A possible new space telescope probably won’t launch for a couple of decades, if at all. But astronomers are already looking for targets for it to study — star systems with planets that could host life.

Habitable Worlds Observatory will have several jobs. As the name suggests, one of those jobs will be to scan planets for signs of life. The telescope will screen out the light from a star, allowing it to take pictures of planets around the star.

Most important, the telescope will analyze the atmospheres of planets in the habitable zone — the region around a star that’s most comfortable for life. The telescope’s instruments will look for oxygen, ozone, methane, and other substances that are pretty good signs of life.

Early estimates say the telescope will cost more than 10 billion dollars, so scientists don’t want to waste any of its time. So they’re already compiling a list of star systems with candidate planets, using findings from many telescopes in space and on the ground.

And they’re trying to learn as much as possible about the systems. They want to know if the orbits of the habitable-zone planets are stable, for example; planets with unstable orbits might not have been in the zone long enough for life to develop.

The list of possible targets already has dozens of planetary systems. But the search continues — for planets that might tell us if there’s life elsewhere in the universe.

Script by Damond Benningfield