On 05/08/2014 4:23 PM, Jeff Findley wrote:
In article ,
says...

Jeff Findley wrote:
In article .at,
says...
I was wondering, SpaceX is flying NASA cargo to the ISS on their
Falcon 9, but are at the same time experimenting with reusable
booster stages. Since these experiments add risk to the flight,
how does NASA feel about all this?

The reusability test happened after stage separation. So, how does this
adds risk to the flight?

Premature landing leg deployment prior to stage separation?

That's the only thing I can think of. As long as everything related to
leg deployment is designed to be "fail safe" (e.g. a failure does *not*
deploy the legs), then it's all good.

There are other possible failure modes. For instance, when performing
the fly back, the booster needs to throttle and/or cut off the engine.
If the software confuses launch with fly back, it could cut off the
engine right after launch.

But I think everyone, including NASA, agrees that the likeliness of
those failure modes are quite low. But then, what's the likeliness of
confusing old fashion measure units with metric units on a spacecraft
headed to Mars?


Alain Fournier