Nasa is trying one last time to contact its record-setting Mars rover Opportunity before calling it quits, after one of the most intense dust storms recorded rendered the rover silent for the past eight months.
Thick dust darkened the sky last summer and, for months, blocked sunlight from the spacecraftâs solar panels.
Nasa said on Tuesday it will issue a final series of recovery commands, on top of more than 1,000 already sent. If thereâs no response by Wednesday â which Nasa suspects will be the case â Opportunity will be declared dead, 15 years after arriving at the red planet.
Team members are already looking back at Opportunityâs achievements, including confirmation water once flowed on Mars. Opportunity was, by far, the longest lasting lander on Mars. Besides endurance, the six-wheeled rover set a roaming record of 45km (28 miles).
Its identical twin, Spirit, was pronounced dead in 2011, a year after it got stuck in sand and communication ceased.
Both outlived and outperformed expectations, on opposite sides of Mars. The golf cart-size rovers were designed to operate as geologists for just three months, after bouncing onto our planetary neighbour inside cushioning airbags in January 2004. They rocketed from Cape Canaveral a month apart in 2003.
Itâs no easier saying goodbye now to Opportunity, than it was to Spirit, said project manager John Callas.
âItâs just like a loved one whoâs gone missing, and you keep holding out hope that they will show up and that theyâre healthy,â he said. âBut each passing day that diminishes, and at some point you have to say âenoughâ and move on with your life.â
Deputy project scientist Abigail Fraeman was a 16-year-old high school student when Opportunity landed on Mars; she was inside the control centre as part of an outreach programme. Inspired, Fraeman went on to become a planetary scientist, joined Nasaâs Jet Propulsion Laboratory in Pasadena, California, and ended up deputy project scientist for Opportunity.
âIt gives you an idea just how long this mission has lasted,â she said. âOpportunityâs just been a workhorse ⌠itâs really a testament, I think, to how well the mission was designed and how careful the team was in operating the vehicle.â
Rather than viewing the dust storm as bad luck, Callas considers it âgood luck that we skirted so many possible stormsâ over the years. Global dust storms typically kick up every few years, and âwe had gone a long time without oneâ.
Unlike Nasaâs nuclear-powered Curiosity rover still chugging along on Mars, Opportunity and Spirit were never designed to endure such severe weather.
Cornell Universityâs Steve Squyres, lead scientist for both Opportunity and Spirit, considers succumbing to a ferocious storm an âhonourable wayâ for the mission to end.
âYou could have lost a lot of money over the years betting against Opportunity,â Squyres said on Tuesday.
The roversâ greatest gift, according to Squyres, was providing a geologic record at two distinct places where water once flowed on Mars, and describing the conditions there that may have supported possible ancient life.
Nasa last heard from Opportunity on June 10. Flight controllers tried to awaken the rover, devising and sending command after command, month after month. The martian skies eventually cleared enough for sunlight to reach the roverâs solar panels, but there was still no response. Now itâs getting colder and darker at Mars, further dimming prospects.
Engineers speculate the roverâs internal clock may have become scrambled during the prolonged outage, disrupting the roverâs sleep cycle and draining on-board batteries. Itâs especially frustrating, according to Callas, not knowing precisely why Opportunity â or Spirit â failed.
Now itâs up to Curiosity and the newly arrived InSight lander to carry on the legacy, he noted, along with spacecraft in orbit around Mars.
As for Opportunity, âIt has given us a larger worldâ, Callas said.
âMars is now part of our neighbourhood.â