NASA looking for another Earth
The US space agency NASA has proposed a mission to directly image planetary systems around Sun-like stars to search for Earth-like exoplanets. The Habitable Exoplanet Imaging Mission or HabEx is one of the four mission concepts currently being studied by the space agency in preparation for the 2020 Astrophysics Decadal Survey.
NASA website describes the HabEx as a large stable optical telescope in space with “unprecedented resolution” to directly image exoplanets and enable galactic, extragalactic, and solar system astrophysics. The agency says that the HabEx concept is ripe for development, being both technologically and scientifically implementable in the next decade.
As compared to the Hubble’s 2.4-metre mirror, the HabEx will have a larger mirror that is 4 meters wide. It will be used in conjunction with a starshade to search the skies for light from other planets.
The starshade would unfold once the satellite reached its orbit and fly nearly 77,000 km from the telescope, blocking light from stars but allowing light reflecting off other planets to reach the telescope’s instruments.
Even though the primary goal of the HabEx is to characterise Earth-like planets, it will also study the full range of exoplanets, providing in particular “the first complete family portraits of planets” around our nearest sun-like neighbours.
The HabEx telescope will be able to sense the ultraviolet, optical, and near-infrared photons making it sensitive to all types of planets. The telescope will characterize the atmospheric content of Earth-like exoplanets and search for signatures of habitability, such as water, by measuring the spectra of these planets. The HabEx will also be sensitive to gases in the atmosphere possibility indicative of biological activity, such as oxygen or ozone.
Hubble Space Telescope is about the size of a large school bus. Hubble has observed locations more than 13.4 billion light years away, meaning it has seen light that existed in the universe 13.4 billion years ago.