Here’s why the loss of SpaceX’s Falcon 9 rocket is a big deal for NASA

[Statistical]

3. The conclusions in the article are not accurate

I know it was posted a while ago but as I now work on this project I felt it was important to clear up the factually incorrect statements.

The IDA1 was lost on CRS-7 but there is a second IDA scheduled to be launched on CRS-9. CRS-9 has a scheduled launch window of Dec 2015 but is on hold pending the investigation of CRS-7. Also NASA had purchased components for a third IDA to use as a ground side spare. It hasn't been assembled yet (more flexible is kept as spare parts) but it may end up being assembled and launched on a future CRS to replace IDA1. There is no need for more than one IDA on the station the use of two is just standard redundancy.



Lastly the statement that the IDA is needed to "dock" is accurate but misleading. The Dragon module from CRS-6 is currently berthed with the ISS using the SBA (standardized berthing adapter) so the delay doesn't jeapordize any future CRS missions. "Berthing" involves the ISS robotic arm to to connect the module to the ISS while docking means the spacecraft can connect or disconnect independently.

The one major limitation of berthing over docking is that it that the module can't be used as the ISS lifeboat because in an emergency it can't separate quickly by automated spacecraft control. Still the Dragon CRS is not crew rated. It won't be until the Dragon V2 that it will carry crew and serve as the lifeboat. That isn't scheduled to happen until 2017 with manned test flight in June and first crew rotation mission in Q4.