The National Aeronautics and Space Administration's Mars Exploration Rover (MER) mission officially ended on Feb. 13, 2019, about eight months after contact with the Opportunity rover was lost.

NASA launched the mission in 2003, sending rovers Opportunity and Spirit on a one-way journey to Mars. Both rovers were given an initial mission lifetime of 90 days. After arriving on Mars in January 2004, Spirit operated for six more years; Opportunity went on to survey the planet for almost 15.

Kevin Cooke, a sixth year Ph.D. student in the Astrophysical Sciences and Technology program explained Opportunity's endurance.

“Opportunity kept going. It ended up working for 55 times its planned lifetime, which is unimaginable to me. If you say a human lifetime is about 80 years, and you live 55 times that, doing work all the while, you’ve lived to be 4,400 years old. Opportunity just persevered in the face of these incredible conditions on Mars: really low air pressure, dust storms that happened all the time — which eventually is what caused it to lose power,” he said.

"Opportunity just persevered in the face of these incredible conditions on Mars."

Over the course of those 15 years, Opportunity traveled a record-setting 28.06 miles across the Martian surface. Along with Spirit, it worked to characterize the climate of Mars in the distant past by observing rock strata and mineral deposits.

NASA refers to Spirit and Opportunity as “the mechanical equivalent[s] of a geologist walking from place to place,” and sometimes the “Adventure Twins.” Their most notable scientific contribution, however, was evidence of the former presence of water and conditions suitable for microbial life on Mars.

“Very early on, after Opportunity landed, they started discovering these small, spherical rocks that they nicknamed blueberries because they’re blue colored. And really it was a combination of compounds that could really only exist due to chemical reactions with liquid water sometime millions of years ago,” Cooke said.

Opportunity had a long and successful life, but every journey must come to an end.

The Final Words

After years of hard work and discovery, Opportunity checked in for the very last time in June 2018.

“Last year, there was the worst dust storm happening across the Martian globe that humanity has ever witnessed on the planet, and what that meant was that only one or two photons out of every million that was arriving at Mars from the sun was making it through the atmosphere to the surface. So with only a millionth of the sunlight reaching the solar panels on the rover, Opportunity just wasn’t going to be able to maintain power,” Cooke recalled.

Cooke further explained how NASA tried to do everything they could to help their most successful rover, but their actions were not enough.

"So they put it in a low-power mode, hoping that it could weather out the storm, but unfortunately the storm just lasted too long, and the dust covering was too much, and so the last message was ‘it’s getting dark and my batteries are running low,’ and that was all we heard of it,” he said.

" ... so the last message was 'it's getting dark and my batteries are running low' ... "

This translation of the rover’s data transmission was originally given by KPCC science reporter Jacob Margolis on Twitter and has since been widely circulated. After the message was received, the NASA mission team waited for the dust to settle and hoped wind would clear Opportunity’s solar panels. They transmitted over 835 recovery commands to the rover in the months that followed, playing thematic music down on Earth that was later cultivated by Space.com into a playlist titled “Wake Up, Opportunity!” Despite their efforts, the rover did not.

A New Beginning

On Feb. 13, 2019, NASA held a press conference to announce the formal mission conclusion. Dr. Michael Richmond, a professor in RIT's School of Physics and Astronomy, explained how one end can lead to a new beginning.

“It’s a sad thing, when one mission ends. But given the limited resources at NASA’s disposal and the limited manpower of people who have expertise in this area, it means that we can now do a different, newer mission,” he said. “I will choose to look forward and say, okay, thanks Opportunity, great job. Who’s next?”

NASA is already hard at work to answer Richmond's question. Opportunity and Spirit's work is continued and built upon by the Curiosity rover, InSight lander and Mars Orbiters. Future missions like the Mars 2020 rover are currently in development. However, the public reaction to the MER mission’s completion suggests some space enthusiasts may need a little more time before they move beyond the “thanks Opportunity” phase.

“Opportunity certainly captured the imagination of many people, in part because it went rolling around on Mars, and Mars has been a very popular planet for a long time, since it’s the closest thing to Earth in our solar system,” Richmond said.

Not only do people become attached to the wonder Opportunity brought to the world, but they also empathize with the trials and tribulations the machine worked through for so many years.

Cooke explained, “It’s much easier to anthropomorphize these probes because they’re moving — they’re moving on a surface instead of flying through space, so you see these either small or even large rovers braving the elements on this alien terrain and you feel for these machines. Even though they are machines, you know that they are tolerating these extreme conditions and really representing us, as we would like to explore those places as well.”

" ... you feel for these machines. Even though they are machines, you know that they are tolerating these extreme conditions and really representing us ... "

The response to Opportunity’s “death” was widespread. Anonymous digital postcards left for the rover and its team on a NASA site showcase some of the emotional connections people have to the MER program:

• "We are all made of star dust. Thanks for touching the brilliance of the universe for us. It may have been dark at the end, but you lit up the world."
• "You launched when I was only 5 years old. Now, I'm 19 and studying astrophysics. I hope to be apart [sic] of future missions just like yours. Hope to see you."
• "I miss the little rover that could."
• "You taught us to reach beyond what we thought possible and to keep going no matter what. You will see the sun again, see you space cowboy ... "
• "Oppy, I still don’t know how you got half the world to mourn a robot millions of miles away, but you brought us together. Thank you for your service [sic]."

The field work done by the MER rovers left Earth with a greater understanding of its neighboring world, a deeper preparation for future exploration of Mars and a heightened sense of wonder. It seems only natural to thank the rovers who gave us that opportunity.