Space Telescopes | Science & Technology for UPSC 2024 (Pre & Mains) PDF Download

 Page 1


 
Hubble Space T elescope 
•NASA named the world’s ?rst space-based optical telescope after American astronomer Edwin P . 
Hubble, who con?rmed an “expanding” universe, which provided the foundation for the big-bang theory 
•
It was launched in April 1990 and it delivered its ?rst image in May 1990 
•Located in Low Earth Orbit, at an altitude of 547 km, inclined 28.5 degrees to the equator 
•
It completes one orbit in about 95 minutes at a speed of 27300 kmph 
•Hubble has no thrusters. T o change angles, it uses Newton’s third law by spinning its wheels in the 
opposite direction 
Spitzer Space T elescope 
•
Launched in 2003, it is the ?nal mission in NASA’s Great Observatories Program - a family of four space-
based observatories, each observing the Universe in a different kind of light  
•
The other missions in the program include the visible-light Hubble Space T elescope (HST), Compton 
Gamma-Ray Observatory (CGRO), and the Chandra X-Ray Observatory (CXO) 
•
It is designed to detect infrared radiation, which is primarily head radiation  
•
Composed of 2 components 
?Cryogenic T elescope Assembly  
?Spacecraft — controls the telescope, provides power to the instruments, handles the scienti?c data 
and communicates with Earth 
•
It needs to be simultaneously warm and cold to function properly  
?Everything in the Cryogenic T elescope Assembly must be cooled to only a few degrees above 
absolute zero. This is achieved with an onboard tank of liquid helium, or cryogen 
?Electronic equipment in the spacecraft portion needs to operate near room temperature 
•Spitzer's highly sensitive instruments allow scientists to peer into cosmic regions that are hidden from 
optical telescopes, including dusty stellar nurseries, the centers of galaxies, and newly forming planetary 
systems 
•Spitzer's infrared eyes also allows astronomers see cooler objects in space, like failed stars (brown 
dwarfs), extrasolar planets, giant molecular clouds, and organic molecules that may hold the secret to life 
on other planets 
Fermi Gamma-ray Space T elescope 
•
Formerly known as Gamma-ray Large Area Space T elescope (GLAST), is a space observatory being used 
to perform gamma-ray astronomy observations from low Earth orbit 
www.YouTube.com/SleepyClasses 
www.SleepyClasses.com 
!
Page 2


 
Hubble Space T elescope 
•NASA named the world’s ?rst space-based optical telescope after American astronomer Edwin P . 
Hubble, who con?rmed an “expanding” universe, which provided the foundation for the big-bang theory 
•
It was launched in April 1990 and it delivered its ?rst image in May 1990 
•Located in Low Earth Orbit, at an altitude of 547 km, inclined 28.5 degrees to the equator 
•
It completes one orbit in about 95 minutes at a speed of 27300 kmph 
•Hubble has no thrusters. T o change angles, it uses Newton’s third law by spinning its wheels in the 
opposite direction 
Spitzer Space T elescope 
•
Launched in 2003, it is the ?nal mission in NASA’s Great Observatories Program - a family of four space-
based observatories, each observing the Universe in a different kind of light  
•
The other missions in the program include the visible-light Hubble Space T elescope (HST), Compton 
Gamma-Ray Observatory (CGRO), and the Chandra X-Ray Observatory (CXO) 
•
It is designed to detect infrared radiation, which is primarily head radiation  
•
Composed of 2 components 
?Cryogenic T elescope Assembly  
?Spacecraft — controls the telescope, provides power to the instruments, handles the scienti?c data 
and communicates with Earth 
•
It needs to be simultaneously warm and cold to function properly  
?Everything in the Cryogenic T elescope Assembly must be cooled to only a few degrees above 
absolute zero. This is achieved with an onboard tank of liquid helium, or cryogen 
?Electronic equipment in the spacecraft portion needs to operate near room temperature 
•Spitzer's highly sensitive instruments allow scientists to peer into cosmic regions that are hidden from 
optical telescopes, including dusty stellar nurseries, the centers of galaxies, and newly forming planetary 
systems 
•Spitzer's infrared eyes also allows astronomers see cooler objects in space, like failed stars (brown 
dwarfs), extrasolar planets, giant molecular clouds, and organic molecules that may hold the secret to life 
on other planets 
Fermi Gamma-ray Space T elescope 
•
Formerly known as Gamma-ray Large Area Space T elescope (GLAST), is a space observatory being used 
to perform gamma-ray astronomy observations from low Earth orbit 
www.YouTube.com/SleepyClasses 
www.SleepyClasses.com 
! 
•Its main instrument is the Large Area T elescope (LAT), with which astronomers mostly intend to perform 
an all-sky survey studying astrophysical and cosmological phenomena such as active galactic nuclei, 
pulsars, other high-energy sources and dark matter 
•It also studies the gamma-ray bursts 
•
Launched in 2008, it was a joint venture of NASA and US DoE and government agencies in France, 
Germany, Italy, Japan and Sweden 
Kepler Mission 
•
It is a retired space telescope launched by NASA to discover Earth-Size planets orbiting other stars 
•
Named after astronomer Johannes Kepler, the spacecraft was launched in 2009, into an Earth-trailing 
heliocentric orbit  
•
Designed to survey a portion of Earth’s region of the Milky Way to discover Earth-size exoplanets in or 
near habitable zones and estimate how many of the billions of stars in the Milky Way have such planets  
Transiting Exoplanet Survey Satellite (TESS) 
•
It is a space telescope for NASA’s Explorers program, designed to search for exoplanets using the transit 
method in an area 400 times larger than that covered by the Kepler mission 
?It is the next step in the search for planets outside of our solar system, including those that could 
support life 
?The mission will ?nd exoplanets that periodically block part of the light from their host stars, events 
called transits 
•
It was launched on April 2018 atop a Falcon 9 rocket  
•Primary mission objective is to survey the brightest stars near the Earth for transiting exoplanets over a 
period of two-years 
•It uses an array of wide-?eld cameras to perform a survey of 85% of the sky 
•
With TESS, it is possible to study the mass, size, density and orbit of a large cohort of small planets  
•
It will provide prime targets for further characterisation by the James Webb Space T elescope  
•While previous sky surveys with ground-based telescopes have mainly detected giant exoplanets, TESS 
will ?nd a large number of small planets around the nearest stars in the sky 
James Webb Space T elescope 
•It is a large, space-based observatory, optimised for infrared wavelengths 
•
It is a joint project of the NASA, the European Space Agency and the Canadian Space Agency 
•
One of its major goals is observing some of the most distant events and objects in the universe, such as 
formation of the ?rst galaxies  
?These types of targets are beyond the reach of current ground ad space based instruments  
www.YouTube.com/SleepyClasses 
www.SleepyClasses.com 
!
Page 3


 
Hubble Space T elescope 
•NASA named the world’s ?rst space-based optical telescope after American astronomer Edwin P . 
Hubble, who con?rmed an “expanding” universe, which provided the foundation for the big-bang theory 
•
It was launched in April 1990 and it delivered its ?rst image in May 1990 
•Located in Low Earth Orbit, at an altitude of 547 km, inclined 28.5 degrees to the equator 
•
It completes one orbit in about 95 minutes at a speed of 27300 kmph 
•Hubble has no thrusters. T o change angles, it uses Newton’s third law by spinning its wheels in the 
opposite direction 
Spitzer Space T elescope 
•
Launched in 2003, it is the ?nal mission in NASA’s Great Observatories Program - a family of four space-
based observatories, each observing the Universe in a different kind of light  
•
The other missions in the program include the visible-light Hubble Space T elescope (HST), Compton 
Gamma-Ray Observatory (CGRO), and the Chandra X-Ray Observatory (CXO) 
•
It is designed to detect infrared radiation, which is primarily head radiation  
•
Composed of 2 components 
?Cryogenic T elescope Assembly  
?Spacecraft — controls the telescope, provides power to the instruments, handles the scienti?c data 
and communicates with Earth 
•
It needs to be simultaneously warm and cold to function properly  
?Everything in the Cryogenic T elescope Assembly must be cooled to only a few degrees above 
absolute zero. This is achieved with an onboard tank of liquid helium, or cryogen 
?Electronic equipment in the spacecraft portion needs to operate near room temperature 
•Spitzer's highly sensitive instruments allow scientists to peer into cosmic regions that are hidden from 
optical telescopes, including dusty stellar nurseries, the centers of galaxies, and newly forming planetary 
systems 
•Spitzer's infrared eyes also allows astronomers see cooler objects in space, like failed stars (brown 
dwarfs), extrasolar planets, giant molecular clouds, and organic molecules that may hold the secret to life 
on other planets 
Fermi Gamma-ray Space T elescope 
•
Formerly known as Gamma-ray Large Area Space T elescope (GLAST), is a space observatory being used 
to perform gamma-ray astronomy observations from low Earth orbit 
www.YouTube.com/SleepyClasses 
www.SleepyClasses.com 
! 
•Its main instrument is the Large Area T elescope (LAT), with which astronomers mostly intend to perform 
an all-sky survey studying astrophysical and cosmological phenomena such as active galactic nuclei, 
pulsars, other high-energy sources and dark matter 
•It also studies the gamma-ray bursts 
•
Launched in 2008, it was a joint venture of NASA and US DoE and government agencies in France, 
Germany, Italy, Japan and Sweden 
Kepler Mission 
•
It is a retired space telescope launched by NASA to discover Earth-Size planets orbiting other stars 
•
Named after astronomer Johannes Kepler, the spacecraft was launched in 2009, into an Earth-trailing 
heliocentric orbit  
•
Designed to survey a portion of Earth’s region of the Milky Way to discover Earth-size exoplanets in or 
near habitable zones and estimate how many of the billions of stars in the Milky Way have such planets  
Transiting Exoplanet Survey Satellite (TESS) 
•
It is a space telescope for NASA’s Explorers program, designed to search for exoplanets using the transit 
method in an area 400 times larger than that covered by the Kepler mission 
?It is the next step in the search for planets outside of our solar system, including those that could 
support life 
?The mission will ?nd exoplanets that periodically block part of the light from their host stars, events 
called transits 
•
It was launched on April 2018 atop a Falcon 9 rocket  
•Primary mission objective is to survey the brightest stars near the Earth for transiting exoplanets over a 
period of two-years 
•It uses an array of wide-?eld cameras to perform a survey of 85% of the sky 
•
With TESS, it is possible to study the mass, size, density and orbit of a large cohort of small planets  
•
It will provide prime targets for further characterisation by the James Webb Space T elescope  
•While previous sky surveys with ground-based telescopes have mainly detected giant exoplanets, TESS 
will ?nd a large number of small planets around the nearest stars in the sky 
James Webb Space T elescope 
•It is a large, space-based observatory, optimised for infrared wavelengths 
•
It is a joint project of the NASA, the European Space Agency and the Canadian Space Agency 
•
One of its major goals is observing some of the most distant events and objects in the universe, such as 
formation of the ?rst galaxies  
?These types of targets are beyond the reach of current ground ad space based instruments  
www.YouTube.com/SleepyClasses 
www.SleepyClasses.com 
! 
•NASA has delayed the launch of JWST, set to be the world’s biggest space observatory, until at least May 
2020 
•It will complete the scienti?c discoveries of Hubble Space T elescope and other science missions  
•
It is 100 times powerful than the Hubble Space T elescope and may ?nd the ?rst galaxies that were 
formed in the early universe 
•The infrared cameras are so sensitive that it needs to be shielded from the rays of the Sun 
?It is protected by a ?ve-layer sunshield, made of kapton 
•It will also be used to study Jupiter’s Great Red Spot by using its mid-infrared instrument (MIRI) 
•
Unlike Hubble, which observes in the near ultraviolet, visible and near infrared spectra, JWST will 
observe in a low frequency range from long-wavelength visible light through mid-infrared 
•It has to be kept very cold to observe in the infrared without interference, so it will be deployed in space 
near the Earth-Sun L2 Lagrangian point  
?L2 is a semi-stable point in the gravitational potential around the Sun and Earth. The L2 point lies 
outside Earth's orbit while it is going around the Sun, keeping all three in a line at all times. The 
combined gravitational forces of the Sun and the Earth can almost hold a spacecraft at this point, 
and it takes relatively little fuel to keep the spacecraft near L2. The cold and stable temperature 
environment of the L2 point will allow Webb to make the very sensitive infrared observations 
needed 
•
Herschel Space Observatory 
?It is an infrared telescope built by the European Space Agency, which too orbited the L2 point  
?The primary difference between Herschel and Webb is the wavelength range: Webb goes from 0.6 
to 28.5 microns; Herschel went from 60 to 500 microns 
www.YouTube.com/SleepyClasses 
www.SleepyClasses.com 
!
Page 4


 
Hubble Space T elescope 
•NASA named the world’s ?rst space-based optical telescope after American astronomer Edwin P . 
Hubble, who con?rmed an “expanding” universe, which provided the foundation for the big-bang theory 
•
It was launched in April 1990 and it delivered its ?rst image in May 1990 
•Located in Low Earth Orbit, at an altitude of 547 km, inclined 28.5 degrees to the equator 
•
It completes one orbit in about 95 minutes at a speed of 27300 kmph 
•Hubble has no thrusters. T o change angles, it uses Newton’s third law by spinning its wheels in the 
opposite direction 
Spitzer Space T elescope 
•
Launched in 2003, it is the ?nal mission in NASA’s Great Observatories Program - a family of four space-
based observatories, each observing the Universe in a different kind of light  
•
The other missions in the program include the visible-light Hubble Space T elescope (HST), Compton 
Gamma-Ray Observatory (CGRO), and the Chandra X-Ray Observatory (CXO) 
•
It is designed to detect infrared radiation, which is primarily head radiation  
•
Composed of 2 components 
?Cryogenic T elescope Assembly  
?Spacecraft — controls the telescope, provides power to the instruments, handles the scienti?c data 
and communicates with Earth 
•
It needs to be simultaneously warm and cold to function properly  
?Everything in the Cryogenic T elescope Assembly must be cooled to only a few degrees above 
absolute zero. This is achieved with an onboard tank of liquid helium, or cryogen 
?Electronic equipment in the spacecraft portion needs to operate near room temperature 
•Spitzer's highly sensitive instruments allow scientists to peer into cosmic regions that are hidden from 
optical telescopes, including dusty stellar nurseries, the centers of galaxies, and newly forming planetary 
systems 
•Spitzer's infrared eyes also allows astronomers see cooler objects in space, like failed stars (brown 
dwarfs), extrasolar planets, giant molecular clouds, and organic molecules that may hold the secret to life 
on other planets 
Fermi Gamma-ray Space T elescope 
•
Formerly known as Gamma-ray Large Area Space T elescope (GLAST), is a space observatory being used 
to perform gamma-ray astronomy observations from low Earth orbit 
www.YouTube.com/SleepyClasses 
www.SleepyClasses.com 
! 
•Its main instrument is the Large Area T elescope (LAT), with which astronomers mostly intend to perform 
an all-sky survey studying astrophysical and cosmological phenomena such as active galactic nuclei, 
pulsars, other high-energy sources and dark matter 
•It also studies the gamma-ray bursts 
•
Launched in 2008, it was a joint venture of NASA and US DoE and government agencies in France, 
Germany, Italy, Japan and Sweden 
Kepler Mission 
•
It is a retired space telescope launched by NASA to discover Earth-Size planets orbiting other stars 
•
Named after astronomer Johannes Kepler, the spacecraft was launched in 2009, into an Earth-trailing 
heliocentric orbit  
•
Designed to survey a portion of Earth’s region of the Milky Way to discover Earth-size exoplanets in or 
near habitable zones and estimate how many of the billions of stars in the Milky Way have such planets  
Transiting Exoplanet Survey Satellite (TESS) 
•
It is a space telescope for NASA’s Explorers program, designed to search for exoplanets using the transit 
method in an area 400 times larger than that covered by the Kepler mission 
?It is the next step in the search for planets outside of our solar system, including those that could 
support life 
?The mission will ?nd exoplanets that periodically block part of the light from their host stars, events 
called transits 
•
It was launched on April 2018 atop a Falcon 9 rocket  
•Primary mission objective is to survey the brightest stars near the Earth for transiting exoplanets over a 
period of two-years 
•It uses an array of wide-?eld cameras to perform a survey of 85% of the sky 
•
With TESS, it is possible to study the mass, size, density and orbit of a large cohort of small planets  
•
It will provide prime targets for further characterisation by the James Webb Space T elescope  
•While previous sky surveys with ground-based telescopes have mainly detected giant exoplanets, TESS 
will ?nd a large number of small planets around the nearest stars in the sky 
James Webb Space T elescope 
•It is a large, space-based observatory, optimised for infrared wavelengths 
•
It is a joint project of the NASA, the European Space Agency and the Canadian Space Agency 
•
One of its major goals is observing some of the most distant events and objects in the universe, such as 
formation of the ?rst galaxies  
?These types of targets are beyond the reach of current ground ad space based instruments  
www.YouTube.com/SleepyClasses 
www.SleepyClasses.com 
! 
•NASA has delayed the launch of JWST, set to be the world’s biggest space observatory, until at least May 
2020 
•It will complete the scienti?c discoveries of Hubble Space T elescope and other science missions  
•
It is 100 times powerful than the Hubble Space T elescope and may ?nd the ?rst galaxies that were 
formed in the early universe 
•The infrared cameras are so sensitive that it needs to be shielded from the rays of the Sun 
?It is protected by a ?ve-layer sunshield, made of kapton 
•It will also be used to study Jupiter’s Great Red Spot by using its mid-infrared instrument (MIRI) 
•
Unlike Hubble, which observes in the near ultraviolet, visible and near infrared spectra, JWST will 
observe in a low frequency range from long-wavelength visible light through mid-infrared 
•It has to be kept very cold to observe in the infrared without interference, so it will be deployed in space 
near the Earth-Sun L2 Lagrangian point  
?L2 is a semi-stable point in the gravitational potential around the Sun and Earth. The L2 point lies 
outside Earth's orbit while it is going around the Sun, keeping all three in a line at all times. The 
combined gravitational forces of the Sun and the Earth can almost hold a spacecraft at this point, 
and it takes relatively little fuel to keep the spacecraft near L2. The cold and stable temperature 
environment of the L2 point will allow Webb to make the very sensitive infrared observations 
needed 
•
Herschel Space Observatory 
?It is an infrared telescope built by the European Space Agency, which too orbited the L2 point  
?The primary difference between Herschel and Webb is the wavelength range: Webb goes from 0.6 
to 28.5 microns; Herschel went from 60 to 500 microns 
www.YouTube.com/SleepyClasses 
www.SleepyClasses.com 
! 
?Herschel looked for the extremes, the most actively star-forming galaxies, which emit most of their 
energy in the far-IR. Webb will ?nd the ?rst ?rst galaxies to form in the early universe for which it 
needs extreme sensitivity  
•It is designed to have a mission lifetime of not less than 5.5 years after launch  
?Lifetime is limited by the amount of fuel used for maintaining the orbit and by proper functioning in 
orbit of the spacecrafts and instruments  
?It is not serviceable like the Hubble  
•
Difference from Hubble 
?It has much larger primary mirror than Hubble (2.7 times larger in diameter, or about 6 times larger 
in area), giving it more light-gathering power 
?It also will have infrared instruments with longer wavelength coverage and greatly improved 
sensitivity than Hubble 
?It will operate much farther from Earth, maintaining its extremely cold operating temperatures, 
stable pointing and higher observing ef?ciency than with Earth-orbiting Hubble  
•
Why do we have to go to space at all? Can we not get these data with large telescopes on the ground, 
using adaptive optics? 
?Earth’s atmosphere is nearly opaque and glows brightly at most of the infrared wavelengths that 
Webb will observe  
?For those wavelengths that are transmitted to the ground, the Earth’s atmosphere blurs the images 
and causes stars to twinkle  
?Arti?cial light beacons created with strong lasers may provide better access to the sky, but the 
technology to provide a wide ?eld of view is still far in the future 
•
Webb can observe everything in our solar system that is further from the Sun than the Earth is  
•Its sensitivity will be most useful in studying the faint rocky and icy objects in the far outer Solar System, 
including the dwarf planet Pluto and other Kuiper belt objects  
•Webb will also observe the moons of the gas giant planets, comets and asteroids and the planets Mars, 
Jupiter, Saturn, Uranus and Neptune 
•
The primary mirror on Webb will be made of beryllium. The addition of beryllium to some alloys often 
results in products that have high heat resistance, improved corrosion resistance, greater hardness, 
greater insulating properties, and better casting qualities 
?Many parts of supersonic aircraft are made of beryllium alloys because of their lightness, stiffness, 
and dimensional stability 
?Other applications make use of the nonmagnetic and nonsparking qualities of beryllium and the 
ability of the metal to conduct electricity. Beryllium is toxic and no attempts should be made to work 
with it before becoming familiar with proper safeguards. The speci?c advantages to Webb are 
beryllium's light weight, stiffness and its stability at very cold temperatures 
www.YouTube.com/SleepyClasses 
www.SleepyClasses.com 
!
Page 5


 
Hubble Space T elescope 
•NASA named the world’s ?rst space-based optical telescope after American astronomer Edwin P . 
Hubble, who con?rmed an “expanding” universe, which provided the foundation for the big-bang theory 
•
It was launched in April 1990 and it delivered its ?rst image in May 1990 
•Located in Low Earth Orbit, at an altitude of 547 km, inclined 28.5 degrees to the equator 
•
It completes one orbit in about 95 minutes at a speed of 27300 kmph 
•Hubble has no thrusters. T o change angles, it uses Newton’s third law by spinning its wheels in the 
opposite direction 
Spitzer Space T elescope 
•
Launched in 2003, it is the ?nal mission in NASA’s Great Observatories Program - a family of four space-
based observatories, each observing the Universe in a different kind of light  
•
The other missions in the program include the visible-light Hubble Space T elescope (HST), Compton 
Gamma-Ray Observatory (CGRO), and the Chandra X-Ray Observatory (CXO) 
•
It is designed to detect infrared radiation, which is primarily head radiation  
•
Composed of 2 components 
?Cryogenic T elescope Assembly  
?Spacecraft — controls the telescope, provides power to the instruments, handles the scienti?c data 
and communicates with Earth 
•
It needs to be simultaneously warm and cold to function properly  
?Everything in the Cryogenic T elescope Assembly must be cooled to only a few degrees above 
absolute zero. This is achieved with an onboard tank of liquid helium, or cryogen 
?Electronic equipment in the spacecraft portion needs to operate near room temperature 
•Spitzer's highly sensitive instruments allow scientists to peer into cosmic regions that are hidden from 
optical telescopes, including dusty stellar nurseries, the centers of galaxies, and newly forming planetary 
systems 
•Spitzer's infrared eyes also allows astronomers see cooler objects in space, like failed stars (brown 
dwarfs), extrasolar planets, giant molecular clouds, and organic molecules that may hold the secret to life 
on other planets 
Fermi Gamma-ray Space T elescope 
•
Formerly known as Gamma-ray Large Area Space T elescope (GLAST), is a space observatory being used 
to perform gamma-ray astronomy observations from low Earth orbit 
www.YouTube.com/SleepyClasses 
www.SleepyClasses.com 
! 
•Its main instrument is the Large Area T elescope (LAT), with which astronomers mostly intend to perform 
an all-sky survey studying astrophysical and cosmological phenomena such as active galactic nuclei, 
pulsars, other high-energy sources and dark matter 
•It also studies the gamma-ray bursts 
•
Launched in 2008, it was a joint venture of NASA and US DoE and government agencies in France, 
Germany, Italy, Japan and Sweden 
Kepler Mission 
•
It is a retired space telescope launched by NASA to discover Earth-Size planets orbiting other stars 
•
Named after astronomer Johannes Kepler, the spacecraft was launched in 2009, into an Earth-trailing 
heliocentric orbit  
•
Designed to survey a portion of Earth’s region of the Milky Way to discover Earth-size exoplanets in or 
near habitable zones and estimate how many of the billions of stars in the Milky Way have such planets  
Transiting Exoplanet Survey Satellite (TESS) 
•
It is a space telescope for NASA’s Explorers program, designed to search for exoplanets using the transit 
method in an area 400 times larger than that covered by the Kepler mission 
?It is the next step in the search for planets outside of our solar system, including those that could 
support life 
?The mission will ?nd exoplanets that periodically block part of the light from their host stars, events 
called transits 
•
It was launched on April 2018 atop a Falcon 9 rocket  
•Primary mission objective is to survey the brightest stars near the Earth for transiting exoplanets over a 
period of two-years 
•It uses an array of wide-?eld cameras to perform a survey of 85% of the sky 
•
With TESS, it is possible to study the mass, size, density and orbit of a large cohort of small planets  
•
It will provide prime targets for further characterisation by the James Webb Space T elescope  
•While previous sky surveys with ground-based telescopes have mainly detected giant exoplanets, TESS 
will ?nd a large number of small planets around the nearest stars in the sky 
James Webb Space T elescope 
•It is a large, space-based observatory, optimised for infrared wavelengths 
•
It is a joint project of the NASA, the European Space Agency and the Canadian Space Agency 
•
One of its major goals is observing some of the most distant events and objects in the universe, such as 
formation of the ?rst galaxies  
?These types of targets are beyond the reach of current ground ad space based instruments  
www.YouTube.com/SleepyClasses 
www.SleepyClasses.com 
! 
•NASA has delayed the launch of JWST, set to be the world’s biggest space observatory, until at least May 
2020 
•It will complete the scienti?c discoveries of Hubble Space T elescope and other science missions  
•
It is 100 times powerful than the Hubble Space T elescope and may ?nd the ?rst galaxies that were 
formed in the early universe 
•The infrared cameras are so sensitive that it needs to be shielded from the rays of the Sun 
?It is protected by a ?ve-layer sunshield, made of kapton 
•It will also be used to study Jupiter’s Great Red Spot by using its mid-infrared instrument (MIRI) 
•
Unlike Hubble, which observes in the near ultraviolet, visible and near infrared spectra, JWST will 
observe in a low frequency range from long-wavelength visible light through mid-infrared 
•It has to be kept very cold to observe in the infrared without interference, so it will be deployed in space 
near the Earth-Sun L2 Lagrangian point  
?L2 is a semi-stable point in the gravitational potential around the Sun and Earth. The L2 point lies 
outside Earth's orbit while it is going around the Sun, keeping all three in a line at all times. The 
combined gravitational forces of the Sun and the Earth can almost hold a spacecraft at this point, 
and it takes relatively little fuel to keep the spacecraft near L2. The cold and stable temperature 
environment of the L2 point will allow Webb to make the very sensitive infrared observations 
needed 
•
Herschel Space Observatory 
?It is an infrared telescope built by the European Space Agency, which too orbited the L2 point  
?The primary difference between Herschel and Webb is the wavelength range: Webb goes from 0.6 
to 28.5 microns; Herschel went from 60 to 500 microns 
www.YouTube.com/SleepyClasses 
www.SleepyClasses.com 
! 
?Herschel looked for the extremes, the most actively star-forming galaxies, which emit most of their 
energy in the far-IR. Webb will ?nd the ?rst ?rst galaxies to form in the early universe for which it 
needs extreme sensitivity  
•It is designed to have a mission lifetime of not less than 5.5 years after launch  
?Lifetime is limited by the amount of fuel used for maintaining the orbit and by proper functioning in 
orbit of the spacecrafts and instruments  
?It is not serviceable like the Hubble  
•
Difference from Hubble 
?It has much larger primary mirror than Hubble (2.7 times larger in diameter, or about 6 times larger 
in area), giving it more light-gathering power 
?It also will have infrared instruments with longer wavelength coverage and greatly improved 
sensitivity than Hubble 
?It will operate much farther from Earth, maintaining its extremely cold operating temperatures, 
stable pointing and higher observing ef?ciency than with Earth-orbiting Hubble  
•
Why do we have to go to space at all? Can we not get these data with large telescopes on the ground, 
using adaptive optics? 
?Earth’s atmosphere is nearly opaque and glows brightly at most of the infrared wavelengths that 
Webb will observe  
?For those wavelengths that are transmitted to the ground, the Earth’s atmosphere blurs the images 
and causes stars to twinkle  
?Arti?cial light beacons created with strong lasers may provide better access to the sky, but the 
technology to provide a wide ?eld of view is still far in the future 
•
Webb can observe everything in our solar system that is further from the Sun than the Earth is  
•Its sensitivity will be most useful in studying the faint rocky and icy objects in the far outer Solar System, 
including the dwarf planet Pluto and other Kuiper belt objects  
•Webb will also observe the moons of the gas giant planets, comets and asteroids and the planets Mars, 
Jupiter, Saturn, Uranus and Neptune 
•
The primary mirror on Webb will be made of beryllium. The addition of beryllium to some alloys often 
results in products that have high heat resistance, improved corrosion resistance, greater hardness, 
greater insulating properties, and better casting qualities 
?Many parts of supersonic aircraft are made of beryllium alloys because of their lightness, stiffness, 
and dimensional stability 
?Other applications make use of the nonmagnetic and nonsparking qualities of beryllium and the 
ability of the metal to conduct electricity. Beryllium is toxic and no attempts should be made to work 
with it before becoming familiar with proper safeguards. The speci?c advantages to Webb are 
beryllium's light weight, stiffness and its stability at very cold temperatures 
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•The re?ective surface on Webb’s mirrors is gold. Although gold absorbs blue light, it re?ects yellow and 
red visible light, and Webb's cameras will detect that visible light 
•
Science goals 
?Search for the ?rst galaxies or luminous objects that formed after the Big Bang 
?Determine how galaxies evolved from their formation until the present 
?Observe the formation of stars from the ?rst stages to the formation of planetary systems 
?Measure the physical and chemical properties of planetary systems and investigate the potential for 
life in those systems 
•Redshift 
?It is a special astronomical case of a physical phenomenon called the Doppler effect which occurs 
when a source sending out waves (either sound or light) is moving with respect to an observer. 
When the source is moving towards the observer, waves arrive earlier than they would in the 
stationary case and the wave peaks arrive closer together (the sound is higher pitch or the light is 
bluer). If the source is moving away from the observer, the waves get more stretched out (the sound 
is lower pitch or the light is redder) 
•How far will Webb see? 
?Because of the time it takes light to travel, the further away an object is, the further back in time we 
are looking 
?Essentially, Hubble can see the equivalent of "toddler galaxies" and Webb T elescope will be able see 
"baby galaxies" . One reason Webb will be able to see the ?rst galaxies is because it is an infrared 
telescope. The universe (and thus the galaxies in it) is expanding. When we talk about the most 
distant objects, Einstein’s General Relatively actually comes into play. It tells us that the expansion 
of the universe means it is the space between objects that actually stretches, causing objects 
(galaxies) to move away from each other. Furthermore, any light in that space will also stretch, 
shifting that light's wavelength to longer wavelengths. This can make distant objects very dim (or 
invisible) at visible wavelengths of light, because that light reaches us as infrared light. Infrared 
telescopes, like Webb, are ideal for observing these early galaxies?  
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