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Starts With A Bang

Today Is The Bittersweet 15th Anniversary Of NASA’s Opportunity Rover Landing On Mars

Although the great Martian dust storm of 2018 may have ended its life, its accomplishments will live on forever.

Note: This article was originally published on January 25, 2019 on Forbes.

On January 24, 2004, the Mars Opportunity rover began its mission on the surface of the red planet. Despite a huge series of failures when it came to missions-to-Mars leading up to it, the combined success of the Mars Pathfinder mission along with the newly developed giant airbag system gave scientists great hope that this new generation of rover would be an unprecedented success.

15 years later, we can look back on Mars Opportunity as an unparalleled triumph of science and engineering as far as robotic missions are concerned. Even though its solar panels were irreparably covered in dust during a storm last year, the fact that Opportunity lasted over 14 years after being designed for a 90-day mission serves as perhaps the most inspirational example of planetary science and exploration since the Apollo program. Here’s a look back.

In 2018, when Mars was at its closest and brightest with respect to Earth, a dust storm blanketing the planet rendered most of the surface features, particularly in the Northern Hemisphere, virtually invisible. Rivaling the great 2001 dust storm, this event likely permanently killed the Opportunity rover, and marks one of the great truths about our astronomical ventures: even when it comes to other planets, we will forever be at the mercy of natural weather events.(NASA, ESA, AND STSCI)

Mars is very, very different from Earth in a lot of important ways that pose some unique challenges. Yes, it’s red instead of blue and it’s smaller and less massive, but it has the following properties that make it an incredible challenge for landing on:

  1. There’s no water to splash down in; you’ve got to land on the unforgiving rocky surface.
  2. The atmosphere is very thin: less than 1% of what we have on Earth. Parachutes need to be huge to be even a little bit useful.
  3. But with so little atmosphere and a rotation period similar to Earth’s, the winds on the planet are spectacularly fast, typically in excess of 150 kilometers-per-hour.

All of that meant that this was incredibly risky. But the airbag solution was ingenious, since even though the rover weighed in at 180 kg (400 pounds), terminal velocity with the inflated airbags ought to be slow enough that it would survive the impact.

After a successful landing on Mars, the Opportunity rover deployed, roved away from its protective airbag sheath, and took this image that was among its first pictures. This is what success looks like. (NASA / JPL / CORNELL)

In January of 2004, both Opportunity and its twin, Spirit, successfully landed on Mars, deployed and began their journeys across the surface of our neighboring world. They were originally designed for a 90-day journey, but were deliberately over-engineered. After all, the rover from Mars Pathfinder, Sojourner, was only designed for a seven-day mission with a possible extension to 30, and yet it lived for eighty-three days.

Why couldn’t these Mars Exploration Rovers do even better? They were bigger, they were more powerful, they had more robust solar panels, and they had the advantage of seven additional years of technology development. Opportunity was designed for a 90-day mission and 2.5 million turns of its wheels, powered by its on-board solar panels (during the day) and by its batteries at night. Only time would tell exactly how Opportunity would wind up performing.

The same panoramic composite image, taken by Opportunity, shown with two different color assignments. Top image is in “true color,” as human eyes would see Mars, while the bottom is in false-color enhanced for color contrast. (NASA / JPL-CALTECH / CORNELL / ARIZONA STATE UNIV.)

After more than 5,000 days, 45 kilometers of total distance traversed, and more than 90 million turns of its wheels, Opportunity had, to its credit, many lifetimes of Martian discoveries. The panorama above, shown in both true color (top) and false color (bottom) to highlight the different features in the terrain, is just one of a myriad of images from this unforgettable mission.

While the Curiosity rover, itself approaching its 7th anniversary on Mars, may be making today’s groundbreaking discoveries on the surface of the red planet, Opportunity still holds a number of records that are unlikely to be broken anytime soon, including the distance record for any human-made device on the surface of another world. In 2015, it became the first vehicle to pass 26.2 miles — or marathon distance — on another planet.

This chart illustrates comparisons among the distances driven by various wheeled vehicles on the surface of Earth’s moon and Mars. Two of the vehicles shown — NASA Mars rovers Opportunity and Curiosity — are still active, and their drive distances shown are as of June 18, 2018. Opportunity holds the off-Earth roving distance record after accruing 25 miles (40 kilometers) of driving on July 27, 2014.(NASA/JPL-CALTECH)

Although it hasn’t been officially declared dead, Opportunity is unlikely to recover. Its legacy isn’t simply one of longevity and perseverance, although those are certainly important components of the story. It’s also a testament to human ingenuity, clever techniques and tactics used to keep it running, and the lucky beneficiary of many cleaning events, where high winds have blown accumulated dust off of the solar panels, extending its life. Many are hoping that such an event could happen again, as it would have the potential to revitalize the rover under some scenarios.

Most importantly, though, Opportunity should be remembered for the series of discoveries it brought us concerning the Martian surface, and the new understanding we gained of what the terrain of Mars is actually like. Here are some of its top highlights.

Shown in the same colors that human eyes would see it, this iron-nickel meteorite represents the first time that humanity ever discovered such a meteorite on the surface of Mars. (NASA / JPL / CORNELL)

It discovered the very first meteorite — an iron-nickel fragment — on the surface of another world.

This iron-nickel meteorite, examined and photographed by Opportunity, represents the first such object ever found on the Martian surface. (NASA / JPL / CORNELL)

It showed, in fact, that these meteorites exhibit the same surface features that windblown sand creates on iron-nickel meteorites found in the desert here on Earth. This is exactly what you’d expect to find on Mars, whose environment very closely resembles the dry, desolate deserts of Earth.

Fram crater, one of the earliest craters encountered by Opportunity, showcases the extreme hazards of driving on Mars. If a few wrong moves were made, Opportunity could have either tipped over or gotten stuck. Both outcomes would have ended Opportunity’s mission very prematurely. (NASA / JPL / CORNELL)

Since it began its journey at Eagle Crater on Mars in 2004, Opportunity has taken an unprecedented journey to some spectacular places, including Endurance crater, where Opportunity was able, for the first time, to take a look at some of the sedimentary history of the Martian surface.

Endurance crater, shown from the outside, contains a number of remarkable but common features, such as the dunes filling the crater’s insides, the steep crater walls, and a large number of stony areas where the sand has been blown away by the Martian winds. (NASA / JPL / CORNELL)

The hills and cliffs inside this crater are so steep that pieces of Mars’ geological history were revealed. This is actually the case for a large number of Martian craters, as the photo of Burns cliff inside Endurance crater shows.

Burns cliff, part of the crater walls of Endurance crater, shows off the various layers that have been built up over time on the surface of the red planet. An impactor from outer space revealed these layers long ago, and Opportunity came by to serendipitously discover and image them. (NASA / JPL / CORNELL)

It also visited a slew of other interesting features, including the beautiful Erebus crater, with the unusual feature known as “Payson ridge” shown in the photo below. More than a decade after its discovery, we still haven’t uncovered the surefire origin of this ridge.

Payson Ridge, shown here, is a feature found on Mars in Erebus crater by Opportunity. Its origin is still unexplained even today. (NASA / JPL / CORNELL)

Opportunity also stopped off by Victoria Crater, which — with the assigned color shown here — looks like it could be right out of a scene here on Earth! Below, you can see it with one of its many outcroppings: Cape St. Vincent.

Cape St. Vincent, shown here in assigned color, is one of many such capes around the rim of Victoria crater. The stratified layers of ground provide evidence for a sedimentary rock history on Mars, which also implies the past presence of liquid water. (NASA / JPL / CORNELL)

In the area surrounding Victoria Crater, as well as in a slew of other places, Opportunity found “Martian blueberries,” or hematite spheres that look to be evidence of past water on Mars.

This iconic photograph of the Martian blueberries, or hematite spheres, was taken by Opportunity in the lowlands of Mars. It is thought that a watery past led to the formation of these spherules, although other explanations may be plausible for the formation of individual spheres. (JPL / NASA / CORNELL UNIVERSITY)

You might look at these spheres and immediately think of all sorts of non-water-based origins for them. Indeed, it’s conceivable that they could have come about through a few other geologic processes that spawned these in isolation.

But then, how would you explain that we’ve found some of them fused together?

As discovered by the Opportunity rover, hematite spheres and spherules have been found on Mars. While there may be mechanisms to form them that don’t necessarily involve liquid water, there are no known mechanisms, even in theory, that can form them fused together as found in the absence of liquid. (NASA / JPL / CORNELL / USGS)

That’s not something that currently has a viable explanation other than a watery past on the Martian surface.

After visiting Victoria crater, the decision was made that Opportunity would run the first Mars-half-marathon, and head to the gigantic Endeavour crater, despite the fact that its solar panels were only operating at 50%, thanks to being covered in years of Martian dust. You have to remember, that after years on the dusty surface and a completely dry atmosphere, Opportunity simply wasn’t prepared to deal with the buildup of material that would come to block the incoming sunlight.

The dusty solar panels shown here accurately represent what Opportunity accumulates during its time on Mars. If not for a series of cleaning events that resulted from winds blowing this dust away, Opportunity would have been left with insufficient power to continue operating long before now. (NASA / JPL)

But part of how Opportunity lasted so long was just this: it got lucky.

For what was neither the first nor the last time, a simple gust of wind came along in 2009 and partially cleared off the panels, giving the eponymous rover the opportunity to make the spectacular journey in less time than anyone had anticipated: just three years! Here’s a rover’s-eye view of the journey.

In 2012, during the Martian winter, Opportunity took the most spectacular panorama of its entire journey: an 817-image-composite of Greeley Haven. Its own tracks are visible in the foreground, at left.

Greeley Haven was where the Opportunity Rover hunkered down for the winter in 2012. The composite panorama, shown here, is the result of more than 800 images stitched together. (NASA / JPL-CALTECH / CORNELL / ARIZONA STATE UNIV.)

Greeley Haven was very close to the destination of Endeavour crater, which is special for a number of reasons. For one, it’s the largest crater ever visited by a rover or lander on another world, even at present. For another, the trip to Endeavour crater marks the longest journey ever taken on another world from source to destination.

But perhaps my favorite bit of trivia is that some of the names of remarkable features along the way have explicit meanings that are like little Easter Eggs for any enthusiast of space exploration.

From its initial landing site at Eagle crater to its ultimate destination surrounding Endeavour crater, Opportunity has traveled farther than any other robotic mission on another planet in history. This image was published in 2014, when Opportunity crested the 25 mile mark. (NASA/JPL-CALTECH/MSSS/NMMNHS)

There’s a crater, marked above, called Lunokhod 2, named after the Soviet lunar rover that was the prior record-holder for traversed distances beyond Earth. The crater was so named because, upon reaching it, Opportunity tied its record.

Marathon Valley, reached in 2014, marked the first time that a vehicle on another world passed the 26.2 mile marker: a complete marathon as we know it on Earth.

The Martian crater named Lunokhod 2, shown here, marks the location where, after a decade of active roving on Mars, Opportunity equaled and broke the record for distance traveled by any vehicle on a world other than Earth. (NASA/JPL-CALTECH/CORNELL/ARIZONA STATE UNIV.)

In hindsight, Opportunity’s demise could have been avoided. If one extra piece of equipment, such as a compressed air blower aboard a robotic arm, were installed, dusty solar panels could have been cleaned at will. Hunkering down to survive a dust storm, even one that blocked 100% of the light, wouldn’t be catastrophic so long as the rovers had enough power stored in their batteries to control and operate the blower mechanism.

For comparison with its dust-covered current state, here’s the Opportunity rover’s self-portrait shortly after a cleaning event. Note how ‘like new’ the solar panels look. If we had installed a mechanism to clean the panels, we could have forcibly cleaned them this at any opportune time. (NASA / JPL-CALTECH)

Had that been in place, Spirit could have saved itself from its 2010 fate, and Opportunity wouldn’t have suffered its likely 2018 demise. Still, even though hindsight is 20/20, it’s pretty hard to be sad about two missions that overachieved beyond anyone’s expectations.

Travel the Universe with astrophysicist Ethan Siegel. Subscribers will get the newsletter every Saturday. All aboard!

Happy anniversary, Opportunity. Although no one’s expecting your return, you exceeded everyone’s expectations. Mars and Earth both are so much richer for what you’ve brought us, and today, after 15 years on the red planet, we celebrate you.

Ethan Siegel is the author of Beyond the Galaxy and Treknology. You can pre-order his third book, currently in development: the Encyclopaedia Cosmologica.


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