The Soviet PrOP-M twin Mars rovers were carried by the Mars 2 and Mars 3 landers in 1971. Each autonomous mobile device was designed to move up to 15 metres over the Martian surface on skis while tethered to its lander, carrying penetrometer and gamma-ray density experiments; Mars 2 crashed and Mars 3 lost communications before rover deployment.
Alerts for directly linked future launches and major activity.