AUSTIN, Texas The weather report from Mars shows a two-month dust storm is clearing. That fact is enabling Opportunity, one of the two solar-powered Mars Rover vehicles, to explore Victoria Crater where it has been poised since the storm began in late July.
The prolonged storm threatened to prevent Opportunity from recharging its batteries. On-board heaters which keep its electronics above 50 degrees Celsius on the cold Martian nights had almost depleted its reserves until recently, said Jim Bell, an associate professor of astronomy at Cornell University who is part of the team overseeing the nine camera systems on each vehicle.
Bell gave an update on the Mars Rovers at the Power.org conference here on Tuesday (Sept 25). "Both systems are working beautifully now 1,325 days into our 90-day mission," Bell crowed to applause from the audience of about 400 engineers.
Researchers thought the dust on Mars would cover the Rovers' solar panels within three months, preventing them from recharging their batteries and ending the mission. But they found strong Martian winds on ridges and hilltops where the robotic vehicles traveled were sufficient to blow the dust off the panels and keep the golf-cart sized Rovers going.
"We keep an eye out for windy ridges now," Bell said.
The vehicles have cataloged a wide variety of volcanic and sedimentary rock formations, giving credence to theories there was once water on the planet. Science Magazine named the Rovers the breakthrough of the year in 2004 for their findings.
"Mars may have been a habitable environment at one time, maybe the most habitable environment we have found outside Earth," said Bell referring to one area Opportunity explored he called a former beach.
The Spirit Rover, which landed in the Gusev Crater, has now traveled some 7.2 kilometers to explore nearby hilltops and ridges, far beyond its anticipated mission of moving about 500 meters. The vehicles travel at a sometimes excruciatingly slow pace. Researchers sometimes learned the hard way about navigating a vehicle on another planet.
On one occasion Opportunity's front wheels became buried in sand. It took remote drivers six weeks to extricate the vehicle.
"We got ultra conservative after that. No more 200-meter days," Bell said of the Rover's pace.
When the robotic motor on one of Spirit's front wheels broke down in May of this year, researchers had to drive the vehicle backwards. The failure turned fortuitous when the small trench the broken wheel created turned up white powder that initially has been identified as a mix of sulfurous salts and silica.
"We are still in the middle of a mystery trying to figure out what these enigmatic deposits are," Bell said.
Infrared signals captured by the Rover's CCD imagers help define the composition of some of the elements on Mars. "Right now we don't have any tools to determine the age of these rocks though, and that's frustrating," he said.
Engineers are now designing a next-generation Rover. Putting more storage on the system and providing more bandwidth between the Rover and an orbiter to which it relays signals are two of the changes they are working on.
"What we have right now is the equivalent of a 56K modem," Bell said. Nevertheless he was able to show numerous panoramic images captured by the vehicles.
The Rovers lifted off in on separate rockets in the summer of 2003 and landed in January 2004. Bell showed video of teams of engineers celebrating the first word that the Rovers landed safely after a five-year effort to design, build and launch them.
"I am sure many of you have been involved in highly stressful projects before, and I hope you live to see big burly engineers weeping with joy when they succeed," Bell said.
"We certainly have been blessed to work on a project like this," he added.