We thought it would be interesting to compare two of the most pimped rover designs of all time.
NASA's two Mars Exploration Rovers (MER) Spirit and Opportunity landed on Mars in early 2004 and are still going strong, racking up impressive distances over the red planet. But way back in the 1970s the Soviet Union landed two equally impressive rovers of its own on the Moon in the Lunakhod programme.
Let's have a look at some key statistics:
Compared to MER, the Lunakhod is more than 4 times the weight, making it a veritable tank. But after almost half a century, NASA will finally catch up on that statistic with its upcoming Mars Science Laboratory rover mission, which will weigh even more than the Lunakhod rovers.
MER Opportunity started its explorations of Mars in January 2004 from its "hole in one" landing site in a martian crater, shown in the below photograph, which was taken from Mars orbit by the Mars Reconnaissance Orbiter (MRO). Since then it has covered an impressive 11.7km of Martian surface, but that is still far short of the 37km achieved by Lunakhod 2. But with both MER rovers are still alive and moving that record may yet fall.
Driving rovers around the Moon is far quicker than on Mars. The round trip time communications delay to the Moon is only a couple of seconds, meaning that a driver on Earth can control a lunar rover in near real-time. The Lunakhod rovers were driven in this manner, controlled by a five-man team of controllers (pictured below) who used TV images taken by the rover's three low-rate TV cameras.
Unlike lunar rovers, Mars rovers have a far greater communications delay to Earth (many minutes) meaning that their route must be pre-programmed with navigation waypoints, hence the lower speed of the MER design.
The Google Lunar X PRIZE (GLXP) mission won't require rovers anywhere near as big as these two giants, but it may be able to re-use at least some aspects of their designs such as navigation software and communications hardware. GLXP teams will have some freedom to choose their rovers' speed since the 500m roving requirement is not very demanding. However, to make their missions more profitable, teams might consider using a relatively high speed rover in order to enable other commercial activities after the primary GLXP mission is completed but before the approximately two weeks of lunar daylight is exhausted.
- JPL's Opportunity mission update page
- Timeline of Soviet Lunar Exploration