Explained: Why is Mars so interesting to scientists – and to the adventurer that lives in us all?

NASA's Mars 2020 Perseverance Rover touched down on the Martian surface in the early hours of Thursday. The results of the experiments by Perseverance will likely define the next couple of decades of Mars exploration. A NASA scientist explains why and how.

Perseverance is not just another Rover Mission. Perseverance is the most advanced, most expensive and most sophisticated mobile laboratory sent to Mars. The results of the experiments on Perseverance will likely define the next couple of decades of Mars exploration – it will determine the course of search for life and a future manned mission to Mars.

Mars Science in the past 30 years

We have come a very long way in understanding Mars from the time of the first generation missions in the 1960s. The Viking missions in the mid-seventies carried out the first chemical analysis of Martian soil, as well as four biology experiments to detect biological activity. The experiments did not yield any conclusive evidence of life.

In the early 1980s, scientists hypothesised, based on mineralogic composition and rock texture, that certain meteorites might have a source region in Mars, in contrast to the asteroid belt. In 1984, a study showed that the isotopic composition of rare gases (Xenon, Krypton, Neon and Argon) matched the isotopic ratios of the Martian atmosphere measured by the Viking spacecraft. This discovery provided a way for geochemists to study Martian samples – and provided a huge boost to our understanding of the geochemical evolution of Mars.

Mars was considered to be a dry planet in the 20th century. This changed in 2001, when the Gamma Ray Spectrometer on board the Mars Odyssey spacecraft detected a fascinating hydrogen signature that seemed to indicate the presence of water ice. But there was ambiguity – this was because hydrogen can be part of many other compounds as well, including organic compounds.

To test for the presence of water, NASA sent a spacecraft to land near the Martian South Pole in 2007. The spacecraft studied the soil around the lander with its robotic arm and was able to establish, without any ambiguity, the presence of water on Mars for the first time.

The Curiosity rover carries an instrument called SAM (or Sample Analysis at Mars), which contains a suite of spectrometers with the goal of detecting organic compounds on Mars. SAM has a mass spectrometer that can measure not just the elements, but the isotopes as well. This instrument has made the fascinating discovery of large chain organic compounds on Mars. It is not known how these organics form on Mars: the process would likely be inanimate, but there is a fascinating possibility that such complex molecules were formed by processes associated with life.

Mars Insight is creating history right now, by monitoring seismic activity and heat flow on Mars – this will help understand the composition of the Martian interior.

Dr Amitabha Ghosh is a NASA Planetary Scientist based in 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.

The enduring fascination with Mars

Why is Mars so interesting to scientists? And to the explorer-adventurer in all of us? There are two primary reasons.

First, Mars is a planet where life may have evolved in the past. Life evolved on Earth 3.8 billion years ago. Conditions on early Mars roughly around 4 billion years ago were very similar to that of Earth. It had a thick atmosphere, which enabled the stability of water on the surface of Mars. If indeed conditions on Mars were similar to those on Earth, there is a real possibility that microscopic life evolved on Mars.

Second, Mars is the only planet that humans can visit or inhabit in the long term. Venus and Mercury have extreme temperatures – the average temperature is greater than 400 degree C, or hotter than a cooking oven. All planets in the outer solar system starting with Jupiter are made of gas – not silicates or rocks – and are very cold. Mars is comparatively hospitable in terms of temperature, with an approximate range between 20 degrees C at the Equator to minus 125 degrees C at the poles.

The mission of Perseverance on Mars

Perseverance addresses both the critical themes around Mars – the search for life, and a human mission to that planet.

Sample Return Mission: Is there life on Mars?

Perseverance is the first step in a multi-step project to bring samples back from Mars. The study of the returned rock samples in sophisticated laboratories all over the world will hopefully provide a decisive answer on whether life existed on Mars in the past.

Here are the steps in the Sample Return:

As the first step, Perseverance will collect rock and soil samples in 43 cigar-sized tubes. The samples will be collected, the canisters will be sealed, and left on the ground.

The second step is for a Mars Fetch Rover (provided by the European Space Agency) to land, drive, and collect all samples from the different locations, and return to the lander.

The Fetch Rover will then transfer the canisters to the Ascent Vehicle. The Mars Ascent Vehicle will meet with an Orbiter after which the Orbiter will carry the samples back to Earth.

This long-term project is called MSR or Mars Sample Return. MSR will revolutionise our understanding of the evolutionary history of Mars. If MSR is successfully executed, we will have a reasonable answer of whether there was microscopic life on Mars.

But MSR does have its risks. If one of the components fails, like the Fetch Rover or the Mars Ascent Vehicle, MSR is doomed. A hidden risk is strategic. At the cost of MSR, there could be 5-10 spacecraft missions to different parts of the solar system: so hence, by choosing MSR, NASA forecloses the option to undertake those other missions.

Producing oxygen on Mars: A critical requirement

For a human mission to Mars to materialise, the cost needs to be reasonable. For costs to be reasonable, there needs to be a technology and infrastructure in place to manufacture oxygen on Mars using raw materials available on Mars.

Without a robust way to manufacture oxygen on Mars, human missions to Mars will be very expensive, and unrealistic. Without a reliable oxygen production plan on Mars, Elon Musk’s plan to provide commercial transportation to Mars will be at risk of failure.

Perseverance will have an instrument – MOXIE, or Mars Oxygen In-Situ Resource Utilisation Experiment – that will use 300 watts of power to produce about 10 grams of oxygen using atmospheric carbon dioxide.

Should this experiment be successful, MOXIE can be scaled up by a factor of 100 to provide the two very critical needs of humans: oxygen for breathing, and rocket fuel for the trip back to Earth.

Looking for underground water on Mars

Perseverance will carry the Radar Imager for Mars’ Subsurface Experiment (RIMFAX). RIMFAX will provide high resolution mapping of the subsurface structure at the landing site. The instrument will also look for subsurface water on Mars – which, if found, will greatly help the case for a human mission or the cause of a human settlement on Mars.

Testing a helicopter to fly on Mars

The Mars Helicopter is really a small drone. It is a technology demonstration experiment: to test whether the helicopter can fly in the sparse atmosphere on Mars.

The low density of the Martian atmosphere makes the odds of actually flying a helicopter or an aircraft on Mars very low. Long-distance transportation on Mars has to rely on vehicles that rely on rocket engines for powered ascent and powered descent.

We are perhaps a decade from two milestones in the exploration of Mars: a human mission to Mars, and a decisive answer to the question of whether Mars harboured – or still harbours – microscopic life. Perseverance is expected to provide significant insight on both questions.

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