NASA scientists at JPL say they're excited and nervous about the rover Perseverance that's scheduled to land on Mars on Thursday.
"I can tell you that Perseverance is operating perfectly right now that all systems are go for landing," says Jennifer Trosper, Perseverance deputy project manager at JPL.
Scientists have to guide the rover down to the surface of the Red Planet which is a major challenge because it's arriving at 12,000 miles an hour.
Perseverance was launched in July.
It'll search for signs of ancient microbial life - and will collect rock and dust samples to take back to Earth.
It'll also test technologies that someday could be used on Mars by astronauts, including a system for converting atmospheric carbon dioxide to oxygen.
This is NASA's 5th Mars rover.