NASA is finally saying goodbye to its Opportunity rover on Mars after spending nearly a year trying to reestablish communication with the silent robot. A team of engineers at NASA’s Jet Propulsion Laboratory (JPL) sent one final radio command to the rover last night but did not receive a response. Now, NASA will stop trying to communicate with Opportunity, effectively bringing the rover’s 15-year mission on Mars to an end.
“I was there yesterday, and I was there with the team as these commands went out into the deep sky. And I learned this morning that we had not heard back,” Thomas Zurbuchen, the associate director for NASA’s science mission directorate, said during a press conference on Wednesday. He later added, “I’m standing here with a sense of deep appreciation and gratitude that I declare the Opportunity mission as complete.”
Opportunity has been radio silent since June 2018 when a massive dust storm overwhelmed the skies of Mars and blotted out the Sun. The storm, one of the thickest NASA has ever seen, made it impossible for Opportunity’s solar panels to stay powered. As a result, the rover’s internal battery drained, and Opportunity went into hibernation mode.
After the storm passed, the mission team for Opportunity was hopeful that they might be able to wake the rover up again. They figured that once light hit Opportunity’s solar panels again, it could get enough power to turn on and establish a radio link with Earth. But it’s been total silence since June 10th when the rover sent back its last message that indicated the environment on Mars was incredibly dark and that the bot’s battery was nearly depleted.
Spent the evening at JPL as the last ever commands were sent to the Opportunity rover on #Mars. There was silence. There were tears. There were hugs. There were memories and laughs shared.#ThankYouOppy #GoodnightOppy pic.twitter.com/JYRPtKZ8T5— Dr. Tanya Harrison (@tanyaofmars) February 13, 2019
The team has tried every possible method of getting Opportunity to phone home again using NASA’s Deep Space Network, an array of massive radio telescopes here on Earth that are used to communicate with spacecraft deep in the Solar System. But they’ve had no luck. One theory is that the dust storm that engulfed Opportunity was so obtrusive that it left a layer of dust on the rover’s solar panels, further preventing it from receiving sunlight. NASA was still hopeful, though, as November through January was considered a particularly windy time on Mars. Engineers hoped that a powerful gust might be able to blow off whatever was blocking the panels.
Another explanation for the quiet is that the storm messed up Opportunity’s internal clock, which confused the bot about when to go to “sleep.” One of the main reasons why the rover has lasted so long is that NASA puts the vehicle into a deep sleep every night. This involves shutting everything off, including the rover’s heaters. When the mission first started, the heaters were left on at night, but they were draining all of the rover’s power. So NASA made the decision to turn them off during the nighttime to save energy. Ultimately, the rover got cold, but not too cold. John Callas, the project manager for Opportunity, likened it to someone turning off their circuit breaker at home every night.
the loss of power may have scrambled Opportunity’s clock
“That means your refrigerator starts to warm up,” he said during the press conference, “but by the morning time, when you wake up and turn the breaker back on, the ice cream hasn’t melted too badly. And you do that every single night. Now imagine doing that for 5,000 nights.”
But the loss of power may have scrambled Opportunity’s clock, Callas says, so it didn’t know when to go into this deep sleep. That meant the heaters could have been stuck on all the time, draining any last bits of power the rover got from the Sun and preventing the vehicle from communicating.
Now, Opportunity’s demise is all but certain, as the rover is about to enter Martian winter. Opportunity needs to stay above negative 40 degrees Fahrenheit (negative 40 degrees Celsius), and when it’s working, it has many ways to keep warm. These include eight small plutonium heating units that give off a small amount of warmth, as well as electrical heaters. Moving around on the planet produces heat for the robot’s battery and components, but with the rover sitting still and drained of power, it hasn’t been able to warm itself up through movement or its electrical heaters.
DSS-14 post track teardown…Goodbye old friend. #ThankYouOppy pic.twitter.com/Htb1ZZQ9V1— Mike Seibert (@mikeseibert) February 13, 2019
This wasn’t as much of a concern during the storm, which occurred in the summertime; temperatures were well above what Opportunity could handle. But now nighttime temperatures could plunge to negative 157 degrees Fahrenheit (negative 105 degrees Celsius). That means many of Opportunity’s components could grow brittle and break.
For those that have worked on Opportunity, it’s a heartbreaking time. Many at NASA JPL said their goodbyes to the rover last night, while the final message was sent to Mars. Numerous NASA scientists revealed that Opportunity didn’t send anything back. Today, NASA made the final determination of the rover’s fate during a press conference, making it clear that the mission is over.
The end is also bittersweet. Opportunity lasted far longer on the Martin surface than anyone expected. NASA launched Opportunity and an identical twin rover called Spirit in the summer of 2003. The two successfully landed on Mars in January 2004 with the goal of each lasting for at least 90 days. Both went well beyond that. Spirit lasted for six years, before getting stuck in a sand trap and losing energy. Opportunity boasts a 15-year lifespan, making it the longest-running rover that NASA has ever had.
Signing off from the dark room. #LoveYouOppy pic.twitter.com/DqLfFxEAmu— Keri Bean (@PlanetaryKeri) February 13, 2019
During its time on Mars, Opportunity did some incredible work. It traversed more than 28 miles (45 kilometers) of Martian terrain — the farthest of any surface robot — exploring multiple craters on the planet. It even survived another dust storm in 2007, though that one was much less intense than the one in June. Both Opportunity and Spirit have helped uncover clues about what Mars’ climate used to be like billions of years ago, revealing that the Red Planet once hosted oceans of liquid water on its surface. This ancient wet climate may have made it possible for alien life, like tiny microbes, to survive on Mars long ago.
Opportunity is leaving a great legacy behind. Still, NASA scientists at JPL will spend this week mourning a spacecraft that some have spent over a decade operating. Many have already started to move on to other missions, such as operating the Curiosity rover on Mars or planning for the next Martian rover launching in 2020, but they’ll bring their experience with Opportunity with them. Maybe we’ll see other rovers lasting beyond 15 years on the Red Planet.
Update February 13th, 2:40PM ET: This post was updated to incorporate new information from a NASA press conference.