Old Gimpy Wheel on Spirit Rover Shows Signs of Life

Could it be true that the old gimpy wheel on the Spirit rover is making a comeback? The right-front wheel, which stopped operating way back on Sol 779 (March 13, 2006), surprised engineers by indicating normal resistance and turning slightly during a resistance test for that wheel. Spirit, which has been stuck in soft soil for several months, recently got bad news that the right rear wheel also stopped working (Nov. 21), leaving her with just four of six wheels operational. Engineers conducted tests on Dec. 12 and the right rear wheel continued to show no motion and exhibited very high resistance in the motor winding. Just for fun (I’m assuming) engineers also test the right front wheel – the wheel that Spirit has limped with in coming down from the top of Husband Hill and making the trek across Gusev Crater to the Home Plate region where she currently sits. In surprises of all surprises, the old gimpy wheel showed signs of life.

Diagnostic tests were run on Spirit’s right-rear wheel and right-front wheel on Sol 2013 (Dec. 12, 2009). The recently stalled right-rear wheel continued to show no motion. Engineers expected nothing from the right front wheel. The last time it was checked was just after its apparent failure in 2006 and at that time indicated an open circuit. JPL says that although no clear theory for failure had been established, the failure was generally regarded as permanent.

JPL also says it is important to remember that the Sol 2013 test of the right-front wheel was only a rotor resistance test, and no conclusions can be drawn at this point without further testing.

The plan for Spirit on Sol 2116 (Dec. 15) is to command a drive, which will test the functionality of both the right-front and the right-rear wheels. The results are expected Wednesday.

Spirit continues to surprise….stay tuned!

Mars Exploration Rover

Mars Rover. Image credit: NASA/JPL


One of the most successful mission ever sent to Mars is the Mars Exploration Rover program, with the two rovers Spirit and Opportunity. They were launched separately to Mars in 2003 and landed safely several months later. They were supposed to last about 3 months on the surface of Mars, but have now survived more than 5 years.

Spirit and Opportunity used technology developed with the Mars Pathfinder mission. They used an airbag system to land on the surface of Mars without using retrorockets to touch down gently. They also use the rover technology first used with the Sojourner rover, but instead of operating from a base, Spirit and Opportunity were designed to be completely independent, able to communicate directly back to Earth.

The purpose of the Mars Exploration Rover mission (MER) was to search the surface of Mars for evidence of past water on the surface of Mars. Spirit landed in the huge Gusev Crater on Mars, a region that could have been an ancient lake on Mars. Opportunity touched down on the other side of the planet in a region called Meridiani Planum.

Both Spirit and Opportunity are equipped with solar panels that supply electricity to let them crawl around the surface of Mars, as well as their scientific instruments that let them study the surface of Mars and its rocks. They’re also equipped with a grinding tool that lets them scrape away the outer layer of rocks and see the material underneath.

Within just a few months of arriving on Mars, both Spirit and Opportunity fulfilled their mission objectives, and discovered evidence that large quantities of water used to be on the surface of Mars. Spirit discovered hints that water had acted on a rock called Humphrey, while Opportunity found layers of sedimentary rock that would have been formed by deposits in water. Both rovers continued to find additional evidence for the presence of water.

Over the course of their mission on the surface of Mars, both rover traveled several kilometers. Spirit climbed a small mountain, and Opportunity crawled into a large crater to sample the walls for evidence of past water. And both rovers continued to perform quite well, for many years beyond their original estimate life spans.

We have written many articles about the Mars Exploration Rovers for Universe Today. Here’s an article about the troubles for the Spirit rover, and here’s an article about Martian weather.

If you’d like more info on the rovers, you should check out the Mars Exploration Rover homepage from NASA.

We’ve also recorded several episodes of Astronomy Cast about the exploration of Mars. Start here, Episode 92: Missions to Mars, Part 1.

Source: NASA

Spirit Rover Makes Progress

A little good news for Spirit! The rover successfully moved; not very much, but it’s the first step of a planned two-step motion to try and get Spirit free from a sand trap on Mars. On Sol 2090 (Nov. 19), the rover spun its wheels for the equivalent of 2.5 meters (8.2 feet) in the forward direction, and the center of the rover moved approximately 12 millimeters (0.5 inch) forward, 7 millimeters (0.3 inch) to the left and about 4 millimeters (0.2 inch) down. Again, not much, but it’s the first good news and good movement the rover has had in months.

Small forward motion was observed with the non-operable right front wheel, and the left front wheel showed indications of climbing, despite the center of the rover moving downward. These motions are too small to establish any trends at this time.

The drive plan had imposed a limit of 1 centimeter (0.4 inch) motion in any direction. The second step of the drive was not performed, because Spirit calculated it had exceeded that limit.

Source: JPL

The data downlink volume from the rover was much better than expected, with all drive-related imagery being received. The team is continuing to analyze results from the drive.

Spirit Extrication, Day 1: Drive Stopped After 1 Second

Mission managers sent the drive commands to the Spirit rover at 4 a.m. EST (0900 GMT) today, — Nov. 17, 2009 and Sol 2088 for the rover — but the data back from the rover indicates the rover stopped less than one second after it began moving its wheels when the rover automatically sensed more lateral tilt than permitted. A tight limit on vehicle roll and pitch of less than 1 degree change was set for this first drive, and as the rover began its first move, it sensed that its roll was outside the allowed limit and safely stopped the drive. Those driving the rover say they are starting cautiously, setting initial parameters with very tight limits with the knowledge that these hair triggers may stop the rover frequently. As the project gains confidence with extrication, these limits may be relaxed. From this limited drive the team now has a more accurate measurement of vehicle roll and pitch that will be used for subsequent drive planning. Analysis is continuing. The team hopes to completion their planning of the next drive on Wednesday, Nov. 18, with possible wheel movement again on the 19th (Sol 2090)

At last week’s press conference about the attempt to extricate Spirit from the Martian sand trap, the rover team stressed this procedure could take weeks or months, with the likelihood of not being successful.

Learn more about the process in this video footage of the rover testing and planning teams.

Source: Free Spirit