The competition to design NASA’s Crew Exploration Vehicle, which will shuttle equipment and astronauts to and from the ISS, and lead the next manned mission to the Moon is at a critical stage. Niall Firth reports.
For those watching on in horror as Columbia splintered and disintegrated upon re-entry to Earth in 2003, it might have seemed as if we were witnessing not only the tragic death of seven astronauts but the final collapse of NASA’s manned space flight ambitions.
However, in January 2004, just one year later, President Bush surprised many when he outlined his Vision for Space Exploration and named a manned mission to the Moon as his main priority. This meant that a new vehicle would be required, not only to achieve the president’s lunar ambitions but also to replace the shuttle, destined for the scrapheap in 2010. The new craft is called the Crew Exploration Vehicle (CEV).
While NASA’s $100bn (£58bn) plan to fly four astronauts to the Moon for a seven-day visit in 2018 will be the first manned lunar mission since 1972, the new spacecraft will — the agency hopes — be in service long before then transporting crew and cargo to and from the International Space Station (ISS).
First impressions of the CEV are rather underwhelming. Compared to the shuttle’s graceful lines, NASA’s preliminary designs for the CEV show a blunt-nosed, cone-shaped capsule that will be attached to a larger rocket and fired into space; the CEV’s resemblance to Apollo is unmistakable. However, according to NASA’s administrator, Mike Griffin, not only was Bush’s speech ‘the best mission statement we’ve had in 40 years’ but the CEV will be like ‘Apollo on steroids’.
The steroids in this case are the advanced technologies and the benefit of 30 years of space exploration experience that NASA now has at its disposal. Small-scale models of preliminary CEV designs are currently at a crucial stage of wind-tunnel testing at NASA’s AMES research centre and its imminent arrival has some of the biggest hitters in aerospace salivating in anticipation of what promises to be one of the largest space contracts since the shuttle.
The competition to design and build the CEV has reached a critical stage, with two teams in the frame to land the lucrative contract. One is led by a Northrop Grumman and Boeing partnership while the other is a Lockheed Martin-led team, with both competing consortiums sub-contracting work to a number of other companies. Alcatel’s Italian space division has joined Northrop, and Honeywell is adding its expertise to the Lockheed team.
Competition is fierce and, with NASA due to decide later this summer which group will take the contract, both are giving passable impersonations of ageing poker aces, desperately keeping their cards close to their chest while they wait for the space agency’s verdict.
No matter which team wins the final contract, the CEV will be built to NASA’s specifications. Over the past 18 months NASA has refined its idea of what it requires and given strict briefs to the competing teams as to the design and capabilities of the eventual successor to the shuttle. One of the most important of these is making a lunar mission possible and helping NASA to eventually establish a permanent base on the Moon’s surface, as well as forming the core vehicle for a future manned mission to Mars.
At around 5m in diameter compared to Apollo’s 4.3m the vehicle will only be slightly larger than its forerunner. But it will have the capability to carry up to six crew, as opposed to Apollo’s maximum capacity of three astronauts.
As the first US space vehicle to use solar-powered wings, the CEV’s innovation also extends to using an oxygen/methane mix in the engines, with the long-term plan to be able eventually to convert elements in the Martian atmosphere into methane fuel. For the 2018 lunar mission, the CEV will carry enough fuel to allow it to land anywhere on the Moon’s surface, instead of just along the equator as was the case with Apollo. Both the lunar lander and any additional cargo that is needed will be launched into low-Earth orbit up to a month ahead of a CEV launch. The crewed CEV will then be able to rendezvous with the unmanned lander module, dock with it, and the CEV’s on-board engines will send the spacecraft on its way towards the Moon.
Once it is in orbit around the Moon, NASA plans for the lander to be deployed carrying the entire crew with the CEV capsule remaining in robotically controlled lunar orbit. For the seven days the astronauts are on the Moon’s surface they should be able to communicate with the craft using advanced broadband communication technologies while they begin to establish the beginnings of a lunar outpost on the surface.
Bob Davis is head of CEV business development for the Northrop Grumman team, and is overseeing the consortium’s bid to win the CEV contract. He sees the CEV as being a giant step up from the original Apollo on which it is, in part, based.
‘Since Apollo there have been substantial advancements in computing, solid state electronics, densification of power management and power conditioning. The miniaturisation of all the components has been an important developmen� too, and so at the very least what has changed is that there is much greater power packaged into the system,’ he said.
Northrop also aims to use the substantial advancement in construction materials and stronger alloys to create a next-generation spacecraft that uses the very latest in composite materials. ‘In Apollo we were having to bolt or weld parts together, now we’re using a far greater degree of composites and more efficient joining technologies that reduce the overall mass,’ said Davis. Understandably reticent at such a crucial stage in the project’s contract negotiations, Davis was nevertheless bullish about his team’s credentials to deliver a next-generation spacecraft.
‘Our team has a wealth of historical experience with having designed, produced and supported Apollo, both the command module and lunar module. We have also been specifically involved as a prime contractor for the ISS and the Shuttle. All of that we did in direct partnership with NASA and we would welcome working with NASA again.’
On the other hand, Lockheed’s CEV deputy programme manager Larry Price, is confident that his firm’s wealth of experience in flying and landing low-risk capsules, including the Stardust and Genesis missions, will sway the competition its way. ‘We are the people who are returning capsules from space, with thermal protection system knowledge, and a good understanding of aero-thermal characteristics and capsule design,’ said Price. ‘This is a competition and we will work as hard as we can to win it right up until the last minute.’
Price added that there was also the possibility of Lockheed collaborating with European firms in the future, including EADS Astrium, to work on other elements of the CEV mission.
Meanwhile, at AMES 2.6 per cent and seven per cent scale models of the CEV are undergoing vigorous and extensive testing. One of the most important tests is the Thermal Protection System Advanced Development Project. While CEV project manager at AMES, George Sarver, is quick to point out that the CEV project is still at an extremely early stage and that many of the design and technology requirements are still to be finalised, the results of this project will be crucial. The thermal protection testing will eventually lead to the choice of material that will protect the CEV on its re-entry.
‘This is a very narrow study, concentrating entirely on the technologies and materials that relate to thermal protection,’ said Sarver. ‘The range of possible materials is extremely broad, with even the Apollo material being one of the candidates.’
Of the many differences between Apollo and its 21st-century upgrade, one of the most obvious is that the CEV is designed to land on solid ground rather than in the sea. While the reasons for this are rather prosaic — retrieval is far cheaper on land than mounting expensive rescue operations using boats and helicopters — the problems it causes engineers are rather more challenging.
At NASA’s Langley Research Centre advanced studies are underway to develop technologies and systems that will allow the CEV to return to Earth safely, including how to control the capsule’s descent using parachutes as well as cushioning systems, such as large inflatable airbags, to protect the capsule when it finally touches down. NASA needs to keep the spacecraft safe as it plans to reuse the CEV up to 10 times, keeping maintenance and refurbishment costs to a minimum. ‘It throws up some real challenges because land is much harder than water. It is far trickier because when you are landing in water all you need to worry about is getting the right flotation,’ said Sarver.
As NASA’s leading IT centre, AMES has also been flexing its computational muscle in support of the CEV project. The Columbia supercomputer, now officially the world’s fourth fastest computer — the fastest is IBM’s BlueGene system at the Lawrence Livermore National Laboratory in California — has been conducting powerful number-crunching exercises modelling the CEV’s aerodynamic properties.
Columbia has also been put to work on the Simulated Assisted Risk Assessment project. In this a variety of possible failures are induced on a computer model of the spacecraft with the effects of the failure being carefully recorded and then built into the thermal protection design. This is particularly important when NASA’s scientists are looking at the integration between the CEV and the proposed Crew Launch Vehicle (CLV).
The CEV will be launched atop a conventional solid rocket booster, the CLV, which will be similar to the rockets that launched the shuttle into orbit. However, perhaps in light of the problems that have plagued the shuttle, including the Challenger and Columbia disasters, NASA plans to make the CEV ‘significantly safer’ than any other space vehicle in its history, according to Griffin. He said that the CEV will have a failure rate that is an order of magnitude better than the hair-raising figure of one in 220 for the shuttle.
While AMES’ failure modelling will undoubtedly contribute to this aspirational safety record, astronauts aboard the CEV will also benefit from the introduction of a ‘launch abort’ safety system.
Escape rockets attached to the CEV will pull it away from the CLV should anything go wrong during take-off. Sophisticated sensing will detect any fault in the craft as it goes through the launch phase, and an automated escape sequence will release the CEV capsule from the main structure. Sarver said that this possibility is in contrast with the shuttle, which left no possibility for escape until after the solid rockets had separated from the vehicle.
‘It is a very complicated process. If it is a very rapid failure — something that will cause the vehicle to break up within three seconds, for example — it will be a completely automatic escape sequence, whereas if it is slower then the crew or the ground staff might be in the loop and be able to make decisions whether to abort.’
As well as more conventional wind tunnels used to test the craft’s aerodynamic properties, engineers at AMES are also using the Arc Jet, a special type of wind tunnel that reproduces the fierce heat the CEV will have to withstand upon re-entry.
Air is fed at high speeds into one end of the Arc Jet and a very powerful electric arc is run through the chamber which heats up the air to extremely high temperatures. Once heated to many thousands of degrees centigrade the air is then projected on to samples of thermal protection materials.
When the CEV contract is won and the spacecraft makes its first flight in around 2011 it will initiate a new era of manned space missions across the solar system and put NASA well on its way to launching the first ever manned mission to Mars. However, the CEV and the manned mission programme have not been without their detractors.
Griffin’s announcement of the project came at a difficult time in the US as the effects of Hurricane Katrina necessitated a multi-million dollar clean-up operation. Some critics asked whether a new multi-billion dollar space programme was really justifiable or whether an expensive manned lunar mission was taking money from the valuable robotic exploration programme.
Griffin was unequivocal in his support for the project. ‘We can go to the Moon. In later decades we can go to Mars. We can service the space station,’ he said. ‘We can undertake the service of the Hubble telescope or other space telescopes, as may exist. We can do anything. This new vehicle is the vehicle that lets us do that and unless the US wants to get out of the manned space flight business completely, then this is the vehicle we need to be building.’
But this vehicle is not the new shuttle, according to NASA. In Sarver’s opinion the space shuttle and the CEV were built for such different objectives that it is impossible to compare the two. ‘The shuttle was designed to bring things into low-Earth orbit and then bring them back. The CEV is designed to go the Moon and eventually on to Mars,’ he said. ‘They are completely different ideas.’
The irony of the CEV’s design is not lost on Sarver. While low-Earth orbit may shortly be populated by shuttle-derived, winged spacecraft such as SpaceShipOne, NASA’s next generation of manned space vehicle will owe its looks to a small pod that sparked the world’s imaginations more than 35 years ago. ‘If you want to go to the Moon, the engineering solutions just keep on bringing you back to Apollo,’ admitted Sarver.