Satellite Technology Feature Article
Curiosity Mars Rover's Slow March
By Doug Mohney, Contributing Editor
The August arrival of NASA's Curiosity Mars Science Lab (MSL) rover to the surface of the Red Planet was dramatically hyped as "Seven Minutes of Terror" for its rapid plunge and deceleration through Mars' atmosphere, followed by a delivery with a "Sky Crane." Having been safely delivered, the $2.5 billion Curiosity rover is now puttering along at a turtle's pace towards its primary objectives.
NASA has been trying to sustain the public surge of enthusiasm in Curiosity's mission to explore Mars with a steady stream of press conferencing and the latest visual science -- i.e., pictures -- but the reality is that interest will soon wane as the rover slowly gets to work -- the key word being "slowly."
Since landing on Mars inside of Gale Crater on August 5, 2012, Curiosity has driven a total of 385 feet and is now stopping for several days of prep work to work out its seven foot robotic arm and all of its tools. NASA Jet Propulsion Laboratory (JPL) Curiosity mission manager Michael Watkins says it will "a week or so" to work out the arm, calibrating instruments.
Curiosity will take another few weeks to travel eastwards towards its first major science destination once it finishes its robotic arm checkout. There are a number of reasons why the rover is moving at a slow pace. The $2.5 billion nuclear powered rover is a one-of-a-kind model with plenty of features operators and scientists are just starting to tap into. There's between four to 22 minutes of communications lag between Earth and Mars depending on the relative distance between the two planets, so each set of rover operations has to be carefully choreographed, tested and uploaded. No one wants to make a mistake that would (figuratively and literally) put the expensive robot into a ditch. There's no AAA service to fix or repair broken parts out on Mars.
Once performed, Curiosity has to transmit back all of the data it has recorded from its instruments and cameras, but it doesn't have much bandwidth to send back results. There's a single X-band radio that can either transmit omni-directionally at a paltry 15 bits per second or at a higher 32 kbps by using a high-gain pointed antenna. Supplementing that are a pair of UHF radios that use two orbiting satellites as relay stations back to earth with speeds between two Mbps and 256kbps, but the orbiters only are in Curiosity's UHF line-of-sight for about eight minutes per day.
Most importantly, Curiosity is on Mars to see new things up close and in fine detail -- and everything it will see roaming around is new. Only two small U.S. rovers have traveled short distances on Mars, so every foot traveled by the rover is another foot adding to our knowledge of the Red Planet.
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Edited by Brooke Neuman