On the surface of the Red Planet, a titanium tube with a rock sample was positioned there by NASA's Perseverance Mars rover.
The rover will set down a total of 10 tubes at the "Three Forks" location over the course of the following two months.
This would create the first sample depot for humans on an extraterrestrial planet, a significant first stage in the Mars Sample Return effort.
Perseverance has been collecting duplicate samples from the mission's chosen rock targets.
The rover would transfer samples to a future robotic lander based on the design of the Mars Sample Return campaign.
The sample container would be captured by another spacecraft and sent back to Earth safely after the lander uses a robotic arm to place the samples in a containment capsule.
If Perseverance is unable to deliver its samples, the depot will act as a backup.
In that situation, two Sample Recovery Helicopters would be dispatched to complete the task.
The mission has programmed a sequence of instructions for Perseverance to carefully tip the tube over using the robotic arm's attachment to the turret.
They'll have more opportunities in the coming weeks as the rover drops off more samples at the Three Forks cache to determine whether Perseverance needs to employ the method.