Short answer: No.
But to read the click-bait headlines circulating on the internet in the last couple of days, you’d think so. All you need to do is read NASA’s own announcement — just the first paragraph:
NASA’s Curiosity rover has found new evidence preserved in rocks on Mars that suggests the planet could have supported ancient life, as well as new evidence in the Martian atmosphere that relates to the search for current life on the Red Planet. While not necessarily evidence of life itself, these findings are a good sign for future missions exploring the planet’s surface and subsurface.
One wonders how many consumers of online content even looked. The internet has trained us to be distracted and think poorly (don’t believe that, then read this telling — and disheartening — book: The Shallows: What the Internet Is Doing to Our Brains).
But let’s say NASA uncovers microbial life on Mars. Is that evidence of panspermia (the idea that life on earth originated from outer space).
Short answer: No.
The reason is simple. You’d have to prove life on Planet A (Mars) got to Planet B (earth). There’s no way to know that. Even if the life forms were of the same type, the process could have worked in reverse. No way to know.
There are two broad theories of panspermia:
(1) cosmic ancestry, which asserts that life has always existed everywhere in the universe. Life has no single point of origin. A discovery of life on Mars would support this view in principle — but you’d need to discover life on all sorts of planetary bodies to actually prove the idea.
(2) life traveled from one place in space to another. This is the more common idea. This one requires some sort of travel mechanism. There are two varieties of this idea: (a) directed (“intelligent”) panspermia (life was put here by intelligent aliens or was part of God’s evolutionary plan — for those theists who embrace evolution), and (b) undirected (“non-intelligent”) panspermia (the mechanism was a random natural event, like a meteor shower).
In view of the above you’ll now see a small (but enduring) spike in the ancient aliens community about how life was put here by aliens, how Zecharia Sitchin was right, how nibiru was part of this, etc., etc. All nonsense — the same as it was a few days ago.