Space shuttle retirement leaves 'yawning gap' in human spaceflight

US space policy is in disarray as the final space shuttle flight approaches, say space scientists
Space shuttle Endeavour silhouetted by landing lights as it touches down at Kennedy Space Centre after its own final mission and the second-last for the shuttle fleet. Photograph: Timothy A Clary/AFP/Getty Images
A replacement for the shuttle is many years away. In the meantime Nasa must buy seats on the Russian Soyuz. Photograph: Timothy A Clary/AFP/Getty Timothy A Clary/AFP/Getty Images

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 US 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 fly astronauts into space, and no clear role in the ongoing human exploration of the solar system.

What's for certain is that the agency will transform over 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. So the thinking goes.

The transition will not be swift. A replacement for the space shuttle is many years off, and until such time that a successor arrives, Nasa must buy seats on the Russian Soyuz rocket to carry its astronauts into orbit. For missions further afield, the agency needs to build a new crew capsule and heavy-lift rocket similar to the huge Saturn five 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. "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 DC 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 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. Thursday's announcement from Congress that Nasa's budget will be cut by $1.64bn will not help.

Earlier this year, Nasa announced that its new multi-purpose crew vehicle (MPCV) – a capsule to carry astronauts into deep space - will be based on the Orion spacecraft developed by Lockheed Martin 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 – the capsule could be set in orbit around a hurtling space rock – 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 told the Guardian.

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 $270m 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 and prove their rockets are safe and satisfy Nasa's strict operational demands.

To help private industry reduce their costs, Nasa is drawing up plans to lease out key buildings, like the vast hangars known as Orbiter Processing Facilities, at Kennedy Space Centre.

Nasa's robotic space exploration programme is more clearly defined, with the Dawn spacecraft due 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 major missions are on shaky ground. Amid Thursday's budget cut announcements, Congress called for all funds to be axed to the James Webb Space Telescope, an observatory lauded as the successor to Hubble, which is already delayed and over-budget.

Other countries have ambitions in space, most prominently China, which has set itself the task of building a small pace station and landing an astronaut on the moon. So far the nation has put a man in orbit, but has years of work to achieve its grander goals.

According to Crawford, there is a silver lining to Nasa's stepping back from human spaceflight. In 2007, 14 space agencies signed up to a global space exploration strategy – a potential precursor to a global space agency – in recognition that the cost of space travel required the world's spacefaring nations to work together. "We should not be relying on the US to lead all the time, but that is the de facto situation. This is our opportunity to develop a more internationalist vision, to which all the spacefaring nations contribute."