NASA's Spitzer Space Telescope could be used to find Mars-size alien planets orbiting strange "failed stars" known as brown dwarfs, according to a new proposal by a multinational astronomy team.

The group, led by a postdoctoral researcher at MIT, proposes to use the venerable observatory to find small, rocky exoplanets around brown dwarfs, which are larger than planets but too small to ignite the nuclear fusion reactions that power stars.

Astronomers will seek planets crossing the face of these brown dwarfs, in the hopes that some of them will end up being capable of supporting life as we know it. [9 Exoplanets That Could Host Alien Life]

The planets sought would orbit more closely than Mercury does to the sun, but the faint warmth of brown dwarfs could still make such inner regions habitable, researchers said.

"Our program represents an essential step towards the atmospheric characterization of terrestrial planets and carries the compelling promise of studying the concept of habitability beyond Earth-like conditions," the team's paper stated.

Spotting small planets around brown dwarfs

The team is aiming for Mars-size planets because of their importance in planetary formation models, lead author Armaury Triaud told SPACE.com.

Models suggest our solar system emerged from a spinning disk of dust and gas, with planets slowly clumping together as particles collided, Triaud said, cautioning that we can't be completely sure of what actually occurred.

Our nascent solar system crossed an important threshold when those protoplanets reached the size of Mars, he said.

"Eventually these planet embryos, the size of Mars, those would collide and form bigger rocky planets, or the core of [gas giant] planets such as Jupiter," Triaud said.

Read this article:

NASA Telescope May Hunt for Rocky Mars-Size Planets Around 'Failed Stars'