NASA's Perseverance, the most advanced rover ever sent to another world, completed its 293-million-mile journey on Feb. 18, landing safely on the surface of Mars. Tanja Bosak, an MIT geobiologist and return sample scientist on the Perseverance team, spoke to Boston Public Radio on Wednesday about the rover's mission now that it's on the Red Planet.

Perseverance will gather samples of Martian rocks and soil, which it will store and study for signs of past life, Bosak said.

"We are looking for remnants of past life," she said. "There won't be anything that's a complex organism, so everything we have to look for is microscopic. All these rocks tell a story. Depending on their chemical properties and the way they look, we can tell a history and then decide which may have been good to preserve life."

Signs of water and key chemical ingredients for life have been found in Mars' geologic history, Bosak noted. But whether or not life acutally existed on the planet remains unanswered. The Perseverance mission hopes to fill in the gaps.

"If we find life, then that will be the answer to all our dreams," Bosak said. "Just showing that some kind of life was possible and present on Mars early on would really extend the number of planets with life from one — Earth — to at least two in the solar system. That would tell us that the possibilities are truly endless."

If the samples collected by Perseverance don't show evidence of life, there's still reason to keep looking, Bosak added.

"The nature of the fossil record is so patchy that not finding something would not be the death knell for life on Mars," she said.

Bosak is featured in NOVA's "Looking For Life On Mars" documentary, which premieres tonight at 9 p.m. on GBH 2 and is streaming on the PBS video app.