Proposed telescope swarm would hunt exoplanet heat for signs of life
A Keck Institute report outlines LIFE, a formation-flying interferometer designed to study exoplanet atmospheres in mid-infrared light.
By Priya Raghavan · Science Reporter
3 min read
A proposed space mission would use several telescopes flying in formation to study nearby exoplanets for gases linked to habitability and life. The concept, called the Large Interferometer For Exoplanets, or LIFE, is outlined in a recent W.M. Keck Institute for Space Studies report and described in a preprint posted to arXiv by Sascha P. Quanz and colleagues.
The idea targets a hard problem in astronomy: planets around other stars are faint and sit close to stars that can outshine them by billions of times. Universe Today reported that existing observatories, including the James Webb Space Telescope, have offered limited looks at exoplanet atmospheres but cannot deliver the detailed measurements needed to settle whether life as known on Earth exists elsewhere.
Many direct-imaging plans use coronagraphs, instruments that block a star’s glare so a telescope can see light reflected by a planet. NASA’s planned Habitable Worlds Observatory is expected to use that approach in visible and ultraviolet wavelengths, according to Universe Today.
LIFE would use a different part of the spectrum. The Keck Institute report says mid-infrared light, which traces heat emitted by a planet, offers a better contrast between planet and star than reflected-light observations. That wavelength range can also reveal atmospheric features associated with water, carbon dioxide, methane, ozone and, in some cases, phosphine.
A single telescope large enough to isolate those faint thermal signals would be too large for current rocket fairings, according to the report. LIFE’s designers instead propose formation-flying null interferometry: several spacecraft would collect light while flying tens to hundreds of meters apart and send it to a central spacecraft for combination.
The optical system would be designed to cancel, or null, much of the central star’s light while strengthening the signal from an orbiting planet. That would allow scientists to infer a planet’s temperature, radius and atmospheric composition from its thermal emission, according to the report.
The approach has a long history, and earlier space interferometer concepts did not advance. Universe Today noted that NASA’s Terrestrial Planet Finder-Interferometer and the European Space Agency’s Darwin concept were canceled after the required technology proved too immature.
The Keck Institute report argues the technical picture has improved. It cites advances in astrophotonics that have reduced some optical systems from bench-scale instruments to microchip-scale devices. It also points to falling commercial launch costs and planned formation-flying demonstrations, including SEIRIOS and SunRISE CubeSat missions, as steps relevant to LIFE’s design.
The report presents LIFE as a companion to the Habitable Worlds Observatory rather than a replacement. HWO would study exoplanets in visible and ultraviolet light, while LIFE would add mid-infrared thermal measurements. Combining the two data sets could help researchers distinguish biological signatures from chemical or geological processes that can mimic them, the report says.
HWO is planned for the 2040s and remains in design, according to Universe Today. LIFE is also under development, and the Keck Institute report says an international partnership would be the preferred way to spread costs rather than relying on one funding source.
The arXiv preprint, titled “Exploring Exoplanets with Interferometry,” does not make LIFE an approved mission. It lays out the case that a coordinated group of space telescopes could give astronomers a new route to testing whether potentially habitable worlds show atmospheric signs consistent with life.
This story draws on original reporting from Phys.org.