https://www.cnbc.com/2017/08/15/solar-eclipse-why-nasa-is-sending-bacteria-into-the-sky-on-balloons.html

As the Moon blocks the Sun's light completely next week in a total solar eclipse, more than 50 high-altitude balloons in over 20 locations across the US will soar up to 100,000 feet in the sky. On board will be Raspberry Pi cameras, weather sensors, and modems to stream live eclipse footage. They'll also have metal tags coated with very hardy bacteria, because NASA wants to know whether they will survive on Mars.

Every time we send a rover to the Red Planet, our own microorganisms latch on to them and hitch a ride across space. What happens to these bacteria once they're on Mars? Do they mutate? Do they die? Or can they continue living undisturbed, colonizing worlds other than our own? To answer these questions we need to run experiments here on Earth, and the eclipse on August 21st provides the perfect opportunity.