Quote from: spacetraveler on 11/05/2017 07:37 pmQuote from: ChrisGebhardt on 11/03/2017 05:59 pmQuote from: rockets4life97 on 11/03/2017 05:34 pmWow. I didn't realize the schedule had such a dour outlook. One option that wasn't discussed in the article was using the same configuration for EM-1 to launch Europa Clipper. Is this possible or is the Exploration Upper Stage needed for its performance?SLS Block 1B w/ EUS is the only thing that can inject Europa Clipper into the desired direct trajectory to Jupiter with no gravity assists.Is there something fundamentally wrong with using gravity assists? I know it takes longer, but I believe all missions to the outer planets so far have used them.They want to launch direct to increase SC Life Expectancy during transit and in the Jupiter System at Europa. Also Congress said so.
Quote from: ChrisGebhardt on 11/03/2017 05:59 pmQuote from: rockets4life97 on 11/03/2017 05:34 pmWow. I didn't realize the schedule had such a dour outlook. One option that wasn't discussed in the article was using the same configuration for EM-1 to launch Europa Clipper. Is this possible or is the Exploration Upper Stage needed for its performance?SLS Block 1B w/ EUS is the only thing that can inject Europa Clipper into the desired direct trajectory to Jupiter with no gravity assists.Is there something fundamentally wrong with using gravity assists? I know it takes longer, but I believe all missions to the outer planets so far have used them.
Quote from: rockets4life97 on 11/03/2017 05:34 pmWow. I didn't realize the schedule had such a dour outlook. One option that wasn't discussed in the article was using the same configuration for EM-1 to launch Europa Clipper. Is this possible or is the Exploration Upper Stage needed for its performance?SLS Block 1B w/ EUS is the only thing that can inject Europa Clipper into the desired direct trajectory to Jupiter with no gravity assists.
Wow. I didn't realize the schedule had such a dour outlook. One option that wasn't discussed in the article was using the same configuration for EM-1 to launch Europa Clipper. Is this possible or is the Exploration Upper Stage needed for its performance?
....You could take the hundreds of millions that are going to be spent on this useless ML redesign and use it to do something useful, like figure out how to produce SLS cheaper so you can actually launch it at a reasonable cadence.
Also, to reduce the human costs of maintaining a highly-trained, highly-PAID staff of hundreds?/a few thousands, and their support mechanisms in working order while the Flagship-class spacecraft is in transit to its destination.The New Horizons team created some creative solutions around these issues (launch in 2006, flyby Pluto/Charon 9 years later), but there's no substitute for launching a mission, and then getting on with the exploration ASAP, via direct trajectory!
Quote from: zubenelgenubi on 11/05/2017 09:11 pmAlso, to reduce the human costs of maintaining a highly-trained, highly-PAID staff of hundreds?/a few thousands, and their support mechanisms in working order while the Flagship-class spacecraft is in transit to its destination.The New Horizons team created some creative solutions around these issues (launch in 2006, flyby Pluto/Charon 9 years later), but there's no substitute for launching a mission, and then getting on with the exploration ASAP, via direct trajectory! I don't think so. Cost reduction is definitely not an advantage of this approach. It will cost MUCH more to launch via SLS with direct trajectory than it would with a smaller launcher using gravity assists and paying the ground support team for a few additional years during transit.
Probable realistic launch plan schedule for SLS:EM-1 May 2020SM-1 July 2023EM-2 June 2024EM-3 June 2025SM-2 2026 (whenever the launch window in this year occurs) (plus this is the first flight of the RS-25Es, ASAP will want a unmanned flight of these engines first before a manned one) (this engine set will not be available to support a flight until this time anyway so it could not be done any earlier)EM-4 2028 (it takes 2 years to deliver 4 RS-25Es on the current contract) (It will require a bigger budget and a new contract to increase the build rate to deliver 4 engines per year instead of the current contract delivery rate of 2 engines per year)Unless the engine build rate is increased there is no more launches in the 2020's.Assumptions:a) That ML-1 is modified to be a cargo only SLS-1B support.b) That an ML-2 is constructed with lessons learned to make a crew version of the ML with a budget funded at a level allowing it to be constructed in 5 years starting Oct 2018. This gets a ML available to support the June 2024 EM-2 date at better than 6 months prior to launch date plus a few months of margin. c) That EC is ready for launch by 6 months prior to its launch date in July 2023.d) That Europa Lander is ready for launch 6 months prior to its window in 2026.
that SLS launch will be part of the 1b validation (meaning it would have to be flown regardless).
Quote from: Khadgars on 11/06/2017 09:35 pmthat SLS launch will be part of the 1b validation (meaning it would have to be flown regardless). Sending your most expensive probe on a test flight, what could possibly go wrong...
There seems to be an assumption peeking out behind most of the negative posts here -- that the SLS will almost inevitably fail on its first flight.What, exactly, is the track record on first flights of new large boosters? I don't want to count smallsat launch vehicles that are built out of old, degrading solid rocket motors handed down from ICBM programs, or things like that. Just new large booster systems.I'm aware of Ariane 5's first flight -- which, IIRC, was an issue with the flight software not being modified from Ariane 4. Not a hardware issue at all. More an issue of the programming staff not being willing to give up one of their 12 weeks of paid vacation for that year... Now, *second* flights, I'm aware of issues, most recently with the CZ-5, and going back at least to to the Saturn V. But, again, out of large, multi-billion-dollar development programs, how many first flights have failed?You gotta fly it first at some point, guys -- and ASAP is gonna push hard against flying the first iteration of a given configuration with crew on board. If it's gonna cost 4 or 5 billion USD to fly the first one, doesn't it make sense to put *something* on it?And, thinking about it, SLS isn't a Saturn V. It's not featuring several previously-unflown engine designs (or, in the case of the J-2, previously unflown in a clustered configuration) -- heck, the first several flights of SLS will use previously flown engines. Has OrbitalATK been pushing to revert the SRB segment joints to the original faulty Shuttle design, or something?In other words why would people assume that Musk and Bezos can create new engines and boosters that will be perfectly wonderful from the get-go, but SLS, featuring extremely mature engine technology, is a horrendous risk that should never be attempted?I am not speaking of cost, or suitability of the booster for specific missions -- just an increasingly-less-unspoken assumption that SLS is inherently likely to fail, especially on its first flight. I'm just not seeing any basis for that prejudice against this launch system.
They are really going to redesign the entire mobile launchers because it will end up with a safety factor of 3.75 instead of 4.0 for the block 1B configuration? Seriously? And that's going to take 3 years?
Quote from: the_other_Doug on 11/07/2017 03:45 pmThere seems to be an assumption peeking out behind most of the negative posts here -- that the SLS will almost inevitably fail on its first flight.What, exactly, is the track record on first flights of new large boosters? I don't want to count smallsat launch vehicles that are built out of old, degrading solid rocket motors handed down from ICBM programs, or things like that. Just new large booster systems.I'm aware of Ariane 5's first flight -- which, IIRC, was an issue with the flight software not being modified from Ariane 4. Not a hardware issue at all. More an issue of the programming staff not being willing to give up one of their 12 weeks of paid vacation for that year... Now, *second* flights, I'm aware of issues, most recently with the CZ-5, and going back at least to to the Saturn V. But, again, out of large, multi-billion-dollar development programs, how many first flights have failed?You gotta fly it first at some point, guys -- and ASAP is gonna push hard against flying the first iteration of a given configuration with crew on board. If it's gonna cost 4 or 5 billion USD to fly the first one, doesn't it make sense to put *something* on it?And, thinking about it, SLS isn't a Saturn V. It's not featuring several previously-unflown engine designs (or, in the case of the J-2, previously unflown in a clustered configuration) -- heck, the first several flights of SLS will use previously flown engines. Has OrbitalATK been pushing to revert the SRB segment joints to the original faulty Shuttle design, or something?In other words why would people assume that Musk and Bezos can create new engines and boosters that will be perfectly wonderful from the get-go, but SLS, featuring extremely mature engine technology, is a horrendous risk that should never be attempted?I am not speaking of cost, or suitability of the booster for specific missions -- just an increasingly-less-unspoken assumption that SLS is inherently likely to fail, especially on its first flight. I'm just not seeing any basis for that prejudice against this launch system.If you're talking about EM-1, it does have the largest single stage and the largest solid motors ever. But the highest risk item is probably avionics and software, which are harder than hardware to test realistically and are all new, to my understanding.Europa Clipper would not be on the first flight of SLS, but the second. It would be the first flight of EUS, which is a new stage, again with new software.
Also, use of EUS and the matching-size PLF would allow a more massive (larger propellant tanks = more propellant = longer mission/greater mission flexibility at mission target), taller, and wider spacecraft, to accommodate the radiation shielding and multiple-instrument payload, would it not?(One of our resident experts would be able to express this better than me, I think.)
They are really going to redesign the entire mobile launchers because it will end up with a safety factor of 3.75 instead of 4.0 for the block 1B configuration? Seriously? And that's going to take 3 years? 4.0 is just a made up round number in some spec somewhere, there's nothing magical about it. Plus, it's not like this structure is going to see a high number of duty cycles where additional structural margin is required to actually build a safe structure with launches taking place off of it once every two years at best. The Saturn V second stage was supposed to be designed to a safety factor of 1.5. North American did a really good job of designing it to 1.5, and it broke pretty much right at 1.5 in integrated loading testing. So, rather than go redesign the entire stage, NASA changed the requirement for manned spaceflight factor of safety to 1.4 and called it good. Since then, every launch vehicle built in the US has been designed to 1.4. We would never have reached the moon by 1970 if NASA of the 60's was ruled by the bureaucrats who have their noses stuck in specification manuals like they do today. If they would have followed the letter of the specification and made North American go redesign the stage to 1.5, we'd never have made it to the moon in '69. Good engineering management requires understanding what is vitally important and what doesn't matter. You have to build additional margin into the areas of critical with high uncertainty, and you can accept significantly less in areas where the loads are extremely well understood (i.e. ground support equipment like the mobile launcher). You could take the hundreds of millions that are going to be spent on this useless ML redesign and use it to do something useful, like figure out how to produce SLS cheaper so you can actually launch it at a reasonable cadence.
This makes the Europa Clipper mission cheaper while not affecting SLS budget at all since it has to be flown before EM-2.
1. In other words why would people assume that Musk and Bezos can create new engines and boosters that will be perfectly wonderful from the get-go, but SLS, featuring extremely mature engine technology, is a horrendous risk that should never be attempted?2. I am not speaking of cost, or suitability of the booster for specific missions -- just an increasingly-less-unspoken assumption that SLS is inherently likely to fail, especially on its first flight. I'm just not seeing any basis for that prejudice against this launch system.
Quote from: oldAtlas_Eguy on 11/04/2017 04:48 pmProbable realistic launch plan schedule for SLS:EM-1 May 2020SM-1 July 2023EM-2 June 2024EM-3 June 2025SM-2 2026 (whenever the launch window in this year occurs) (plus this is the first flight of the RS-25Es, ASAP will want a unmanned flight of these engines first before a manned one) (this engine set will not be available to support a flight until this time anyway so it could not be done any earlier)EM-4 2028 (it takes 2 years to deliver 4 RS-25Es on the current contract) (It will require a bigger budget and a new contract to increase the build rate to deliver 4 engines per year instead of the current contract delivery rate of 2 engines per year)Unless the engine build rate is increased there is no more launches in the 2020's.Assumptions:a) That ML-1 is modified to be a cargo only SLS-1B support.b) That an ML-2 is constructed with lessons learned to make a crew version of the ML with a budget funded at a level allowing it to be constructed in 5 years starting Oct 2018. This gets a ML available to support the June 2024 EM-2 date at better than 6 months prior to launch date plus a few months of margin. c) That EC is ready for launch by 6 months prior to its launch date in July 2023.d) That Europa Lander is ready for launch 6 months prior to its window in 2026.6 launches by 2028.... By then we would have spent >$40 billion on the SLS program.good god$6.7 billion per flight. That's $20 from every man, woman, and child in America to throw one of these up.