WASHINGTON -- The notion of landing astronauts on Mars has long been more fantasy than reality: The planet is, on average, 225 million kilometres from Earth, and its atmosphere isn't hospitable to human life.
But a human voyage to the planet is now, for the first time, within the realm of possibility, according to space advocates inside and outside the United States government. As a result, plans for a mission around the planet, and ultimately for lengthier stays, have been sprouting like springtime flowers.
The new momentum, some space experts say, comes from the successful landing of the large rover Curiosity in a Martian crater last year, the growing eagerness of space entrepreneurs to mount and fund missions to Mars and encouraging new data about the radiation risks of such an expedition.
NASA says it hopes to land astronauts on the planet within the next two decades, and the agency is developing a heavy-lift rocket and a new space capsule to achieve this goal. It has even established an optimal time frame for this event -- in the early 2030s, when the very different orbits of the two planets brings them closest to each other.
The challenges of space technology -- including how to keep astronauts alive en route and on the planet -- as well as government support and funding remain daunting, but the goal of landing humans on Mars is seeming less and less like a pipe dream.
"A human mission to Mars is a priority, and our entire exploration program is aligned to support this goal," said NASA administrator Charles Bolden.
NASA has "overcome the technical challenges of landing and operating spacecraft on Mars" robotically, Bolden said. "We're developing today the technologies needed to send humans to Mars in the 2030s."
With both the promise and the obstacles in mind, Bolden and other top NASA planners, rocket developers and scientists, as well as leaders from the commercial space industry and organizations and agencies abroad, met Monday at a conference at George Washington University. Buzz Aldrin, the second man to walk on the moon in 1969, was a keynote speaker at the three-day gathering. He has just written a book that he refers to as a manifesto laying out the reasons humans can and should set their sights on not only landing on Mars but also setting up a permanent settlement there.
It is "human destiny" to explore space and settle on other planets, he writes in Mission to Mars, which is being released this week. He has his own step-by-step plans on how to accomplish a Mars campaign, but he makes room for others as well.
"Our world isn't just Earth anymore, and we need to get much more serious about that," Aldrin said in an interview, adding the leaders who take us to Mars and the pioneers who inhabit it "will go down in human history as heroes and be honoured for thousands and thousands of years."
A Plymouth or Jamestown colony on Mars is by all accounts a distant goal, but the timetable for sending humans there for a quick orbit and return to Earth, or even a landing on one of its moons, could be considerably faster.
Investment adviser Dennis Tito, who paid $20 million to go to the International Space Station in 2001, recently announced plans to send two astronauts to Mars for a 2018 flyby; a Dutch group called Mars One is raising funds for a landing in the 2020s. Elon Musk of the rocket and capsule company SpaceX says he will unveil his company's Mars exploration plans in the months ahead.
Unlike the others, Musk has a significant spaceflight track record. His Dragon spacecraft has docked three times at the international space station during NASA-funded cargo runs.
Musk got into the space business with the ambition of sending many people to Mars.
The first of these missions is "further off than I would like," he said, "but far closer than many expect."
The successful landing of Curiosity at one tonne, by far the largest vehicle ever flown to Mars -- is put forward as one reason a human mission is increasingly conceivable. There's still a long way to go in terms of landing technology, said Michael Gazarik, associate administrator of the NASA's Space Technology Mission Directorate, because a Mars descent with humans would require a capsule weighing something like 40 tonnes. Nonetheless, Gazarik said the technology is being developed, and having a Mars lander by the 2030s is "plausible."
Another reason is the health risks associated with radiation in space and on Mars appear to be somewhat lower than previously believed.
Radiation measurements made by an instrument on Curiosity have found high -- but not prohibitively high -- levels of high-energy cosmic and solar rays both en route to Mars and on the surface of the planet. Extensive shielding of astronauts would be needed, scientists have found, but the risk of later illness due to radiation would not be significantly higher going to Mars than after a long-term stay on the space station, according to Bent Ehresmann, a member of the Curiosity radiation monitoring team.
Long-term isolation is also a significant issue, and astronauts will be staying longer at the International Space Station in the years ahead to study that concern. And, of course, NASA will have to design spacesuits that can withstand the bitter cold of Mars as well as its thin atmosphere, made up largely of carbon dioxide.
The biggest impediment, though, may be money. U.S. President Barack Obama has challenged NASA to send astronauts to Mars in the 2030s, but NASA's budget is now a small fraction of what it was in the years after former president John F. Kennedy set a precise timetable for landing on the moon.
The agency gets less than 0.5 per cent of the federal budget; at the peak of the Apollo program, it was four per cent. Also, Obama will have left office long before the big decisions about a 2030s mission are made, and his successors might have different priorities.
The funding problem is one reason private companies and space agencies from other nations are expected to play a significant role in any human mission to Mars.
-- The Washington Post