Mars Exploration Rover team members on July 21, 2009, tested how altering the order in which individual wheels turn for steering affects how those turns dig the wheels deeper into soft soil. From left: Alfonso Herrera, Vandana Verma, Bruce Banerdt.
Today, NASA is offering a chance to go one-on-one with the team of engineers who are working to free the stuck Mars rover Spirit.
So if you've got an idea for how to liberate the Martian rover from its sandy trap on the red planet ? or have a question for how the engineers are working on ways to get the rover out ? today?s NASA webcast is the time to ask. Call it Operation: Free Spirit.
Spirit has been stuck in Martian dirt up to its hubcaps since May 6, when it became mired in a dirt patch (now called "Troy") while driving backward.
Because they don't want to damage Spirit while trying out ways to get the rover out of its sand trap, mission engineers are using a replica model here on Earth.
Two members of the engineering team ? John Callas, project manager for NASA's Mars Exploration Rovers, and Ashley Stroupe, deputy lead for "Free Spirit" testing ? will talk about their efforts in a live webcast from NASA's Jet Propulsion Laboratory in Pasadena, Calif. at 6 p.m. EDT at the following web address: http://www.ustream.tv/channel/nasajpl
Questions can be submitted via Ustream or Twitter (to @NASAJPL using the hashtag #FreeSpirit) during the webcast and in advance to email@example.com.
The team has already received suggestions from fans of the hard luck rover, including using the robotic arm to hoist the robot out of the sand. But the arm doesn't have enough force to lift the hefty rover, Callas said.
"The rover's far too massive, far too heavy," Callas said. Spirit and its robotic twin Opportunity are each the size of a golf cart.
Other suggestions have included using the robotic arm to push sand away from the wheels, or underneath them for better traction. "And that's an interesting idea," Callas said, but would have to be looked at much later in the testing process.
At the end of June, the test rover was set up in a plywood rig in a dirt pit at JPL. The rig is filled with a dirt concoction mixed to mimic the properties of the sand in which Spirit is stuck. It is also tilted at a 10-degree angle - the same angle of the slope that Spirit is stuck on.
Engineers also placed a rock underneath the test rover's belly because images taken last month by the microscopic imager at the end of Spirit's robotic arm. After analyzing the image, mission managers determined that a dark blob in the middle was a rock positioned underneath the rover.
Mission engineers finally began testing out possible maneuvers on July 6. So far, they have tried out driving forward, backward, and then a series of crab-like moves. They have also tried out pivoting around the rover's bum right-front wheel, which has been inoperable for three years.
"We're looking at all the kinds of motion we can try," Callas said.
Some of these tests will be played during the live webcast.
Mission operators have found evidence that the dirt in which Spirit is stuck isn't uniform: the sand on the right side of the rover seems to be more compacted and have better traction than that on the right," so we want to try and exploit that," Callas told SPACE.com.
To better simulate Spirit's situation, the engineers plan to take out the mock Mars sand under the right side of the test rover and replace it with dirt that has properties closer to the stuff under Spirit.
After the team has run through their series of test moves with the new dirt mixture, they hope they'll have an idea of what maneuver might work best.
"We want to try the very best thing the first time," Callas said. "Our first chance will be our best chance" to get the rover free.
"We do want to start trying things on Mars fairly soon," Callas said. But since the rover has plenty of juice and is doing science in its current spot, the team isn't in any hurry.
"We have time on our hands," Callas said.
- SPACE.com Video Show - Rover Tracks on Mars
- Video - Spirit: The Little Rover That Could
- The Most Amazing Mars Rover Discoveries
To watch NASA?s Mars rover webcast at 6 p.m. EDT today, visit here: http://www.ustream.tv/channel/nasajpl