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
- 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
- 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.
- 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.
- 21. References https://www.jwst.nasa.gov/ http://webbtelescope.org/ https://en.wikipedia.org/wiki/James_Webb_Space_Telescope https://www.space.com/21925-james-webb-space-telescope-jwst.html https://www.youtube.com/user/NASAWebbTelescope
- 22. THANK YOU !