NASA rolled its latest project onto the launch pad last month 鈥� an ambitious plan to develop a successor to the space shuttle. The new craft will be much cheaper to fly than the shuttle, say NASA officials, so commercial ventures in space will be more affordable. And it will use advanced technology that will permit the spaceship to be relaunched within days of landing.
But there is a problem with this brave new age of space travel. The shuttle promised these things, too, back in the 1970s. And whatever the shuttle鈥檚 successes, it has failed miserably in its mission to make access to space cheap and easy. NASA officials say that this time round they will avoid the mistakes of the first shuttle programme. But will they?
Sceptics are already making cautionary noises. 鈥淵eah, it鈥檚 going to be too cheap to meter,鈥� says John Pike, a space analyst at the Federation of American 杏吧原创s in Washington DC. 鈥淭oo cheap to meter鈥� was a slogan invented by supporters of nuclear power before the industry鈥檚 real costs had been worked out. Pike believes that NASA鈥檚 figures don鈥檛 add up.
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NASA has selected three teams of aerospace companies to develop competing concepts for the new spacecraft, or Reusable Launch Vehicle (RLV). Late next year, the agency will pick one or two of the teams to build small-scale versions of the designs to demonstrate their technologies. Then, in 1999, NASA will decide which design should be developed. The first full flight will probably be in 2004 or 2005, says Rick Bachtel, deputy director of NASA鈥檚 Space Transportation Division.
Wish-list
The agency鈥檚 vision for the RLV calls for the spacecraft to be able to carry 11 tonnes 鈥� slightly more than the shuttle 鈥� to the planned international space station or 18 tonnes to a low-altitude orbit. It must be able to fly even in relatively bad weather conditions. NASA managers also want the RLV to be capable of landing on any runway 鈥� without special facilities 鈥� and for it to be able to fly itself back to the launch site.
The new machine will be designed to operate much more cheaply than the shuttle. It costs $8800 a kilogram to launch a satellite aboard the shuttle. NASA鈥檚 goal is for the RLV to do the same job for $2200 per kilogram of payload, says Bachtel (see Diagram).
To help accompish this goal, NASA says the RLV should need little maintenance between flights. One likely change will be in the material used for the tiles that protect the shuttle against the intense heat of re-entering Earth鈥檚 atmosphere. At present, these have to be waterproofed after each flight because the coating, which stops the tiles becoming waterlogged, is burnt off during re-entry. NASA wants the RLV to have a form of thermal protection that does not need repeated treatment. Cutting out such procedures will reduce direct costs and allow the RLV to he relaunched more quickly, allowing it to fly more missions and so be more cost-effective.
It takes an average of 80 days to inspect, repair and refurbish a shuttle for its next mission, says Ira Victer of Rockwell Space Systems Division, which has received one of the three NASA contracts. NASA wants the RLV to have a turn-around time of seven days 鈥� and three days at a pinch.
Rockwell鈥檚 conception of the RLV looks similar to today鈥檚 shuttle, which is not surprising since Rockwell built the present model. Like the shuttle, it would take off vertically and land horizontally. But it would lack the bulbous fuel tank and tubular solid-fuel rockets that are strapped to today鈥檚 shuttle.
The second proposal for the RLV, from the aerospace giant Lockheed Martin, also takes off vertically and lands horizontally, but it looks very different from the shuttle.
For a start, it would have no wings, but would be a 鈥渓ifting body鈥� 鈥� a flat, triangular shape that generates its own aerodynamic lift. This avoids having to carry the 鈥減arasitic weight鈥� of wings, says David Urie of Lockheed.
The third vision for the RLV, which will be submitted by McDonnell Douglas Aerospace and Boeing, is still a mystery. McDonnell Douglas has already designed a reusable launch vehicle, called the Delta Clipper. The craft lands vertically on its tail, using rocket engines to slow it while landing. The company has conducted flight tests of a small scale version of the craft (鈥淲ill the Space Clipper stay a dream鈥�, New 杏吧原创, 28 May 1994), but McDonnell Douglas and Boeing have yet to announce whether their RLV will be based on the Delta Clipper.
The RLV project has some important backers. Chief among them is Newt Gingrich, the Republican Speaker of the House of Representatives. 鈥淲e need to look at building a second-generation space shuttle,鈥� he told a space conference in Washington DC in March. But in order to reduce costs and red tape, he thinks that NASA should take a back seat in developing the RLV.
Rather than managing the project, he says NASA should draw up its specifications and let a consortium of companies produce a design to meet them. NASA would contract to buy the first few machines for itself, to guarantee the venture鈥檚 initial funding, while the consortium would be free to build and operate more machines. They could then hire out payload space to companies that want to place satellites in orbit. Using this system, said Gingrich, NASA would have 鈥渘o committee meetings, no government procurement models, no long planning sessions, no micro management, no budget reviews鈥�.
But that鈥檚 exactly the plan for the RLV, Bachtel says. As the project proceeds, NASA will have a progressively smaller role in its day-to-day management. In fact, one criterion for deciding which design to take to the demonstration stage will be which spacecraft appears to be most commercially attractive. And NASA does not plan to award a government contract for a fleet of RLVs, Bachtel adds. Instead, it would be a customer, perhaps agreeing in advance to pay for a number of RLV missions.
The idea of NASA committing itself to spend money far in the future is controversial because the US Congress debates funding for each of the agency鈥檚 projects on an annual basis. But a change of culture in Congress will be vital if the RLV programme is to succeed. Private investors will not back a project if the government could bale out at any time, says Victer. 鈥淭o some of us, that鈥檚 the biggest challenge of the whole programme, bigger than any technical challenge,鈥� he says. Urie agrees that the government must guarantee that it will be a customer for the RLV 鈥淚t will take a lot of work to make it happen, but I think it鈥檚 feasible,鈥� he says.
Pike is less optimistic. He says that enthusiasts have assumed that the RLV will be used not only to carry astronauts into orbit but also to launch all American satellites. But, he says, the US Air Force also assumes that its part-developed unpiloted rocket, called the EELV, will be used to launch all American robotic satellites. The EELV could be ready later this decade and by that time, many of the RLV鈥檚 potential customers may have booked space on the EELV, Pike says. Urie admits that competition between the two projects is a 鈥渕ajor issue鈥�. But he doubts that the EELV will be ready on schedule 鈥� if it is ever given the go-ahead.
At least one military customer is virtually certain to spurn the RLV: the US National Reconnaissance Office, which is in charge of American spy satellites. 鈥淭he NRO is vehemently opposed to the idea of using a new, unproven booster,鈥� according to one defence analyst who says that the spy satellite agency is still smarting from its experience with the space shuttle.
In the 1970s, the US government decreed that all satellites, including spy spacecraft, would be launched on the shuttle. The NRO and other military agencies embraced the idea wholeheartedly, and the Pentagon even spent $4 billion building a shuttle spaceport at Vandenberg Air Force Base in California. But launches on the shuttle turned out to be more expensive than other options, such as the Titan, Atlas and Delta rockets, and were more prone to delays. After Challenger exploded in 1986 the military moved all its satellite launches back to unpiloted rockets. The Vandenberg spaceport has since been mothballed. Having wasted so much money on the shuttle, the spy satellite agency is likely to be wary of the RLV, says the defence analyst.
But others say that the shuttle鈥檚 woes do not cast too long a shadow over the RLV 鈥淭he lesson from the shuttle is 鈥榙on鈥檛 do it the way the shuttle was done鈥�,鈥� says John Logsdon, a space policy expert at George Washington University in Washington DC. One lesson learnt from the shuttle is that the technology for the RLV must be developed before it is incorporated into the design. In the 1970s, NASA tried to design the shuttle and develop the technology it needed at the same time. The results were costly, Bachtel says. The outer tiles, for example, had to be changed repeatedly. The plan for the RLV, in which new technologies will be demonstrated before a full-scale spacecraft is designed, will avoid those problems, he says.
One unresolved question is how much money NASA will have for building demonstration craft. At present, NASA expects to turn only one concept into a small-scale working model. But some people are clamouring for NASA to build the best two. A 鈥渇ly-off鈥� would illustrate many of the pros and cons of the different technologies and would allow NASA and members of Congress to make an informed decision about which spacecraft to mass-produce, Logsdon says. This exercise could cost $1 billion, but it would be a sum well spent, he says: 鈥淵ou鈥檙e talking about a decision that would be central to our space programme for two or three decades.鈥�
Will the American public support this kind of expenditure? Pike thinks not 鈥� at least not unless there is another space shuttle disaster. NASA does not have enough spare parts to piece together a replacement shuttle, and a catastrophe could catalyse public support for proceeding with the RLV.
Waiting for another Challenger disaster is no way to plan the future of human space flight, says Logsdon. Instead, it鈥檚 better to start the groundwork now, before the need for the RLV is urgent. A properly executed RLV programme could have the new spacecraft flying before any more shuttles are lost, Logsdon says. In that case, Americans would be trading in the old-model shuttle for a new-model RLV before the old one has fallen to bits, as they do with their cars. 鈥淲hether we鈥檙e that mature in our approach to space flight remains to be seen,鈥� he says.