posted 04-22-2009 08:01 PM               

NASA engineers are "on the verge" of pulling two crew seats from their design for the Orion crew exploration vehicle, at least at first, to save weight.

That would mean that when NASA regains the ability to fly astronauts to orbit in the post-shuttle era, it will start with a crew of four instead of six. Four seats have been the baseline for the version of Orion that would take astronauts back to the Moon, but the initial operational capability (IOC) to deliver crew to the International Space Station (ISS) currently calls for a six-seat version.

Jeff Hanley, manager of the Constellation Program that is developing the Orion, its Ares I crew launch vehicle and the follow-on lunar vehicles, told Aviation Week on April 22 that the Orion design is within "plus or minus a couple of hundred pounds" of the 21,000-pound maximum for the command module set by a requirement to land safely with only two of the three main parachutes deployed.

"Right now we're studying and really on the verge of deciding that we're going to start with four," Hanley said. "That gives us a common lunar and ISS version, but we've sized the system and have a design for six, so we'll grow our capability as we need it."

posted 04-28-2009 11:53 AM               

NASA is slimming down its Orion Crew Exploration Vehicle by removing two seats and cutting its crew size from six people to four, a space agency spokesman confirmed late Monday.

"As part of the Constellation Program's Integrated Program Review on April 14-17, NASA decided that the Orion will be baselined to initially carry four, instead of six, crew to the International Space Station," Hautaluoma said. "The Orion crew module's size and shape, which can support a six-person crew option, will not change as a result of this decision, thus giving NASA the flexibility to carry six crew for other missions."

NASA made the crew size change "in order to improve schedule and cost confidence by minimizing multiple configurations under simultaneous development during the Program's early phases," Hautaluoma said. "While a four-person crew would save some mass, the issue of mass savings was not a major factor in the decision-making process."

posted 04-29-2009 02:18 AM               

1. No cash.
   
2. Booster can't deliver the goods.

posted 04-29-2009 07:18 AM               

quote:

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Originally posted by Apollo Redux:
Only one of two reasons for this.

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posted 04-29-2009 08:55 AM               

quote:

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Originally posted by Mr Meek:
...the realist in me knows that rides to the ISS and moon just got 33% harder to get.

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posted 04-29-2009 11:08 AM               

quote:

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Originally posted by Robert Pearlman:
If NASA, for example, exercises its COTS D option...

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posted 04-29-2009 11:44 AM               

However, as those options have matured, the need for a six-seat Orion have taken a back seat to the need for a four seat lunar-capable vehicle. And, as the latter is the long pole under the Constellation tent, NASA has chosen to streamline Orion's development to just one, four-seat version.

Think of it this way: when NASA was first building Apollo, they weren't concurrently developing both a three-seat lunar version and a five seat rescue configuration. The latter was always possible, but work didn't start on its design until 1970.

posted 04-29-2009 01:15 PM               

Considering your explanation I'm coming back to my question of the difference between the two versions which I think cannot be that significant.

What would help me to understand better is the original specification of the two versions and the differences justifying two development streamlines.

posted 04-29-2009 01:27 PM               

Nor is adding two more seats to Orion the equivalent of re-installing the back row in a minivan. These designs are not modular; they are for all intents and purposes two different vehicles sharing a common hull. Each must pass their own battery of tests and reviews before they can be declared flight worthy, which adds more time to the schedule.