In the summer of 2003, NASA’s Jet Propulsion Laboratory launched two robots to explore Mars. Named Spirit and Opportunity, they were born identical twins, but as they began to investigate opposite sides of the planet in January 2004, the four-foot-11-inch Mars Exploration Rovers developed distinct personalities: Spirit was a problem child and drama queen; Opportunity, a goody-goody and star performer. Both rovers, though, showed amazing durability. As the twins searched for water, they found the Fountain of Youth, living 24 times their intended 90 days. As they triumphed over one hazard after another, sending back wondrous images from another planet, those of us watching from Earth began to root for them and to consider the robustness of their engineering as “pluck.” In fact, when Spirit became stranded in deep soil last spring, the Planetary Society’s A.J.S. Rayl blogged optimistically that clean solar panels had made Spirit flush with power, and she spoke for all rover boosters when she wrote that the twins were now among “the community of planetary explorers deemed robot royalty.”
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Maybe one reason for their success is that they’re so light on their feet, each weighing 400 pounds on Earth but just 150 pounds on Mars, which has 38 percent the mass of Earth. Another reason is luck. Martian wind coated the rovers’ solar panels with dust, ruining their capacity to draw energy, but then blew the dust off, enabling the solar cells to restore their vitality. And another reason is surely the ingenuity of the Jet Propulsion Laboratory scientists and engineers who built and operate the rovers, and have found clever ways to extend their lives as parts begin to break down. Whatever combination of luck and skill has made them successful, Spirit and Opportunity have deeply charmed the public.
One reason we’re hooked is that once the mission began, anyone with an Internet connection could get images of Mars. “The policy on the [rover] team to release images to the public as soon as they came down was a novel move,” says Janet Vertesi, a post-doctoral researcher in the Department of Informatics at the University of California at Irvine, who recently wrote her dissertation on the Mars Rover team’s operations. It was one of the first times NASA released photographs so quickly, she notes. “I think there was this excitement about being able to log on to the Web with your cup of coffee each morning and see what’s on Mars that day. Now with Twitter feeds, Facebook groups, [and] blog posts, that has snowballed.”
Vertesi’s graduate research, conducted at Cornell University in New York, grew out of her interest in the history and sociology of science. She is intrigued by human-computer interaction, and is delving into the social organization of robotic spacecraft teams, examining how scientists use images to do their work, she says. The Mars Exploration Rover Mission was ideal for her work. She was able to observe team members using images to analyze Martian geology and to interact with the planet through the rovers from millions of miles away.
To understand the scientist-rover connection, Vertesi became a participant-observer alongside scientists and engineers on the team, both at JPL, in Pasadena, California, and around the country. A Canadian citizen, she was restricted in where she could go at JPL; for instance, she could not enter rooms where controllers were issuing commands to the rovers. But she was given full access to the science team as they did their daily work on Mars, and got to know many science and engineering team members personally. (The science team is widely distributed, yet tightly woven through daily conference calls.)
She observed a complex relationship between the team and Spirit and Opportunity. “No one knows more than the drivers and scientists do that the rovers are not autonomous,” says Vertesi. “The team has to be very careful about what they tell them to do.” Her work, she states on her Web site, “brought up more questions than just about digital images.”At a 2008 conference in Italy, sponsored by the Special Interest Group on Computer Human Interaction, Vertesi presented a paper titled“ ‘Seeing Like a Rover’: Embodied Experience on the Mars Exploration Rover Mission,” in which she wrote, “While the Rovers are located millions of miles away from their human teammates, the scientists and engineers engaged in their daily operation have developed an uncanny sympathy for the Rovers that they credit as essential to mission success.”
Team members are happy to talk about this relationship. “You’re so involved with these machines that they sort of cease to be machines,” says Sharon Laubach, who holds a Ph.D. in robotics and is chief of the JPL group that develops the software instructions for the rovers. “We send them commands, like letters and missives, and they do what they want and write home at the end of the day. These girls are off on their own, and we hope they do what we ask them to.”
These girls. They’re not the first machines to attract emotional attachment from their handlers. Laubach recalls developing a strong bond with Rocky 7, a test-bed rover that never left Earth.
Spirit and Opportunity, by contrast, have endured nights of temperatures at –150 degrees Fahrenheit. Since day two, Opportunity’s arm has suffered a faulty shoulder joint. A bum wheel on Spirit has forced it torollbackwardsince2006, while more recently, another of its wheels began having problems turning. In 2005, Spirit scampered up Husband Hill—at 269 feet almost the height of the Statue of Liberty—all on borrowed time. There the rover took inspiring panoramas of the Martian landscape that no one had anticipated. The same year, Opportunity got itself marooned in soft soil at Purgatory Dune for a month and a half. A year before that, Spirit had turned its eyes to the sky and taken the only picture of Earth from the surface of another planet.
Last spring, NASA put out a press release that framed the rovers’ latest problems in unusually human terms: Spirit was “failing to wake up” from regular midday “naps” that conserve power. There were “bouts of amnesia” when Spirit didn’t record data from the day’s activities into solid-state memory. Both rovers showed “symptoms of aging.”