NASA astronomer discusses the search for other habitable worlds
Is there another planet somewhere that might host life?
Scientists have been asking that question for decades.
NASA employee Stephen Rinehart discussed what a habitable world looks like and the process of searching for them.
Researchers including Rinehart himself are looking for exoplanets, or planets outside of our solar system, that might exhibit signs of habitability.
People theorized the idea of planets outside our system long before one had actually been discovered. Rinehart pointed out that science fiction novels had been describing all these fantasy worlds for decades before actual discovery.
“One thing that all these bits of science fiction have in common is that while they envision all sorts of different kinds of worlds, we had no evidence whatsoever there were any planets outside our solar system,” said Rinehart.
That was until 1995, when the first exoplanet was found.
NASA has searched for these planets with missions like Kepler, which found 3,779 exoplanets, but many of them are not habitable.
Rinehart said three characteristics must be present for life as we know it. The planet needs an energy source and to be a solid rock. The planet also must be within a specific distance from the sun for liquid water to be present on that planet; all life needs water to live.
Rinehart and a team of astrophysicists launched the Transiting Exoplanet Survey Satellite (TESS) in April to discover these planets.
This past week, the team released two papers about two planets found by TESS, Rinehart said. However, any astrophysicist is decades from actually finding a habitable world.
“We are not finding habitable worlds yet; we are finding planets that are not, not habitable,” said Rinehart.
Aside from the three main characteristics that must be present for habitability, the gases in the atmosphere of the planet must be suitable for life, said Rinehart. He explained why atmosphere is important by comparing Earth and Venus.
“Earth and Venus are both rocks. They have about the same diameter. They have about the same mass. They’re both made out of basically the same thing,” said Rinehart. “They’re both in the habitable zone, but one of them is habitable, and one of them is not.”
Venus is extremely hot and only has carbon dioxide in its atmosphere.
Unfortunately, figuring out what is in a planet’s atmosphere is difficult because the atmosphere is like an onion’s skin compared to the whole onion, said Rinehart.
Scientists are still years away from finding another habitable planet, but Rinehart’s work puts them one step closer to this possibility.
As for what the implications might be if we found another habitable planet, it’s hard to say, said Rinehart.
“What would it mean if we discovered that there are no other habitable planets out there, that earth is truly one in a billion?" Rinehart asked. "What would it mean, on the other hand, if we find out there are planets like earth all over the place?”
