3 days ago
James Webb Space Telescope rules out Earth-like atmosphere on rocky planet
The James Webb Space Telescope has found no signs of an Earth-like atmosphere on planet TRAPPIST-1 d, according to a study published Tuesday in The Astrophysical Journal. Using Webb's Near-Infrared Spectrograph (NIRSpec), researchers did not detect common terrestrial gases such as water vapor, methane or carbon dioxide, NASA said.
'At this point we can rule out TRAPPIST-1 d from a list of potential Earth twins or cousins,' lead author Caroline Piaulet-Ghorayeb said.
TRAPPIST-1 d is a rocky planet in a seven-world system 40 light-years away. Orbiting a cool red dwarf at just 2 per cent of Earth's distance from the Sun, it sits at the inner edge of the star's temperate, or 'Goldilocks,' zone and completes an orbit every four Earth days, NASA noted.
NIRSpec observations showed no spectral fingerprints of key atmospheric molecules.
Piaulet-Ghorayeb outlined scenarios that remain possible: an extremely thin atmosphere like Mars; a cloud-shrouded world akin to Venus that hides gases from detection; or a bare, airless rock. 'There are a few potential reasons why we don't detect an atmosphere around TRAPPIST-1 d,' she said.
Frequent high-energy flares from the system's red dwarf star can strip atmospheres from close-in planets, making retention particularly difficult.
Even so, scientists continue to probe the TRAPPIST-1 worlds because red dwarfs are the most common stars in the Milky Way, NASA said. 'We're really just getting started… and to define the line between planets that can hold onto an atmosphere, and those that cannot,' added co-author Björn Benneke.
Webb observations of planets e, f, g and h are underway. Their greater distance from the star could improve the odds of intact atmospheres, though colder conditions make detections tougher, according to NASA. 'All hope is not lost for atmospheres around the TRAPPIST-1 planets,' Piaulet-Ghorayeb said.
'As NASA leads the way in searching for life outside our solar system, one of the most important avenues we can pursue is understanding which planets retain their atmospheres, and why,' said Shawn Domagal-Goldman, acting director of NASA's Astrophysics Division.
Results from Webb lay groundwork for future missions like the Habitable Worlds Observatory.
(With inputs from NASA's official website)
