A presentation about The James Webb Space Telescope (JWST) which will be launched in 2019. The presentation covers basic information about the telescope, its primary mirror, its orbit & the Sunshield. It also explains why the telescope will work in infrared region of electromagnetic spectrum and how it truly is an Engineering marvel.
James Webb Space Telescope- in search of our origin
1. THE JAMES WEBB SPACE TELESCOPE
In search of our origin…
Kshitij Bane
M.Tech, Astronomical Instrumentation
Dept. Of Applied Optics & Photonics, Calcutta University
2. JWST- an engineering marvel
The largest telescope ever to put into space
6.5 m diameter primary mirror
Successor to the Hubble space telescope
Named after James Webb, NASA’s second administrator
An international collaboration : NASA, ESA, CSA
Launch scheduled on an Ariane 5 rocket in 2019
Total cost $8.8 billion
Will be the premier infrared observatory of the next decade
3. The WEBB’s main Science Themes
First Light & Reionization: The end of Dark ages
The assembly of Galaxies
Birth of stars and protoplanetary systems
The origins of life
4. Important points to discuss
Why Infrared ?
The orbit
The Primary mirror
The Sunshield
5. To Explore the Infrared Universe…
Webb's instruments will be designed to work primarily in the infrared range of the
electromagnetic spectrum with some capability in the visible range.
It will be sensitive to light from 0.6 to 28 μm wavelength.
6. • JWST will act like a time machine
• It will see 13.5 billion years into the past
• To see the first galaxies and stars that formed in the Universe
7. The Cosmological red shift
• The space itself is expanding
• The light from 13.5 billion years ago reaches us as Infrared
8.
9. To see beyond the dusty cloud…
• Birth place of stars
• Difficult to see through the gas & dust clouds
• But JWST’s Infrared eyes can !
11. The JWST will come equipped with four science instruments
• Near-Infrared Camera (NIRCam)
• Near-Infrared Spectrograph (NIRSpec)
• Mid-Infrared Instrument (MIRI)
• Fine Guidance Sensor/Near InfraRed Imager and Slitless Spectrograph
(FGS/NIRISS)
But one problem….
Everything has to be ‘COLD’
And also heat from SUN, EARTH, MOON will saturate the IR sensors
Even heat from the spacecraft bus itself can be lethal
Solution ?
12. WEBB’s Orbit…
The JWST must be kept very cold (under 50 K)
JWST will Not orbit the earth
But will orbit the Sun at 1.5 million km away from the Earth at Lagrange point L2
13. JWST uses a large sunshield to block light and heat from
the Sun, Earth, and Moon
L2 point keeps all three bodies on the same side of the spacecraft at all times.
14. The Sunshield
The sunshield serves to separate the sensitive mirrors and instruments from not only the Sun
and Earth/Moon, but also the spacecraft bus.
• A tennis-court sized Sunshield made of five thin
layers of Kapton
• The layers do not touch each other
• Coated on the sunward side with silicon, which
reflects the incoming sunlight
15.
16. THE PRIMARY MIRROR
• Folding, segmented primary mirror
• It consists of 18 individual hexagonal mirror segments
• Ultra-lightweight beryllium optics (705 kg, HST : 820 kg)
• Coated with Gold
• Focal length: 131.4m
• Optical Resolution : 0.1 arc sec
• Field of view: 2.2 by 4.4 arcmin sq.
17. • Each segment is attached to 6 actuators allowing the mirrors to tilt, twist,
and shift to face the correct direction and position achieving a single perfect
focus
• An additional actuator at center that adjusts its curvature
• Gets aligned in space by commands from Earth.
18.
19. SECONDARY AND TERTIARY MIRROR
It’s a 3 mirror anastigmat
Uses 3 curved mirrors to minimize all three main optical aberrations -
spherical aberration, coma & astigmatism.
The single secondary mirror is perfectly rounded and convex
The tertiary mirror is the only fixed mirror in the system
20. TO CONCLUDE…
• JWST capabilities will enable a broad range of investigations across the
fields of astronomy and cosmology.
• It will observe some of the most distant objects in the Universe, beyond
the reach of current ground and space based instruments.
• In order to carry out its mission, several innovative and powerful new
technologies ranging from optics to detectors to thermal control systems
are being developed.
• It will uncover the history of the universe from the Big Bang to alien
planet formation and beyond.
• It’s truly in engineering marvel into space.
