Since we know that material from Mars has reached earth in the form of meteorites, it is indeed possible (if not probable) that earth materials have been blasted out and have landed on Mars.
We should obviously always be careful, but methinks this may be much ado about something that’s already happened - through natural forces.
Here we go.
“We found life on Mars but we might have been the ones that sent it there...”
I am 100% convinced they absolutely already know there is life there, and NOT life we sent, but are afraid of announcing it, and will make up whatever it takes to avoid it!
I actually have a Mars meteorite, it’s a piece of a rock discovered, I believe, in Antarctica.
It’s very, very possible, even extremely likely, that some of the meteor/asteroid impacts on Earth in the past have sent material far enough up and away to eventually get to Mars.