The ISS. The closest thing we currently have to a space colony is the International Space Station. While it can be considered a success in terms of international cooperation and scientific research, the ISS far from self-sufficient. Sweat and urine can be recycled into fresh water and filters and scrubbers keep the air breathable, but without regular resupply missions, the station's occupants wouldn't last long. Still, the future looks bright up there – NASA has several ISS missions scheduled for 2010, expanding the station and adding new components (as well as spare parts).

Lunar Colonization. The best prospect for a human colony on the moon seems to be NASA's Constellation project. The Altair Lunar lander will be able to carry a crew of four astronauts to the moon and support them there for a seven-day mission. Alternately, it can descend robotically to the moon carrying critical infrastructure for a longer-term lunar outpost. When completed, that outpost will support a crew of four for up to 180 days. NASA has a slick interactive website that explains Constellation.

A great deal of thought is being put into what astronauts will live in on the moon. The first moon base will likely be an inflatable dome. NASA has been testing such a design at McMurdo Station in Antarctica to see how it deals with extreme cold. Although there are no blizzards on the moon, the test will also prove whether or not the "lunar bounce house" is tough enough for a long-term mission. An inflatable habitat has the advantages of being light-weight and only requiring a few hours to set up.

Beyond that preliminary outpost, lunar settlers will require something a bit more sturdy and permanent. Rigid, durable building materials are too heavy to send from the Earth's surface to the moon – it would be impossibly expensive. The best option, then, is to create building supplies from the raw materials already present on the moon. The recent discovery of a large amount of water on the moon makes the production of concrete using lunar regolith much more feasible, but even without water, it's possible. In 2007, a paper published in the Journal of Aerospace Engineering explained how the regolith could be processed into sulfur, which could then be mixed with regolith to make waterless concrete. They even examined the physical properties of said concrete, and proposed a cylindrical habitat structure.

A more recent paper in the same journal studied potential lunar colonization in-depth, examining potential structural designs, insulation, power needs and other factors. If you're not willing to take the researchers' word for it, you could always study space architecture yourself. The University of Houston College of Architecture boats the Sasakawa International Center for Space Architecture (SICSAl). Students design and model space vehicles, orbital stations, and lunar and Martian habitats. Many of their designs come directly from NASA requests. While fun, it is a challenging curriculum, since designers must incorporate radiation shielding and variations in gravity, problems terrestrial architects rarely have to consider.

Martian Colony. We're a long way from colonizing Mars – decades, at least. However, NASA's Constellation program does have a Martian outpost as its ultimate goal. Creating a colony on the moon will generate an enormous amount of data that will directly aid the quest to put humans on Mars.

The European Space Agency isn't waiting around, though. They're currently screening volunteers to take part in a 520-day simulated mission to Mars. This year, they wrapped up a 105-day precursor simulation. The long-term test will examine the physical and psychological effects of such a mission.

Candidates should be aged 20-50, motivated, in good health and no taller than 185 cm. They should speak one of the working languages: English and Russian. Candidates must have a background and work experience in medicine, biology, life support systems engineering, computer engineering, electronic engineering or mechanical engineering.

Beyond. The "moon to Mars" path for human colonization of space isn't the only idea out there. In 2008, a group of researchers proposed a "company town" model for creating a space mining colony. What would they be mining? Water. Where would they be mining it? From the inside of comet 4015 Wilson-Harrington. Sometimes considered an asteroid, 4015 may in fact be a burned-out or intermittently active comet. The researchers believe that finding a large supply of water somewhere other than Earth is the key to post-Earth survival of the human race. Their company town model proposes an entire economic system that would support up to 10,000 colonists.

Image: NASA Ames Research Center

In 1969, it took just eight days to reach the moon but, as Aldrin notes, getting a manned spacecraft to Mars would take the better part of a year. After all that time and expense, a trip to Mars might not be worthwhile unless the astronauts were there long term:

"That's why you [should] send people there permanently," said Aldrin. "If we are not willing to do that, then I don't think we should just go once and have the expense of doing that and then stop."

He asked: "If we are going to put a few people down there and ensure their appropriate safety, would you then go through all that trouble and then bring them back immediately, after a year, a year and a half?"

Currently, NASA’s Constellation program plans for a manned mission to Mars in 2030. Under the current plan, the crew’s return vehicle would arrive ahead of the actual expedition ship. But NASA is also scheduled to break ground on the lunar outpost in 2019, and there could be a fully operational base on the moon by 2024. If the lunar outpost proves a success, it might make sense for humans to erect similar colonies on Mars, where oxygen and water are more readily available. Of course, the challenge would be finding colonists willing to sacrifice a terrestrial existence in the name of the Martian frontier:

"They need to go there more with the psychology of knowing that you are a pioneering settler and you don't look forward to go back home again after a couple a years," he said.

"At age 30, they are given an opportunity. If they accept, then we train them, at age 35, we send them. At age 65, who knows what advances have taken place. They can retire there, or maybe we can bring them back."

Mars pioneers should stay there permanently, says Buzz Aldrin [Physorg via Universe Today]

In 2004, the Bush administration introduced its “vision for space exploration,” which includes retiring NASA’s existing shuttle fleet and introducing Constellation, a new launching program using an updated capsule and rocket system. However, the administration, not wanting to inflate NASA’s budget, decided that manned space missions would go on a five-year hiatus, and that American astronauts should instead fly on Russian spacecraft.

But the recent political tensions between the US and Russia have complicated this plan. Although NASA does not doubt Russia’s commitment to transporting US astronauts, the US’s commitment to manned spaceflight will be greatly tested if relations with Russia continue to deteriorate. Following Russia’s military action in Georgia, Congress was stalled the bill to approve NASA’s purchase of seats on Russian spacecraft beyond 2011. The approval for the purchase of seats through 2016 did ultimately pass, but the incident prompted NASA administrator Michael D. Griffin to speak out against the current policy, which he called "unseemly in the extreme":

In an e-mail message he sent to his top advisers in August, Dr. Griffin wrote that “events have unfolded in a way that makes it clear how unwise it was for the U.S. to adopt a policy of deliberate dependence on another power.”

Griffin further suggests that the gap poses an unnecessary risk to the US space program:

“In a rational world, we would have been allowed to pick a shuttle retirement date to be consistent with Ares/Orion availability,” Dr. Griffin wrote. Within the administration, he wrote, “retiring the shuttle is a jihad rather than an engineering and program management decision.”

Griffin fears the consequences of any delay in the Constellation program, which comes at a time when China’s space program is rapidly advancing. Even if the current plans go according to schedule, the US will not return to the moon until 2020. Proponents fear that by then, the US will already be behind the curve.

One Way Up: U.S. Space Plan Relies on Russia [NY Times]

With more than 8,000 NASA employees looking for jobs when the Shuttle Program wraps up, the private sector space industry could get a serious brain injection.

NASA will continue sending up rockets to launch new satellites between 2010 and 2015, the market for crewed missions to conduct repairs on existing satellites or other sensitive missions isn't likely to shrink. With all those aerospace engineers looking for something to do with their degrees, I predict we will see a burst of private space industry startups. The demand is there. The expertise is there. The real question — will the money be there? Image by NASA. [Information Week]