Some time in the next few days NASA will launch a new rover at Mars. Called the Mars Science Laboratory (MSL), the mission will land a one ton, Pu-238 powered robotic explorer on Mars. Called Curiosity, the vehicle will explore the surface of Mars far more extensively than other rovers; bigger, better and more powerful.
Landing a large mass on Mars is a difficult challenge. The atmosphere is thick enough to prevent rockets being used to provide significant deceleration, as flying into the plume at supersonic speed is notoriously unstable. Also, the atmosphere is too thin for parachutes and aerobraking alone to be effective. Although some previous missions have used airbags to cushion the shock of landing, the MSL is too large for this to be an option.
Hence the final touchdown of the vehicle will be achieved by using a robotic “skycrane”. “At roughly 7.5 m (25 ft) below the descent stage the sky crane system slows to a halt and the rover touches down. After the rover touches down it waits 2 seconds to confirm that it is on solid ground and fires several pyros (small explosive devices) activating cable cutters on the bridle and umbilical cords to free itself from the descent stage.”
All the known planets of the solar system, including Pluto (if one still considers it a planet) are now the subject of unmanned missions. Advances in autonomous robotics will make these missions more capable. One spacecraft, New Horizons, is halfway to Pluto and what it finds may tell us more about the composition of the further reaches of the Kuiper Belt.
The sophistication of robotic devices has now attained a gee-whiz quality. It is hard to believe that when Ray Bradbury watched the photos from Viking being beamed back in 1976 at the JPL he was moved to say “WE are the Martians! We’re going to be here for the next million years. At long last, WE ARE MARTIANS!” That was primitive stuff compared to what is possible today.
Certainly an indigenous Martian might be alarmed at seeing Curiosity trundle along? How would an indigenous Martian regard the descent of terrestrial robotic explorers? Here’s one video which explores exactly that scenario.