The document discusses electromagnetic formation flight (EMFF) as an alternative to traditional spacecraft propulsion. EMFF uses electromagnetic forces and reaction wheels, instead of propellant, to control the relative positions and orientations of spacecraft in a cluster formation. It proposes using electromagnetic dipoles to generate the necessary inter-spacecraft forces and torques for full controllability. Disturbance rejection from gravitational effects and managing excess angular momentum buildup are challenges that EMFF would need to address for practical applications such as the Terrestrial Planet Finder mission.
A coupled Electromagnetic-Mechanical analysis of next generation Radio Telesc...Altair
This work considers the design of large and complex receivers used in the field of radio astronomy, e.g. for the Square Kilometer Array (SKA) project. The purpose of this work is to consider a coupled simulation where the electromagnetic analysis, performed with the computational electromagnetic software package FEKO, is enhanced by the structural analysis offered by HyperWorks products such as HyperMesh and Optistruct. External influences such as gravity, wind-loading and thermal properties will be taken into account. This will enhance the electromagnetic simulation results, thereby aiding designers to mitigate these environmental effects.
Speakers
Dr. Danie Ludick, Postdoctoral researcher, Stellenbosch University
A coupled Electromagnetic-Mechanical analysis of next generation Radio Telesc...Altair
This work considers the design of large and complex receivers used in the field of radio astronomy, e.g. for the Square Kilometer Array (SKA) project. The purpose of this work is to consider a coupled simulation where the electromagnetic analysis, performed with the computational electromagnetic software package FEKO, is enhanced by the structural analysis offered by HyperWorks products such as HyperMesh and Optistruct. External influences such as gravity, wind-loading and thermal properties will be taken into account. This will enhance the electromagnetic simulation results, thereby aiding designers to mitigate these environmental effects.
Speakers
Dr. Danie Ludick, Postdoctoral researcher, Stellenbosch University
Space Radiation & It's Effects On Space Systems & Astronauts Technical Traini...Jim Jenkins
This course is designed for technical and management personnel who wish to gain an understanding of the fundamentals and the effects of space radiation on space systems and astronauts. The radiation environment imposes strict design requirements on many space systems and is the primary limitation to human exploration outside of the Earth's magnetosphere. The course specifically addresses issues of relevance and concern for participants who expect to plan, design, build, integrate, test, launch, operate or manage spacecraft and spacecraft subsystems for robotic or crewed missions. The primary goal is to assist attendees in attainment of their professional potential by providing them with a basic understanding of the interaction of radiation with non-biological and biological materials, the radiation environment, and the tools available to simulate and evaluate the effects of radiation on materials, circuits, and humans
The Centurion Orbit Transfer Vehicle (OTV) was part of our Aerospace Engineering Senior Design project at the University of Illinois at Urbana-Champaign. It is equipped with the latest technologies, including a nuclear thermal propulsion system. The structure weighs 89,000 kg and is capable of transporting cargo to Lagrange points L1 or L2.
Attitude & orbital control system, TTC & M system, Power system, Communication subsystem, Satellite antenna, Space qualification, Equipment Reliability, redundancy
The SpaceDrive Project - First Results on EMDrive and Mach-Effect ThrustersSérgio Sacani
Propellantless propulsion is believed to be the best option for interstellar travel. However, photon rockets or solar sails have thrusts so low that maybe only nano-scaled spacecraft may reach the next star within our lifetime using very high-power laser beams. Following into the footsteps of earlier breakthrough propulsion programs, we are investigating different concepts based on non-classical/revolutionary propulsion ideas that claim to be at least an order of magnitude more efficient in producing thrust compared to photon rockets. Our intention is to develop an excellent research infrastructure to test new ideas and measure thrusts and/or artefacts with high confidence to determine if a concept works and if it does how to scale it up. At present, we are focusing on two possible revolutionary concepts: The EMDrive and the Mach-Effect Thruster. The first concept uses microwaves in a truncated cone-shaped cavity that is claimed to produce thrust. Although it is not clear on which theoretical basis this can work, several experimental tests have been reported in the literature, which warrants a closer examination. The second concept is believed to generate mass fluctuations in a piezo-crystal stack that creates non-zero time-averaged thrusts. Here we are reporting first results of our improved thrust balance as well as EMDrive and Mach-Effect thruster models. Special attention is given to the investigation and identification of error sources that cause false thrust signals. Our results show that the magnetic interaction from not sufficiently shielded cables or thrusters are a major factor that needs to be taken into account for proper μN thrust measurements for these type of devices.
Advances in Satellite Conjunction Analysis with OR.A.SIAntonios Arkas
As the number of the manmade objects increases in space, so does the interest and the research effort on the critical and interesting issues of collision probability assessment and decision making for cases of close approach events.
New interesting theoretical analysis has been recently published by Michael Scott Balch, Ryan Martin and Scott Ferson, on the mathematical subtleties connecting the phenomenon of probability dilution with the fundamental difference between frequentist and Bayesian approaches in statistical inference, and inspirational work has been presented from CNES by F.Laporte through his papers which describe JAC software and his approach to covariance realism.
OR.A.SI, the Flight Dynamics software for GEO and LEO that I’ve been developing for the last 17 years in C++, has been endowed since 2012 with early close approach detection based on the TLE files released from JSpOC, calculation of collision probability (S.Alfano method) based on the secondary object details found in CDM (Conjunction Data Message), Middle Man features (processing and analysis of CDM batches released for the same event) and evasive manoeuvre computation.
This new presentation exposes the latest enhancements, of the already powerful OR.A.SI routines, with all these new exiting advances. In brief the contents of the attached presentation are the following:
1. CASI (Close Approach Simulator) – Development of an analytic simulator which produces close approach events for whatever regime (LEO, MEO and GEO), and renders the probabilistic study and analysis of such events independent from the need of a CDM.
2. Computation and visualization of the probability dilution area in the two dimensional space of Kp and Ks scale factors used for the computation of the scaled probability of collision.
3. Computation of the scale factor interval in order to increase covariance realism, based on hypothesis testing with the Kolmogorov-Smirnov test (F.Laporte - CNES).
4. Computation of the effect of evasive manoeuvres, parametrized in time and velocity increment, on the scaled probability of collision.
I welcome you to the subtle but beautiful world of probabilities and inferential statistics or else how we managed to harness our ignorance to precise science!
Cuento de Don Carnal y Doña Cuaresma encontrado en la siguiente página: http://educacioninfantilparacompartir.blogspot.com.es/2013/02/don-carnal-y-dona-cuaresma.html
Space Radiation & It's Effects On Space Systems & Astronauts Technical Traini...Jim Jenkins
This course is designed for technical and management personnel who wish to gain an understanding of the fundamentals and the effects of space radiation on space systems and astronauts. The radiation environment imposes strict design requirements on many space systems and is the primary limitation to human exploration outside of the Earth's magnetosphere. The course specifically addresses issues of relevance and concern for participants who expect to plan, design, build, integrate, test, launch, operate or manage spacecraft and spacecraft subsystems for robotic or crewed missions. The primary goal is to assist attendees in attainment of their professional potential by providing them with a basic understanding of the interaction of radiation with non-biological and biological materials, the radiation environment, and the tools available to simulate and evaluate the effects of radiation on materials, circuits, and humans
The Centurion Orbit Transfer Vehicle (OTV) was part of our Aerospace Engineering Senior Design project at the University of Illinois at Urbana-Champaign. It is equipped with the latest technologies, including a nuclear thermal propulsion system. The structure weighs 89,000 kg and is capable of transporting cargo to Lagrange points L1 or L2.
Attitude & orbital control system, TTC & M system, Power system, Communication subsystem, Satellite antenna, Space qualification, Equipment Reliability, redundancy
The SpaceDrive Project - First Results on EMDrive and Mach-Effect ThrustersSérgio Sacani
Propellantless propulsion is believed to be the best option for interstellar travel. However, photon rockets or solar sails have thrusts so low that maybe only nano-scaled spacecraft may reach the next star within our lifetime using very high-power laser beams. Following into the footsteps of earlier breakthrough propulsion programs, we are investigating different concepts based on non-classical/revolutionary propulsion ideas that claim to be at least an order of magnitude more efficient in producing thrust compared to photon rockets. Our intention is to develop an excellent research infrastructure to test new ideas and measure thrusts and/or artefacts with high confidence to determine if a concept works and if it does how to scale it up. At present, we are focusing on two possible revolutionary concepts: The EMDrive and the Mach-Effect Thruster. The first concept uses microwaves in a truncated cone-shaped cavity that is claimed to produce thrust. Although it is not clear on which theoretical basis this can work, several experimental tests have been reported in the literature, which warrants a closer examination. The second concept is believed to generate mass fluctuations in a piezo-crystal stack that creates non-zero time-averaged thrusts. Here we are reporting first results of our improved thrust balance as well as EMDrive and Mach-Effect thruster models. Special attention is given to the investigation and identification of error sources that cause false thrust signals. Our results show that the magnetic interaction from not sufficiently shielded cables or thrusters are a major factor that needs to be taken into account for proper μN thrust measurements for these type of devices.
Advances in Satellite Conjunction Analysis with OR.A.SIAntonios Arkas
As the number of the manmade objects increases in space, so does the interest and the research effort on the critical and interesting issues of collision probability assessment and decision making for cases of close approach events.
New interesting theoretical analysis has been recently published by Michael Scott Balch, Ryan Martin and Scott Ferson, on the mathematical subtleties connecting the phenomenon of probability dilution with the fundamental difference between frequentist and Bayesian approaches in statistical inference, and inspirational work has been presented from CNES by F.Laporte through his papers which describe JAC software and his approach to covariance realism.
OR.A.SI, the Flight Dynamics software for GEO and LEO that I’ve been developing for the last 17 years in C++, has been endowed since 2012 with early close approach detection based on the TLE files released from JSpOC, calculation of collision probability (S.Alfano method) based on the secondary object details found in CDM (Conjunction Data Message), Middle Man features (processing and analysis of CDM batches released for the same event) and evasive manoeuvre computation.
This new presentation exposes the latest enhancements, of the already powerful OR.A.SI routines, with all these new exiting advances. In brief the contents of the attached presentation are the following:
1. CASI (Close Approach Simulator) – Development of an analytic simulator which produces close approach events for whatever regime (LEO, MEO and GEO), and renders the probabilistic study and analysis of such events independent from the need of a CDM.
2. Computation and visualization of the probability dilution area in the two dimensional space of Kp and Ks scale factors used for the computation of the scaled probability of collision.
3. Computation of the scale factor interval in order to increase covariance realism, based on hypothesis testing with the Kolmogorov-Smirnov test (F.Laporte - CNES).
4. Computation of the effect of evasive manoeuvres, parametrized in time and velocity increment, on the scaled probability of collision.
I welcome you to the subtle but beautiful world of probabilities and inferential statistics or else how we managed to harness our ignorance to precise science!
Cuento de Don Carnal y Doña Cuaresma encontrado en la siguiente página: http://educacioninfantilparacompartir.blogspot.com.es/2013/02/don-carnal-y-dona-cuaresma.html
Enriquece tu experiencia laboral brindando consultoría empresarial a pequeños y micro empresarios en equipos multidisciplinares conformados por otros jóvenes profesionales como tu.
Importance of SSPS in SDG and ESG, and importance of antennas in SSPSAdvanced-Concepts-Team
A space solar power satellite system or SSPS can generates electricity without CO2 gas nor harmful debris with competitive cost. So, it should be attached importance in SDG and ESG programs. The SSPS is a huge system working in space so that several key technologies have to be innovated or verified in space before the final manufacture. I will introduce those key technologies in terms of difficulty in applying to SSPS. In a research and development plan, key technologies with more difficulty should be ranked higher. Antennas are typically difficult ones. It is explained how the antenna is challenging compared with the existing antennas on the ground and in space. Finally, I will show you a R&D plan to put SSPS into practical use in about 30 years.
Multiphase Flow Modeling and Simulation: HPC-Enabled Capabilities Today and T...inside-BigData.com
In this video from the 2014 HPC User Forum in Seattle, Igor Bolotnov from North Carolina State University presents: Multiphase Flow Modeling and Simulation: HPC-Enabled Capabilities Today and Tomorrow.
Learn more: http://insidehpc.com/video-gallery-hpc-user-forum-2014-seattle/
A presentation on upcoming Solar Power Technologies as a viable means of efficiently harnessing solar energy. Part of Self Study Phase-2 at RV College of Engineering, Bangalore.
Part 1 is here: http://www.slideshare.net/Jayanth-R/solar-power-satellites
Electric Propulsion (EP) is a class of space propulsion which makes use of electrical power to accelerate a propellant by different possible electrical and/or magnetic means. The use of electrical power enhances the propulsive performances of the EP thrusters compared with conventional chemical thrusters. Unlike chemical systems, electric propulsion requires very little mass to accelerate a spacecraft. The propellant is ejected up to twenty times faster than from a classical chemical thruster and therefore the overall system is many times more mass efficient.
Electric Propulsion, when compared with chemical propulsion, is not limited in energy, but is only limited by the available electrical power on-board the spacecraft. Therefore EP is suitable for low- thrust (micro and milli-newton levels) long-duration applications on board spacecrafts. The propellant used in EP systems varies with the type of thruster and can be a rare gas (i.e. xenon or argon), a liquid metal or, in some cases, a conventional propellant.
Electric Propulsion System components
An Electric Propulsion System is composed by four different building blocks:
The thruster components,
The propellant components or fluidic management system, The power components, which includes the PPU,
The pointing mechanisms (optional).
Wireless power transmission via Space Based Solar Powernikhil gaurav
this presentation tells about how the power is transmitting wireless and how it helps to decrease the losses in power transmission and thus increases efficiency and more important is uses a renewable source of energy(SUN).
Sliding motion and adhesion control through magnetic domaminsAndrea Benassi
Actuation and control of motion in micro mechanical systems are technological challenges, since they are accompanied by mechanical friction and wear, principal and well known sources of device lifetime reduction. In this theoretical work we propose a non-contact motion control technique based on the introduction of a tunable magnetic interaction. The latter is realized by coating two non-touching sliding bodies with ferromagnetic films. The resulting dynamics is determined by shape, size and ordering of magnetic domains arising in the films below the Curie temperature. We demonstrate that the domain behavior can be tailored by acting on handles like ferromagnetic coating preparation, external magnetic fields and the finite distance between the plates. In this way, motion control can be achieved without mechanical contact. Moreover, we discuss how such handles can disclose a variety of sliding regimes. Finally, we propose how to practically implement the proposed model sliding system.
A NOVEL APPROACH TO OBTAIN MAXIMUM POWER OUTPUT FROM SOLAR PANEL USING PSOijsrd.com
The configuration of a most extreme force point following (MPPT) controller for a sun based photovoltaic force framework is proposed using a help converter topology utilizing PSO calculation. Sunlight based board voltage and current are consistently checked by a shut circle focused around PSO microcontroller control framework, and the obligation cycle of the help converter persistently changed in accordance with concentrate greatest force. Framework testing affirms crest force following under changing lighting conditions. Under particular conditions, efficiencies in overabundance of 96% are demonstrated to be conceivable.
solar power satellite & microwave power transmissionbhavisha patel
In this seminar topic,I included all the things related SPS system & how microwave power transmission can done through magetron,retro directive beam controlling scheme & all.I also mentioned the design of optical rectenna & economic evolution of the topic.
Similar to Electromagnetic formationflightoct02 (20)
1. Electromagnetic Formation Flight (EMFF)
NIAC Phase I Review
October 23-24, 2002
PI: David Miller
Co-I: Raymond Sedwick
Massachusetts Institute of Technology
Space Systems Laboratory
2. Motivation
• Traditional propulsion uses propellant as a reaction mass
• Advantages
– Ability to move center of mass of spacecraft
(Momentum conserved when propellant is included)
– Independent (and complete) control of individual spacecraft
• Disadvantages
– Propellant is a limited resource
– Momentum conservation requires that propellant mass increase
exponentially with the velocity increment (ΔV)
– Some propellants can be a surface contaminant to precision optics and
solar arrays
– Lingering propellant clouds can obscure or blind infrared telescopes
• Is there an alternative ??
NIAC Phase I Midterm Review Oct 23, 2002
3. A Candidate Solution
• Yes… inter-spacecraft forces can be used…
– …provided it is not necessary to alter the center of mass motion of the
system
• What forces must be transmitted between satellites to allow for all relative
degrees of freedom to be controlled?
– In 2 dimensions, N spacecraft have 3N DOFs, but we are at most able to
control 3N-2 (no translation of the center of mass)
– For 2 spacecraft, that’s a total of 4:
1 2 3 4
• DOFs 1-3 can be controlled with inter-spacecraft axial forces and on-board
torques, but 4 requires a transverse force
• Electrostatic monopoles cannot provide this type of force, but Electromagnetic
and electrostatic dipoles can!
• Tethers attached away from the center of mass of the spacecraft will also work,
but that’s a different project…
• So, are there missions where controlling cluster center of mass doesn’t matter?
NIAC Phase I Midterm Review Oct 23, 2002
4. EMFF Applications in 10-20 Years
-3000
Terrestrial Planet Finder
-1500
Image from 1999 TPF Book
Cluster Reconfiguring
0
1500
-3000 3000
-1500
0
1500
1500
750
0
-750
-1500
3000
NGST
Docking
NIAC Phase I Midterm Review Oct 23, 2002
5. EMFF Applications in 30-40 Years
Reconfigurable Arrays & Staged Deployment
Adaptive Membrane for Imaging
Planet Imager
Image from 1999 TPF Book
NIAC Phase I Midterm Review Oct 23, 2002
6. Electromagnetics vs. Electrostatics
• Electromagnetic Dipoles
– Force Scaling:
7 2 πμ μ π
3
2
4
2
= −
I NA EM ~ ( ) [ ]
F
a
x
4 10 0
0
– a = coil radius, x = separation distance, I = current (Amp-turns)
• Electrostatic Dipoles
– Force Scaling:
4
= −
α π ε ε 12 2
V NV ES ~ 24 2 8.85(10 ) [ ]
F
a
x
0
2
0
– a = electrode spacing, α = electrode radius / a, V = Voltage difference
F
F
μ
I
ε V
α
=
⇒ ≈
1
16
94
0
2
EM V I
α
2
ES
0
(For break-even and comparable size)
NIAC Phase I Midterm Review Oct 23, 2002
7. Is This a Lot?
Current (amp-turns) vs. Force .
140.0
120.0
100.0
80.0
60.0
40.0
20.0
0.0
0.0 0.2 0.4 0.6 0.8 1.0
Force (N) .
Current (kA)
x/a
30
25
20
15
10
• For regular wire… yes (except for low force or close operations)
• For high temperature superconducting wire… no!
– Commercially available wire will carry 13 kA/cm2
– Laboratory demonstrations up to 6 MA/cm2 (even in high B-field)
• However, voltages required for Electrostatics are prohibitive
• Debye shielding in LEO also a problem for electrostatics
NIAC Phase I Midterm Review Oct 23, 2002
8. EM Design: Steerable Dipoles
• Using ferromagnetic cores in a tetrahedron,
the dipole direction can be steered by
energizing different combinations
• Tend to be heavy for a given force
• Likewise, a set of 3 orthogonal coils
can achieve the same effect
• Much lighter weight
• A set of 3 orthogonal gimbaled reaction wheels used in conjunction with these
steerable dipoles will decouple spacecraft orientation from EM control
• Gimbals could be locked during spin-up maneuver, and unlocked during steady-state
spin to eliminate gyroscopic stiffening
NIAC Phase I Midterm Review Oct 23, 2002
9. Satellite Formation Spin-Up
• Electromagnets exert forces/torques on each other
– Equal and opposite “shearing” forces
– Torques in the same direction
• Reaction wheels counteract EM torques
S N
– Resultant is shearing force
– Angular momentum conserved by spin of the system
S
N
EM Torque RW
• There are many possible combinations of EM strength and dipole
orientation, causing different distributions of angular momentum storage.
Torque
NIAC Phase I Midterm Review Oct 23, 2002
10. • Steady-state spin
Steady-State Spin
– Constant spin rate for data collection
– Relative position and orientation maintenance
– Disturbance rejection
– Linearized dynamics about nominal spin
• Optimal control design
λ
– Choose ratio of penalties on state and control ( )
– Can stabilize dynamics and reject disturbances
• Experimental validation on linear air track
– Similar unstable dynamics
– Stabilized using optimal control
acentrifugal
acentrifugal
N S N S
Ω
FEM FEM
ρ Unstable poles:
= ±Ω 1,2 s
Open-Loop: Closed-Loop:
NIAC Phase I Midterm Review Oct 23, 2002
11. Radar Mode Geolocation Mode
* Figure courtesy of AFOSR Techsat21
Research Review (29 Feb - 1 Mar 2000)
-3000
500m 5km
-1500
Optimal Cluster Reconfiguration
0
1500
Reconfigure
-3000 3000
-1500
0
1500
1500
750
0
-750
-1500
3000
• Multiple trajectories to initialize or
resize the EMFF cluster
• Can be framed as an optimal
control problem with Quadratic
cost function (Energy) and Linear
dynamics (Hill Equations)
• Balancing between power
requirements for reaction wheels
and electromagnets
• Reaction wheel torques and
power constraints must also be
considered
• Previous work applied to TechSat
21 clusters for both cluster
initialization and geo-location
problems
Optimal Techsat21 Cluster Re-sizing
NIAC Phase I Midterm Review Oct 23, 2002
12. Disturbance Rejection
• EMFF must counteract the disturbances present in LEO
– Earth’s Gravitational Potential (J2)
• Differential forces causes satellite formations to separate
• Causes Satellite Formations to ‘Tumble’
– Differential Drag
– Earth’s Magnetic Field
• When counteracting the disturbances, EMFF produces unwanted
torques on each spacecraft.
• Reaction wheels are used to
temporarily store the change
in the angular momentum
• The reaction wheels must be
de-saturated by means other
than traditional propulsion
Differential J2 acc. (mm/s2)
1 2 3 4 5 6
0.0001
0.00005
- 0.00005
- 0.0001
Normal Tangential
NIAC Phase I Midterm Review Oct 23, 2002
13. Angular Momentum Management
• Zero net angular momentum gain
– There is a limited subset of
formation designs that produce
zero net angular momentum gain
• Re-phasing of the formation
– Re-phasing causes the torques to be
applied in the opposite direction.
Thus de-spinning the wheels.
Ang. Mom. (N mm s)
Re-phase
2 4 6 8 10
0.8
0.6
0.4
0.2
- 0.2
Ang. Mom. (N mm s)
2 4 6 8 10
0.05
- 0.05
- 0.1
- 0.15
Orbit
Orbit
Normal Tangential Normal Tangential
• Earth’s magnetic field
– By varying the dipole strength, the torque distribution can be varied without
affecting the resulting forces.
– If the Earth is considered as another dipole, some of the torques can be
preferentially distributed to the earth
NIAC Phase I Midterm Review Oct 23, 2002
14. Case Study: TPF Retrofit
• PPTs
– Higher efficiency system but still
requires significant propellant over
a 10 year mission lifetime
• FEEPs
– Ideal for very short mission lifetime
systems (less than 6 yrs)
– Must consider contamination issue
• EM coil (R = 4 m) (Mtot = 4198 kg)
– Less ideal option when compared
to FEEPs even for long mission
lifetime
• EM Super Conducting Coil (R = 2 m)
(Mtot = 3089 kg)
– Best option if mission lifetime of
greater than 6.2 years is desired
– No additional mass is required to
increase mission lifetime
PPTs
Colloids
FEEPs
Cold Gas
EM Coil
EM SuperCon
Total Dry Mass
0 1 2 3 4 5 6 7 8 9 10
4400
4200
4000
3800
3600
3400
3200
3000
• Cold Gas and Colloids
– Low Isp systems translate to high
propellant requirements
– Not viable options
NIAC Phase I Midterm Review Oct 23, 2002
15. EMFF System Trades
• Identical or Mother-Daughter Configuration for spinning case?
• Define Mass Fractions:
Center Spacecraft experiences no
translation ! no mass penalty ! suggests
larger center spacecraft
M M inner totalarray =γ
M =γ −1
M outer 2
totalarray • Identical Configuration is non-optimal
• Higher rotation rate for mother-daughter
configuration for fixed masses
NIAC Phase I Midterm Review Oct 23, 2002
16. Phase II Objectives
• Conduct more in-depth systems trades using various NASA missions
– Terrestrial Planet Finder
– Life Finder
– Constellation-X
• Analyze impact on various subsystems
– Tolerance of avionics
– Inter-vehicle power coupling
– Inter-vehicle communications
– Angular momentum redistribution for enabling precision operations
• Formulate arbitrary n-body dynamics to analyze control complexity growth as a
function of array growth
• Build a prototype to test simultaneous control in translation and rotation
– Coordinate with undergraduate design-build class
– Previous classes developed SPHERES and ARGOS testbeds
– Provides opportunity for undergraduates to participate in, and have impact
on, space research
NIAC Phase I Midterm Review Oct 23, 2002
17. Conclusions (1)
• Lifetime and contamination are two compelling reasons to seek
alternate solutions to using propellants
• Dipole fields and reaction wheels can produce all of the necessary
actuation for complete controllability of relative degrees of freedom
• There are many missions where relative DOF control is all that is
necessary
– Agencies that have interest: JPL, GSFC, LMCO, NRO
• Debye shielding in LEO, and problems with high E-fields in general
make electrostatic dipoles less attractive (no pun intended)
– Electrostatic monopoles could provide a stronger attractive force for
constant spin rate, but charge exchange between spacecraft is an
issue
NIAC Phase I Midterm Review Oct 23, 2002
18. Conclusions (2)
• Constrained Steady-state spin control has been
demonstrated in hardware
• In LEO, disturbance rejection is the main concern and
angular momentum management is the biggest problem
– Three approaches: Zero not torque solution, Re-phasing,
Using Earth’s Field
• EMFF retrofit of TPF looks like the best solution if FEEP
contamination is a high risk
• Optimal distribution of Torque for TPF-like maneuver is not
necessarily to have identical spacecraft
NIAC Phase I Midterm Review Oct 23, 2002