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« on: 02/21/2012 05:53 AM » |
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Paul Howard
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« Reply #1 on: 02/21/2012 06:40 AM » |
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Great read! Really enjoyed how much info is in this!
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rusty
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« Reply #2 on: 02/21/2012 09:57 AM » |
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"After impact in the Atlantic Ocean, the boosters will sink."
That was news to me. Does that includes the existing solids, or only for a possible follow on solid/liquid booster?
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woods170
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« Reply #3 on: 02/21/2012 10:04 AM » |
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"After impact in the Atlantic Ocean, the boosters will sink."
That was news to me. Does that includes the existing solids, or only for a possible follow on solid/liquid booster?
That includes the solids for the initial flights as well. Booster recovery is currently not baselined for any version of SLS.
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Chris Bergin
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« Reply #4 on: 02/21/2012 03:55 PM » |
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Great read! Really enjoyed how much info is in this!
Thanks! Was a lot of fun to write up.
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TomH
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« Reply #5 on: 02/22/2012 02:28 AM » |
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"After impact in the Atlantic Ocean, the boosters will sink."
That was news to me. Does that includes the existing solids, or only for a possible follow on solid/liquid booster?
The 5 segment solids are a 25% increase in the number of segments (I don't know about propellant mass as internal shape is different) while elimination of chutes/recovery gear allows a 30% increase in total thrust, in contrast to STS 4 segment solids. It is my understanding they wanted to squeeze every n/m possible out of the boosters as refurbishment wasn't overly cost effective anyway. Also, and this is sheer speculation on my part, a heavier booster would possibly require an entire lengthy recertification process for the parachutes. If you are only going to use these 5 segment solids 2 or 3 times before transitioning to Block 1A with advanced boosters, the cost of all that certification may not be worth it for so few uses. Overall it would be cheaper just to toss the things, especially since there are enough steel casings in existence to cover those 2 or 3 launches and they would be of no future use after that anyway. May as well dump them in the ocean instead of retrieve them only to melt down as a bit of scrap.
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Mark S
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« Reply #6 on: 02/22/2012 02:57 AM » |
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Wasn't Ares-I first stage going to be recovered? And weren't the parachutes pretty far along in development?
This is not going to look good to any member of the public who is at least somewhat familiar with recent history, probably including most members of Congress. The thought process will be something like: "We recovered Shuttle boosters for 30 years to save money, and now NASA just wants to throw them away. NASA must have more money than it needs if it can just dump those huge boosters in the ocean after every launch! Time to cut their budget some more..."
This is going to be one of those penny-wise, pound-foolish decisions that is going to come back to bite NASA.
Mark S.
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rusty
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« Reply #7 on: 02/22/2012 04:03 AM » |
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That includes the solids for the initial flights as well. Booster recovery is currently not baselined for any version of SLS. Thanks. I was out of the loop for a while and missed this article (linked in the OP's) http://www.nasaspaceflight.com/2011/09/atk-and-nasa-ground-test-five-segment-motor/"As far as ATK’s role in SLS ... available assets that can support up to 11 SLS missions prior to asset depletion in 2020. ATK are proposing the initial use of boosters in their expendable mode, thus eliminating several hundred million dollars worth of recovery and refurbishment costs. ... an upgraded booster may include recently proposed change to a HTPB (Hydroxyl-terminated polybutadiene) fueled solid in “composite over wrapped steel cases”..."
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edkyle99
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« Reply #8 on: 02/22/2012 04:03 AM » |
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Wasn't Ares-I first stage going to be recovered? And weren't the parachutes pretty far along in development?
This is not going to look good to any member of the public who is at least somewhat familiar with recent history, probably including most members of Congress. The thought process will be something like: "We recovered Shuttle boosters for 30 years to save money, and now NASA just wants to throw them away. NASA must have more money than it needs if it can just dump those huge boosters in the ocean after every launch! Time to cut their budget some more..."
This is going to be one of those penny-wise, pound-foolish decisions that is going to come back to bite NASA.
Mark S.
I don't see it that way. It looks like a good move to me. NASA only plans to launch two RSRMV-boosted SLS rockets. It would be a big waste to develop and field a recovery system, complete with recovery ships and recovery teams and refurbishment facilities, etc., for only two flights. After that, SLS will use either composite case solids or liquid boosters. Neither of those will be reusable, so there is no reason to create a recovery infrastructure, nor would there be any payoff in doing so. SLS is only going to fly perhaps once every two years, well below the flight rate needed to make any recovery payoff. - Ed Kyle
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Chris Bergin
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« Reply #9 on: 02/22/2012 04:08 AM » |
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I could have saved myself three hours and just written "SLS. You know that big rocket - well the boosters aren't recoverable. The end!" 
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the_roche_lobe
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« Reply #10 on: 02/22/2012 04:39 AM » |
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Great article - pity it all seems aeons away.
"...after which the ICPS performs any necessary maneuvers for safe disposal..."
So does that mean disposal into solar orbit, a lunar impact, or is the thing on a free return trajectory into Earth's atmosphere?
P
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rusty
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« Reply #11 on: 02/22/2012 05:20 AM » |
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I could have saved myself three hours and just written "SLS. You know that big rocket - well the boosters aren't recoverable. The end!"
An interesting article and time well spent. If I had known a simple question could sidetrack the discussion -- I'd still ask as I bear no responsibility for the comments of sdsds, TomH, MarkS or edkyle99.
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Proponent
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« Reply #12 on: 02/22/2012 05:52 AM » |
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Wasn't the argument made for the Shuttle that recovering the SRBs was important for safety, i.e., to see how they'd performed, since test-firings of solids are expensive? It was because of recoverd SRBs that ATK's engineers were able to warn NASA of the dangers of launching Challenger in cold weather (if only they'd been listened to). Given the Congressional requirement the SLS be human-rated, wouldn't recovery be indicated for safety reasons?
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STS Tony
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« Reply #13 on: 02/22/2012 05:55 AM » |
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I could have saved myself three hours and just written "SLS. You know that big rocket - well the boosters aren't recoverable. The end!"
An interesting article and time well spent. If I had known a simple question could sidetrack the discussion -- I'd still ask as I bear no responsibility for the comments of sdsds, TomH, MarkS or edkyle99.
Calm down, didn't you notice the big smiley on the end. Chris likes a bit of sarcasm! 
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woods170
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« Reply #14 on: 02/22/2012 07:27 AM » |
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Wasn't the argument made for the Shuttle that recovering the SRBs was important for safety, i.e., to see how they'd performed, since test-firings of solids are expensive? It was because of recoverd SRBs that ATK's engineers were able to warn NASA of the dangers of launching Challenger in cold weather (if only they'd been listened to). Given the Congressional requirement the SLS be human-rated, wouldn't recovery be indicated for safety reasons?
Short answer: No. Long answer: Congress did not specifically ask for the SLS boosters to be recovered. Other rationale: the behaviour of SRB's under a range of conditions is now well understood, thanks to 250+ succesfull flights of an ATK SRB.
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