By: Amitabha Ghosh
Last Sunday, the Nasa Mars rover, Opportunity, broke the record for off-Earth driving, previously held by the moon rover, Lunokhod 2, which was launched by the former USSR in 1973. Not only has Opportunity driven 25 miles, it has heralded long-term robotic presence on the surface of another planet.
While life continued on Earth, on July 27, unknown to most outside the mission team, Opportunity completed a spectacular drive on Mars, surpassing 25 miles, and in the process became the vehicle to drive the longest distance outside Earth. Opportunity landed on Mars in January 2004, with the objective of surviving 90 days and driving one kilometre. Ten years and 40 km later, Opportunity is still trooping forward on Mars, continuing its mission to explore an unknown world, to feast its eyes on landscapes that no human has seen before and to leave its wheel tracks where no vehicle has driven before. Opportunity shows some signs of ageing, but for the most part, it is functional. In fact, its solar arrays are clean and the energy generated by the arrays is comparable to the first year of the mission.
Opportunity landed at Eagle Crater, but it has driven far beyond to Endeavour Crater. It is trying to track down the signs of clay minerals in the western rim of Endeavour Crater seen from orbit by CRISM, a spectrometer on board the Mars Reconnaissance Orbiter. Clay minerals help scientists figure out questions related to water and to the hospitality of past environments for life on Mars.
The longest road trip that I have been on was two days long, when I drove from Washington DC to Florida. But Opportunity has been on the road for 10 years, exposed to the sun, winds, dust and radiation. It has been witness to the change in seasons, the regional dust storms on Mars that obliterate the sun and the freezing temperatures of five Martian winters. And of course, as it drove, Opportunity has seen the wonderful vistas of Mars — from Martian sunsets to iron meteorites, from cirrus clouds to the spectacular world of Martian rocks — that have been viewed for the first time through its microscopic imager. Throughout the roadtrip, Opportunity has had no physical repairs. It has never had the luxury of swapping some old parts for new, no new lubrication for the wheels, no new battery or motherboard for the onboard computer.
In the broader scheme of things, courtesy five orbiters, four rovers and one lander, we have covered significant ground in Mars exploration over the last 18 years — since the Mars Global Surveyor landed on that planet in 1996. We have confirmed the presence of ice at the Martian poles and evidence of liquid water in the past. Spirit and Opportunity, together with Curiosity, have set the stage for the next rover mission, Mars 2020, which will likely have the capability of looking for biological evidence related to life and a mechanism to generate oxygen on Mars. We have made huge strides in obtaining geologic, chemical, mineralogic and atmospheric data from Mars, which have greatly helped scientists understand the geologic and atmospheric evolution of that planet. Mars has transitioned from a distant object to an accessible planet that is inundating us with new data every day from two rovers and four orbiters.
Behind Opportunity lies a team that has developed and operated the vehicle. The team has battled incredible odds to operate a vehicle about 200 million km away. From landing on Mars to driving across it, it has been a journey into an unknown parameter space from an engineering standpoint, which calls for customisation, iterative learning and reworking. A strategic mistake in preparing for the long term or an oversight in planning a single observation on Mars has the potential to cause irreversible damage to the rover. For more than 3,735 sols (or Martian days), the team has commandeered activities that have balanced the requirements of science, the adventurism of trying something new and the conservativeness of not taking irrational risks.
The writer is science operations working group chair of Opportunity and leads the operations team that plans the rover’s activity on Mars