NASA's twin Mars Exploration Rovers, Spirit and Opportunity, were launched from Earth in 2003. The two rovers were designed as robotic geologists, and were to spend 90 days roaming the surface of the red planet and studying the history of liquid water on Mars.

Spirit was the first of the two rovers to launch and land on Mars. Spirit left Earth on June 10, 2003, and touched down in Gusev Crater on January 4th, 2004 (UTC). Opportunity launched on July 7, 2003, and landed on Mars' Meridiani Planum on January 25, 2004 (UTC).

The rovers were designed for a three-month mission. However, due to their sturdy construction and the talented team of scientists that control them from Earth, Spirit and Opportunity survived on Mars well past their expiration dates. In fact, Opportunity is still going and will celebrate a decade of scientific discovery this month.

Starting the celebrations
To kick off the MER anniversary celebrations this month, The Smithsonian National Air and Space Museum in Washington DC hosted a two-panel discussion in collaboration with NASA. The panels provided some powerful and personal insight into the continuing story of the long-lived rovers. The first was led by Dr. Pamela (Pan) Conrad, Mars senior scientist at NASA Goddard Space Flight Center.

"This is a really special occasion," said Conrad in her opening remarks. "Who wouldn't fall in love with two awesome robots who lasted about a bazillion times longer than they were supposed to?"

Panelists John Grant and David Lavery gave an overview of the mission and the technologies that allowed the rovers to make so many incredible discoveries over the past 10 years.

"The 'new rover smell' wore off after about 90 sols and they kept going and going and going," said Dr. John Grant of the Smithsonian Institution. "These rovers especially in this case Opportunity, which is continuing-just are doing a fantastic job in making discoveries and exploring the surface of Mars."

"There were [many technologies] that were developed as a part of the process that actually enabled us to put these rovers down on the surface and have them live, not just once or twice, but many multiples of tens of times past their lifetime," said David Lavery, NASA's program executive for Solar System Exploration.

Pan Conrad asked Steven Squyres, principal investigator for the Mars Exploration Rover mission, some interesting questions during the discussion about how the mission might have been different if he had known the rovers would last so long.

"I look back now at decisions that we made... we landed with Opportunity in this marvelous treasure trove of a crater that we named Eagle Crater," Squyres said thoughtfully. "It was 45 days into the mission and we were still tooling around in this little crater. There was wonderful science there, but I'm thinking '90-day mission, and we've spent half of it already in a little hole in the ground!'"

"In retrospect, today is day three thousand... five hundred and... something... I would've given them a little more time had I known," Squyres laughed.

Conrad also questioned Squyres about which of Opportunity's discoveries surprised him the most.

"The most surprising thing scientifically, I think, came right when we landed with Opportunity," answered Squyres. "I did not expect that the evidence for liquid water at and below the surface of Mars was going to be THAT compelling."

"The first picture that we took, there was layered sedimentary rock right in front of the vehicle," he continued. "To me, the most surprising thing with Opportunity was how easy it was. And Spirit... Spirit had to work for everything."

The second panel discussed NASA's scientific interest in Mars and future exploration efforts, both robotic and human, on the red planet. James Green, the director of Planetary Science at NASA Headquarters, acted as moderator for the panel. The participants included Dr. Mary Voytek, director of Astrobiology at NASA, who spoke about how astrobiology research in extreme environments on Earth is helping to shape NASA's goals for Mars.

The major questions surrounding Mars exploration deal with habitability. Is there life on Mars? If there's not life now, was there ever life in Mars' past?

Previous exploration efforts have been built around the 'follow the water' model. The MER mission collected data that helped scientists determine liquid water did indeed persist at the surface of ancient Mars. Curiosity has confirmed this fact. With this in mind, scientists are now beginning to focus on the best locations to look for signs of life.

"Now we're getting a better sense of where on Mars we might look for existing life," said Voytek. "We believe that the harsh environment on the surface - really dry, high radiation - may drive life today - if it exists - underground."

Voytek explained that if we identify life in the Solar System, it will most likely be microbial. To search for life under the surface of Mars, or on other worlds, future missions will need to look for identifying features of microbial life.

"We would look for morphology that looked like a microbe, which is microscopic," said Voytek, "or the chemistry that microbes would need to exist and would use to build their cell walls and all of their cellular machinery."

The participants also touched on the role that robotics and Earth-based science will play in developing human missions.

"The robots that we put down on Mars, both on the surface and in orbit, are our avatars right now," said John Connolly, acting Chief Exploration Scientist at NASA Headquarters. "There are a lot of unknowns about Mars, and without the robots going there first and finding out a lot about these unknowns, it would be a very, very risky endeavor to send people there."

For the near future, robotic exploration of Mars is set to continue, building on the technology and scientific accomplishments of Opportunity and Spirit. NASA landed the Curiosity rover on Mars in 2012, and scientific data from the larger, more powerful cousin of the MERs is already pouring in. The European Space Agency (ESA) is continuing development of its ExoMars program, and plans are already underway at NASA for a new Mars rover in 2020.

However, Dr. John Grunsfeld, astronaut and associate administrator of the Science Mission Directorate at NASA Headquarters, pointed out that robots are not able to explore Mars on their own.

"They're just our tools," said Grunsfeld during the NASA/Smithsonian anniversary event. "It's people, it's scientists here on Earth that are making all the discoveries and we shouldn't forget that."

But Grunsfeld, who has personal experience living beyond the atmosphere of Earth, had strong feelings about the potential for human exploration on the red planet.

"It won't be until we get people on Mars that the big transformation in both science - and humans as a species - will occur," he continued. "However, we need to go one step at a time."

Video of the discussion is available online here.

A month of activity
There are many other activities happening around the United States this month to celebrate the decade of achievements made by the MER mission. NASA's Jet Propulsion Laboratories (JPL) in Pasadena, California, will be hosting a public celebration on Thursday, January 16.

On January 16th, JPL will hold a public celebration at Caltech's Beckman Auditorium in Pasadena, California, at 7pm PST. The event includes John Callas, MER Project Manager, Charles Elachi, JPL Director, Steve Squyres, and Bill Nye of the Planetary Society. For those not based in Southern California, the event will be streamed live at: http://ustream.tv/NASAJPL On Friday, January 17th, John Callas will give a public lecture in The Vosloh Forum at Pasadena City College at 7pm. This event will also be streamed live at: http://ustream.tv/NASAJPL

On January 23rd, 2014, JPL will also hold a media briefing about Opportunity's ten years of science at 11 a.m. PST. The event includes participants John Callas, Steve Squyres and Ray Arvidson, MER deputy Principle Investigator. NASA Television will provide live coverage. http://www.nasa.gov/nasatv

NASA's Mars program also has a special selection of outreach products for the 10-year anniversary at: http://mars.nasa.gov/mer10/ . Products include a gallery of selected images that highlight some of the major achievements of each rover, and a interactive slideshow that helps explain why the rovers have lasted so long past their primary mission.

And finally, the Smithsonian National Air and Space Museum is hosting a special exhibit: Spirit and Opportunity: 10 Years Roving Across Mars. The exhibit will be open through September of 2014. So if you're in Washington D.C., stop by the museum to see an impressive collection of images and displays that explain some of the scientific highlights of the MER mission. More information is available here: http://airandspace.si.edu/exhibitions/mer/

The mission continues
Opportunity is currently positioned at the rim of Endeavour Crater at a sight dubbed 'Solander Point.' The rover is positioned in such a way that its solar panels can produce as much power as possible in order to keep the mission going.

Opportunity touched down on Mars with the goal of driving up to 1 kilometer in 90 days. The last mission update released on January 9th, 2014, placed the rover's odometer at 38.73 km.

On January 7th, 2014, Opportunity took a moment to take a few "anniversary inspired" selfies. Reflecting on the incredible and unexpected distance the robot has travel, the mission team also snapped some pictures of the tracks that the rover continues to leave in the dust on Mars.

NASA and Smithsonian Host 10 Year Anniversary Events for Mars Rovers