends only on the distance from the rotation axis, in accor-dance with the Taylor- Proudman theorem. Although the Sun was expected to be such a body, helioseismology showed that the rotation rate in the convection zone is closer to constant on radii. It has been postulated that this deviation is due to the poles being warmer than the equator by a few degrees. Using numerical simulations, we show that the pole- to-equator temperature difference cannot exceed 7 kelvin as a result of the back- reaction of the high- latitude baroclinically unstable inertial modes. The observed amplitudes of the modes further indicate that this maximum temperature difference is reached in the Sun. We conclude that the Sun’s latitudinal differential rotation reaches its maximum allowed value
Artigo que descreve o trabalho feito com o Chandra nos aglomerados de galáxias de Perseus e Virgo sobre a descoberta de uma turbulência cósmica que impede a formação de novas estrelas.
Magma oceans and enhanced volcanism on TRAPPIST-1 planets due to induction he...Sérgio Sacani
Low-mass M stars are plentiful in the Universe and often host small, rocky planets detectable with current instrumentation.
These stars host magnetic fields, some of which have been observed to exceed a few hundred gauss. Recently, seven small
planets have been discovered orbiting the ultra-cool M dwarf TRAPPIST-1, which has an observed magnetic field of 600 G. We
suggest electromagnetic induction heating as an energy source inside these planets. If the stellar rotation and magnetic dipole
axes are inclined with respect to each other, induction heating can melt the upper mantle and enormously increase volcanic
activity, sometimes producing a magma ocean below the planetary surface. We show that induction heating leads the four
innermost TRAPPIST-1 planets, one of which is in the habitable zone, either to evolve towards a molten mantle planet, or to
experience increased outgassing and volcanic activity, while the three outermost planets remain mostly unaffected.
Long-lived volcanic resurfacing of Venus driven by early collisionsSérgio Sacani
The geodynamics of Earth and Venus operate in strikingly distinct ways,
in spite of their similar size and bulk density, resulting in Venus’s absence
of plate tectonics and young surface age (0.2–1 billion years). Venus’s
geophysical models have sought to explain these observations by invoking
either stagnant lid tectonics and protracted volcanic resurfacing, or by
a late episode of catastrophic mantle overturn. These scenarios, however,
are sensitive to poorly understood internal initial conditions and rheological
properties, and their ability to explain Venus’s young surface age remains
unclear. Here we show that long-lived volcanism, driven by early, energetic
collisions on Venus, ofers an explanation of its young surface age with
stagnant lid tectonics. This volcanic activity is fuelled by a superheated
core, resulting in vigorous internal melting regardless of initial conditions.
Furthermore, we fnd that energetic impacts stir Venus’s core, suggesting
that its low magnetic feld is not likely to be caused by a compositionally
stratifed core, as previously proposed.
Characterization of Quasi-Keplerian, Differentially Rotating, Free-Boundary L...Sérgio Sacani
We present results from pulsed-power driven differentially rotating plasma experiments designed to
simulate physics relevant to astrophysical disks and jets. In these experiments, angular momentum is injected
by the ram pressure of the ablation flows from a wire array Z pinch. In contrast to previous liquid metal and
plasma experiments, rotation is not driven by boundary forces. Axial pressure gradients launch a rotating
plasma jet upward, which is confined by a combination of ram, thermal, and magnetic pressure of a
surrounding plasma halo. The jet has subsonic rotation, with a maximum rotation velocity 23 3 km=s. The
rotational velocity profile is quasi-Keplerian with a positive Rayleigh discriminant κ2 ∝ r−2.80.8 rad2=s2.
The plasma completes 0.5–2 full rotations in the experimental time frame (∼150 ns).
The Equation Based on the Rotational and Orbital Motion of the PlanetsIJERA Editor
Equations of dependence of rotational and orbital motions of planets are given, their rotation angles are calculated. Wave principles of direct and reverse rotation of planets are established. The established dependencies are demonstrated at different scale levels of structural interactions, in biosystems as well. The accuracy of calculations corresponds to the accuracy of experimental data
Atmospheric flows are governed by the equations of fluid dynamics. These equations are nonlinear. But because atmospheric flows are inhomogeneous and anisotropic, the nonlinearity may manifest itself only weakly through interactions of non-trivial mean flows with disturbances or eddies. In such situations, the quasi-linear (QL) approximation, that retains eddy-mean flow interactions but neglect eddy-eddy interactions, hold promise in resolving large-scale atmospheric dynamics. The statistics of the QL system corresponds to closing the hierarchy of statistical moments at the second order.
Hence, exploring QL dynamics paves the way for the development of direct statistical simulations of geophysical flows.
Using a hierarchy of idealized general circulation models, we identify when the QL approximation captures large-scale dynamics. We show that the QL dynamics fails to capture the flow when the dissipation of large-scale eddies occurs through strongly nonlinear eddy-eddy interactions in upper tropospheric surf zones, as it is often the case on Earth. But we demonstrate that the QL approximation captures eddy absorption when it arises from the shearing by the mean flow, for example when the eddy amplitude is small enough or the planetary rotation rate is large enough.
These results illustrate different classes of nonlinear processes that can control wave dissipation in the upper troposphere and show that in some parameter regimes the QL approximation is accurate to resolve large-scale dynamics.
Breaking waves on the surface of the heartbeat star MACHO 80.7443.1718Sérgio Sacani
Massive astrophysical compact halo object (MACHO) 80.7443.1718 is a high mass, eccentric binary system exhibiting the largest-known-amplitude tidally excited oscillations. The system’s ±20% photometric amplitude, along with the high mass of the primary star, ~35 M⊙, make this the most extreme of the class of periodically perturbed ‘heartbeat stars.’ Here, we use a hydrodynamic simulation to demonstrate that with each periapse passage, an unseen companion star raises tidal waves so large that they break, shock-heating and dissipating energy and angular momentum on the surface of the star. The shock-heated material forms a rapidly rotating circumstellar atmosphere, which is stripped and reassembled with each periapse passage. The dissipation of nonlinear tides through surface wave breaking explains the super-synchronous rotation of the primary star, the evolution of spectral emission features and the observed decay of the binary orbital period. Connecting these features demonstrates that MACHO 80.7443.1718 is a natural product of massive binary star evolution, and that it provides an ideal laboratory for the direct study of nonlinear tidal dissipation.
Mechanical wave descriptions for planets and asteroid fields: kinematic model...Premier Publishers
Models with wave dynamics and oscillations in the solar system are presented. A solitonial solution (Korteweg-de Vries), for a density field, is related to the formations of planets. A new nonlinear equation for a solitonial, will be derived, and denoted ‘J-T equation’. The linearized version has solutions, which are small vibrations with eigen frequency proportional to the parameters describing the solitonial wave, around a constant level, which is 2/3 of the maximum solitonial density. The location and orbital motion of Mercury and Venus are compared with wave dynamics. The tidal effect for Earth is analysed in terms of dynamics. Related phenomena for other planetary objects are discussed in conjunction with assuming a Roche limit.
The caustic that occur in geodesics in space-times which are solutions to the gravitational field equations with the energy-momentum tensor satisfying the dominant energy condition can be circumvented if quantum variations are allowed. An action is developed such that the variation yields the field equations
and the geodesic condition, and its quantization provides a method for determining the extent of the wave packet around the classical path.
The caustic that occur in geodesics in space-times which are solutions to the gravitational field equations
with the energy-momentum tensor satisfying the dominant energy condition can be circumvented if
quantum variations are allowed. An action is developed such that the variation yields the field equations
and the geodesic condition, and its quantization provides a method for determining the extent of the wave
packet around the classical path.
The caustic that occur in geodesics in space-times which are solutions to the gravitational field equations
with the energy-momentum tensor satisfying the dominant energy condition can be circumvented if
quantum variations are allowed. An action is developed such that the variation yields the field equations
and the geodesic condition, and its quantization provides a method for determining the extent of the wave
packet around the classical path.
The caustic that occur in geodesics in space-times which are solutions to the gravitational field equations with the energy-momentum tensor satisfying the dominant energy condition can be circumvented if quantum variations are allowed. An action is developed such that the variation yields the field equations and the geodesic condition, and its quantization provides a method for determining the extent of the wave packet around the classical path.
The caustic that occur in geodesics in space-times which are solutions to the gravitational field equations
with the energy-momentum tensor satisfying the dominant energy condition can be circumvented if
quantum variations are allowed. An action is developed such that the variation yields the field equations
and the geodesic condition, and its quantization provides a method for determining the extent of the wave
packet around the classical path.
The caustic that occur in geodesics in space-times which are solutions to the gravitational field equations with the energy-momentum tensor satisfying the dominant energy condition can be circumvented if quantum variations are allowed. An action is developed such that the variation yields the field equations
and the geodesic condition, and its quantization provides a method for determining the extent of the wave packet around the classical path.
The Illustration of Mechanism and development of Atmospheric dynamic peripher...iosrjce
This research papers illustrates and justify the soil shifting and a pre determinant mechanism of
testing and real time analysis of soil composition and the behavior by concentric waveform generation and the
field effect of the concentric waves thus formed. The waveforms generated are being analyzed using a field wire
enclosure structure having a non conducting cylinder with circular magnetic field effect induction. The
electrical pulses being generated are plotted against fluid viscosity behavior. The research paper illustrates
with conclusion and analysis that a correlation simulation model is possible with fluid properties to generate
non obvious prediction mechanism to possible pulse generator.
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
Earliest Galaxies in the JADES Origins Field: Luminosity Function and Cosmic ...Sérgio Sacani
We characterize the earliest galaxy population in the JADES Origins Field (JOF), the deepest
imaging field observed with JWST. We make use of the ancillary Hubble optical images (5 filters
spanning 0.4−0.9µm) and novel JWST images with 14 filters spanning 0.8−5µm, including 7 mediumband filters, and reaching total exposure times of up to 46 hours per filter. We combine all our data
at > 2.3µm to construct an ultradeep image, reaching as deep as ≈ 31.4 AB mag in the stack and
30.3-31.0 AB mag (5σ, r = 0.1” circular aperture) in individual filters. We measure photometric
redshifts and use robust selection criteria to identify a sample of eight galaxy candidates at redshifts
z = 11.5 − 15. These objects show compact half-light radii of R1/2 ∼ 50 − 200pc, stellar masses of
M⋆ ∼ 107−108M⊙, and star-formation rates of SFR ∼ 0.1−1 M⊙ yr−1
. Our search finds no candidates
at 15 < z < 20, placing upper limits at these redshifts. We develop a forward modeling approach to
infer the properties of the evolving luminosity function without binning in redshift or luminosity that
marginalizes over the photometric redshift uncertainty of our candidate galaxies and incorporates the
impact of non-detections. We find a z = 12 luminosity function in good agreement with prior results,
and that the luminosity function normalization and UV luminosity density decline by a factor of ∼ 2.5
from z = 12 to z = 14. We discuss the possible implications of our results in the context of theoretical
models for evolution of the dark matter halo mass function.
More Related Content
Similar to Earth-like lithospheric thickness and heat flow on Venus consistent with active rifting
The Equation Based on the Rotational and Orbital Motion of the PlanetsIJERA Editor
Equations of dependence of rotational and orbital motions of planets are given, their rotation angles are calculated. Wave principles of direct and reverse rotation of planets are established. The established dependencies are demonstrated at different scale levels of structural interactions, in biosystems as well. The accuracy of calculations corresponds to the accuracy of experimental data
Atmospheric flows are governed by the equations of fluid dynamics. These equations are nonlinear. But because atmospheric flows are inhomogeneous and anisotropic, the nonlinearity may manifest itself only weakly through interactions of non-trivial mean flows with disturbances or eddies. In such situations, the quasi-linear (QL) approximation, that retains eddy-mean flow interactions but neglect eddy-eddy interactions, hold promise in resolving large-scale atmospheric dynamics. The statistics of the QL system corresponds to closing the hierarchy of statistical moments at the second order.
Hence, exploring QL dynamics paves the way for the development of direct statistical simulations of geophysical flows.
Using a hierarchy of idealized general circulation models, we identify when the QL approximation captures large-scale dynamics. We show that the QL dynamics fails to capture the flow when the dissipation of large-scale eddies occurs through strongly nonlinear eddy-eddy interactions in upper tropospheric surf zones, as it is often the case on Earth. But we demonstrate that the QL approximation captures eddy absorption when it arises from the shearing by the mean flow, for example when the eddy amplitude is small enough or the planetary rotation rate is large enough.
These results illustrate different classes of nonlinear processes that can control wave dissipation in the upper troposphere and show that in some parameter regimes the QL approximation is accurate to resolve large-scale dynamics.
Breaking waves on the surface of the heartbeat star MACHO 80.7443.1718Sérgio Sacani
Massive astrophysical compact halo object (MACHO) 80.7443.1718 is a high mass, eccentric binary system exhibiting the largest-known-amplitude tidally excited oscillations. The system’s ±20% photometric amplitude, along with the high mass of the primary star, ~35 M⊙, make this the most extreme of the class of periodically perturbed ‘heartbeat stars.’ Here, we use a hydrodynamic simulation to demonstrate that with each periapse passage, an unseen companion star raises tidal waves so large that they break, shock-heating and dissipating energy and angular momentum on the surface of the star. The shock-heated material forms a rapidly rotating circumstellar atmosphere, which is stripped and reassembled with each periapse passage. The dissipation of nonlinear tides through surface wave breaking explains the super-synchronous rotation of the primary star, the evolution of spectral emission features and the observed decay of the binary orbital period. Connecting these features demonstrates that MACHO 80.7443.1718 is a natural product of massive binary star evolution, and that it provides an ideal laboratory for the direct study of nonlinear tidal dissipation.
Mechanical wave descriptions for planets and asteroid fields: kinematic model...Premier Publishers
Models with wave dynamics and oscillations in the solar system are presented. A solitonial solution (Korteweg-de Vries), for a density field, is related to the formations of planets. A new nonlinear equation for a solitonial, will be derived, and denoted ‘J-T equation’. The linearized version has solutions, which are small vibrations with eigen frequency proportional to the parameters describing the solitonial wave, around a constant level, which is 2/3 of the maximum solitonial density. The location and orbital motion of Mercury and Venus are compared with wave dynamics. The tidal effect for Earth is analysed in terms of dynamics. Related phenomena for other planetary objects are discussed in conjunction with assuming a Roche limit.
The caustic that occur in geodesics in space-times which are solutions to the gravitational field equations with the energy-momentum tensor satisfying the dominant energy condition can be circumvented if quantum variations are allowed. An action is developed such that the variation yields the field equations
and the geodesic condition, and its quantization provides a method for determining the extent of the wave packet around the classical path.
The caustic that occur in geodesics in space-times which are solutions to the gravitational field equations
with the energy-momentum tensor satisfying the dominant energy condition can be circumvented if
quantum variations are allowed. An action is developed such that the variation yields the field equations
and the geodesic condition, and its quantization provides a method for determining the extent of the wave
packet around the classical path.
The caustic that occur in geodesics in space-times which are solutions to the gravitational field equations
with the energy-momentum tensor satisfying the dominant energy condition can be circumvented if
quantum variations are allowed. An action is developed such that the variation yields the field equations
and the geodesic condition, and its quantization provides a method for determining the extent of the wave
packet around the classical path.
The caustic that occur in geodesics in space-times which are solutions to the gravitational field equations with the energy-momentum tensor satisfying the dominant energy condition can be circumvented if quantum variations are allowed. An action is developed such that the variation yields the field equations and the geodesic condition, and its quantization provides a method for determining the extent of the wave packet around the classical path.
The caustic that occur in geodesics in space-times which are solutions to the gravitational field equations
with the energy-momentum tensor satisfying the dominant energy condition can be circumvented if
quantum variations are allowed. An action is developed such that the variation yields the field equations
and the geodesic condition, and its quantization provides a method for determining the extent of the wave
packet around the classical path.
The caustic that occur in geodesics in space-times which are solutions to the gravitational field equations with the energy-momentum tensor satisfying the dominant energy condition can be circumvented if quantum variations are allowed. An action is developed such that the variation yields the field equations
and the geodesic condition, and its quantization provides a method for determining the extent of the wave packet around the classical path.
The Illustration of Mechanism and development of Atmospheric dynamic peripher...iosrjce
This research papers illustrates and justify the soil shifting and a pre determinant mechanism of
testing and real time analysis of soil composition and the behavior by concentric waveform generation and the
field effect of the concentric waves thus formed. The waveforms generated are being analyzed using a field wire
enclosure structure having a non conducting cylinder with circular magnetic field effect induction. The
electrical pulses being generated are plotted against fluid viscosity behavior. The research paper illustrates
with conclusion and analysis that a correlation simulation model is possible with fluid properties to generate
non obvious prediction mechanism to possible pulse generator.
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
Earliest Galaxies in the JADES Origins Field: Luminosity Function and Cosmic ...Sérgio Sacani
We characterize the earliest galaxy population in the JADES Origins Field (JOF), the deepest
imaging field observed with JWST. We make use of the ancillary Hubble optical images (5 filters
spanning 0.4−0.9µm) and novel JWST images with 14 filters spanning 0.8−5µm, including 7 mediumband filters, and reaching total exposure times of up to 46 hours per filter. We combine all our data
at > 2.3µm to construct an ultradeep image, reaching as deep as ≈ 31.4 AB mag in the stack and
30.3-31.0 AB mag (5σ, r = 0.1” circular aperture) in individual filters. We measure photometric
redshifts and use robust selection criteria to identify a sample of eight galaxy candidates at redshifts
z = 11.5 − 15. These objects show compact half-light radii of R1/2 ∼ 50 − 200pc, stellar masses of
M⋆ ∼ 107−108M⊙, and star-formation rates of SFR ∼ 0.1−1 M⊙ yr−1
. Our search finds no candidates
at 15 < z < 20, placing upper limits at these redshifts. We develop a forward modeling approach to
infer the properties of the evolving luminosity function without binning in redshift or luminosity that
marginalizes over the photometric redshift uncertainty of our candidate galaxies and incorporates the
impact of non-detections. We find a z = 12 luminosity function in good agreement with prior results,
and that the luminosity function normalization and UV luminosity density decline by a factor of ∼ 2.5
from z = 12 to z = 14. We discuss the possible implications of our results in the context of theoretical
models for evolution of the dark matter halo mass function.
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
Multi-source connectivity as the driver of solar wind variability in the heli...Sérgio Sacani
The ambient solar wind that flls the heliosphere originates from multiple
sources in the solar corona and is highly structured. It is often described
as high-speed, relatively homogeneous, plasma streams from coronal
holes and slow-speed, highly variable, streams whose source regions are
under debate. A key goal of ESA/NASA’s Solar Orbiter mission is to identify
solar wind sources and understand what drives the complexity seen in the
heliosphere. By combining magnetic feld modelling and spectroscopic
techniques with high-resolution observations and measurements, we show
that the solar wind variability detected in situ by Solar Orbiter in March
2022 is driven by spatio-temporal changes in the magnetic connectivity to
multiple sources in the solar atmosphere. The magnetic feld footpoints
connected to the spacecraft moved from the boundaries of a coronal hole
to one active region (12961) and then across to another region (12957). This
is refected in the in situ measurements, which show the transition from fast
to highly Alfvénic then to slow solar wind that is disrupted by the arrival of
a coronal mass ejection. Our results describe solar wind variability at 0.5 au
but are applicable to near-Earth observatories.
Gliese 12 b: A Temperate Earth-sized Planet at 12 pc Ideal for Atmospheric Tr...Sérgio Sacani
Recent discoveries of Earth-sized planets transiting nearby M dwarfs have made it possible to characterize the
atmospheres of terrestrial planets via follow-up spectroscopic observations. However, the number of such planets
receiving low insolation is still small, limiting our ability to understand the diversity of the atmospheric
composition and climates of temperate terrestrial planets. We report the discovery of an Earth-sized planet
transiting the nearby (12 pc) inactive M3.0 dwarf Gliese 12 (TOI-6251) with an orbital period (Porb) of 12.76 days.
The planet, Gliese 12 b, was initially identified as a candidate with an ambiguous Porb from TESS data. We
confirmed the transit signal and Porb using ground-based photometry with MuSCAT2 and MuSCAT3, and
validated the planetary nature of the signal using high-resolution images from Gemini/NIRI and Keck/NIRC2 as
well as radial velocity (RV) measurements from the InfraRed Doppler instrument on the Subaru 8.2 m telescope
and from CARMENES on the CAHA 3.5 m telescope. X-ray observations with XMM-Newton showed the host
star is inactive, with an X-ray-to-bolometric luminosity ratio of log 5.7 L L X bol » - . Joint analysis of the light
curves and RV measurements revealed that Gliese 12 b has a radius of 0.96 ± 0.05 R⊕,a3σ mass upper limit of
3.9 M⊕, and an equilibrium temperature of 315 ± 6 K assuming zero albedo. The transmission spectroscopy metric
(TSM) value of Gliese 12 b is close to the TSM values of the TRAPPIST-1 planets, adding Gliese 12 b to the small
list of potentially terrestrial, temperate planets amenable to atmospheric characterization with JWST.
Gliese 12 b, a temperate Earth-sized planet at 12 parsecs discovered with TES...Sérgio Sacani
We report on the discovery of Gliese 12 b, the nearest transiting temperate, Earth-sized planet found to date. Gliese 12 is a
bright (V = 12.6 mag, K = 7.8 mag) metal-poor M4V star only 12.162 ± 0.005 pc away from the Solar system with one of the
lowest stellar activity levels known for M-dwarfs. A planet candidate was detected by TESS based on only 3 transits in sectors
42, 43, and 57, with an ambiguity in the orbital period due to observational gaps. We performed follow-up transit observations
with CHEOPS and ground-based photometry with MINERVA-Australis, SPECULOOS, and Purple Mountain Observatory,
as well as further TESS observations in sector 70. We statistically validate Gliese 12 b as a planet with an orbital period of
12.76144 ± 0.00006 d and a radius of 1.0 ± 0.1 R⊕, resulting in an equilibrium temperature of ∼315 K. Gliese 12 b has excellent
future prospects for precise mass measurement, which may inform how planetary internal structure is affected by the stellar
compositional environment. Gliese 12 b also represents one of the best targets to study whether Earth-like planets orbiting cool
stars can retain their atmospheres, a crucial step to advance our understanding of habitability on Earth and across the galaxy.
The importance of continents, oceans and plate tectonics for the evolution of...Sérgio Sacani
Within the uncertainties of involved astronomical and biological parameters, the Drake Equation
typically predicts that there should be many exoplanets in our galaxy hosting active, communicative
civilizations (ACCs). These optimistic calculations are however not supported by evidence, which is
often referred to as the Fermi Paradox. Here, we elaborate on this long-standing enigma by showing
the importance of planetary tectonic style for biological evolution. We summarize growing evidence
that a prolonged transition from Mesoproterozoic active single lid tectonics (1.6 to 1.0 Ga) to modern
plate tectonics occurred in the Neoproterozoic Era (1.0 to 0.541 Ga), which dramatically accelerated
emergence and evolution of complex species. We further suggest that both continents and oceans
are required for ACCs because early evolution of simple life must happen in water but late evolution
of advanced life capable of creating technology must happen on land. We resolve the Fermi Paradox
(1) by adding two additional terms to the Drake Equation: foc
(the fraction of habitable exoplanets
with significant continents and oceans) and fpt
(the fraction of habitable exoplanets with significant
continents and oceans that have had plate tectonics operating for at least 0.5 Ga); and (2) by
demonstrating that the product of foc
and fpt
is very small (< 0.00003–0.002). We propose that the lack
of evidence for ACCs reflects the scarcity of long-lived plate tectonics and/or continents and oceans on
exoplanets with primitive life.
A Giant Impact Origin for the First Subduction on EarthSérgio Sacani
Hadean zircons provide a potential record of Earth's earliest subduction 4.3 billion years ago. Itremains enigmatic how subduction could be initiated so soon after the presumably Moon‐forming giant impact(MGI). Earlier studies found an increase in Earth's core‐mantle boundary (CMB) temperature due to theaccumulation of the impactor's core, and our recent work shows Earth's lower mantle remains largely solid, withsome of the impactor's mantle potentially surviving as the large low‐shear velocity provinces (LLSVPs). Here,we show that a hot post‐impact CMB drives the initiation of strong mantle plumes that can induce subductioninitiation ∼200 Myr after the MGI. 2D and 3D thermomechanical computations show that a high CMBtemperature is the primary factor triggering early subduction, with enrichment of heat‐producing elements inLLSVPs as another potential factor. The models link the earliest subduction to the MGI with implications forunderstanding the diverse tectonic regimes of rocky planets.
Climate extremes likely to drive land mammal extinction during next supercont...Sérgio Sacani
Mammals have dominated Earth for approximately 55 Myr thanks to their
adaptations and resilience to warming and cooling during the Cenozoic. All
life will eventually perish in a runaway greenhouse once absorbed solar
radiation exceeds the emission of thermal radiation in several billions of
years. However, conditions rendering the Earth naturally inhospitable to
mammals may develop sooner because of long-term processes linked to
plate tectonics (short-term perturbations are not considered here). In
~250 Myr, all continents will converge to form Earth’s next supercontinent,
Pangea Ultima. A natural consequence of the creation and decay of Pangea
Ultima will be extremes in pCO2 due to changes in volcanic rifting and
outgassing. Here we show that increased pCO2, solar energy (F⨀;
approximately +2.5% W m−2 greater than today) and continentality (larger
range in temperatures away from the ocean) lead to increasing warming
hostile to mammalian life. We assess their impact on mammalian
physiological limits (dry bulb, wet bulb and Humidex heat stress indicators)
as well as a planetary habitability index. Given mammals’ continued survival,
predicted background pCO2 levels of 410–816 ppm combined with increased
F⨀ will probably lead to a climate tipping point and their mass extinction.
The results also highlight how global landmass configuration, pCO2 and F⨀
play a critical role in planetary habitability.
Constraints on Neutrino Natal Kicks from Black-Hole Binary VFTS 243Sérgio Sacani
The recently reported observation of VFTS 243 is the first example of a massive black-hole binary
system with negligible binary interaction following black-hole formation. The black-hole mass (≈10M⊙)
and near-circular orbit (e ≈ 0.02) of VFTS 243 suggest that the progenitor star experienced complete
collapse, with energy-momentum being lost predominantly through neutrinos. VFTS 243 enables us to
constrain the natal kick and neutrino-emission asymmetry during black-hole formation. At 68% confidence
level, the natal kick velocity (mass decrement) is ≲10 km=s (≲1.0M⊙), with a full probability distribution
that peaks when ≈0.3M⊙ were ejected, presumably in neutrinos, and the black hole experienced a natal
kick of 4 km=s. The neutrino-emission asymmetry is ≲4%, with best fit values of ∼0–0.2%. Such a small
neutrino natal kick accompanying black-hole formation is in agreement with theoretical predictions.
Detectability of Solar Panels as a TechnosignatureSérgio Sacani
In this work, we assess the potential detectability of solar panels made of silicon on an Earth-like
exoplanet as a potential technosignature. Silicon-based photovoltaic cells have high reflectance in the
UV-VIS and in the near-IR, within the wavelength range of a space-based flagship mission concept
like the Habitable Worlds Observatory (HWO). Assuming that only solar energy is used to provide
the 2022 human energy needs with a land cover of ∼ 2.4%, and projecting the future energy demand
assuming various growth-rate scenarios, we assess the detectability with an 8 m HWO-like telescope.
Assuming the most favorable viewing orientation, and focusing on the strong absorption edge in the
ultraviolet-to-visible (0.34 − 0.52 µm), we find that several 100s of hours of observation time is needed
to reach a SNR of 5 for an Earth-like planet around a Sun-like star at 10pc, even with a solar panel
coverage of ∼ 23% land coverage of a future Earth. We discuss the necessity of concepts like Kardeshev
Type I/II civilizations and Dyson spheres, which would aim to harness vast amounts of energy. Even
with much larger populations than today, the total energy use of human civilization would be orders of
magnitude below the threshold for causing direct thermal heating or reaching the scale of a Kardashev
Type I civilization. Any extraterrrestrial civilization that likewise achieves sustainable population
levels may also find a limit on its need to expand, which suggests that a galaxy-spanning civilization
as imagined in the Fermi paradox may not exist.
Jet reorientation in central galaxies of clusters and groups: insights from V...Sérgio Sacani
Recent observations of galaxy clusters and groups with misalignments between their central AGN jets
and X-ray cavities, or with multiple misaligned cavities, have raised concerns about the jet – bubble
connection in cooling cores, and the processes responsible for jet realignment. To investigate the
frequency and causes of such misalignments, we construct a sample of 16 cool core galaxy clusters and
groups. Using VLBA radio data we measure the parsec-scale position angle of the jets, and compare
it with the position angle of the X-ray cavities detected in Chandra data. Using the overall sample
and selected subsets, we consistently find that there is a 30% – 38% chance to find a misalignment
larger than ∆Ψ = 45◦ when observing a cluster/group with a detected jet and at least one cavity. We
determine that projection may account for an apparently large ∆Ψ only in a fraction of objects (∼35%),
and given that gas dynamical disturbances (as sloshing) are found in both aligned and misaligned
systems, we exclude environmental perturbation as the main driver of cavity – jet misalignment.
Moreover, we find that large misalignments (up to ∼ 90◦
) are favored over smaller ones (45◦ ≤ ∆Ψ ≤
70◦
), and that the change in jet direction can occur on timescales between one and a few tens of Myr.
We conclude that misalignments are more likely related to actual reorientation of the jet axis, and we
discuss several engine-based mechanisms that may cause these dramatic changes.
The solar dynamo begins near the surfaceSérgio Sacani
The magnetic dynamo cycle of the Sun features a distinct pattern: a propagating
region of sunspot emergence appears around 30° latitude and vanishes near the
equator every 11 years (ref. 1). Moreover, longitudinal flows called torsional oscillations
closely shadow sunspot migration, undoubtedly sharing a common cause2. Contrary
to theories suggesting deep origins of these phenomena, helioseismology pinpoints
low-latitude torsional oscillations to the outer 5–10% of the Sun, the near-surface
shear layer3,4. Within this zone, inwardly increasing differential rotation coupled with
a poloidal magnetic field strongly implicates the magneto-rotational instability5,6,
prominent in accretion-disk theory and observed in laboratory experiments7.
Together, these two facts prompt the general question: whether the solar dynamo is
possibly a near-surface instability. Here we report strong affirmative evidence in stark
contrast to traditional models8 focusing on the deeper tachocline. Simple analytic
estimates show that the near-surface magneto-rotational instability better explains
the spatiotemporal scales of the torsional oscillations and inferred subsurface
magnetic field amplitudes9. State-of-the-art numerical simulations corroborate these
estimates and reproduce hemispherical magnetic current helicity laws10. The dynamo
resulting from a well-understood near-surface phenomenon improves prospects
for accurate predictions of full magnetic cycles and space weather, affecting the
electromagnetic infrastructure of Earth.
Extensive Pollution of Uranus and Neptune’s Atmospheres by Upsweep of Icy Mat...Sérgio Sacani
In the Nice model of solar system formation, Uranus and Neptune undergo an orbital upheaval,
sweeping through a planetesimal disk. The region of the disk from which material is accreted by
the ice giants during this phase of their evolution has not previously been identified. We perform
direct N-body orbital simulations of the four giant planets to determine the amount and origin of solid
accretion during this orbital upheaval. We find that the ice giants undergo an extreme bombardment
event, with collision rates as much as ∼3 per hour assuming km-sized planetesimals, increasing the
total planet mass by up to ∼0.35%. In all cases, the initially outermost ice giant experiences the
largest total enhancement. We determine that for some plausible planetesimal properties, the resulting
atmospheric enrichment could potentially produce sufficient latent heat to alter the planetary cooling
timescale according to existing models. Our findings suggest that substantial accretion during this
phase of planetary evolution may have been sufficient to impact the atmospheric composition and
thermal evolution of the ice giants, motivating future work on the fate of deposited solid material.
Exomoons & Exorings with the Habitable Worlds Observatory I: On the Detection...Sérgio Sacani
The highest priority recommendation of the Astro2020 Decadal Survey for space-based astronomy
was the construction of an observatory capable of characterizing habitable worlds. In this paper series
we explore the detectability of and interference from exomoons and exorings serendipitously observed
with the proposed Habitable Worlds Observatory (HWO) as it seeks to characterize exoplanets, starting
in this manuscript with Earth-Moon analog mutual events. Unlike transits, which only occur in systems
viewed near edge-on, shadow (i.e., solar eclipse) and lunar eclipse mutual events occur in almost every
star-planet-moon system. The cadence of these events can vary widely from ∼yearly to multiple events
per day, as was the case in our younger Earth-Moon system. Leveraging previous space-based (EPOXI)
lightcurves of a Moon transit and performance predictions from the LUVOIR-B concept, we derive
the detectability of Moon analogs with HWO. We determine that Earth-Moon analogs are detectable
with observation of ∼2-20 mutual events for systems within 10 pc, and larger moons should remain
detectable out to 20 pc. We explore the extent to which exomoon mutual events can mimic planet
features and weather. We find that HWO wavelength coverage in the near-IR, specifically in the 1.4 µm
water band where large moons can outshine their host planet, will aid in differentiating exomoon signals
from exoplanet variability. Finally, we predict that exomoons formed through collision processes akin
to our Moon are more likely to be detected in younger systems, where shorter orbital periods and
favorable geometry enhance the probability and frequency of mutual events.
Emergent ribozyme behaviors in oxychlorine brines indicate a unique niche for...Sérgio Sacani
Mars is a particularly attractive candidate among known astronomical objects
to potentially host life. Results from space exploration missions have provided
insights into Martian geochemistry that indicate oxychlorine species, particularly perchlorate, are ubiquitous features of the Martian geochemical landscape. Perchlorate presents potential obstacles for known forms of life due to
its toxicity. However, it can also provide potential benefits, such as producing
brines by deliquescence, like those thought to exist on present-day Mars. Here
we show perchlorate brines support folding and catalysis of functional RNAs,
while inactivating representative protein enzymes. Additionally, we show
perchlorate and other oxychlorine species enable ribozyme functions,
including homeostasis-like regulatory behavior and ribozyme-catalyzed
chlorination of organic molecules. We suggest nucleic acids are uniquely wellsuited to hypersaline Martian environments. Furthermore, Martian near- or
subsurface oxychlorine brines, and brines found in potential lifeforms, could
provide a unique niche for biomolecular evolution.
Continuum emission from within the plunging region of black hole discsSérgio Sacani
The thermal continuum emission observed from accreting black holes across X-ray bands has the potential to be leveraged as a
powerful probe of the mass and spin of the central black hole. The vast majority of existing ‘continuum fitting’ models neglect
emission sourced at and within the innermost stable circular orbit (ISCO) of the black hole. Numerical simulations, however,
find non-zero emission sourced from these regions. In this work, we extend existing techniques by including the emission
sourced from within the plunging region, utilizing new analytical models that reproduce the properties of numerical accretion
simulations. We show that in general the neglected intra-ISCO emission produces a hot-and-small quasi-blackbody component,
but can also produce a weak power-law tail for more extreme parameter regions. A similar hot-and-small blackbody component
has been added in by hand in an ad hoc manner to previous analyses of X-ray binary spectra. We show that the X-ray spectrum
of MAXI J1820+070 in a soft-state outburst is extremely well described by a full Kerr black hole disc, while conventional
models that neglect intra-ISCO emission are unable to reproduce the data. We believe this represents the first robust detection of
intra-ISCO emission in the literature, and allows additional constraints to be placed on the MAXI J1820 + 070 black hole spin
which must be low a• < 0.5 to allow a detectable intra-ISCO region. Emission from within the ISCO is the dominant emission
component in the MAXI J1820 + 070 spectrum between 6 and 10 keV, highlighting the necessity of including this region. Our
continuum fitting model is made publicly available.
WASP-69b’s Escaping Envelope Is Confined to a Tail Extending at Least 7 RpSérgio Sacani
Studying the escaping atmospheres of highly irradiated exoplanets is critical for understanding the physical
mechanisms that shape the demographics of close-in planets. A number of planetary outflows have been observed
as excess H/He absorption during/after transit. Such an outflow has been observed for WASP-69b by multiple
groups that disagree on the geometry and velocity structure of the outflow. Here, we report the detection of this
planet’s outflow using Keck/NIRSPEC for the first time. We observed the outflow 1.28 hr after egress until the
target set, demonstrating the outflow extends at least 5.8 × 105 km or 7.5 Rp This detection is significantly longer
than previous observations, which report an outflow extending ∼2.2 planet radii just 1 yr prior. The outflow is
blueshifted by −23 km s−1 in the planetary rest frame. We estimate a current mass-loss rate of 1 M⊕ Gyr−1
. Our
observations are most consistent with an outflow that is strongly sculpted by ram pressure from the stellar wind.
However, potential variability in the outflow could be due to time-varying interactions with the stellar wind or
differences in instrumental precision.
X-rays from a Central “Exhaust Vent” of the Galactic Center ChimneySérgio Sacani
Using deep archival observations from the Chandra X-ray Observatory, we present an analysis of
linear X-ray-emitting features located within the southern portion of the Galactic center chimney,
and oriented orthogonal to the Galactic plane, centered at coordinates l = 0.08◦
, b = −1.42◦
. The
surface brightness and hardness ratio patterns are suggestive of a cylindrical morphology which may
have been produced by a plasma outflow channel extending from the Galactic center. Our fits of the
feature’s spectra favor a complex two-component model consisting of thermal and recombining plasma
components, possibly a sign of shock compression or heating of the interstellar medium by outflowing
material. Assuming a recombining plasma scenario, we further estimate the cooling timescale of this
plasma to be on the order of a few hundred to thousands of years, leading us to speculate that a
sequence of accretion events onto the Galactic Black Hole may be a plausible quasi-continuous energy
source to sustain the observed morphology
Slide 1: Title Slide
Extrachromosomal Inheritance
Slide 2: Introduction to Extrachromosomal Inheritance
Definition: Extrachromosomal inheritance refers to the transmission of genetic material that is not found within the nucleus.
Key Components: Involves genes located in mitochondria, chloroplasts, and plasmids.
Slide 3: Mitochondrial Inheritance
Mitochondria: Organelles responsible for energy production.
Mitochondrial DNA (mtDNA): Circular DNA molecule found in mitochondria.
Inheritance Pattern: Maternally inherited, meaning it is passed from mothers to all their offspring.
Diseases: Examples include Leber’s hereditary optic neuropathy (LHON) and mitochondrial myopathy.
Slide 4: Chloroplast Inheritance
Chloroplasts: Organelles responsible for photosynthesis in plants.
Chloroplast DNA (cpDNA): Circular DNA molecule found in chloroplasts.
Inheritance Pattern: Often maternally inherited in most plants, but can vary in some species.
Examples: Variegation in plants, where leaf color patterns are determined by chloroplast DNA.
Slide 5: Plasmid Inheritance
Plasmids: Small, circular DNA molecules found in bacteria and some eukaryotes.
Features: Can carry antibiotic resistance genes and can be transferred between cells through processes like conjugation.
Significance: Important in biotechnology for gene cloning and genetic engineering.
Slide 6: Mechanisms of Extrachromosomal Inheritance
Non-Mendelian Patterns: Do not follow Mendel’s laws of inheritance.
Cytoplasmic Segregation: During cell division, organelles like mitochondria and chloroplasts are randomly distributed to daughter cells.
Heteroplasmy: Presence of more than one type of organellar genome within a cell, leading to variation in expression.
Slide 7: Examples of Extrachromosomal Inheritance
Four O’clock Plant (Mirabilis jalapa): Shows variegated leaves due to different cpDNA in leaf cells.
Petite Mutants in Yeast: Result from mutations in mitochondrial DNA affecting respiration.
Slide 8: Importance of Extrachromosomal Inheritance
Evolution: Provides insight into the evolution of eukaryotic cells.
Medicine: Understanding mitochondrial inheritance helps in diagnosing and treating mitochondrial diseases.
Agriculture: Chloroplast inheritance can be used in plant breeding and genetic modification.
Slide 9: Recent Research and Advances
Gene Editing: Techniques like CRISPR-Cas9 are being used to edit mitochondrial and chloroplast DNA.
Therapies: Development of mitochondrial replacement therapy (MRT) for preventing mitochondrial diseases.
Slide 10: Conclusion
Summary: Extrachromosomal inheritance involves the transmission of genetic material outside the nucleus and plays a crucial role in genetics, medicine, and biotechnology.
Future Directions: Continued research and technological advancements hold promise for new treatments and applications.
Slide 11: Questions and Discussion
Invite Audience: Open the floor for any questions or further discussion on the topic.
(May 29th, 2024) Advancements in Intravital Microscopy- Insights for Preclini...Scintica Instrumentation
Intravital microscopy (IVM) is a powerful tool utilized to study cellular behavior over time and space in vivo. Much of our understanding of cell biology has been accomplished using various in vitro and ex vivo methods; however, these studies do not necessarily reflect the natural dynamics of biological processes. Unlike traditional cell culture or fixed tissue imaging, IVM allows for the ultra-fast high-resolution imaging of cellular processes over time and space and were studied in its natural environment. Real-time visualization of biological processes in the context of an intact organism helps maintain physiological relevance and provide insights into the progression of disease, response to treatments or developmental processes.
In this webinar we give an overview of advanced applications of the IVM system in preclinical research. IVIM technology is a provider of all-in-one intravital microscopy systems and solutions optimized for in vivo imaging of live animal models at sub-micron resolution. The system’s unique features and user-friendly software enables researchers to probe fast dynamic biological processes such as immune cell tracking, cell-cell interaction as well as vascularization and tumor metastasis with exceptional detail. This webinar will also give an overview of IVM being utilized in drug development, offering a view into the intricate interaction between drugs/nanoparticles and tissues in vivo and allows for the evaluation of therapeutic intervention in a variety of tissues and organs. This interdisciplinary collaboration continues to drive the advancements of novel therapeutic strategies.
Professional air quality monitoring systems provide immediate, on-site data for analysis, compliance, and decision-making.
Monitor common gases, weather parameters, particulates.
Cancer cell metabolism: special Reference to Lactate PathwayAADYARAJPANDEY1
Normal Cell Metabolism:
Cellular respiration describes the series of steps that cells use to break down sugar and other chemicals to get the energy we need to function.
Energy is stored in the bonds of glucose and when glucose is broken down, much of that energy is released.
Cell utilize energy in the form of ATP.
The first step of respiration is called glycolysis. In a series of steps, glycolysis breaks glucose into two smaller molecules - a chemical called pyruvate. A small amount of ATP is formed during this process.
Most healthy cells continue the breakdown in a second process, called the Kreb's cycle. The Kreb's cycle allows cells to “burn” the pyruvates made in glycolysis to get more ATP.
The last step in the breakdown of glucose is called oxidative phosphorylation (Ox-Phos).
It takes place in specialized cell structures called mitochondria. This process produces a large amount of ATP. Importantly, cells need oxygen to complete oxidative phosphorylation.
If a cell completes only glycolysis, only 2 molecules of ATP are made per glucose. However, if the cell completes the entire respiration process (glycolysis - Kreb's - oxidative phosphorylation), about 36 molecules of ATP are created, giving it much more energy to use.
IN CANCER CELL:
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
introduction to WARBERG PHENOMENA:
WARBURG EFFECT Usually, cancer cells are highly glycolytic (glucose addiction) and take up more glucose than do normal cells from outside.
Otto Heinrich Warburg (; 8 October 1883 – 1 August 1970) In 1931 was awarded the Nobel Prize in Physiology for his "discovery of the nature and mode of action of the respiratory enzyme.
WARNBURG EFFECT : cancer cells under aerobic (well-oxygenated) conditions to metabolize glucose to lactate (aerobic glycolysis) is known as the Warburg effect. Warburg made the observation that tumor slices consume glucose and secrete lactate at a higher rate than normal tissues.
Richard's aventures in two entangled wonderlandsRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
Unveiling the Energy Potential of Marshmallow Deposits.pdf
Earth-like lithospheric thickness and heat flow on Venus consistent with active rifting
1. Nature Geoscience
naturegeoscience
https://doi.org/10.1038/s41561-022-01068-0
Article
Earth-likelithosphericthicknessandheat
flowonVenusconsistentwithactiverifting
Suzanne E. Smrekar 1
, Colby Ostberg2
& Joseph G. O’Rourke 3
VenusisEarth’stwininsizeandradiogenicheatbudget,yetitremains
unclearhowVenuslosesitsheatabsentplatetectonics.MostVenusian
stagnant-lidmodelspredictathicklithospherewithheatflowabouthalf
thatofEarth’smobile-lidregime.Hereweestimateelasticlithospheric
thicknessat75locationsonVenususingtopographicflexureat65coronae—
quasi-circularvolcano-tectonicfeatures—determinedfromMagellan
altimetrydata.Wefindanaveragethicknessatcoronaeof11 ± 7 km.This
impliesanaverageheatflowof101 ± 88 mW m−2
,higherthanEarth’s
averagebutsimilartoterrestrialvaluesinactivelyextendingareas.For
somelocations,suchasthePargaChasmariftzone,weestimateheatflow
exceeding75 mW m−2
.Combinedwithalow-resolutionmapofglobalelastic
thickness,thissuggeststhatcoronaetypicallyformonthinlithosphere,
insteadoflocallythinningthelithosphereviaplumeheating,andthatmost
regionsoflowelasticthicknessarebestexplainedbyhighheatflowrather
thancrustalcompensation.Ouranalysisidentifieslikelyareasofactive
extensionandsuggeststhatVenushasEarth-likelithosphericthickness
andglobalheatflowranges.Togetherwiththeplanet’sgeologichistory,
ourfindingssupportasquishy-lidconvectiveregimethatreliesonplumes,
intrusivemagmatismanddelaminationtoincreaseheatflow.
Venusisageodynamicpuzzle.Theimpact-craterpopulationyieldsan
average surface age of ~150–1,000 Myr1,2
. Despite this young surface
age, there is no evidence of an Earth-like global, interconnected net-
workofplateswithanassociatedvariationinage3
.Thespatialdistribu-
tion of ~1,000 impacts cannot be distinguished from a random one,
andfewcratersareunambiguouslymodifiedbylatergeologicactivity.
Two models with very different implications for interior dynamics
and present-day geologic activity can reproduce these observa-
tions: (1) ‘catastrophic’ resurfacing, in which all craters are removed
rapidly, followed by little geologic activity (for example, ref. 4
),
and (2) regional resurfacing, with geologic processes operating on
a scale of 100 s to ~1,000 km to remove craters at regionally variable
rates5
. Recent models6,7
, analysis supporting interpretation of ~80%
ofcratersasvolcanicallyflooded2
anddataanalysissuggestingrecent
volcanic activity2,8–10
all support regional resurfacing and ongoing
geologic activity.
Catastrophic resurfacing, and the implied lack of geologic activ-
ity,longdominatedthinkingaboutVenus.Thishypothesismotivates
episodic-lidconvectivemodels,inwhichVenushasathickstagnantlid
at present but cycled between stagnant and mobile lids in the past to
permitenhancedheatflow11–13
.Earth’smobile-lidplatetectonicsystem
efficiently loses heat via the formation of new lithosphere at spread-
ing ridges and subduction of relatively cold lithosphere back into the
interior. Venus has evidence of roll-back subduction, in which a plate
locallysinksintothemantlewithoutlateralplatemotionandhugerift
systems.MostepisodicmodelspredictthatVenus’sstagnantlidallows
at most 50% of Earth’s heat loss at present11–14
. Some models predict
a ‘sluggish’ lid with limited surface motion15,16
or a ‘squishy lid’ with
abundant intrusive magmatism17
yielding higher, roughly Earth-like
heatflowtoday.
Modelling topographic bending due to lithospheric loading and
flexureprovidesanopportunitytoestimatetheelasticthickness(Te),
Received: 17 March 2022
Accepted: 3 October 2022
Published online: xx xx xxxx
Check for updates
1
Jet Propulsion Laboratory/California Institute of Technology, Pasadena, CA, USA. 2
Department of Earth and Planetary Sciences, University of California,
Riverside, CA, USA. 3
School of Earth and Space Exploration, Arizona State University, Tempe, AZ, USA. e-mail: ssmrekar@jpl.nasa.gov
2. Nature Geoscience
Article https://doi.org/10.1038/s41561-022-01068-0
Proposed models include small-scale plume upwelling19,20
, lith-
ospheric dripping followed by isostatic rebound21–23
, a combination
of upwelling leading to lithospheric dripping24,25
, plume-induced
roll-back subduction26
and plume-induced crustal convection25
.
Some coronae appear transitional with volcanoes, motivating vol-
canic construction models27–29
.
We also estimate Venus’s global heat loss by comparing local Te
estimates from this and previous studies with a near-global Te map30
derived from modelling admittance, the transfer function of gravity
and topography in the spectral domain. The comparison between
local and regional Te from admittance provides an independent
means of accessing the accuracy of Te from admittance, as well as a
test of whether lithospheric flexure is the dominant compensation
process.
which generally corresponds to the region where faulting occurs.
These models also return estimates of the mechanical thickness (Tm),
which includes both elastic and viscous behaviour. Adding a rheo-
logical model for the lithosphere allows for a conversion from Tm and
the observed curvature to the surface heat flow (Fs) and the thermal
lithospheric thickness (Tl, the portion of the lithosphere that does
notconvect),whicharekeytogeodynamicmodelsasmeasuresofthe
planetaryheatbudget.
Most topographic flexure signatures on Venus are found at
coronae. Coronae are quasi-circular, volcano-tectonic features
defined by an annulus of fractures (Fig. 1). A majority of Venus’s
~500 coronae (mean diameter ~260 km) are concentrated along rifts
and fracture zones18
. They may form via multiple mechanisms and
offer clues as to Venus’s unique lithosphere–mantle interactions.
152° E
150° E
1
2
3
4
5
148° E
146° E
2°
S
4°
S
6°
S
400
Normalized
elevation
(m)
200
0
400
200
0
400
200
0
400
200
0
400 1
2
3
4
5
0 100 200 300 400
Stereo topography
Best fit (MCMC)
0 100 200 300 400
0 100 200 300 400
0 100 200
Distance (km)
300 400
0 100 200 300 400
200
0
1°
40’
S
Latitude
Longitude Longitude
Latitude
2°
30’
S
145° 50’ E
145° E
a b
c
146° 40’ E
Fig.1|HepatCoronaexhibitsdoublefractureannulaeandatopographic
rimthatiswellfitbyanelasticflexuremodel. a,Magellanradarimagingshows
thatsomefractureshavethesteep,pairedwallsofextensionalgraben.b,Profiles
aretakenfromMagellantopography,whichshowsanelevationdifferenceof
roughly500 mbetweenthetrough(yellowring)andtheinteriorofthecorona.
ThenumberedblacklinesillustratetopographicalprofilelocationsforHepat
East;thelowerlinesetindicatesthelocationsofHepatSoutheastprofiles
(SupplementaryTable1).c,Topographicprofilescorrespondwiththenumbered
linesinb,alongwiththebest-fitflexuralbendingmodelsshownindashedlines.
MCMC,MarkovchainMonteCarlo.
3. Nature Geoscience
Article https://doi.org/10.1038/s41561-022-01068-0
Estimatesofelasticlithosphericthickness
We examine the topography of ~200 of the largest coronae for signs
of flexure of the elastic lithosphere on scales of several hundred kilo-
metres (Fig. 1). We find a good fit for an elastic plate bending model
(Methods) at 65 coronae, yielding 75 Te estimates (Supplementary
Table 1). We also include 14 previously published Te values (Supple-
mentary Table 2)31–34
for a total of 89 corona Te values. All but six are
<20 km,consistentwithref.32
.Weusestandardmethodsandreason-
able rheological assumptions to derive the Tm, which includes both
the brittle and ductile strength of the lithosphere. We also estimate
theTl andFs (MethodsandExtendedDataFig.1).WelistderivedTe,Fs,
Tm and Tl, along with data for flexural fits, in Supplementary Table 1.
Given that important parameters such as strain rate and yield stress
must be assumed for Venus, we conduct a sensitivity analysis of
various parameters (Methods and Extended Data Fig. 2).
WecompareTe valuesfromcoronaeplussevenfromriftflankloca-
tions(SupplementaryTable3)withglobalanalysesofgravityandtopog-
raphy data. Admittance analysis for Venus requires averaging over an
area >2,000 km in diameter, thus providing a regional estimate of Te.
Ourcomparisonbetweenanear-globalTe mapfromadmittance30
and
localcoronaevaluesshowsthat45,28,7,and9oftheTe estimatesarein
the‘good,’‘reasonable,’‘none’or‘unconstrained’agreementcategories
(MethodsandExtendedDataFig.3),respectively(Fig.2andSupplemen-
tary Table 1). Te values from steep-sided domes, which have a larger Te
onaveragethancoronae,showasimilarlygoodagreementwithglobal
Te estimates35
. Flexure around one steep-sided dome, Narina Tholus,
thatformedatopthefractureannulusofAramaitiCoronarevealslowTe
(<10 km,comparedwith~14 kmforAramaitiinSupplementaryTable1).
Ref. 36
attributes this to local lithospheric fractures and thinning36
.
Evidenceforelevatedheatflowatcertainlocalareasisconsistentwith
overallEarth-likeheatflowonVenus.Thegeneralagreementbetween
theregionalandlocalTe valuesholdsoverarangeofgeologicfeatures,
methodologiesandTe values,forexample,aridgebelt37
andanimpact
simulationatMeadBasin38
whereTe is>60 km.Thisgeneralagreement
suggestsanaccuracyof±10 kmforTe estimatesfromadmittance,atleast
forvalues<60 km,ratherthanthe±15 kmadoptedbyref.30
.
WealsocompareourTl estimates,whichwedefneasthedepthto
atemperatureof1,013 K(Methods),withglobalgeoid-to-topography
ratios(GTRs)andassociatedapparentdepthsofcompensation,calcu-
latedoveraregion1,200 kmindiameter39
.Amajorityofthecoronaein
thisstudyhaveGTRvalues<10 m km–1
,indicatingdynamiccompensa-
tionatdepthsof<100 km.
OurTe andFs valuesandtheircorrelationswithglobaladmittance
andGTRresultsrequireare-evaluationoftheinterpretationofglobal
Te and global geodynamics and how coronae interact with the litho-
sphere. In particular, the geodynamic paradigm of a stagnant lid with
agloballythicklithospherethathasinfusedthinkingaboutVenusfor
decadesmustbereconsidered.
Thinlithosphereonpresent-dayVenus
The first step in interpreting Te is to assess whether it represents
present-day lithospheric thickness or a ‘fossil’ value. Mars exhibits
‘fossil’orpreservedflexuralsignaturesoflowTe fromterrainsdatingto
itsfirstseveralbillionyears40
.Venus’syoungsurfacehastoofewimpact
craters to allow dating of local areas, which precludes assessing Te as
a function of surface age3
. Modelling of stress relaxation shows that a
flexuralsignaturecanbepreservedifthelithospherethickenswithtime
undersomeconditions41,42
.Earth’soceanicplatespredictablythicken
withtimeandthusrepresentagoodlocationtoinvestigatethisprocess.
OceanicTe generallycorrelateswithpredictedplatecoolingvalues,but
withconsiderablescatter43
.Ref.41
examinedtherelaxationofa40 Myr
old oceanic plate (Tl ~80 km) but noted that thinner lithosphere will
resistfreezinginTe duetorapidstressrelaxation.Stressrelaxationand
high strain rate are also likely in a volcanic environment44
, relevant to
coronae.GivenVenus’syoungsurfaceage,thechallengeofpreserving
low Te values and volcanism at coronae, most coronae Te values prob-
ably represent current conditions.
In contrast to Te, which reflects the mechanically strong surface
layer, the geoid is more sensitive to deeper forces and density con-
trasts that typically reflect a combination of dynamic processes and
the Tl. For example, larger geoid values clearly reflect regions of thin
terrestrial ocean lithosphere over much of the seafloor45
. Thus, the
180° W 150° W 120° W 90° W 60° W 30° W
Longitude
0°
0°
30° S
Latitude
30° N
60° N
90° N
60° S
90° S
0°
30° S
30° N
60° N
90° N
60° S
90° S
30° E 60° E 90° E 120° E 150° E 180° E
180° W 150° W 120° W 90° W 60° W 30° W 0° 30° E 60° E 90° E 120° E 150° E 180° E
Good
Reasonable
None
Unconstrained
Agreement:
> 75
≤ 75
> 75
≤ 75
Coronae:
Rifts:
Heat flow (mW m–2):
Fig.2|Localandregionalheatflowvaluesmostlyagreeandshow
concentrationsofhighheatflowinsomeareas.Heatflowestimatesgreater
thantheaveragevalueof75 mW m−2
(+symbols)occuraroundtheglobe,witha
majorconcentrationinPargaChasma(latitude20–35° S,longitude75–130° E).
SquaresindicateTe values≤ 75 mW m−2
.Symbolcolourindicatesagreement,with
mostlocationsingood(blue)orreasonable(yellow)agreementwiththeregional
valuesfromgravityandtopography.Riftlocations46
areshowninnavyblue.In
additiontocoronae,weshowsevenTe estimatesfromriftflankflexureascircles
forthosewithTe > 75 mW m−2
oratriangleforonewithTe ≤ 75 mW m−2
.
4. Nature Geoscience
Article https://doi.org/10.1038/s41561-022-01068-0
geoidisanadditionaltooltoidentifyregionswithcurrentlythinlitho-
sphere. A majority of coronae with thin Te also have low GTRs, with
exceptions probably due to factors such as low gravity field resolu-
tion, fossil Te, incorrect Te estimates due to non-flexural influence on
topography or major variations in crustal thickness. Parga Chasma is
oneexampleofthinTe,highheatflowandlowGTRandthusrepresents
alikelyactiveregion.Further,thecorrelationwithgeoidgradientand
the stress field orientation derived for a ‘swell-push’ model supports
present-day stresses and deformation at Parga Chasma and some
otherlargerifts46,47
.
The high Fs estimates at some coronae, and in particular at Parga
Chasma and some smaller fracture zones (Fig. 2), are comparable to
valuesfoundatactivelyspreadingregionsonEarth(Fig.3).Typicalter-
restrialoceanicheatflowisintherangeof~50–100 mW m−2
,butvalues
>250 mW m−2
areobservednearspreadingridges48
.Similarly,continen-
tal heat flow is much larger at active environments, up to 125 mW m−2
or higher49
. This evidence for high Fs, similar to values found at active
areasonEarth,providesevidenceforsimilarlyactiveareasonVenus.
Morphologyisanotherpossibleindicatorofcoronaactivity.Ref.25
modelled corona formation using hot, shallow plumes and very thin
lithosphere. They argued for present-day activity at coronae with
elevated interiors and inactivity at those with interior depressions,
sincemanymodelsofcoronaformationaboveupwellingplumespre-
dictaprogressionfromdomestodepressions20,25,50
.Ref.25
mappedthe
locationsofapartiallistofcoronaewithelevatedordepressedinteriors
to suggest active regions. Our locations of low Te, high Fs agree with
theirproposedactiveareasatsomeregions,suchasatPargaChasma,
and disagree in other areas. Corona formation via downwelling23,51
givesadifferenttopographicsequenceandcouldaccountforsomeof
thesedifferences.
Implicationsforcoronaformation
Corona formation models are sensitive to Tl. We find Tl to be
70.0 ± 47.3 km, with a range of 7–284 km (Fig. 3 and Methods). Most
modelsthatpredicttheformationofcoronaewithtypicaldiameters,
including upwelling and downwelling, require Tl to be in the range of
50–100 km20,23,25,50,51
.Thus,modelsofbothupwellinganddownwelling
are consistent with our results.
Many of the largest coronae are proposed to be sites of roll-back
subduction (Fig. 3). The initiation of subduction triggered by a large
mantle plume first uplifts and breaks the lithosphere. Volcanic load-
ing of the lithosphere leads it to sink26
, providing an excellent fit
to many of the observed characteristics of large coronae, such as a
trench surrounding a portion of the corona. A thick thermal litho-
sphere (>100 km) is needed to facilitate sinking and roll-back of the
lithosphere,consistentwiththegenerallylargerTe andTl atproposed
subductionsites(Fig.3).QuetzelpetlatlCoronaeisanunusualcasein
thatoursmallTe estimate(3.2 km)isconsiderablylessthanthe24.5 km
found by ref. 31
and the regional value derived from admittance. Vol-
canicfloodingofthetrenchatQuetzelpetlatlcouldaccountforvariable
Te estimates. The average of the largest estimates for these coronae
from any study is ~28 km (Supplementary Table 2), much larger than
theoverallcoronaeaverage.
Animportantquestionforcoronaformationistheextenttowhich
heat flow estimates at coronae are elevated above the background
values due to local lithospheric thinning by upwelling plumes. Ref. 32
comparedhighcoronaFs valueswithlowFs estimatesfromstagnant-lid
convectionmodelsandconcludedthatlocalizedlithosphericthinning
overaplumeisneededtoaccountforhighcoronaheatflow.Similarly,
ref.25
modelledcoronaeasverybuoyantplumesatthebaseofthelitho-
sphere, thus producing transient heat flow substantially higher than
0 5 10 15 20 25 30
Te (km)
0
50
100
150
200
250
300
350
400
450
Heat
flow
(mW
m
–2
)
0
20
40
60
80
100
120
140
160
180
T
l
(km)
Fig.3|Heatflowestimatesaremostlygreaterthanstagnant-lidvaluesand
overlapwithterrestrialvalues,includingthoseforactiveregions.Higher
heatflow(stars)occursonthinnerTl (crosses),withtherangeofvaluesthat
correspondtoagivenTe aresultofdifferentplatecurvatures.Thecoronae
proposedtobesubductionsites31
(SupplementaryTable2)areshownasred
stars.Therangeofmodelledstagnant-lidheatflow11–14
forVenusisshownasa
blackbar.Thedarkbluearrowshowstherangeofterrestrialoceanicheatflow,
withtheaveragenotedasastar.Thelargestvaluesoccurclosesttotheridge,
includingthoseinexcessof250 mW m−2
(ref.48
).Thelightbluearrowshowsthe
rangeofcontinentalheatflow,withtheaveragenotedasastar;largervalues
areassociatedwithextensionalregions10
.Thethreebarsdonotcorrespondtoa
specificTe.ArtemisCorona,withTe of45 kmandTl of112 km,isnotshowntomake
theplotmorecompact.Forclarity,errorbarsarenotshownonthisplot.Te errors
aregiveninSupplementaryTable1.Mostarelessthan2 km,butinafewcasesare
upto5–10 km.
5. Nature Geoscience
Article https://doi.org/10.1038/s41561-022-01068-0
thehighestvaluesfoundinthisstudy.However,atmostcoronae,local
Te agrees with regional values. Thus, lithospheric thinning is typically
limited, at least to within our error bar of ±10 km. Indeed, the appar-
ent formation of coronae on thin lithosphere is consistent with their
occurrence predominantly in rift- or fracture-zone environments18
and Fig. 2. The coronae where local and regional Te values disagree
mayindicatelocalizedthinningsometimesoccursasthelocalTe isless
than the regional value for six of the seven coronae in this category.
Future improvements in gravity data should enable this question to
beansweredwithgreaterfidelity.
Globallithosphericthicknessandheatflow
As with corona formation, the agreement between local and regional
Te valuesleadstoarevisedinterpretationofglobalTe.Ref.30
proposed
that the low values (<20 km over ~50% of the planet) indicate either
crustal isostasy with no substantial mechanical lithospheric support
or compensation by a thin elastic lithosphere. They argued for crus-
tal isostasy on the basis of the prevailing view of Venus as inactive.
However, topographic flexure at coronae is a direct manifestation
of mechanical support of surface loads consistent with thin Te. The
globalpatternoflowTe occursmainlyinrifts,plainsandtesseraregions.
The tessera plateaus (~7–8% of the surface) are probably isostatically
compensated, which is also consistent with low GTRs found using a
range of window sizes for the larger tessera plateaus39
. Although Te
fromadmittanceincludesvaluesupto100 km,ref.30
pointedoutthat
the larger values are probably affected by methodology. The largest
localTe estimateis45 km,soaplausibleupperboundmightbe~55 km.
The near-global Te map can be converted to Fs estimates, although
with additional assumptions, and thus greater uncertainty, relative
to values from topographic curvature (Methods and Extended Data
Fig. 1). For low Te values of 5–15 km, Fs ranges from 155 to 52 mW m−2
.
Thus, for the ~40% of the planet (excluding tesserae) with Te < 20 km,
heatflowiscertainly>50 mW m−2
.Fortheremaining~45%oftheplanet
with Te of ~25–55+ km, Fs is ≤15–30 mW m−2
. For comparison, Earth’s
10,000 sofhigh-precisionmeasurementsyieldaverageoceanic,con-
tinental and global heat flow is 94, 65 and 89 mW m−2
, respectively52
.
Thus, global heat flow on Venus spans the range of terrestrial values,
fromArchaeancontinentalregionswithcurrentheatflowintherange
of~23–30 mW m−2
totheveryhighvaluesinactivelyextendingareas52
(Fig. 3). Thus, the concept that a single value of Te or Fs can be used to
represent Venus needs to be abandoned.
The concept of a mobile- versus stagnant-lid convective mode is
based on Earth’s geodynamic system of plate tectonics. Understand-
ingwhyEarth’sneartwinlacksterrestrial-styleplatetectonicsisakey
question for understanding rocky planet evolution. Most of Venus’s
surface (~80%) is covered by volcanic processes, including coronae.
The heat-pipe model of heat loss requires too high a rate of extru-
sive volcanism given Venus’s size to be consistent with the observed
impact-crater population53
. The squishy-lid model17
has very limited
surfacemobility,small-scaleplumes,dominantlyintrusivemagmatism
andlithosphericdelaminationandvariabilityinthickness.Thismodel,
which predicts Earth-like heat flow, is consistent with Venus’s young
surface age, abundant volcanism and formation of coronae via both
upwelling and downwelling. Further, the scale of ongoing, localized
activityisconsistentwiththeimpact-craterrecord7,32
andwiththescale
ofTe variationsseenglobally30
.
Venusoffersaglimpseofanothermodeofrockyplanetgeodynam-
icsonanEarth-sizedplanet.Understandingdifferentconvectivemodes
is essential to predicting the characteristics of habitable Earth-sized
exoplanets54
. Although Venus’s geodynamic system appears very dif-
ferentfrompresent-dayEarth,Venus’sclimate-drivenhighsurfacetem-
peraturemayresultinahotlithosphereanalogoustothatofearlyEarth.
Coronae are unique to Venus or, at minimum, uniquely common and
maybearesultofVenus’shotlithosphere55
andasquishy-lidconvective
mode. Coronae that exhibit a plume-induced subduction signature
tend to have thicker elastic lithosphere (>20 km), which occurs over
roughly half of Venus. Plume-induced subduction is one hypothesis
for how terrestrial plate tectonics began26
. Thus, Venus today may be
an analogue of the Archaean Earth, illustrating how a squishy lid with
limited mobility could evolve to an active lid with substantial surface
velocityglobally.Recentlyselectedmissions56–58
willprovideessential
dataforfurtherunlockingVenus’sgeodynamicmysteries.
Onlinecontent
Anymethods,additionalreferences,NaturePortfolioreportingsum-
maries, source data, extended data, supplementary information,
acknowledgements,peerreviewinformation;detailsofauthorcontri-
butionsandcompetinginterests;andstatementsofdataandcodeavail-
abilityareavailableathttps://doi.org/10.1038/s41561-022-01068-0.
References
1. McKinnon, W. B., Zahnle, K. J., Ivanov, B. A. & Melosh, H. J. in Venus
II (eds Bougher, S. W. et al.) 969–1014 (Univ. Arizona Press, 1997).
2. Herrick, R. R. & Rumpf, M. E. Postimpact modification by volcanic
or tectonic processes as the rule, not the exception, for Venusian
craters. J. Geophys. Res. Planets 116, E02004 (2011).
3. Campbell, B. A. Surface formation rates and impact crater
densities on Venus. J. Geophys. Res. Planets 104, 21951–21955
(1999).
4. Strom, R. G., Schaber, G. G. & Dawson, D. D. The global
resurfacing of Venus. J. Geophys. Res. Planets 99, 10899–10926
(1994).
5. Phillips, R. J. & Izenberg, N. R. Ejecta correlations with spatial
crater density and Venus resurfacing history. Geophys. Res. Lett.
22, 1517–1520 (1995).
6. O’Rourke, J. G., Wolf, A. S. & Ehlmann, B. L. Venus: interpreting the
spatial distribution of volcanically modified craters. Geophys. Res.
Lett. 41, 8252–8260 (2014).
7. Bjonnes, E., Hansen, V. L., James, B. & Swenson, J. B. Equilibrium
resurfacing of Venus: results from new Monte Carlo modeling
and implications for Venus surface histories. Icarus 217, 451–461
(2012).
8. Smrekar, S. E. et al. Recent hotspot volcanism on
Venus from VIRTIS emissivity data. Science 328,
605–608 (2010).
9. Brossier, J., Gilmore, M. & Toner, K. Low radar emissivity signatures
on Venus volcanoes and coronae: new insights on relative
composition and age. Icarus 343, 113693 (2020).
10. Campbell, B. A. et al. Pyroclastic flow deposits on Venus as
indicators of renewed magmatic activity. J. Geophys. Res. Planets
122, 1580–1596 (2017).
11. Solomatov, V. & Moresi, L. N. Stagnant lid convection on Venus.
J. Geophys. Res. Planets 101, 4737–4753 (1996).
12. Weller, M. B. & Kiefer, W. S. The physics of changing tectonic
regimes: implications for the temporal evolution of mantle
convection and the thermal history of Venus. J. Geophys. Res.
Planets 125, e2019JE005960 (2020).
13. Gillmann, C. & Tackley, P. Atmosphere/mantle coupling
and feedbacks on Venus. J. Geophys. Res. Planets 119,
1189–1217 (2014).
14. Huang, J., Yang, A. & Zhong, S. Constraints of the topography,
gravity and volcanism on Venusian mantle dynamics and
generation of plate tectonics. Earth Planet. Sci. Lett. 362,
207–214 (2013).
15. Noack, L., Breuer, D. & Spohn, T. Coupling the atmosphere with
interior dynamics: implications for the resurfacing of Venus.
Icarus 217, 484–498 (2012).
16. Lenardic, A. The diversity of tectonic modes and thoughts
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20170416 (2018).
7. Nature Geoscience
Article https://doi.org/10.1038/s41561-022-01068-0
Methods
Elastic thickness estimation from topographic flexure
We examine ~200 of the largest coronae. First, we visually inspect the
Magellan global topographic data record, which is oversampled at a
spatial resolution of 4.6 km. The actual footprint size for each obser-
vation is ~12–25 km, with variations due to latitude and along-track
versuscross-trackresolution59
.WeuseArcMap,asoftwarepackagefor
analysing geographical information system datasets, to create topo-
graphicprofilesoftheflexureobservedaroundcoronae(forexample,
Fig. 1). If a trench and flexural bulge appear to be present, we create
topographic profiles perpendicular to the trench for each corona. If
not, we eliminate the corona from our analysis. Profiles within each
setarespacedaminimumof10 kmapartandextendfromtheinterior
of each corona out to a distance of at least 300 km (Fig. 1). To create
thesecondsetofprofiles,newprofilesaredrawnclose(<10 kmapart)
to the profiles in the first set to test the sensitivity of our analyses to
small changes in profile length, orientation and location. All profiles
areanalysediftheyincludeatroughandaflexuralbulgethattapersto
arelativelyflatoruniformlyslopedarea.
We use the same approach as previous studies32,33
to extract the
elasticthicknessfromthetopographicprofiles.Surfacedeflectiondue
togeologicfeaturesiscommonlydescribedwiththephysicsofelastic
platebendingunderanappliedload.Platescanbebrokenorunbroken
where the load is applied. The load itself can have either Cartesian or
axisymmetric geometry. As shown previously33
and later verified32
,
Cartesian and axisymmetric models typically provide overlapping
estimatesofTe forcoronaebecausetheradiiofcoronaearelargerthan
their flexural parameters. For simplicity, we assumed only Cartesian
geometryinthisstudy.Weassumedthattheplateisbrokenbecauseof
thestressesinvolvedinformingcoronaeandtheevidenceforsubduc-
tion or delamination at some coronae31,34
. However, as with Cartesian
versusaxisymmetricgeometry,thischoicehasnoconsistenteffectfor
coronae32,33
. The flexural profile created by applying a load to the end
ofabrokenplateisthendescribedbythestandardequation:
w(x) = exp (−
x
α
) [c1 cos (
x
α
) + c2 sin (
x
α
)] + srx + w0, (1)
wherewiselevation(inmetres),xisthedistancealongthetopographic
profile (in metres), sr is the slope of the terrain exterior to the flexural
bulge(inverticalmetresperhorizontalmetre),w0 isthemeanelevation
oftheterrainexteriortotheflexuralbulge(inmetres),andc1 andc2 are
constants related to the magnitudes of the applied load and bending
moment. We normalized x to equal 0 in the trough at the minimum
elevation.Next,theflexuralparameterisdefinedas
α = (
4D
Δρg
)
1
4
, (2)
whereΔρ = 3,300 kg m–3
isthedifferenceindensitybetweenthemate-
rialaboveandbelowtheplate(thatis,theatmosphereandlithospheric
mantle) and g = 8.87 m s–2
is the gravitational acceleration at the sur-
face. We assume that the crust is always thinner than the lithosphere,
soweuseonlythenetdensitycontrastacrossthelithosphereandnot,
separately,thedensitycontrastbetweenthecrustandthelithospheric
mantle.However,previousstudiesprovideawiderangeofestimatesfor
themeanthicknessofthecrust,forexample,from~8to45 km(ref.39
).
We cannot exclude the possibility that the crust is thicker than the
lithosphere at some locations. Wherever the crust is thicker than the
lithosphere,alowerdensitycontrast(forexample,Δρ ~ 2,800 kg m–3
)
should be used in equation (2). Future studies could also explore the
possibility of lower crustal flow in such a scenario. In any case, the
flexuralrigidityisdefinedas
D =
ET3
e
12 (1 − ν2)
, (3)
where E = 100 GPa is Young’s modulus and ν = 0.25 is Poisson’s ratio.
Once α is retrieved from a topographic profile (equation (1)), we can
thuscalculateTe usingequations(2)and(3).
We used two separate methods to fit models of plate bending to
the two sets of topographic profiles. First, we used a Python package
calledemcee60
thatimplementsaMarkovchainMonteCarlo(MCMC)
algorithm. We used an emcee fitting method32
. Second, we used the
Levenberg–Marquardt (LM) algorithm as implemented in the SciPy
package for Python, which is a nonlinear, least-squares technique.
Both methods yield overlapping estimates of the best-fit values and
standarddeviationsofmodelparameters,includingelasticthickness.
WeincludedcoronaeinSupplementaryTable1onlyifatleastthree
topographic profiles could be fitted via either method. To obtain a
singleestimatefortheelasticthicknessateachcorona,wemultiplied
together the probability distributions for Te derived from each value.
The mean value and standard deviation of the resulting probability
distributionwasthenreportedasthebest-fitvalueandtheuncertainty
(1-sigma) of the elastic thickness. We excluded any values where the
derived uncertainty is >30 km, which indicated a very poor fit or a
profile of low quality. If both the LM and MCMC methods were suc-
cessfully applied, we reported the results from the MCMC method,
whichistechnicallymorerigorous.Overall,theTe valuesderivedfrom
both analyses agreed within ±10 km at coronae where both methods
returnedfitstothesameprofile.
In total, we obtained new estimates of Te at 65 coronae using a
combination of MCMC and LM fitting methods. An additional 10 Te
estimates come from different locations around their trench, such
as at Hepat Corona (Fig. 1). We combined our results with estimates
of Te at 14 other coronae32
, yielding 89 Te estimates for 79 coronae in
total (Supplementary Table 1). Further, we include seven estimates
from profiles of rift flanks that occur near coronae. We re-estimate
Te at 15 additional features with previously published values31,33,34
for
consistencyofmethodologyandparameters(SupplementaryTable2).
For 12 of these coronae, our estimates agree within ±10 km (Supple-
mentary Table 2). There was no clear bias between the agreement (or
lackthereof)obtainedwiththeMCMCorLMmethods.Onedifference
is that some of these studies used a Young’s modulus of 65 GPa rather
than the 100 GPa value used here, which produces a Te estimate 15%
larger. Another difference is the use of topographic profiles along
thetrackoftheMagellanorbiterratherthanthegriddedtopographic
datausedhere.AtthetimeoftheMagellan-erastudies,thealong-track
profiles provided the best topographic resolution but were typically
notexactlyperpendiculartothetrenchandthuscouldyieldartificially
highestimatesofthelocalelasticthickness.
Convertingelasticthicknessintomechanicalthicknessand
heatflow
Analytic flexure models estimate only the elastic thickness of the
lithosphere. The yield strength envelope (YSE) describes the full vis-
coelasticstrengthofthelithosphere,orTm,asafunctionofstress,tem-
perature and strain rate. We use established methods61
diagrammed
inExtendedDataFig.1toderivethethicknessofthemechanicallitho-
sphere and the associated thermal gradient and heat flow. First, we
calculate the curvature of the plate using equation (1) and the best-
fit parameters:
κ (x) =
d2
w
dx2
=
2
α2
exp (−
x
α
) [c1 sin (
x
α
) − c2 cos (
x
α
)] , (4)
Weextractedthecurvatureatthefirstzerocrossingoftheflexural
profile(atxwherew(x)firstequalsw0).Thelocationofthemaximum
curvature (~20–50% larger than at the first zero crossing) is usually
located closer to the corona in the trench. Then we used a YSE for dry
olivineintheuppermantle.Atthetopoftheplate,thebrittlestrength
is calculated from Byerlee’s law and the Anderson theory of faulting
8. Nature Geoscience
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using 0.85 as the coefficient of static friction. A stress–strain relation
governstheductilestrengthatthebaseoftheplate:
Δσ = [
̇
ϵ
A
exp (
Q
RT
)]
1
n
, (5)
whereΔσisdeviatoricstress,ϵ̇isstrainrate,Ristheuniversalgascon-
stant and T is temperature. Both deviatoric stress and strain rate are
tensor quantities in reality but are represented here as scalars that
are effectively based on the second invariant of each tensor62
. For
olivine, we used Q = 450 kJ mol–1
as the activation energy and n = 3 as
the stress exponent62,63
. We assumed that the bottom of the mechani-
cal lithosphere corresponds to a ductile strength of 50 MPa and a
temperatureofT = 1,013 K(740 °C),inaccordancewithpreviousstud-
ies34,64
offlexuralfeaturesonVenusthatwerebasedonearlierwork61,63
.
ProducingthesevaluesofΔσandTatastrainrateof10−16
s−1
requiresa
pre-exponential factor of A = 1.2718 × 10−16
s–1
Pa–3
. Scientists can also
constrainthispre-exponentialfactorusingexperimentsperformedina
triaxialrig.Applyingtheseexperimentalresultstoplanestrainrequires
onlytheapplicationofageometricalcorrectionfactor62
.
Once we determine the mechanical thickness of the lithosphere,
wecalculatetheaveragethermalgradientas
dT
dz
=
T (Tm) − TS
Tm
, (6)
wherezisdepth(inmetres),TS ≈ 737 Kisthesurfacetemperatureand
T(Tm) is the temperature at the base of the lithosphere. The heat flow
throughthelithosphereisthengivenbyFourier’slaw:
FS = k
dT
dz
, (7)
where k ≈ 3 W m−1
K−1
is the thermal conductivity of the crust. Accord-
ing to this sign convention, heat flow out of the lithosphere into the
atmosphere is positive. Ref. 32
tested the effects of using the ductile
flowlawsdeterminedfortwotypesofdrydiabase65
.Thestrongertype
ofdiabaseisroughlyequivalenttodryolivine,whereasusingtherheol-
ogy of the weaker type of dry diabase would increase the thickness of
the mechanical lithosphere by ~25% and proportionally decrease the
impliedvalueofthesurfaceheatflow.
ExtendedDataFig.2illustratessomeoftheuncertaintiesinherent
to our method for converting between elastic and mechanical thick-
ness using topographic data and flexural models. We first tested the
impactofvaryingoneofthreeparametersatatime:Young’smodulus
(E),thepre-exponentialfactorintheductileflowlaw(A)andthestrain
ratethatdrivesductileflow.
First, we test the effects of varying perhaps the most uncer-
tain parameter governing the elastic response of the lithosphere.
As explained in the preceding, increasing Young’s modulus in these
models would increase the total moment in the elastic plate and thus
alsothepredictedmechanicalthickness(ExtendedDataFig.2a).Ifthe
rheological parameters in the ductile flow law (equation (5)) remain
constant, then the predicted heat flow must decrease in tandem with
theincreasingmechanicalthickness(ExtendedDataFig.2b).Likewise,
the predicted heat flow increases if we estimate lower values for the
mechanicalthicknessbecausethebasaltemperaturestaysfixed.
Next, we test the effects of varying the pre-exponential factor
in the ductile flow law. At a fixed strain rate, changing A modifies
the deviatoric stress reached at a given temperature. That is, a lower
value of A means that a certain deviatoric stress is found at a higher
temperature. At a fixed temperature, the predicted stress difference
increases if A decreases. Since we define the base of the mechanical
plate as the depth where the deviatoric stress falls below a cut-off
strength,thenchangingAisequivalenttovaryingthetemperatureat
this depth (Extended Data Fig. 2c,d). We find that changing the basal
temperature has little effect on the predicted mechanical thickness
becausethetotalmomentintheYSEmustremainconstant(Extended
DataFig.2c).However,wewouldestimateahigherorlowerheatflow
proportionaltothetemperatureincreaseordecreaseusingthispro-
cedure (Extended Data Fig. 2d). Alternatively, we could set the plate
boundary at the depth where the temperature first exceeds 1,013 K.
In this case, changing A is equivalent to varying the cut-off strength
atthebottomoftheplate.Ifthatcut-offstrengthislowered,thenthe
mechanical lithosphere extends to greater depths (Extended Data
Fig.2e).Especiallyatrelativelylowcut-offvaluesofΔσ,thelowermost
part of the plate does not contribute much to the total moment. The
predicted heat flow again drops if the mechanical lithosphere grows
(andviceversa)—butlessrapidlythaninExtendedDataFig.2dbecause
the temperature at the bottom of the plate is fixed by assumption.
Finally, we performed a sensitivity test to illustrate the effects of
assuming different strain rates in these calculations. Here we hold A
constantandagaindefinethebaseoftheplateasthedepthwherethe
deviatoricstressfallsbelowafixedcut-offvalue.Atahigherstrainrate,
thebaseofthelithosphereisthenassociatedwithahottertemperature.
However, the strain rate does not affect the predicted stress distribu-
tion in the elastic lithosphere, meaning that the total moment in the
YSE for the mechanical lithosphere should not change. Therefore, as
in Extended Data Fig. 2c,d, using a faster strain rate would not much
change the predicted mechanical thicknesses. However, assuming
higher strain rates could lead to higher estimates for the heat flow
throughthelithosphere.Ultimately,thisapproachtoestimatinglith-
ospheric strength and the associated properties such as heat flow is a
veryvaluablemethodologybutislimitedbyourknowledgeofVenus.
Terrestrial deformation studies, which can incorporate vastly more
constraints, can take a more nuanced approach44
. Our approach is to
highlighttheuncertaintythatexists.
YSEuncertainty
Many models of lithospheric deformation require somewhat weaker
rheology than estimated in the laboratory and represented in most
YSEs to reproduce observations. Ref. 66
examined this issue for
flexural-loadingmodelsofterrestrialoceaniclithospherebycompar-
ingmodelresultswithdeflectionofthecrustseeninseismicdata.They
foundthelargestsourceoferrors(>4 kminTe)comesfromoverestima-
tionoflithosphericstrengthbasedonlaboratorydataandestimation
of strain rate. Specifically, they found a reduction in the maximum
yield stress of up to several hundred megapascals provides the best
fittoobservations.Itisunclearwhetherthisspecificreductionshould
apply to Venus, with its higher surface temperature and probably dry
crust, but numerous mechanisms for reducing rock strength over a
widerangeofconditionshavebeenproposed44
.Astrainrateof10−16
s−1
,
a typical intraplate value, is often assumed for Venus33
(for example,
ref. 3
). Ref. 44
showed that strain rates can be as high as 10−10
–10−13
s−1
in
terrestrialvolcanicregions,whichisprobablyrelevanttomostcoronae.
Forexample,anextremelyhighstrainrateof10−10
s−1
yieldsapredicted
heatflowof~120–130 mW m–2
.
A key brittle-strength parameter is the Young’s modulus (E).
Laboratory measurements of E for intact rocks are much higher than
for fractured rock. Ref. 36
modelled topography at a steep-sided vol-
canic dome on the rim of Aramaiti Corona as flexural bending. They
found that E of 5 GPa, versus a more standard value of 65–100 GPa,
better predicts agreement for the location of maximum stresses
compared with observed fractures. A decrease in Efrom 100 to 5 GPa
results in a factor of ~2.7 increase in Tm (equation (3)). This low value
of E might seem most appropriate for coronae, which are defined
by their fracture annuli. However, our Te estimate of ~13.8 km using
E = 100 GPa for Aramaiti Corona is somewhat larger than the value of
9.1 km derived using E = 5 GPa for the volcanic dome located on the
coronarim36
.ThiscomparisonsuggeststhatTe isnotunderestimated
9. Nature Geoscience
Article https://doi.org/10.1038/s41561-022-01068-0
at Aramaiti corona. It is possible that small values of corona Te, per-
haps <5–10 km, may be more affected by pervasive fracturing at
shallow depths. A detailed assessment of predicted bending stresses
versus fracture locations at individual coronae, ideally coupled with
higher-resolution image data, may be needed to fully assess the
preferred choice of E.
ComparingTe derivedfromflexureandadmittance
Comparison of our local Te corona values with regional Te values,
derived from gravity and topography, informs both error estimation
and interpretation. Analysis of the Magellan gravity and topography
datainthespectraldomain,oradmittance,requiresaveragingoveran
area >2,000 km in diameter, thus providing a regional estimate of Te.
Topographic flexure occurs over several hundreds of kilometres and
thusprovidesamorelocalestimateofTe.Thegravitydatahavevariable
resolution67
, such that many Te fits have large error bars, up to ±15 km
for models with bottom loading30
. Over ~8% of the planet, poor data
precludeanyestimate.
Forthecomparison,weusetheaveragecoordinates(latitudeand
longitude) of the topographic profiles used to calculate Te (profiles
extendupto500 kmbeyondthetrough)ratherthanthecentreofthe
coronae. To determine Te from the global map, we account for grav-
ity field resolution by converting the maximum spherical harmonic
resolution at that location (S, dimensionless) to spatial resolution (l,
inkilometres)usingtheapproximateconversion
l =
πR
S
, (8)
whereR = 6,052 km,themeanradiusofVenus.
At each location, we projected a circular area with a radius
equivalent to the resolution of the gravity field onto the map of the
admittance-derivedestimatesofTe,whichwasbinnedintoTe inincre-
ments of 10 km using ArcGIS30
. We used the midpoint value of each Te
bin (for example, 5 km, 15 km, 25 km) for comparison with the local Te
values.Localandregionalvaluesweredeterminedtoagreeifthelocal
Te values were within ±10 km of the regional Te value. This agreement
rangeisbasedonthebinsizeanderrorestimatesfromref.30
.However,
theglobalTe maphasareasthatexhibitlargevariationsinTe,aswellas
other areas that have no Te estimates. We accounted for this variabil-
ity by defining four categories of agreement (Extended Data Fig. 3):
‘Good’, where at least 50% of the regional Te values within a resolution
circle agree with the associated Te value; ‘Reasonable’, where <50%
of the regional Te values agree with the local Te value; ‘None’, where
there is no agreement between the local and regional Te values; and
‘Uncertain’, where a comparison could not be made due to a lack of
regionalTe values.
Our comparison between these regional and local values shows
that 45, 28, 7 and 9 of the Te estimates are in the ‘good’, ‘reasonable’,
‘none’and‘unconstrained’agreementcategories,respectively(Fig.2
and Supplementary Table 1). The averages for local Te values in good
and reasonable agreement are 10.1 km and 16.7 km, respectively. All
but one of the seven coronae with no agreement have smaller local
Te values than the regional values. The unconstrained class contains
regionswhereref.30
wasunabletoderiveTe.
Dataavailability
AllMagellandataareavailableinthePlanetaryDataSystem.Theglobal
topography is at https://planetarymaps.usgs.gov/mosaic/Venus_
Magellan_Topography_Global_4641m_v02.tif. The global synthetic
aperture radar map is at https://planetarymaps.usgs.gov/mosaic/
Venus_Magellan_LeftLook_mosaic_global_75m.tif. Supplementary
Tables1–3areavailableathttps://doi.org/10.5281/zenodo.7114821.The
globalVenuselasticthicknessmapfromref.30
isavailableathttps://doi.
org/10.5281/zenodo.7113940.
Codeavailability
ARCGISandMATLABarecommercialcodes.MATLABanalysiscodeis
availablefromtheauthorsonrequest.
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Acknowledgements
S.E.S. thanks past undergraduate students who contributed to
the early stages of this work: V. Auerbach, C. Miao and E. Tucker.
We thank F. Bilotte for providing his rift map. A portion of this
work was performed at the Jet Propulsion Laboratory, California
Institute of Technology, under contract with NASA. This work was
supported by NASA’s Solar System Workings programme (grant
#811073.02.35.04.55), which funded S.E.S., J.G.O. and C.O.
Authorcontributions
S.E.S., J.G.O. and C.O. conceptualized the project. J.G.O., C.O. and
S.E.S. devised the methodology. C.O., S.E.S. and J.G.O. carried out the
investigation. Visualization was done by C.O., S.E.S. and J.G.O. Funding
acquisition was handled by S.E.S. S.E.S. was in charge of project
administration and supervision. The original draft was written by S.E.S.,
C.O. and J.G.O. It was reviewed and edited by S.E.S., C.O. and J.G.O.
Competinginterests
The authors declare no competing interests.
Additionalinformation
Extended data is available for this paper at https://doi.org/10.1038/
s41561-022-01068-0.
Supplementary information The online version contains
supplementary material available at https://doi.org/10.1038/s41561-
022-01068-0.
Correspondence and requests for materialsshould be addressed to
Suzanne E. Smrekar.
Peer review information Nature Geoscience thanks Shijie Zhong
and the other, anonymous, reviewer(s) for their contribution to the
peer review of this work. Primary Handling Editor: Tamara Goldin, in
collaboration with the Nature Geoscience team.
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