CDS (II) 2022 General Knowledge · Question 30 of 120

Correct — C, Both 1 and 2. NASA's own mission page carries both claims in almost the words the paper used. On size it says 'The Webb Space Telescope is the largest, most powerful and most complex telescope ever launched into space', which settles statement 1. The number behind that is the primary mirror: 6.5 metres across, built from eighteen gold-coated beryllium hexagons that had to be folded to fit inside the rocket and unfolded afterwards, against the 2.4-metre single mirror of Hubble. On ownership NASA says 'It is a joint NASA/ESA/CSA mission', which settles statement 2. The division of labour is worth remembering, because it explains why the partnership is real rather than nominal — the European Space Agency supplied the Ariane 5 launch from Kourou in French Guiana on 25 December 2021 along with two of the four science instruments, and the Canadian Space Agency supplied the Fine Guidance Sensor that keeps the telescope pointed steady, together with an imager and slitless spectrograph.

• (a)1 only — Accepts the size claim but drops the partnership. Webb is not a NASA-only project; the European and Canadian agencies are formal partners and each contributed flight hardware, and ESA also provided the launch.
• (b)2 only — Accepts the partnership but rejects the size claim. It is tempting if you are thinking of the International Space Station, which is far larger — but the station is not a telescope or an observatory, and among space observatories Webb is the largest ever flown.
• (d)Neither 1 nor 2 — Both statements are supported by NASA's own description of the mission, so nothing here is left to reject.

The James Webb Space Telescope is an infrared observatory, and that single fact explains its design. Infrared light is heat, so the telescope must be kept extremely cold or its own glow would drown the sky; hence the tennis-court-sized five-layer sunshield and a station far from the warmth and light of Earth. Webb does not orbit the Earth. It works in a halo orbit around the Sun-Earth L2 point, roughly 15 lakh kilometres beyond Earth's orbit, circling the Sun in step with the Earth so that the Sun, Earth and Moon stay on the same side and can all be blocked by the one shield. Working in the infrared lets it see the most distant galaxies, whose light has been stretched into those wavelengths by the expansion of the universe, and see through the dust that hides star formation from optical telescopes.

For the September 2022 exam this was fresh news rather than settled syllabus: Webb had launched on 25 December 2021, reached L2 in January 2022, and released its first full-colour science images on 11 July 2022, entering service the next day. Both statements were therefore easy for a candidate who had read that year's science pages. The reasonable-sounding way to talk yourself out of statement 1 is to think of something bigger in orbit — but 'observatory' is the operative word, and the comparison that matters is with Hubble, Spitzer, Herschel and Chandra, all of which Webb dwarfs. Statement 2 rewards the habit of noticing who else is on a mission patch. On present-day status, Webb has been returning science continuously since July 2022 and, unlike Hubble, sits far too distant to be visited or repaired; its lifetime is set by the fuel it carries for station-keeping, and the unusually accurate Ariane 5 launch left it with enough for well beyond its ten-year target.

• NASA describes Webb as 'the largest, most powerful and most complex telescope ever launched into space'.
• It is a joint NASA, European Space Agency and Canadian Space Agency mission; ESA also provided the Ariane 5 launch.
• It launched on 25 December 2021 from Kourou in French Guiana, and entered full science service on 12 July 2022.
• Its primary mirror is 6.5 metres across, made of eighteen gold-coated beryllium segments, against Hubble's single 2.4-metre mirror.
• It observes in the infrared and operates in a halo orbit about the Sun-Earth L2 point, about 15 lakh kilometres beyond Earth's orbit — it orbits the Sun, not the Earth, and nothing is ever stationary at L2.

• Saying Webb orbits the Earth, or that it is stationary at L2; it orbits the Sun in a halo path around that point.
• Assuming a mission with a NASA name must be a NASA-only mission.
• Treating Webb as a replacement for Hubble; they observe different wavelengths and overlap only at the red end.

As a two-statement item on ownership and superlatives, or as a single-line question on where Webb actually sits.

• practice — not a real PYQ

  The James Webb Space Telescope observes the universe chiefly in which part of the electromagnetic spectrum?

  • (a)X-ray
  • (b)Infrared
  • (c)Radio
  • (d)Ultraviolet

  Answer(b) Infrared — which is why it carries a five-layer sunshield and is stationed far from the warmth of the Earth.

• practice — not a real PYQ

  The James Webb Space Telescope was launched in December 2021 on a rocket supplied by which agency?

  • (a)NASA
  • (b)The Canadian Space Agency
  • (c)The European Space Agency
  • (d)Roscosmos

  Answer(c) The European Space Agency — an Ariane 5 from Kourou in French Guiana, ESA's contribution to the joint mission alongside two science instruments.