Free Astronomy Magazine March-April 2022

10 small adjustments will be required with its onboard thrusters to main- tain Webb’s halo orbit. Despite the massive sunshield sandwiched be- tween the mirrors and we observers, the JWST geometry still allows it to observe any part of 40% of the uni- verse at any one time. With this wide access, JWST can observe any point in the IR-observable universe – with the notable exception of any location within the Sun-JWST radius, of course – in just the six months it takes it and ourselves to make one- half orbit around the Sun. To solve the problem of radiation from internal components, JWST used the same solution – move the entire equipment bus to the Sun- side of the five sunshields, leaving the telescope optics, detectors, and support structures almost completely isolated from the hardware doing the movement, data processing, and communications with the NASA Deep Space Network. With the five sunshields and additional radiators I n this photo provided by NASA, the James Webb Space Telescope is separated in space on Saturday, Dec. 25, 2021. The instrument soared from French Guiana on South Amer- ica’s northeastern coast, carried by a European Ariane 5 rocket into the Christmas morning sky. The $10 bil- lion infrared observatory is intended as the successor to the aging Hubble Space Telescope. [NASA via AP] in place, the mirrors and detectors can all be kept under 50 K (-223 °C, or -370 °F) by the 5 th layer, below the temperature at which any of the directly between the Sun and Earth, leading/training the Earth in its orbit (and exposed to both bodies), or completely on the other side of the Sun. In the arrangement at L2 and with its massive sunshield in place and oriented back towards the Sun, the limits of the telescope sensitivity are determined by other nearby ce- lestial sources – for which a source as faint as zodiacal light is a primary limiter. Its placement at L2 also means that gravity alone will do the work of moving the scope to study the universe and only relatively