A titanium tube containing a rock sample is resting on the Red Planet's surface after being placed there on 21 December by NASA's Perseverance Mars rover.
Over the next two months, the rover will deposit a total of 10 tubes at the location, called Three Forks, building humanity's first sample depot on another planet.
The depot marks a historic early step in the Mars Sample Return campaign. Perseverance has been taking duplicate samples from rock targets the mission selects.
The rover currently has the other 17 samples (including one atmospheric sample) taken so far in its belly. Based on the architecture of the Mars Sample Return campaign, the rover would deliver samples to a future robotic lander.
The lander would, in turn, use a robotic arm to place the samples in a containment capsule aboard a small rocket that would blast off to Mars orbit, where another spacecraft would capture the sample container and return it safely to Earth.
The depot will serve as a backup if Perseverance can't deliver its samples. In that case, a pair of Sample Recovery Helicopters would be called upon to finish the job.
"Seeing our first sample on the ground is a great capstone to our prime mission period, which ends on Jan. 6," said Rick Welch, Perseverance's deputy project manager at the Jet Propulsion Laboratory (JPL). "It's a nice alignment that, just as we're starting our cache, we're also closing this first chapter of the mission."