Whenever I give public talks and mention the remarkable longevity of the Mars Exploration Rovers, people always ask, “How long do you think they will last?”
I always respond with a quip from Jim Bell, leader of the color cameras on the rovers and my doctoral adviser: “How long do you think your toaster will last?”
Things break for unpredictable reasons, and there’s simply no way to know when that will happen, even for those of us working on the mission. But now that the day has finally come and 15 years into its 90-day mission Opportunity has officially been declared dead, I realize that my glib response does a disservice to the rovers because they were so much more than toasters.
Spirit and Opportunity were uniquely charismatic. It is almost impossible not to anthropomorphize them: They are roughly the size of a human, with a “head” (the remote sensing mast), “eyes” (cameras), an arm, and a “hand” (contact instruments). They moved according to commands that were invisible to most people, even many of us on the mission, making it seem like they were exploring the surface of Mars on their own.
Most importantly, they were the stars of a compelling story. Two little rovers, alone in a vast and hostile environment, surviving against all odds for years past their expected lifetime, uncovering the secrets of a watery past in a dry and desolate world. It’s irresistible; you can’t not root for them.
Not only were they the charismatic stars of a dramatic mission, they also shared all of their pictures with the world immediately. Everyone with an Internet connection could follow along, looking at postcards from Mars the same way you might see pictures from a friend’s vacation on social media.
Of course, social media barely existed in early 2004 when Spirit and Opportunity landed (Facebook started during their 90-day primary mission), but that didn’t stop people. Even in those early days, people loved the rovers and assigned them personalities. Someone made Myspace pages for each rover as if they were teenage girls: Opportunity was all dark and goth, whereas Spirit was pink sparkles and rainbows. The rovers inspired fan art, tribute songs, and even tattoos.
1/ #ThanksOppy This tattoo means more to me than just Oppy. Of course, the biggest significance is this is Oppy’s final measurement. I studied tau (atmospheric optical depth) as a student researcher. Don’t worry, I consulted my advisor on the value before committing to the ink pic.twitter.com/vhShtDBR3Z
— Keri Bean (@PlanetaryKeri) February 13, 2019
Online communities of space exploration enthusiasts took the daily photos from Mars and ran with them, producing beautiful panoramas and detailed maps and speculating about the rovers’ activities and discoveries along every step of the process.
Nobody Loved Them More Than Us
The world fell in love with the rovers, but nobody loved them more than those of us on the mission.
As a scientist, a part of me tries to stay impartial and removed. We had the data. We knew Opportunity was showing its age; we knew the odds of recovery were slim after major storms covered the rover in dust last June.
But this was not like orbiter missions, which tend to end when they run out of fuel and are deliberately crashed. For those missions, you know when the mission will end down to the second. You know when to grieve.
The death of a rover is slow. You don’t know if it may still wake up and phone home—NASA tried for months after the storms to reconnect but never received any signs of life. In orbital images, you can still see it sitting there on the surface. So although you always hope for reconnection, at some point you have to let go.
Now that the mission is over, the absence of Spirit and Opportunity is tangible. It is hard to understand that there will never be another new picture from the two rovers. It is hard to accept that we won’t receive any new data from them to help solve our many unanswered questions. Our window on those parts of Mars has closed. Most of all, it is hard to comprehend that something that was so central to so many of our lives is gone and it is never coming back.
The End of an Era, the Start of Another
The rovers were much more than toasters, but their loss is also not the same as the loss of a living, breathing friend. I mourn them not because they were alive in any real sense, but because their death marks the end of an era.
Spirit and Opportunity landed on Mars while I was in college, around the time that I officially decided to major in astronomy and physics so that I could pursue my interest in space. After my first summer internship in astronomy, I vividly remember going to a conference in early 2005 and listening with rapt attention to a keynote lecture by Steve Squyres, the leader of the mission.
As my academic career progressed, I steered toward planetary science, inspired by the writings of Carl Sagan and drawn toward the rovers like a compass needle toward magnetic north. I went to graduate school at Cornell, where Sagan had been a professor and where Steve Squyres and Jim Bell both worked. Jim was my thesis adviser, and Steve was on my committee, and I was able to get involved in the day-to-day operations of the rovers.
As part of the rover team, I made professional connections that led to a graduate fellowship, involvement with the Curiosity rover mission that launched just as I was finishing my degree, and a postdoctoral position at the U.S. Geological Survey’s Astrogeology Science Center that eventually turned into a permanent position.
Spirit and Opportunity have been exploring Mars for the entirety of my career in planetary science. They were a constant presence, a source of pride, a guiding influence that set the trajectory of my career.
The sadness I feel at the end of this mission is less like that of a funeral and more like that of a graduation or upon closing the door to the house you grew up in for the last time. It is the bittersweet feeling of growing up, of moving on, and the loss of all that must be left behind. It is the reminder that time marches inexorably onward, that all things must end, and that you can never go back.
A chapter in all of our lives has ended, but with the pain of loss comes pride, knowing that we were lucky enough to play even a small role in such a great mission. Spirit and Opportunity revolutionized the exploration of Mars. Scientifically, they found abundant evidence of past liquid water on the surface. They showed that our detection of minerals from orbit can be verified on the ground but also that treasure troves of fascinating minerals could be waiting just beneath the surface, hidden from our orbital view.
They also revolutionized Mars exploration in a different way. By sharing their images with the world immediately and by lasting far longer than anyone hoped, Spirit and Opportunity made it seem normal to constantly be exploring Mars, constantly seeing things nobody had ever seen before. They paved the way for the Curiosity rover and its successor, the Mars 2020 rover, which will maintain a continuous active presence on Mars for many years to come. Spirit and Opportunity also inspired an entire generation of planetary scientists to enter the field. Many of us who started our careers as Spirit and Opportunity were landing are now leading current and upcoming missions to Mars and across the solar system.
And, of course, Spirit and Opportunity, those two plucky rovers, captured the hearts and minds of the public. They made science and exploration compelling and showed the enormous return on investment that is possible when our tax dollars are spent well. In a world where current events have taken a darker turn, the rovers have been an enduring reminder that we humans can achieve amazing things when we work together. Spirit and Opportunity reminded us that we are part of a larger universe and that we can understand it if we try.
—Ryan Anderson (@Ryan_B_Anderson), Astrogeology Science Center, U.S. Geological Survey
This article is part of a series made possible through the generous collaboration of the writers and editors of Earth magazine, formerly published by the American Geosciences Institute.