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15 Jul 2011 12:52
Nasa’s fond farewell to the aged shuttle fleet draws a permanent line under 30 years of missions that defined modern space flight, but the United States space agency cannot afford to dwell on its past achievements.
The closure of the shuttle programme has left Nasa facing a deeply uncertain future, with no means to ferry astronauts into space and no clear role in the continuing human exploration of the solar system.
What is for certain is that the agency will be transformed in the next decade. The Obama administration has instructed Nasa to hand over to private companies the bread-and-butter job of ferrying astronauts to and from the International Space Station.
That will free Nasa to focus on tougher and more ambitious goals, ultimately to take crews beyond the realm of low Earth orbit.
The transition will not be swift. A replacement for the space shuttle is many years off and until then Nasa must buy seats on the Russian Soyuz rocket to carry its astronauts into orbit. For missions further afield it needs to build a crew capsule and heavy-lift rocket similar to the huge Saturn V launcher of the Apollo era.
The inevitable hiatus in the US human space programme has left some observers unnerved. “We are looking at a yawning gap in human spaceflight right now. It could be 10 years, easily, before anything comes to fruition and the impetus could simply fade away in that time,” said Martin Barstow, professor of space science at Leicester University, England. “The focus is not there. It may come back but I see a lot of things losing momentum.”
Speaking at the National Press Club in Washington last week Nasa administrator Charles Bolden listed the moon, near-Earth asteroids and Mars as future destinations, but what plans exist are extremely tentative.
Mars is too far and too difficult to reach with today’s technology, leaving a visit to an asteroid the most likely contender.
“US space policy is in disarray and there is no way around that. They have wandered into a situation where they’ve retired the shuttle and, for whatever reasons, haven’t got a replacement ready. The hiatus has left real uncertainty and it’s likely to be years before a firm space policy emerges,” said Ian Crawford, a planetary scientist at Birkbeck College, London.
Last week’s announcement from Congress that Nasa’s budget will be cut by $1.64-billion will not help.
Earlier this year Nasa announced that its new multipurpose crew vehicle—a capsule to carry astronauts into deep space—will be based on the Orion spacecraft developed for the cancelled Constellation programme. The capsule—somewhat roomier than its Apollo predecessor—will carry four astronauts for 21-day missions and will be able to land in the Pacific Ocean off the coast of California.
But even Orion faces major obstacles. A trip to an asteroid could take months and risks exposing the crew to dangerous levels of cosmic radiation.
“When people really sit down to look at this, they’ll see an awful lot of new stuff has to be developed to send people to asteroids, just because they’ll be in the space environment for so long. Until they find a solution to radiation it may be a bridge too far just with an Orion capsule,” Crawford said.
Alongside a new rocket and capsule Nasa is investing in other technology it hopes will open up access to deep space. Top of the list are new forms of propulsion but other items include in-orbit refuelling depots, better life-support systems and even inflatable space habitats. All of these, Bolden has said, are “just the early days” of the agency’s push into the next chapter of human spaceflight.
In April Nasa awarded $270-million of seed funds to four companies it wants to develop astronaut “taxis” to replace the shuttle. Three of these, including the California-based SpaceX, headed by PayPal co-founder Elon Musk, are bullish on their prospects, claiming they will have astronauts in orbit by 2014 or 2015. But none is close to a manned test flight, an undertaking Barstow points out is “very different to putting satellites in orbit”.
Nasa has never built its own rockets but it designed them and paid for their development, then owned and operated them. The shift in policy hands much of the cost and responsibility to industry. To land a contract companies will have to compete with one another to prove their rockets are safe and satisfy Nasa’s strict operational demands.
To help private industry reduce costs Nasa is drawing up plans to lease out key buildings, such as the vast hangars known as Orbiter Processing Facilities, at Kennedy Space Centre in Florida.
Nasa’s robotic space exploration programme is more clearly defined, with the Dawn spacecraft set to go into orbit around an asteroid later this month, the Juno mission heading to Jupiter and a Mars rover launching before the end of the year. But other big missions are on shaky ground.
Amid the budget cut announcements Congress called for the axing of all funds for the James Webb Space Telescope, an observatory lauded as the successor to Hubble, which is delayed and over budget.
Other countries have ambitions in space, most notably China, which has set itself the task of building a small space station and landing an astronaut on the moon. So far it has put a man in orbit, but has years of work to achieve its grander goals.—
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