NASA’s beloved Mars rover, Opportunity, has been officially laid to rest more than seven months after it was engulfed by a gigantic dust storm and fell silent.
That planet-wide tempest of sand and debris in June was particularly powerful, leaving Opportunity’s solar panels saturated with material. Starved of sunlight, the poor rover didn’t have the energy to wake up from an electronic coma, and remained unresponsive to radio commands.
“I declare the Opportunity rover mission as complete,” Thomas Zurbuchen, NASA’s Associate Administrator, declared during a press briefing on Wednesday.
Built to last for 90 sols, a fancy word for Martian solar days, the gallant instrument-laden bot plowed on for 5,351 sols, or about 15 Earth years.
Opportunity was part of the NASA’s larger Mars Exploration Rover mission, and was sent to space in 2004 alongside its twin rover, Spirit, carrying pieces of the World Trade Center. Spirit died in 2010 when it got stuck in a sand trap and failed to charge its batteries. Zurbuchen thanked the hundreds of scientists and engineers for working for almost two decades on the mission. “Science is an emotional affair, it’s a team sport,” he said.
Trundling along at five centimetres per second (0.1 miles per hour), Opportunity covered 28 miles of Martian ground in its time, and took a peek at many of the Red Planet’s impact craters.
First, it landed on Eagle crater, a 22-metre-long ditch, and found tiny spherical structures, nicknamed “blueberries”, made from hematite. The mineral, a form of iron oxide, can only be formed in solution, so it was a promising sign that the crater was once filled with liquid.
Next, it wheeled itself to Endurance crater to discover strange bedrock organised into sets of straight parallel lines. It teetered close to the sand dunes, but didn’t dare enter them for fear of getting stuck. In fact, it did get stuck once when it tried surfing on sand, and NASA engineers put it in reverse and accelerated hard to push it out of its misery.
Opportunity was described as an “overachiever.” It managed to outlive its life expectancy by both chance and engineering. John Callas, project manager of the Mars Exploration Rover project, said: “We thought dust falling out of the air would eventually choke it of power after 90 days, but wind unexpectedly came along and blew it off so we could keep going and exploring.”
He also said it was decked out with the “finest batteries in the solar system,” capable of getting through 5,000 charge and discharge cycles “to get through the coldest, darkest parts of Mars.” Every night it would enter deep sleep mode, and everything would be turned off including its heaters. The rover always managed to stay just warm enough to power back up in the morning, though.
You may be interested to know that Opportunity was powered by VxWorks on a 20MHz IBM RAD6000 CPU – a RISC Single Chip based on Big Blue's POWER1 architecture – with 128MB of RAM, 256MB of flash memory, and 3MB of EEPROM storage. This system, hardened to withstand radiation, drew from the solar cells, and a pair of 8-amp-hour rechargeable lithium batteries each made of eight cells.
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The machines changed our understanding of Mars. Steve Squyres, a professor at Cornell University in the US studying the history of water on the Red Planet, called Mars a “dry, desolate world.”
“It’s a place, where not much happens. But in the past it was a violent, hot, steamy place with impacts," he said. "We saw profound evidence for hydrothermal events. It had hot springs, and was probably suitable for very hardy microbes. It was a place that was habitable.”
NASA is planning to send more rovers to Mars, and some may even end up as robo-comrades alongside human explorers, if or when they show up. The second stage of the space agency's Mars Exploration Rover mission will deploy on the Red Planet Mars 2020, an upgraded rover armed with a handy drill to collect samples from the surface.
“The goal is to discover life on another world: that is what we’re trying to achieve,” said Jim Bridenstine, Administrator of NASA.
Finally, let’s not forget the twin rovers, Opportunity and Spirit, also had a cheeky side. The pair etched what appeared to be a penis on the Martian surface, as they merrily rolled along. ®