How Engineers Beat the Odds and Landed Two Rovers on Mars

"This is my favorite picture ever," said Chris Lewicki as he flashed a photo of the Mars Exploration Rover, Spirit, on a giant screen in UA's Aerospace and Mechanical Engineering auditorium.

The photo showed Spirit just after it had safely placed all six of its wheels on the Red Planet's surface.

"It would be difficult to imagine any photo that tops it," he added. "It represents everything that I had stressed over for two years and all the risks we had taken and the thrill of victory and agony of defeat along the way. This really meant that we had a fully operational rover on the surface and that we had actually done it."

The Odds Were Against Them
The odds had been against seeing this photo last January. Never before had NASA and the Jet Propulsion Laboratory attempted such a complex space mission on such a short time scale. In fact, Lewicki showed a graph dotted with tiny squares representing previous missions. One axis rated complexity and the other axis showed the amount of time spent on designing and building the mission before launch.

A diagonal line running through the graph showed that most missions above the line succeeded, while most below the line failed. The Mars Exploration Rover (MER) Mission was far out in left field with failed missions that were too complex and built too fast.

But if Lewicki is any indication of the talent, dedication, and meticulous attention to detail that JPL engineers and scientists put into MER, the reason it beat the odds is obvious.


Lewicki, who graduated from UA in 2000 with a master's degree in Aerospace Engineering, literally dedicated three years of his life to the project. Not three years of 40-hour weeks, but three full years minus the time he spent sleeping.

"The schedule was of the utmost importance," he said. "It involved many, many, many late nights and lots of overtime — pretty much all the weekends during those three years were taken up. And there were not many holidays." 18-hour days were routine.

During the early part of the mission — which is still going on as the rovers continue to gather data on Mars — Lewicki served as flight director and was in charge of events from the time the landers bounced onto the ground until the rovers left tracks in the dust.

Huge Complexity and Millions of Details
But his involvement in the project began long before MER headed toward Mars aboard a Delta II rocket. He described his two-year involvement in the design, construction and testing of MER's rovers during his talk to faculty and students, detailing the extreme complexity and attention to detail that characterized the project.

For example:

The rovers, Spirit and Opportunity, weren't plug-and-play devices. JPL engineers assembled the rovers using parts from different areas of the lab and from different parts of the globe. Each part had to be carefully tested and retested before it was installed.

Part of Lewicki's job was to integrate all the motors on the rovers — 39 brush DC motors, 4 brushless DC motors and three stepper motors on each rover.

The landing team went through seven practice landings — the last three beginning at 3 a.m., just as they would when the real landing took place — to become entirely familiar with the procedure.

Lewicki and other JPL engineers looked at everything that could go wrong with the rover between the time it landed, went through an incredibly complex metamorphosis to unfold and assemble itself, and the time it finally drove off the lander. In the process, they conducted 40 airbag retraction and lander deployment tests, covering many scenarios. Each test took an entire day.

For one year, Lewicki was in charge of keeping the wiring straight. Each rover and the support gear to get it to Mars included 10,000 independent wiring connections and several miles of cable. A single wiring error could destroy the entire mission.

The engineers conducted 500 rover test drives in the small area on top of the lander to discover every cable that it might trip over and every other nasty hazard that could leave it stranded. If the wheels stuck on some part of the lander, the rover's long journey to Mars would end in failure, just 50 centimeters short of the surface.

Software Written as the Rovers Flew
The mission time schedule was so tight that the software to direct landing operations had not yet been uploaded to the spacecraft when it left the launch pad. In fact, some of the software hadn't yet been written.


Engineers had no doubt, however, that the software would be completed and uploaded by the time it was needed. They were confident that the mission would succeed — at least on an intellectual level, Lewicki said.

On the gut level, it was different.

"There are always those nagging doubts when you're dealing with multi-million-dollar spacecraft from more than 100 million miles away," he said in an earlier interview. "You know everything is tested and reliable, but on the inside you're saying, 'How can this possibly work? We have 126 pyrotechnic devices that must all work correctly just to get the lander onto the surface. How can it all go perfectly?"

Despite a few minor hang-ups early on, everything did go just about perfectly, and Lewicki found himself sitting in a JPL planning room late one night reviewing plans for the next day's rover operations and marveling at the images being returned by the mission.

"I had to stop everyone and remind them that we had a rover on Mars, sitting at the edge of a crater," Lewicki said. "I just thought that was totally cool because you go from the planning software to actually being there. And it really, literally is — with the resolution of the cameras we have, and the fact that we can turn these plans into action every day, and the sophistication of our planning tools — it really is just like being there."

As the mission continues, it's getting even more interesting for Lewicki because his role continues to expand. With a bit less to do in each area, he has now taken over the jobs originally done by four people and is expanding his knowledge and meeting a widely diverse set of engineering challenges.

Amazingly, after 36 months of intensive, stressful, all-consuming work on MER, Lewicki hasn't burned out. His enthusiasm for space exploration was evident in nearly every word he spoke.

"It (the MER Project) has been really a wonderful, exciting, and fantastically stressful experience," he said. "And I would do it again any day. I completely loved it."

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