Starshade could help space telescopes to observe exoplanets
– News of June 9, 2019 –
To observe exoplanets is very difficult. We must work on contrasts. The stars are indeed much brighter than their planets. Ideally, it is much easier to be able to hide the light of the star to focus only on the surrounding planets. This is what we try to do with coronographers like the one that will equip the WFIRST space observatory.
NASA is currently studying another solution called Starshade. It is a huge sun visor whose mission would be to block the light of a star while letting the light of its planetary system. Given its size, it should be placed at a great distance from the telescope with which it will work to get the right angle, typically tens of thousands of kilometers. The big advantage of a device like Starshade is that it can work with an already launched space telescope. James Webb Space Telescope or WFIRST would for example be very good candidates to form a duet with Starshade.
Starshade’s petal shape is designed to eliminate as much of the star’s diffraction pattern as possible. With such a system, it should be possible to directly observe exoplanets evolving around stars up to 30 light years from us. If enough light is collected, spectroscopy could be made to determine the composition of the atmosphere and the surface of the exoplanets.
NASA assembled a small demonstrator of Starshade in 2014. The project is estimated at $ 750 million for the sun visor alone, 3 billion if we add a dedicated telescope. For the moment, the Starshade project is not funded, but NASA is continuing research on the technologies needed for its development.
Image by NASA / JPL