SpaceOdysseyHub · Mission Worksheet

JWST: Seeing the Invisible

Ages 11–14 · Ages 14–18 · 40 min · spaceodysseyhub.com/replays/jwst

Name: Date:

Mission objectives

Explain why Webb observes in infrared light and why that requires the telescope to be extremely cold
Describe why Webb orbits the Sun–Earth L2 point 1.5 million km away instead of orbiting Earth like Hubble
Analyze the engineering risk of the deployment sequence — 344 single-point failures with no possibility of repair
Interpret what a deep-field image shows: thousands of galaxies whose light left them more than 13 billion years ago

1.Put these mission events in order: sunshield deployment · launch from Kourou · first deep field released · arrival at L2 · mirror wings latched.short answer
2.Webb is about 1.5 million km away and light travels about 300,000 km each second. Calculate the one-way delay for a radio command, and the round trip for command-plus-confirmation.calculation
3.During the First Light stop, study the deep field for one minute. Write down three different things you notice about the shapes or colours of the galaxies.observation
4.Hubble could be repaired by astronauts; Webb never can be. If you ran the mission, which would you choose for the next great telescope — serviceable but warm in Earth orbit, or unreachable but cold at L2? Defend your answer.discussion
5.In your own words: why does looking at very distant galaxies mean looking back in time?short answer

infrared: — Light with wavelengths longer than red — invisible to our eyes, but we feel it as heat. Webb is built to see it.
sunshield: — Webb's five-layer, tennis-court-sized screen of thin Kapton film that blocks heat from the Sun, Earth, and Moon so the telescope can stay cold.
L2 (Lagrange point): — A gravitational balance point about 1.5 million km beyond Earth where a spacecraft can orbit the Sun in step with Earth, keeping Sun, Earth, and Moon all in one direction.
deep field: — A long-exposure image of a tiny, seemingly empty patch of sky that reveals thousands of extremely distant galaxies.
redshift: — The stretching of light to longer, redder wavelengths as the universe expands — light from the first galaxies has been stretched all the way into the infrared.

Teacher answer key — do not photocopy with page 1

1.Launch (Dec 25, 2021) → sunshield deployment → mirror wings latched → arrival at L2 (30 days after launch) → first deep field released (July 12, 2022).
2.One way: 1,500,000 ÷ 300,000 = 5 seconds. Round trip: about 10 seconds.
3.Open response — no fixed answer.
4.Open response — no fixed answer.
5.Light travels at a finite speed, so light from a galaxy 13 billion light-years away took 13 billion years to arrive — we see the galaxy as it was when the light left, not as it is now.

Why must Webb's telescope side be kept near −233 °C? — A warm telescope would glow in infrared and drown out the faint signals it hunts
What made Webb's deployment the most nerve-racking month in its mission? — It had 344 single-point failures that each had to work perfectly, with no repair possible
Webb's primary mirror is made of… — 18 gold-coated beryllium hexagons forming a 6.5-metre mirror
Why does Webb orbit the Sun–Earth L2 point instead of orbiting Earth? — At L2 the Sun, Earth, and Moon stay in one direction, so one sunshield can block all their heat
Webb's first deep field (SMACS 0723) covers a patch of sky about the size of… — A grain of sand held at arm's length