Boulder, Colorado

NASA last week revealed its plans for the next generation of space vehicles, designed to get humans back to the Moon and, eventually, to Mars.

On 13 August, Christopher Shank, special assistant to NASA administrator Michael Griffin, described the agency's future exploration machinery, which is proposed to replace the shuttle in 2010.

His talk, given at the Mars Society Conference in Boulder, Colorado, precedes a full report scheduled for release this month, called the Exploration Systems Architecture Study. This will lay out how NASA intends to meet President George W. Bush's goal of sending humans back to the Moon by 2020 in preparation for a Mars mission.

“It will be a ‘go as you can afford to pay’ approach,” Shank told the 300 members of the Mars Society, a private group whose mission is to promote human exploration and colonization of the red planet. “Let the long, hard slog begin.”

That, he said, means deferring other programmes, such as future research on the International Space Station (ISS) and lunar-base development, until the new space vehicles come online. The first vehicle will be a 25-tonne Crew Exploration Vehicle (CEV), which will ride into space on a modified shuttle booster rocket; this will initially supply and return ISS crews. After 2010, work will begin on a 100-tonne Heavy Lift Vehicle (HLV) that can carry heavier payloads. The HLV will also use a rocket modified from the shuttle's boosters and external fuel tank.

One of the designs for the Crew Exploration Vehicle, which would service the space station. Credit: LOCKHEED MARTIN

Lockheed Martin and a team at Northrop Grumman–Boeing have contracts to develop the three- to six-person CEVs. Potential designs include a large Apollo-like capsule or a smaller, slimmer shuttle. NASA will pick the winning design in 2006.

Mars Society members were thrilled to hear about the vehicle plans and they support Griffin in getting started. But they object to the proposed timeline, and the size of the CEV. They want to see a 7-tonne vehicle being used as this could take humans directly to the Moon and back, and so accelerate lunar-base construction. NASA's 25-tonne CEV could carry six people as well as ISS supplies and parts. But to reach the Moon it would need to rendezvous with another, as yet undeveloped, vehicle in lunar orbit before returning to Earth.

“It's a choice between having a Cadillac ISS programme or a lunar base,” says Robert Zubrin, society president. He argues that continuing to focus on the ISS does little to further the goal of getting to Mars. Shank counters that NASA does not separate the ISS from Moon and Mars missions, as the same components are integral to both.

Zubrin and his fellow enthusiasts applauded the plans for an HLV, which is critical for a martian journey. But some, such as David Schuman, a lawyer at NASA's Goddard Space Flight Center in Greenbelt, Maryland, criticized the decision to delay HLV development until after 2010.

Without solutions to the shuttle's current safety issues, he notes, “we could be left without any heavy-lift capability”. That would delay ISS completion, pushing Moon and Mars timelines back another decade. As it is 36 years since the first lunar landing, Zubrin and fellow exploration proponents say that delay is not only unbelievable — it is unacceptable.