Earth-like planet that may contain water studied by NASA’s Webb telescope

Scientists are observing an Earth-like exoplanet that may contain water using NASA’s James Webb Space Telescope, the space agency said in a news release. 

The exoplanet, known as TRAPPIST-1 e, orbits the red dwarf star TRAPPIST-1. The system was discovered in 2017. There are seven Earth-sized worlds orbiting the star, but planet e is the only one that is at a distance where water on the surface is “theoretically possible,” NASA said. However, astronomers still need to determine if the planet has an atmosphere. 

To look for an atmosphere, NASA scientists directed the Webb telescope’s Near-Infrared Spectrograph instrument at the TRAPPIST-1 system as planet e passed in front of the star. If the planet has an atmosphere, the starlight that passes through it will be partially absorbed. That will create dips in the light spectrum that reaches the spectrograph. Those dips will allow scientists to determine if the planet has an atmosphere and what chemicals it might be made of. 

Scientists are also studying the light spectrum of another exoplanet in the system called TRAPPIST-1 b. Researchers have determined that planet has no atmosphere, NASA said, so comparing its output to that of TRAPPIST-1 e allows for a fuller picture of the potential atmosphere on that planet. 

“Webb’s infrared instruments are giving us more detail than we’ve ever had access to before, and the initial four observations we’ve been able to make of planet e are showing us what we will have to work with when the rest of the information comes in,” said Néstor Espinoza of the Space Telescope Science Institute in Baltimore, Maryland, a principal investigator on the research team. Espinoza and the research team recently published two scientific papers outlining their initial results. 

Researchers “feel confident” that TRAPPIST-1 e does not have a primary atmosphere. A primary atmosphere would be made of hydrogen and helium that would have been present when the planet was formed. But the star the planet orbits is “very active,” with “frequent flares,” NASA said, which create stellar radiation that may have “stripped off” that primary atmosphere. However, TRAPPIST-1 e may have built up a “heavier secondary atmosphere.” Many planets, including Earth, have done this, NASA said. Further research with the Webb telescope and its instruments will determine the types of atmosphere and its makeup.

There are also many possibilities for water on the planet. There may be none at all, NASA said. TRAPPIST-1 e might also contain an ocean or wide swath of water. One side of the planet is always in darkness, so there may also be ice, NASA said. If there is liquid water on the planet, the NASA researchers say there would also be a greenhouse effect, where gases like carbon dioxide keep the atmosphere stable and warm the planet. 

“We are really still in the early stages of learning what kind of amazing science we can do with Webb. It’s incredible to measure the details of starlight around Earth-sized planets 40 light-years away and learn what it might be like there, if life could be possible there,” said Ana Glidden, a post-doctoral researcher at Massachusetts Institute of Technology’s Kavli Institute for Astrophysics and Space Research, who led the research on possible atmospheres for planet e, in NASA’s news release. “We’re in a new age of exploration that’s very exciting to be a part of,” she said.