Last summer, with a dense, planet-wide dust storm approaching its position in Mars' Perseverance Valley, NASA's Opportunity rover shut down all systems on June 10 and entered hibernation mode. Months after the dust settled, NASA has officially declared the rover dead.
"It is because of trailblazing missions such as Opportunity that there will come a day when our brave astronauts walk on the surface of Mars," said NASA Administrator Jim Bridenstine. "And when that day arrives, some portion of that first footprint will be owned by the men and women of Opportunity, and a little rover that defied the odds and did so much in the name of exploration."
But NASA didn't call it quits until trying every possible method to get Opportunity to phone home.
"Over the past seven months we have attempted to contact Opportunity over 600 times," said John Callas, project manager for Opportunity at Jet Propulsion Laboratory.
Initially, NASA engineers used NASA's Deep Space Network to ping the rover during scheduled "wake up" windows. They also sifted through radio signals emanating from Mars to see if one might happen to be Opportunity's "voice." However, the rover still wouldn't respond.
In a final attempt to make contact, the team implemented new transmission strategies to determine if low-likelihood events were preventing the rover from sending signals.
"We have and will continue to use multiple techniques in our attempts to contact the rover," said Callas at the time. "These new command strategies are in addition to the 'sweep and beep' commands we have been transmitting up to the rover since September."
The scenarios they investigated were:
- The rover's primary X-band radio — which Opportunity uses to communicate with Earth — has failed.
- Both its primary and secondary X-band radios have failed.
- The rover's internal clock, which provides a timeframe for its computer brain, is offset.
Finding Opportunity through all the dust
There was a glimmer of hope though on Sept. 20 when HiRISE, a high-resolution camera onboard NASA's Mars Reconnaissance Orbiter, captured a satellite image showing Opportunity. Look closely at the image above and you can see a tiny white dot in the center of the square.
Unlike the Curiosity rover, which runs off a nuclear-powered battery, Opportunity relied purely on solar cells to charge its lithium batteries. While the rover endured massive dust storms before, the intensity of this one — described by NASA officials as a "dark, perpetual night" –– coupled with its unprecedented length, proved to be too much for the plucky little robot.
The little rover that could
Engineered for a mission that was expected to last only 90 days, Opportunity has defied all odds by surviving and conducting explorations on the surface of Mars for nearly 15 years. Even its twin, Spirit, which landed three weeks before Opportunity in January 2004, managed to function until 2010.
As it currently stands, Opportunity holds the off-Earth roving record with a distance of more than 28 miles along with these other achievements:
- Set a one-day Mars driving record March 20, 2005, when it traveled 721 feet (220 meters).
- Returned more than 217,000 images, including 15 360-degree color panoramas.
- Exposed the surfaces of 52 rocks to reveal fresh mineral surfaces for analysis and cleared 72 additional targets with a brush to prepare them for inspection with spectrometers and a microscopic imager.
- Found hematite, a mineral that forms in water, at its landing site.
- Discovered strong indications at Endeavour Crater of the action of ancient water similar to the drinkable water of a pond or lake on Earth.
"For more than a decade, Opportunity has been an icon in the field of planetary exploration, teaching us about Mars' ancient past as a wet, potentially habitable planet, and revealing uncharted Martian landscapes," said Thomas Zurbuchen, associate administrator for NASA's Science Mission Directorate. "Whatever loss we feel now must be tempered with the knowledge that the legacy of Opportunity continues – both on the surface of Mars with the Curiosity rover and InSight lander – and in the clean rooms of JPL, where the upcoming Mars 2020 rover is taking shape."
In memory of Opportunity, NASA released a video timeline featuring highlights from the rover's 15-year adventure.
"When I think of Opportunity, I will recall that place on Mars where our intrepid rover far exceeded everyone's expectations," Callas said. "But what I suppose I'll cherish most is the impact Opportunity had on us here on Earth. It's the accomplished exploration and phenomenal discoveries. It’s the generation of young scientists and engineers who became space explorers with this mission. It's the public that followed along with our every step. And it's the technical legacy of the Mars Exploration Rovers, which is carried aboard Curiosity and the upcoming Mars 2020 mission. Farewell, Opportunity, and well done."
Editor's note: This article has been updated since it was originally published in August 2018.