Imagine driving on the loneliest road in the world. For the traveller, it is a cathartic experience. One can drive for hours on end without seeing another car or human being. There is the wilderness, the landscape of mountains and valleys, the open sky above and the spectacular night bejewelled by stars. Driving on Mars is a somewhat similar experience. Except there is no road. The rover can drive anywhere it chooses to, and is able to. Except no human or machine has driven on the road before. That is the rush of operating a rover on Mars.
What has NASA’s experience been with multiple generations of Mars rovers?
NASA’s incredible journey of driving on Mars started about 23 years ago, in 1997: when the Mars Pathfinder Mission with the Sojourner rover egressed on the Martian soil. It was an unforgettable experience to be part of the Operations team for Mars Pathfinder: a mission put together on a very tight budget that many thought would fail. However, Mars Pathfinder would succeed and in the process would change the subsequent history of Mars Exploration. Thus, NASA would go on to send the twin rovers, Spirit and Opportunity, to Mars in 2003, followed by Curiosity in 2012, followed by Perseverance that is scheduled to launch later today.
The Sojourner rover, a technology demonstration mission, lasted for 83 days. Spirit and Opportunity set a new paradigm of a long term robotic presence on Mars, lasting about 6 and 15 years, respectively. Curiosity landed in 2012: and continues to operate today. With each rover generation, the number and the complexity of scientific instruments increased. Sojourner was a small rover, almost like a toy, a couple of feet in length and width. Spirit and Opportunity were much larger: about the size of a golf cart. Curiosity and Perseverance are the size of a small car.
The science returns of exploring Mars with a rover have been very significant. Rovers provide a way to study the local area in much higher resolution than is possible from an orbiting spacecraft. In addition, rovers have a suite of instruments from drills to spectrometers to microscopic imagers: these instruments help understand the local geology much like a field geologist would study rocks on Earth. In addition, starting with Spirit and Opportunity, rovers have acted as mobile weather stations on Mars that monitor changes in the Martian atmosphere continuously over multiple years.
With each new generation of rovers, NASA has added new capabilities and a somewhat different instrument suite to answer important scientific questions. Examples would be the addition of a drill on Spirit and Opportunity, and a mass spectrometer, an instrument to measure isotopes of different elements, for Curiosity. With the launch of Mars Perseverance, the fourth generation of Mars rovers, NASA will take forward this tradition.
Dr Amitabha Ghosh is a NASA Planetary Scientist based out of Washington DC. He has worked for multiple NASA Mars Missions starting with the Mars Pathfinder Mission in 1997. He served as Chair of the Science Operations Working Group for the Mars Exploration Rover Mission and was tasked with leading tactical Rover Operations on Mars for more than 10 years. He helped analyse the first rock on Mars, which incidentally happened to be the first rock analysed from another planet.
What is new with Perseverance?
First, Perseverance will carry a unique instrument, MOXIE or Mars Oxygen ISRU Experiment: which for the first time will manufacture molecular oxygen on Mars using carbon dioxide from the carbon-dioxide-rich atmosphere. There is the new push for ISRU at NASA: in NASA jargon, ISRU means In Situ Resource Utilization: or the use of local resources to meet human needs or requirements of the spacecraft. Without ISRU, exploration of Mars in the future decades will be incredibly expensive and thereby impossible. If astronauts have to carry oxygen or water or rocket fuel for their journey for a two-year journey to Mars and back, the cost will be understandably excessive. In a way, this is similar to a traveller from New Delhi having to carry their own oxygen, food supplies and aircraft fuel for a two-year stay in New York: the cost per passenger will be incredibly high. If oxygen can be successfully extracted on Mars in some significant scale, this can have two direct advantages: first, the oxygen can be used for human visitors to Mars, and second, the oxygen can be used to manufacture rocket fuel for the return journey. Thus, if the technology demonstration is successful, NASA can easily scale up the oxygen generation rate per day for MOXIE by a hundred times: this would be of great use for a future human mission to Mars.
Second, Perseverance will carry Ingenuity, the first ever helicopter to fly on Mars. This is the first time NASA will fly a helicopter on another planet or satellite. Ingenuity is a technology demonstration: the challenge, of course, is to fly the helicopter in the thin atmosphere of Mars. Like a drone on Earth, a Mars helicopter can help in rover drive planning and in fetching samples from locations that the rover cannot safely drive to. If this technology demonstration is successful, we will see a greater role for such helicopters in future missions.
Third, Perseverance is the planned first step to bring back rock samples from Mars for analysis in sophisticated laboratories on Earth: with the goal of looking for biosignatures: or signatures of present or past life. Perseverance will collect samples and a second rover mission will fly within a decade to help transport the rock samples back to Earth.
The analysis of Martian rocks on Earth will likely provide a reliable indication of whether life on Mars is feasible in the past or at present.
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What is the reason for the near-term interest in Mars?
Mars is a fascinating planet for humankind. Located in the very near backyard (about 200 million km away), Mars is a planet that humans can aspire to visit or to stay for a longer duration. Mars had flowing water and an atmosphere in the distant past: and perhaps conditions to support life.
But, in the near term, the increase in interest related to Mars is because of Elon Musk’s plans for commercial travel. A human mission to Mars has always been an aspiration for different space agencies including NASA. Though technologically possible, the cost was known to be prohibitive: perhaps of the order of $500 billion or 20 times NASA’s budget. Hence, NASA’s plans to send astronauts to Mars have been, in large part, aspirational: in other words, without adequate funding.
Musk has unveiled a new architecture to get to Mars. Musk’s vision is to use a combination of cost-saving measures, like reusable launch vehicles, in-orbit refueling and manufacturing rocket fuel on Mars, to reduce the cost of a journey to Mars down by 1/1000th. Thus, the price per passenger for going to Mars on his Starship Spaceship would be on the order of $200,000 or Rs 1.5 crore. The launch vehicle at the centre of Elon Musk’s plans is the Starship Spacecraft: the most powerful launch vehicle ever built, with the ability to transport 100 metric tonnes to Earth Orbit. SpaceX is scheduled to fly around the Moon with its first private passenger in 2023: and has the goal for a crewed mission to Mars as early as 2024. As we speak, the Starship is being built and tested in a sleepy South Texas town called Boca Chica. In a decade, SpaceX with its Starship Spacecraft, might transform space travel and realise Musk’s dream of turning humankind into a multi-planetary species.
This article first appeared in the print edition on July 30, 2020 under the title ‘Destination Mars’.