In article ,
says...

On 2018-12-06 06:06, Jeff Findley wrote:

Now obviously there was a failure. Musk tweeted that a grid fin pump
failed.


I wonder if they would be considering increasing redundancy for the
fins. (either adding another one so that there is enough aerodynamic
authority to ovveride 1 fin stuck in wrong direction) or working on the
hydraulics (or electric) modtors for the fins to increase redundancy.

Musk has already Tweeted that they're looking into adding another pump
for redundancy.

When you bet your business model on the ability to recover the stages,
it's the weakest link that jeoperdizes this, so they might have to look
at increasing redundancy for the fins.

A Falcon 9 first stage costs about $25 million to manufacture (by
unofficial estimates based on the price they're charging for a launch).
Losing one every once in a while isn't the end of the world. It's far
more important to achieve success on the primary mission. Recovering a
Falcon 9 booster is still very much a secondary mission.

Yesterday SpaceX launched a GPS III satellite for DOD. This is there
first launch of a DOD satellite deemed critical for active military
troops. There was no attempt at recovering the first stage as the Air
Force wanted to reserve all available additional propellant in order to
achieve the primary mission. No grid fins or landing legs were
installed.

So, even if SpaceX wants to reuse first stages, sometimes the customer
simply won't allow it (hint: GPS III satellites cost a hell of a lot
more to make than a Falcon 9 first stage).

Jeff
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