TORONTO -- It's been a long time since we believed there could be "little green men" on Mars – but the debate over life on the red planet could soon be reignited.
At least, that's the dream of the scientists behind the three Martian missions arriving at their destinations this month.
The United Arab Emirates-developed Amal orbiter and China's Tianwen-1 combination orbiter and rover have already arrived at the red planet, and NASA's Perseverance rover is scheduled to land there Feb. 18.
The confluence of these three missions is more about timing than teamwork – they were all launched last summer, to take advantage of the window when Earth and Mars are at their closest – but they're all designed to further global understanding about the only other planet in our solar system that is considered potentially habitable.
"Each of these missions have different goals, but ultimately it's to learn more about the habitability of Mars and whether it's suitable for life, or was suitable for life," Sara Mazrouei, an educational developer at Ryerson University in Toronto and planetary scientist, told CTVNews.ca via telephone on Wednesday.
WHAT WE'RE AFTER
Amal, the first-ever planetary mission from the Arab world, will spend two years studying the Martian atmosphere from above. Its observations may give scientists clues as to how Mars went from having a fairly Earth-like atmosphere to leaking its atmospheric gases into space.
"It started out just like the Earth. It had water, it had an atmosphere, and things were going great. Our planet stayed like that, and their planet – all of a sudden the atmosphere just disappeared, and it got very cold, and it all just went to hell," Â鶹´«Ã½ Science and Technology Analyst Dan Riskin told CTVNews.ca on Wednesday via telephone.
"One big question is 'What went wrong, and is that something we should worry about?'"
Tianwen-1, meanwhile, will send its rover to the surface in May to explore for evidence of subsurface ice. This is important for improving our understanding of water on Mars, and potentially life too, Mazrouei said – but also crucial knowledge for planning to send astronauts to the planet, which a space program as ambitious as China's might want to try someday.
As she explained it, a crewed spacecraft journeying to Mars and back will not be able to carry a full set of supplies for its astronauts, the way ships to the moon can. As a result, based on current technology and thinking, the astronauts will need to be able to obtain some of their own supplies from the planet's surface.
"Figuring out if there is water ice below the surface, and how much of it, will really determine where we might land humans in the future," she said.
China's rover will be touching down on Utopia Planitia, a wide-open space where the U.S. first landed a spacecraft in 1976.
Riskin noted that landing site decisions are the result of what he called a "really interesting tension" between those looking to avoid the possibility of a crash-landing and those looking to maximize the possibilities for discovery.
"You have engineers who want to nail the landing, and so they look for the place on the planet that is the safest place to land. They would like it to be a flat, barren landscape with nothing interesting," he said.
"Then you have another team, which is not the engineers but the scientists, and the scientists want to go to the most interesting place possible."
The engineers seem to have won that battle in China, but not in the U.S. Perseverance is expected to touch down at Jezero Crater – a jagged, rocky area that will make for a tricky landing and has never before been explored by a rover.
SELECTING SAMPLES
If Perseverance lands safely and is able to perform its mission, it will take key samples from the soil and set them aside. Plans are underway to send another rover in Mars in a decade or so to retrieve these samples and bring them back to Earth in what would be a historic first. To this point, we have only ever sent spacecraft to the moon and back to retrieve samples.
"The samples that it's going to be setting aside are going to be really, really interesting," Mazrouei said.
Evidence of clay in the crater has been detected from orbit. Because clay forms when water is present, scientists believe Jezero is as likely a spot as any on Mars to have once been underwater – offering up the tantalizing possibility that it also once harboured life.
"It's an ancient river delta, in a sense," Mazrouei said.
There is also a Canadian connection to this work. Chris Herd, a professor of earth and atmospheric sciences at the University of Alberta, is one of the scientists selected by NASA to participate in the project – meaning if the samples collected by Perseverance do make it back to Earth, he'll be one of the first experts to analyze them.
Riskin said Herd's selection for this task is one example of the outsized role Canada plays in space discovery and research. The deal to send a Canadian astronaut on a future NASA moon mission is another.
"We do a really good job getting our foot in the door and playing a pivotal role," he said.
That seems to be as true now as it was in 2008, when it was Canadian scientists – appropriately enough – who discovered on Mars via NASA's Phoenix lander.
Since then, NASA rovers including Curiosity and Opportunity have helped enhance our understanding about everything from Mars' dust storms to its seasonal climate.
"We have so many missions on Mars, but every one of them seems to discover something new," Mazrouei said.
THERE'S WATER, BUT IS THERE LIFE?
Our understanding of Mars has come a long way from centuries ago, when astronomers observed the planet through telescopes and saw what they thought were signs of existing canals.
The idea of widespread water on the planet was disproven by the 1960s, when the first orbiters revealed that, while Mars does indeed contain landscapes that could have been formed by bodies of water, they are now dry and barren.
That's not true of the whole planet, though. Its polar regions are covered in ice, and scientists have found evidence of water hiding beneath that ice cover. Because the existence of water seems to correlate with the existence of life on Earth, scientists believe learning more about water on Mars will help us better understand any form of life that may exist or have existed there.
"We're going back to figure out 'How much water? Is there any subsurface ice water? Was there any life, and what happened to that life?'" Mazrouei said.
We don't know any of that at this point. We don't know if any samples collected by Perseverance will help us figure out those answers, if they'll make it back to Earth, or if they'll even be collected to begin with.
All we can say with certainty is that Perseverance is scheduled to land on Mars shortly before 4 p.m. EST on Thursday, Feb. 18.
Like so many others around the world, Mazrouei will be paying rapt attention.
"It never gets old, watching in anticipation," she said.
"It doesn't matter which space agency has sent a mission, or which planetary body [is involved] – it's always just as exciting as the first time."
