Image: "Courtesy NASA/JPL-Caltech." An artist's concept portrays a NASA Mars Exploration Rover on the surface of Mars. Two rovers have been built for 2003 launches and January 2004 arrival at two sites on Mars. Each rover has the mobility and toolkit to function as a robotic geologist.
One of the most fascinating stories in space exploration has been the two little rovers on the surface of Mars. The rovers were named "Spirit" and "Opportunity", and were parachuted onto opposite sides of the red planet. Landing three weeks apart, Spirit touched down on January 3rd, 2004, while Opportunity arrived on January 25th, 2004.
The twins mission was to explore the surface of Mars and gather scientific data for three months. These rovers will go down in history as the little rovers that could!
I call them little rovers, but these mobile science labs are about 5.2 foot long, 4.9 foot tall and weighing in at 384 pounds!
Talk about your over-achievers. It has been over seven years since they landed, and Opportunity is still going strong. Each of these machines were only supposed to travel about a half mile in their original three-month mission, but as of today, their current odometry readings show that Spirit has traveled 4.8 miles, and Opportunity has traveled 18.46 miles!
Five and a half months after they landed, Spirit developed a problem with its right-front wheel. This wheel issue has caused the scientists and engineers at NASA to come up with some creative driving techniques. At times Spirit has been adjusting its remaining wheels to compensate for the injured wheel, and for a lot of the time it has had to drive backwards to drive forward.
In 2009 Spirit became stuck during a routine drive, it’s bum-wheel didn’t help matters any. This presented a problem for the rover because its solar panels need to be turned toward the sun to keep the on-board systems fully functional.
Despite the setback, Spirit continued to provide information from experiments it could do in its stationary predicament. Unfortunately, with the loss of ability to maneuver and keep its systems fully operational, which included the heaters to combat the extreme cold temperatures, Spirit lost contact with the Earth. It’s last communication was on March 22nd, 2010.
NASA has tried to reestablish contact, hoping that the warmth of the Martian Springtime would help energize it’s systems once more, but it seems now that Spirit might just be silent permanently.
Following is a letter that Mars Exploration Rover Project Manager, John Callas, sent to his team shortly after the final command was sent to the now unresponsive Spirit.
Dear Team,
Last night, just after midnight, the last recovery command was sent to Spirit. It would be an understatement to say that this was a significant moment. Since the last communication from Spirit on March 22, 2010 (Sol 2210), as she entered her fourth Martian winter, nothing has been heard from her. There is a continued silence from the Gusev site on Mars.
We must remember that we are at this point because we did what we said we would do, to wear the rovers out exploring. For Spirit, we have done that, and then some.
Spirit was designed as a 3-month mission with a kilometer of traverse capability. The rover lasted over 6 years and drove over 7.7 kilometers [4.8 miles] and returned over 124,000 images.
Importantly, it is not how long the rover lasted, but how much exploration and discovery Spirit has done.
This is a rover that faced continuous challenges and had to fight for every discovery. Nothing came easy for Spirit. When she landed, she had the Sol 18 flash memory anomaly that threatened her survival. Scientifically, Mars threw a curveball. What was to be a site for lakebed sediments at Gusev, turned out to be a plain of volcanic material as far as the rover eye could see. So Spirit dashed across the plains in an attempt to reach the distant Columbia Hills, believed to be more ancient than the plains.
Exceeding her prime mission duration and odometry, Spirit scrambled up the Columbia Hills, performing Martian mountaineering, something she was never designed to do. There Spirit found her first evidence of water-altered rocks, and later, carbonates.
The environment for Spirit was always harsher than for Opportunity. The winters are deeper and darker. And Gusev is much dustier than Meridiani. Spirit had an ever-increasing accumulation of dust on her arrays. Each winter became harder than the last.
It was after her second Earth year on Mars when Spirit descended down the other side of the Columbia Hills that she experienced the first major failure of the mission, her right-front wheel failed. Spirit had to re-learn to drive with just five wheels, driving mostly backwards dragging her failed wheel. It is out of this failure that Spirit made one of the most significant discoveries of the mission. Out of lemons, Spirit made lemonade.
Each winter was hard for Spirit. But with ever-accumulating dust and the failed wheel that limited the maximum achievable slope, Spirit had no options for surviving the looming fourth winter. So we made a hard push toward some high-value science to the south. But the first path there, up onto Home Plate, was not passable. So we went for Plan B, around to the northeast of Home Plate. That too was not passable and the clock was ticking. We were left with our last choice, the longest and most risky, to head around Home Plate to the west.
It was along this path that Spirit, with her degraded 5-wheel driving, broke through an unseen hazard and became embedded in unconsolidated fine material that trapped the rover. Even this unfortunate event turned into another exciting scientific discovery. We conducted a very ambitious extrication effort, but the extrication on Mars ran out of time with the fourth winter and was further complicated by another wheel failure.
With no favorable tilt and more dust on the arrays, Spirit likely ran out of energy and succumbed to the cold temperatures during the fourth winter. There was a plausible expectation that the rover might survive the cold and wake up in the spring, but a lack of response from the rover after more than 1,200 recovery commands were sent to rouse her indicates that Spirit will sleep forever.
But let’s remember the adventure we have had. Spirit has climbed mountains, survived rover-killing dust storms, rode out three cold, dark winters and made some of the most spectacular discoveries on Mars. She has told us that Mars was once like Earth. There was water and hot springs, the conditions that could have supported life. She has given us a foundation to further explore the Red Planet and to understand ourselves and our place in the universe.
But in addition to all the scientific discoveries Spirit has given us in her long, productive rover life, she has also given us a great intangible. Mars is no longer a strange, distant and unknown place. Mars is now our neighborhood. And we all go to work on Mars every day. Thank you, Spirit. Well done, little rover.
And to all of you, well done, too.
Sincerely,
John
Rest In Peace Spirit, I enjoyed following your exploits.
For more information on this fantastic journey please visit the Rover Mission Home Site
