John Young, an accomplished former astronaut and NASA’s first space shuttle commander, believes the space agency’s next spaceship – the Crew Exploration Vehicle (CEV) – is too large for the job at hand, which is mainly launching astronauts back to the Moon.

Young should know, too. He’s been to the Moon twice, first as pilot of the Apollo 10 command module and then as commander of 1972’s Apollo 16 flight when he actually walked on the lunar surface. He also commanded NASA’s premiere STS-1 shuttle flight aboard Columbia, which happened to launch 25 years ago today.

“I think the Crew Exploration Vehicle should be a reliable anytime abort vehicle, it should be a reliable entry vehicle, and making a big vehicle doesn’t make any sense,” Young told me in a recent phone call – he said as much again today in a public press conference – adding that he’s served as consultant for NASA’s CEV team. “You get to the space station in a couple or three orbits, you could get to the Moon in three or four days and you don’t need a big vehicle to do that.”

Young said that the CEV in its current incarnation is too heavy – with a heat shield up to 30 percent larger than needed – and that the capsule need not be as spacious, even for a long-duration mission to Mars.

“You’re sure not going to go to Mars with that size vehicle anyway, you’d have a habitat module screwed on to it,” Young told me.

NASA, it seems, is listening at least in part. Earlier this year, the agency pared down its plans for the CEV capsule from its initial 18-foot (5.5-meter) diameter to about 16.4 feet (five meters).

But even the reduced CEV is still a bit larger than the Apollo capsules Young rode to the Moon, which were about 12.8 feet (four meters) wide. 

“By building stuff you don’t need to build, it makes it less reliable,” Young said. “Whether you like it or not, that’s just the way it is.”