Orion Takes a Backseat to Nobody
NASA recently announced that the Orion Spacecraft will be initially limited to a crew of four, even for ISS missions. This is another step backwards from the ESAS Study which called for a crew of six on ISS missions and four on lunar missions.
There is a very clear reason why ESAS had a requirement for six crew to the ISS on Orion. The ISS has a crew of six, and it makes sense for Orion to deliver a full crew compliment to ISS and return them to earth. The alternative, in the post-shuttle era, is to send two Soyuz capsules (or one Dragon, if SpaceX ever sees COTS-D funding.) Apparently NASA is counting on one Orion and one Soyuz being docked at ISS at all times. If the station had to be evacuated in an emergency, NASA will have to hope that both capsules work properly to get the full crew compliment home.
Officially, NASA is justifying the smaller crew because it will eliminate the need for two different seat configurations in Orion. Development costs and mass savings have nothing to do with it. Yet this argument is pretty weak when considering that Apollo supported three crew for lunar missions and five crew in the Skylab Rescue configuration. The difference between 1973 and today is that NASA was willing to seat its astronauts in two rows during the Apollo era. Orion is significantly bigger than Apollo, in part because NASA is unwilling to have astronauts sitting in two rows during a hard landing. Only time and testing will validate this safety fear.
With the growing likelihood that ISS will see a life extension to 2020 or beyond, it doesn't make a lot of sense to take seats out of Orion and prevent it from serving as an ISS lifeboat.
There is a very clear reason why ESAS had a requirement for six crew to the ISS on Orion. The ISS has a crew of six, and it makes sense for Orion to deliver a full crew compliment to ISS and return them to earth. The alternative, in the post-shuttle era, is to send two Soyuz capsules (or one Dragon, if SpaceX ever sees COTS-D funding.) Apparently NASA is counting on one Orion and one Soyuz being docked at ISS at all times. If the station had to be evacuated in an emergency, NASA will have to hope that both capsules work properly to get the full crew compliment home.
Officially, NASA is justifying the smaller crew because it will eliminate the need for two different seat configurations in Orion. Development costs and mass savings have nothing to do with it. Yet this argument is pretty weak when considering that Apollo supported three crew for lunar missions and five crew in the Skylab Rescue configuration. The difference between 1973 and today is that NASA was willing to seat its astronauts in two rows during the Apollo era. Orion is significantly bigger than Apollo, in part because NASA is unwilling to have astronauts sitting in two rows during a hard landing. Only time and testing will validate this safety fear.
With the growing likelihood that ISS will see a life extension to 2020 or beyond, it doesn't make a lot of sense to take seats out of Orion and prevent it from serving as an ISS lifeboat.
posted by Mr. X at
9:51 AM
