health & science
Could RotoVegas become RotoMars?
The upcoming 2020 Mars Rover mission is looking specifically for evidence of life on Mars, and New Zealand’s unique geology and our scientists’ research are helping determine where that search will occur. Baz Macdonald reports.
Tourism and cultural mecca Rotorua has long been likened to Las Vegas, earning itself the nickname Rotovegas, but now it is being linked with an altogether bigger destination - Mars.
So much so that a "Rotorua on Mars" project exists within the academic ranks at the University of Auckland.
The reason? Scientists, including Kiwi researchers, are trying to learn from the existing hot pools of Rotorua about the likelihood of life long ago at former hot pools on the Red Planet.
The search for life elsewhere in our solar system takes a big leap forward in 2020, when NASA sends the first rover to Mars with the primary goal of finding evidence of extra-terrestrial organisms.
This mission is still in its planning phase, with many aspects yet to be decided – including where on the red planet the search will take place.
The determination of the landing site has been an ongoing process, and New Zealand, due to Rotorua, is playing a key role in the discussion.
A University of Auckland paleoecologist, Kathy Campbell, is part of the team arguing the landing site should be Columbia Hills, in the Gusev Crater - the same site used for the 2004 Spirit rover mission.
There is evidence this site contains ancient hot pools and Campbell and her team believe these pools hold the best chance of finding evidence of past life on Mars.
“This is an incredibly exciting moment. [NASA] are specifically trying to track bio-signatures, and not just water or habitable environments where there could have been microbes,” Campbell said.
“But, it is a very tricky thing to do because it is like looking for a needle in haystack. There are lots and lots of reasons why it could have been there, and you’d never find it.”
The 2020 expedition has been emboldened by the discoveries of the Curiosity Mars Rover. In recent weeks, NASA announced Curiosity had found organic chemicals in the lakebed sediment of Gale Crater. These organic compounds do not necessarily confirm that there has been, or is, life on Mars, but they do strengthen the case that the planet could once have been home to organisms.
These discoveries also raise the stakes for this next mission, and scientists are more determined than ever to pick the landing site with the highest chance of discovering evidence of organic life. Campbell and her team believe ancient hot pools are the answer, and Rotorua is helping to prove it.
Campbell became involved with the 2020 landing site 'submission' in 2016 when she hosted astrobiologist Steve Ruff of Arizona State University and others on a field expedition to Rotorua. Ruff was part of the Spirit rover team and was already an advocate of returning to the same site for the upcoming mission. Campbell and Ruff’s teams hit it off and decided to join forces in promoting the Spirit site as a potential landing target.
Ruff’s focus on the Spirit mission was in analysing the silica samples from Columbia Hills. In the time since, he has been working to compare these samples to hot springs across Earth. This shaped the submission Ruff and Campbell’s team made to scientists and engineers at a Jet Propulsion Lab and NASA at a workshop early last year.
This submission focused on how almost all silica found near hot springs on Earth have some evidence of microbial life within them – which, in turn, means if there was life on Mars there is a good chance Martian hot springs would also contain well-preserved bio-signatures.
Campbell and her team have conducted research in this field in Rotorua and are now trying to match the character of the hot spring deposits found in Rotorua with what they think will be a similarly diverse area on Mars. In Columbia Hills, oddly shaped finger-like silica growths may have formed from microbes in hot springs, similar to what is seen on Earth, including around Rotorua.
Bolstering the submission is a University of Auckland-funded project called “Rotorua on Mars”, in which Campbell and her team conduct a range of experiments, from mapping areas with drones to deciphering hot spring microbiology, to compare with the Columbia Hills landscape and makeup.
At the submission workshop in February, eight teams presented arguments for their proposals and the group of scientists and engineers discussed the strengths and weaknesses of the sites offered before a committee shortlisted three sites – Columbia Hills, Jezero Delta and North East Syrtis Major.
Though the shortlist sites weren’t ranked, it was clear, Campbell said, Jezero Delta was the front-runner. Like the site Curiosity is exploring, Jezero was once believed to be a lake on Mars and the Delta has ancient river beds feeding into it. On Earth, there is increased organic matter found in the muddy outer edges of deltas, and so some scientists believe a Martian lakebed may be the best chance of finding bio-signatures during the 2020 rover mission.
There are multiple advantages and disadvantages for each potential landing site. For instance, although deltas have a high chance of preserving organic material, it could be difficult to determine the origin of the carbon that could be buried there – as it is likely to have come downstream when there was flowing water.
With the hot springs at Columbia Hills, not only will silica have potentially preserved organic signatures better than a lakebed but any fossils found will have originated in the same area. However, Columbia Hills also has the disadvantage of being dusty, which Campbell said is surmountable but is another complication.
Although the primary goal of this mission is the identification of bio-signatures, it also has a secondary long-term goal which would favour Columbia Hills. This mission will not only collect samples but cache them so a future mission to Mars can fetch them by remotely operated vehicles and send them back to Earth. Campbell said the fact that we already know so much about Columbia Hills from the Spirit mission makes the caching of materials much easier, as the scientists already know the geology of the area, the engineering constraints and so know what materials to collect and potential places they could store them.
Because of this, the 2020 NASA mission is not the be all and end all for Campbell and her team’s argument for returning to Colombia Hills. There are other agencies around the world which look at creating sample retrieval missions, and Campbell has contributed to how this could be possible.
The final meeting to determine the landing site for NASA’s 2020 mission is in October. Campbell said she had been unsure of whether their site would be selected, but that the discovery by Curiosity of organic matter in the Gale Crater Delta “gives them all the more reason to go to another delta – and that would be Jezero”.
“But, perhaps in the future there would be a sample return mission just to get those rocks at Columbia Hills. That could happen, and it doesn’t even have to be NASA – China could do it, or even the combined NZ/Australia Space Agency could decide to do it someday. Why not?” Campbell said. “Or maybe even humans will go to collect those samples from Columbia Hills.”
“I’m pretty relaxed about when it happens, but if they are really serious about finding ancient life then I reckon they have to return to Columbia Hills at some point.”
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