Launcher problems are clouding the USA's new space vision as NASA looks for greater lift

Project Constellation, the new US space vision, could be undone by the vehicle that would make it all possible. At the Farnborough air show, NASA and its exploration partners confirmed the need for a heavylift launcher, but questions have arisen about the type of vehicle and its timetable.

When the space vision was announced on 14 January, neither US President George Bush nor NASA administrator Sean O'Keefe spoke of the need for greater lift capabilities. However, the subsequent commission on presidential implementation of the vision, headed by former astronaut Pete Aldridge, recommended the development of a new heavylift vehicle. It would be required to fly both crew and cargo for missions to the Moon, Mars and beyond.

The envisioned new Crew Exploration Vehicle (CEV), which could carry up to six astronauts, would fly atop the heavylift vehicle, with a target date for its first flight of 2014. The earliest date for a Moon mission would be 12 months later. So, by 2015, Project Constellation could need a launcher that can send up to six people to the Moon and return them safely to the Earth.

Under the Apollo programme, the Saturn V rocket sent just three astronauts to the Moon. It had a lift capacity of about 100t to low-Earth orbit (LEO), which begins at 185km (115 miles). During the Apollo flights, spacecraft began their journey to the Moon from LEO. In comparison, the Space Shuttle can place just 29.5t into LEO and none of the world's expendable launch vehicles have a LEO capability like this. The closest is Boeing's Delta IV Heavy launcher, at 23t, but its maiden flight has been delayed from early July to September.

It is no surprise that the Aldridge Commission concluded that NASA needs a new vehicle. The European Space Agency (ESA) arrived at a similar conclusion in its studies of possible human missions to the Moon, published in December 2003, and to Mars, published in February. It estimated that a chemically powered Mars mission rocket could have a mass of over 1,000t. Built in orbit, its component parts, ESA concludes, would be launched by Russia's Energia rocket, which can place 100t to LEO. The Energia can also place 18t into GTO, but the booster is no longer in production. This sort of capability was also identified as necessary in ESA's Moon study.

Shuttle proposal

Beyond buying Russia's Energia, discussions about the type of launcher have encompassed enhanced versions of existing expendable boosters or an entirely new vehicle. At Farnborough, NASA said these discussions will be aided by the level 1 requirements for the CEV that will be released in September, as they will identify the number of crew the CEV will carry.

One possibility is a Shuttle-derived launcher. The proposed Shuttle C would have a capability of up to 68t to LEO, but this is not enough. Whether it is Shuttle-derived or not, the conundrum that NASA has to solve is that the Shuttle takes up much of the agency's budget until it is retired in 2010. That leaves four to five years to develop a new 100t-plus LEO launcher.

That is a tight timetable, compared with the Apollo. The first test firing of Saturn I was in 1961, and in 1968 Saturn V took a crew around the Moon and back. In those seven years NASA had far more funding for launchers than it has under Constellation, which has none. "There is no money in the [new NASA] budget for a heavylift vehicle. It will require some more money down the road for the budget," says John Logsdon, director of the University of George Washington's Space Policy Institute. NASA does not dispute this. At Farnborough, it said of the programme's funding and launchers: "We will take it year by year."

Meanwhile, its potential launcher suppliers have different views on vehicle development. Boeing has decided to use improved versions of its Delta IV Heavy. The company unveiled its ideas on Project Constellation early, declaring its thoughts on a Moon mission in January. It has designed a modular spacecraft with "four or five elements for a lunar mission. It would include a command capsule section, a habitat section and a specialised power module." Each module, launched by a Delta IV Heavy, would link in LEO before going to the Moon.

Lockheed Martin is yet to declare its hand and its Moon mission designers are irritated by the obsession with launchers. Vice-president for space exploration John Karas says the mission needs to be agreed first: "Once you've got your mission architecture in place, then you can think about heavylift. This is the mistake everyone is making, thinking about the launch vehicle first."


Source: Flight International