When the newest Mars rover lands on the Red Planet in February 2021, following a seven-month journey, we’ll be able to hear sounds from the surface of Mars for the very first time.
With construction about to commence, NASA has announced that the unnamed rover, temporarily known as Mars 2020, will have better cameras, multiple microphones and thicker wheels to keep if from breaking down.
Given the rover’s main objective is looking for signs of life, it will also feature a ground-penetrating radar and coring drill to go below the surface of Mars.
Other on-board devices will allow the rover to analyse organic chemicals and test the planet’s ability to form oxygen, in the hopes of one day colonising the Red Planet.
The design leverages many successful features of NASA's Curiosity rover, which landed on Mars in 2012, but also adds new science instruments and a sampling system to carry out new goals for the 2020 mission [Image: NASA/JPL-Caltech]
Back down on Earth, the specimens will be examined for evidence of life and potential hazards for future human visitors.
“The Mars 2020 rover is the first step in a potential multi-mission campaign to return carefully selected and sealed samples of Martian rocks and soil to Earth,” said Geoffrey Yoder, acting associate administrator of NASA's Science Mission Directorate in Washington.
“This mission marks a significant milestone in NASA's Journey to Mars – to determine whether life has ever existed on Mars, and to advance our goal of sending humans to the Red Planet.”
If the new design seems familiar, that’s because it’s based on the highly successful Curiosity rover that landed on Mars in 2012 and is still in working order. After almost four years on the Red Planet, the rover has made many startling discoveries.
1. Early Mars was habitable, perhaps for a long time.
After concluding that rivers and streams once flowed into Gale Crater, the Curiosity team has now reported that a lake existed there as well. That surface water, as well as groundwater that likely went down hundreds of meters, possessed all that was needed to support microbial life.
The period when Gale Crater was warmer, wetter, and habitable was broadly between 3.5 and 4 billion or more years ago. That period is when life on Earth is understood to have arisen.
Was Mars once home to primitive extra-terrestrial life? Curiosity can't and won't make that determination, but its discoveries have made the possibility of Martian life significantly more plausible.
2. Water once flowed on many parts of Mars.
NASA’s Mars Reconnaissance Orbiter (MRO) has provided the strongest evidence yet that liquid water is flowing intermittently on Mars.
We’ve known for a while about dark streaks on the surface of the red planet, but this is the first confirmation that the markings were made by flowing water.
This new discovery is the first evidence of its kind, and the first step in confirming life can exist on Mars.
According to Jim Green, NASA’s Director of Planetary Science, the next step is to find the source of the water.
“This is tremendously exciting. We haven’t been able to answer the question “does life exist beyond Earth?” But following water is a critical element of that,” he said.
While the possibility of microbial lifeforms on Mars is exciting on its own, the presence of water also opens up other possibilities – like the potential for humans to live on the red planet.
3. "Follow the carbon" has been vindicated.
The search for Martian carbon-based organic compounds—one of the major goals of the Curiosity mission—has been and will continue to be complicated and trying.
While as many as six different organic compounds have been identified so far by the miniature chemistry lab called Sample Analysis at Mars (SAM), their origin remain unclear.
"There's no doubt that SAM has identified organics, but we can't say with confidence yet that they are Martian in origin," said Douglas Ming of NASA's Johnson Space Center, and author of one of the six Curiosity papers in Science.
There are at least two sources of the confounding results: The presence on Mars of a chlorine-based compound that, when heated in the SAM oven with any organic material, largely destroys the compounds. And the leak into the SAM ovens of an organic solvent brought to Mars as part of a wet chemistry experiment.
The search for Martian organics is nonetheless making progress. With each collection of Martian sand or rock, the number of organics found and their concentration has increased—suggesting that different samples of Martian material are leading to different results. If the organics were all contaminants from Earth, those concentrations would likely be steadier.
"SAM is probably the most complex and important instrument ever brought to another planet," Ming said. "Inevitably, it has taken time to figure out how best to work with it."
4. Mars gets pounded by radiation.
Galactic cosmic rays and solar eruptions bombard Mars, and their high-energy particles break the bonds that allow organisms to survive. TheRadiation Assessment Detector on Curiosity has made the first measurements ever of radiation on the surface of Mars, and the results are sobering.
In another Science paper, RAD principal investigator Donald Hasslerreports that the radiation would almost certainly be fatal within a few million years to any microbial life on the surface or less than several meters deep.
The RAD team used as their model the terrestrial bacteria Deinococcus radiodurans, which is capable of withstanding enormous doses of radiation, to make that assessment.
Notwithstanding the high levels of radiation, Hassler reported that life could theoretically still survive on Mars today under special circumstances. If a bacteria similar to D. radiodurans appeared when early Mars was wetter, warmer, and had a more protective atmosphere, he wrote, it could have survived over the epochs through long periods of dormancy.
5. Mars radiation also damages normal chemistry.
Many on the Curiosity team point to radiation damage of all carbon chemistry on Mars as a major reason why it has been so difficult to identify organics on the surface.
That effort, however, may have gotten a significant boost from one of the most unexpected developments to come out of the mission so far?a method to date how long surfaces have been exposed to the sky on Mars.
Using measurements of radioactive decay also employed on Earth, Kenneth Farley of the California Institute of Technology reports that the surface of Yellowknife Bay has been exposed for some 80 million years.
The discovery points to a method for finding places for the rover to drill where there has been less chemistry-damaging radiation exposure.
Essentially, Farley said, the team has to look for cliffs or overhangs being undercut by the surface wind?as happened in Yellowknife Bay?and where radiation would be blocked by the rocks above. "If we find that kind of formation," he said, "drill there."
6. Detours sometimes turn out to be interesting.
The Curiosity rover was scheduled to head for the scientifically alluring Mount Sharp in the centre of Gale Crater soon after landing. More than 480 days into the mission, the rover is still months away from its prime destination.
The detour to Yellowknife Bay is the main reason why, and it has turned out to be a gold mine of data. But now the rover is on what is called the "rapid transit route" to three-mile-high Mount Sharp, driving most of the time and passing many potentially interesting sites.
Having already found and analysed the first potentially habitable environment ever discovered on Mars, the Curiosity team will be looking for more. And with their increased knowledge about which potential drill sites are likely to have been protected from radiation, the search for Martian organics will go into high gear as the rover approaches the target-rich Mount Sharp.