No one knows exactly how they'll land or take off again. How they'll eat, get water and oxygen, move about, shelter from bitter temperatures and deadly barrages of cosmic rays and radiation.
No one knows how they'll handle the stress of living in a small space on an alien world that seems specifically engineered to kill them.
But NASA and other space agencies, as well as advocacy groups and academics, are brainstorming to figure it out.
They're dreaming up in-space habitats and emergency radiation shelters for the six- to nine-month journey there, then back again. They're assembling the world's most advanced Space Launch System rocket and crew vehicle -- the Orion -- for deep-space missions. Mock Mars habitats are set up in inhospitable places around the globe.
"We have to go beyond the Earth for a variety of reasons," McKay said. "Partly just to see if we can, partly because the Earth will face challenges, impacts, possible disasters. Eventually, the Earth will become uninhabitable in the long-term, so there's a long-term directive that pushes us away from Earth.
"And when we look at where we could take the first step in that direction, the answer is the moon. But where could we take the first significant step? The answer is Mars. Mars is the first place we could imagine humans would live and work somewhat independently of Earth for a long time."
Not everyone, however, is a fan of the current how-to.
A former NASA deputy administrator,
NASA has test flights for the SLS set to begin in 2017, and for the Orion later this year. After that, the national space policy calls for crewed missions in five years or so to retrieve an asteroid for study to refine the technology and crew training for a Mars mission in the early 2030s.
Putting down roots
To keep to its timetable, NASA says it must lock down certain elements by 2020 -- the type of propulsion and number of launches. By 2025, it's pencils down on major vehicles and technologies.
Still to be decided: Will NASA's first astronauts land on Mars or one of its moons? Will they orbit and leave? Will they dash down, plant a flag and dash off again?
"I'm not aware that there's any well-articulated plan," McKay said.
But McKay is rooting for something large-scale and permanent. His vision isn't to step onto another planet, pack up some rocks and leave again -- like the "self-contained camping trips" of lunar astronauts decades ago -- but to put down roots.
A good model, he said, is
There are two possible approaches to that first trip, McKay said: Stay a month or so to collect samples for study then leave, meaning a longer transit time from Earth, or stay a couple of years and minimize the transit.
Either way, he said, the first astronauts would likely live in the same craft they land in, with inflatable expansion units, if they're lucky.
His own preferred vision would be a marathon, not a sprint. It would go something like this:
Begin round-trip robotic missions to Mars to collect rocks and dirt samples for study, building up the science and capability. In time, start making massive cargo runs to build a base using robots operated from Earth.
"Set up lights, couch, TV, build water tanks," McKay said. "Put a generator in, get it all working -- home away from home. Get it built and developed and test it for a couple of years so you have absolute confidence that, if astronauts land there, they are safe."
It could be 30 or 40 years before a turn-key habitat would be ready, he said, but the engineering would be honed and the human risk minimized.
"You want to be pushing the bounds of where we are, and that's what exploration is," Cosgrove said. "But we want to do it in a way that you have a really good opportunity of learning. And even failure teaches you something."
Nail the landing
The first Mars landing will be in one of 58 "geologically interesting" areas with names such as
These sites were hand-picked by the Human Exploration of
Last spring, Levine tasked the students in his planetary geology course to dream up "field trips" for each landing site to enable astronauts to answer key scientific questions.
"Mostly geology, but some chemistry and physics," Levine said. "Defining where humans should go and how they should go and what they should do."
He said he presented their results last May at the Humans 2 Mars Summit in
That first Mars landing, though, could be preceded by a trip to one or both of its moons, said
"Robots are progressing at a tremendous rate," Troutman said. "Twenty years from now, it could be a whole other thing -- robots would be doing the dirty work."
The actual landing on Mars still presents a challenge: Because of the planet's thin atmosphere, parachutes don't work well. And NASA will have to land 20 to 40 tons at a time in order to land astronauts, Troutman said. So far the heaviest object to land safely is the one-ton Curiosity rover.
Live off the land
Once on Mars, astronauts will have to fend for themselves like never before.
The engineering challenge at home, then, is to design a closed-system environment of interchangeable parts and redundancies, said Troutman. And for astronauts -- accustomed to strict timetables and constant communication with ground control -- to learn to be ultra self-sufficient.
"In order to go to Mars, we'll have to live off the land," Troutman said. "We can't order out a pizza."
Whatever the initial habitat, each time an astronaut leaves it she'll have to wear a sealed spacesuit and pack oxygen.
The Martian gravity is about a third that of Earth -- enough to keep food in a bowl -- so experts say simple cooking is actually possible. Last year, NASA funded a nutrition study with volunteers sealed for several months in a small dome on the slope of a Hawaiian volcano. HI-SEAS, or Hawaiian Space Exploration Analog and Simulation, also field-tested antimicrobial clothing, robotic rovers and sleep patterns.
But a crucial challenge of a Mars mission, said Troutman, is living in the high-radiation environment of space.
"Right now from what we know," Troutman said, "we can go maybe 180 days before we have to worry about astronauts getting cancer later in life."
"We're really trying to chip away at that," said
Cerro is technical lead for the
"We're starting to address both types of radiation," Cerro said. "If you can eliminate the dosage from that quick event, he (the astronaut) can take more of the long-term radiation coming at him."
"We'd have to make sure it's not very much," he added. "
Some experts wonder if Mars' underground caves or lava tubes might offer life-saving shelter -- or even harbor an elusive form of Martian life.
Much will hinge on that initial trip.
"After the first human mission, we're going to increase our knowledge of Mars -- the surface and geology -- by an order of magnitude," Levine said. "I think we're going to learn things that could make future colonization practical or possible."
There are plausible studies on terraforming the red planet, he said, by increasing its thin atmosphere and generating oxygen. Liquid water could be extracted from the ice believed locked beneath the surface.
"The time-scales are hundreds to thousands of years," Levine said. "In the future, I think there are ways we can modify Mars and make it more Earthlike."
'Glad you're there'
A few months before he died in 1996, astronomer and author
"I don't know why you're on Mars, but whatever the reason for going to Mars is, I'm glad you're there and I wish I was with you."
Who those first settlers will be is unknown, as are the best criteria for choosing them.
Upcoming HI-SEAS experiments will study the psychology of putting a small group of people in a confined space in a harsh environment over a long period.
"Basically, how to support a crew and pick a crew so they don't end up wanting to kill each other," one of the principal investigators,
She's also one of more than 1,000 applicants chosen in December for the next round of the Mars One project -- an international effort begun by a Dutch entrepreneur to send colonists on a one-way trip to Mars beginning in 2024.
Also making that first cut is a
"There's a lot of unknowns," Beemer conceded. "But the good thing is, we still have 10 years to figure it all out. And, of course, there's always inherent risk in any exploration ever done on Earth, or from the Apollo era."
And where there's risk, there are those who will rise to the challenge.
"There's an urge for human exploration and human discovery," Levine said. "I read a paper that it's genetic -- it's in our genes to explore. And Mars offers such an exciting target for scientific discovery.
"Sending humans to Mars will be one of the greatest adventures of the human race."
Dietrich can be reached by phone at 757-247-7892.
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