On 2022-11-20 9:09 PM, Sylvia Else wrote:
On 17/11/2022 11:49 pm, David Spain wrote:
I'm happy SLS got off the ground. I'd be even more happy if it were
reconfigured to deliver cargo only and we could use up the supply of
this expensive, ill-conceived rocket to put one and done cargo into
space. Perhaps in either lunar or Lagrange Point orbits.
Not a big fan of the gateway/toll-booth either....
Dave
I seem to remember the USAF [*] doing a study that showed that a solid
rocket failure after lift-off could be unsurvivable because bits of
burning solid rocket fuel would destroy the capsule's parachutes. I
don't believe a solution was found.
That was for the "Liberty" Constellation configuration, aka Ares I aka
'The Stick'. This was a single 5 segment SRB with a TBD second stage to
boost the Orion Capsule into LEO only. I believe the original plan
called for the second stage to use LH2/LO2 and a modified J-2 rocket
engine first used on the upper stages of the
Saturn V and to be called the J-2X. However, the J-2X eventually ended
up being a 'clean-sheet' design and did not evolve from the J2 due to performance requirements needed for the Ares I/V program.
Constellation was cancelled by the Obama Administration and I believe
the J2-X died with it along with Ares I. Ares V moved on to morph into
the SLS. SLS upper stage currently is the DCSS (Delta Cryogenic Second
Stage) to eventually be replaced by the ESA developed Exploration Upper
Stage EUS. The latter will extend the SLS in height requiring a new
launch tower to accommodate it. It's in the works as they say, even if
it tilts slightly off-center (or at least it used to)!.
The AF range safety folks based out of Patrick AFB at the Cape did a
study which suggested the LAS system for the Orion capsule on an Ares I
would not be able to boost it beyond the debris field should the SRB
explode or be launch destructed via side splitting munitions on the way
up. Flaming segments of solid fuel could melt the nylon parachute
material used to make up the Orion parachutes should the capsule fall
through this debris field. I believe there are videos available of a
Delta II explosion that used SRBs that show the effect of this flaming
debris quite nicely. Here's one from Scott Manley:
https://youtu.be/ey-bbM7m1L8
I don't know what analysis was done for SLS. Perhaps the abort plan is
to jettison the SRBs and remain on the core booster long enough to fly
clear any SRB debris? If the core booster goes first maybe it is just as
risky? I don't know.
Liberty flew exactly once. Uncrewed, with dummy payload simulators for
the capsule and upper-stage. As NASA PAO said at the time: "Testing new concepts in space exploration..."
So relegating it to cargo only would certainly make sense, if there
really is no cheaper alternative available.
Sylvia.
There is, but might as well leverage sunk cost if you can.
[*] Yes - I don't know why the USAF was doing that either.They are responsible for range safety at the Cape.
Dave
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