Habitable Exoplanets Observatory

The Habitable Exoplanet Observatory (HabEx) is a space telescope concept that would be optimized to search for and image Earth-size habitable exoplanets in the habitable zones of their stars, where liquid water can exist. HabEx would aim to understand how common terrestrial worlds beyond the Solar System may be and determine the range of their characteristics. It would be an optical, UV and infrared telescope that would also use spectrographs to study planetary atmospheres and eclipse starlight with either an internal coronagraph or an external starshade.

The proposal, first made in 2016, is for a large strategic science missions NASA mission. It would operate at the Lagrange point L2.

In January 2023, a new space telescope concept was proposed called the Habitable Worlds Observatory (HWO), which draws upon HabEx and the Large Ultraviolet Optical Infrared Surveyor (LUVOIR).

In 2016, NASA began considering four different space telescopes as the next Flagship (Large strategic science missions) following the James Webb Space Telescope and Nancy Grace Roman Space Telescope. They are the Habitable Exoplanet Observatory (HabEx), Large Ultraviolet Optical Infrared Surveyor (LUVOIR), Origins Space Telescope, and Lynx X-ray Surveyor. In 2019, the four teams turned their final reports over to the National Academy of Sciences, whose independent Decadal Survey committee advises NASA on which mission should take top priority.

The Habitable Exoplanet Imaging Mission (HabEx) is a concept for a mission to directly image planetary systems around Sun-like stars. HabEx will be sensitive to all types of planets; however its main goal is to directly image Earth-size rocky exoplanets, and characterize their atmospheric content. By measuring the spectra of these planets, HabEx will search for signatures of habitability such as water, and be sensitive to gases in the atmosphere potentially indicative of biological activity, such as oxygen or ozone.

In 2021, the National Academy of Sciences released its final recommendations in the Decadal Survey. It recommended that NASA consider a new 6-meter (20-foot) aperture telescope combining design elements of LUVOIR and HabEx. The new telescope would be called the Habitable Worlds Observatory (HWO). A preliminary launch date was set for 2040, and the budget was estimated to be $11 billion.

HabEx's prime science goal is the discovery and characterization of Earth-sized planets in the habitable zones of nearby main sequence stars, it will also study the full range of exoplanets within the systems and also enable a wide range of general astrophysics science.

In particular, the mission will be designed to search for signs of habitability and biosignatures in the atmospheres of Earth-sized rocky planets located in the habitable zone of nearby solar type stars. Absorption features from CH
₄, H
₂O, NH
₃, and CO, and emission features from Na and K, are all within the wavelength range of anticipated HabEx observations.