Could Orion be Downgraded from a Six to Four Astronaut Vehicle?

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To save on weight, NASA engineers are considering the option to remove two seats from the Orion crew exploration vehicle. According to the manager of the Constellation Program, a possible redesign option has been discussed with the International Space Station (ISS) partners despite the fact that the initial operational capability (IOC) to deliver crew to the ISS calls for a six-seat version. Although the space station crew will have expanded to six by the end of next month, NASA is confident the loss of two seats on Orion won’t cause any operational problems… at least we’ll still have Soyuz.

Today, the Orlando Sentinel reported that the Constellation Program, due to budget problems, probably won’t be ready for a return trip to the Moon until 2020, two years later than officially planned (NASA hoped for a 2018 mission). Now NASA engineers are concerned that the lunar mission may slip even further behind schedule.

To compound this bad news, NASA is weighing up its options to free up some mass from the initial Orion launches atop the Ares I rocket. This issue arose after Jeff Hanley, manager of the Constellation Program and Orion developer, said the Orion design was within “plus or minus a couple of hundred pounds” of the 21,000-pound maximum for the command module set by a safety requirement to land with only two of the three main parachutes deployed should one fail after reentry.

“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.” So it’s not all bad news, the first launches may consist of four astronauts, but Orion could be modified to cater for six.

Hanley is keen to point out that although the brand new NASA manned space vehicle may be operating at a reduced capacity, at least Roscosmos will be able to help out. “Our Russian partners are always going to fly Soyuz or something derivative to that, so we’ll have the full coverage of being able to get the crew off the station in a pinch on the Soyuz and in the Orion,” he added. Soyuz is a three-crew space vehicle and is currently used by the space station as a “lifeboat” should an emergency crop up in orbit.

Apparently the Orion weight problem has been around for a while as the design of Orion is based on predicted weights, and not actual launch weight; if the actual weight exceeds that of the safety margin, cutbacks would be required. In this case the cutback may include two crew members.

Hanley points out that although the early Constellation flights may include a four-crew IOC, it would stand NASA in good stead so a good understanding of how well it performs with four seats before the possibility of expanding it to six.

Source: Aviation Week