Would the safest path be for NASA to concentrate solely on the LEO vehicle but make it able to accept a comercially available upper stage for the BEO role eg. ACES 41/71/181 as the mission requires I mean, does the legislation actually direct NASA to develop the upper stage or just to be able to use one to go BEO Mick.
does the legislation actually direct NASA to develop the upper stage or just to be able to use one to go BEO
Quote from: MickQ on 10/07/2010 05:48 amWould the safest path be for NASA to concentrate solely on the LEO vehicle but make it able to accept a comercially available upper stage for the BEO role eg. ACES 41/71/181 as the mission requires I mean, does the legislation actually direct NASA to develop the upper stage or just to be able to use one to go BEO Mick.The problem with the commercial route is I don't think any are available. ACES if I recall correctly wanted NASA to pay for it. ULA would then use ACES on all its boosters. The ACES 70 would fit in well with SLS, but not sure NASA has the funds and the clout to kick money over to that route.
The only significant BEO time-line that exists presently (AFAIK) is President Obama's proposal that BEO pathfinder missions begin in the early 2020s with the first NEO encounter in 2025 and the Phobos encounter/Mars orbiter in 2030 with a human landing on Mars "soon thereafter". IMO, that means that the upper stage needs to get to hardware testing in space really no later than 2018/19.There are basically three options for the upper stage right now:* 5.4m Centaur-heritage with 2, 4 or 6 RL-10C engines (ACES family);* 5.5m AIUS-heritage with 1 x J-2X or 4 x RL-10 (I suspect this is the Senate's choice, from the language in the authorisation bill);* 8.4m with 6 x RL-10 (JUS).As stated above, I suspect that the political winds are behind AIUS (I call it 'Ares-IA'). Nonetheless, the ACES family, including the stretched-length version for the Atlas-V Phase 3A, is probably the best choice from a programmatic standpoint and the JUS from a standpoint of capability.With respect to the ACES family, does the stretched version used on the Atlas-V P3A have a specific designation?
I really don't know what the 5.5 AIUS-derived is supposed to be like; HEFT speaks of making it into something with RL-10 and very low boiloff, but after removing the orange foam I'm not sure what it retains in common with AIUS.
Quote from: alexw on 10/07/2010 08:57 am I really don't know what the 5.5 AIUS-derived is supposed to be like; HEFT speaks of making it into something with RL-10 and very low boiloff, but after removing the orange foam I'm not sure what it retains in common with AIUS.It would have the 5.5m barrel, the avionics ring and the common bulkhead propellent tanks in common.
Regarding ACES, I might be wrong, but it was my impression that the were to have a 5.4m diameter because that maches the OML of the Atlas-V 5m PLF.
There are basically three options for the upper stage right now...
Quote from: Proponent on 10/06/2010 04:36 amif the backers of SLS/Orion are seriously interested in going beyond LEO and they're setting deadlines, they ought at to set a deadline for a BEO-capable system (SLS with an upper stage), not for an LEO-only system.The past is littered with bills that set deadlines so far in the future they became meaningless. CxP and Obama's FY11 proposal share that same flaw.No more. It is time we focus on regaining base capability, setting realistic near-term deadlines, and not getting too far ahead of ourselves.
if the backers of SLS/Orion are seriously interested in going beyond LEO and they're setting deadlines, they ought at to set a deadline for a BEO-capable system (SLS with an upper stage), not for an LEO-only system.
Jorge is spot-on regarding the point that anything in these bills referring to a time beyond a few years into the future is pretty meaningless.During DIRECT, the term we use for anything beyond the current 4-year Presidential cycle, was "fantasyland".At best, NASA will get a steady path until the next President is elected, or until both Congressional Houses change parties.I don't know how Congress will look next year, so I can't even begin to predict what might happen there.I do not expect Obama will win a second term, so I expect NASA has until no later than the middle of the next President's first year (mid-2013) to nail this new program down hard enough that it can't be uprooted.This is the main reason why I simply do not believe that a 6-8 year Ares-V development effort can survive to operational flights, while a 3-4 year Jupiter-130 'foundational system' has a real chance of success. IMHO, once you have that basic capability set in stone, an upgrade (Jupiter 24x) really becomes more a matter of 'when', not 'if' -- you may have to wait for a NASA-friendly President/Congress to get the J-24x upgrades, but they won't cancel the basic J-130 capability if it is already flying when they come into power.
Quote from: Proponent on 10/06/2010 05:01 amAfter all, the Saturn V flew all up on its very first flight in 1967, and that was with all-new first and second stages. This little change would make me feel a heck of a lot better about the Senate bill.The Saturn V had several times the budget SLS will. The plain facts are that in this budgetary environment, the upper stage must be developed serially, *after* the core elements. Therefore it is foolish to specify a deadline for it because it is too far in the future. This is not a "little" change.
After all, the Saturn V flew all up on its very first flight in 1967, and that was with all-new first and second stages. This little change would make me feel a heck of a lot better about the Senate bill.
I have no such argument. Jorge is right. Set a goal out to far, and it's meaningless, including an advanced upper stage. Proponent, you're right that that means no BLEO exploration. The only answer (to allow BLEO exploration) is to use a cheap upper stage, which basically means one we already have. That's what I think OV-106 has been hinting at. Is that correct?
Quote from: Robotbeat on 10/08/2010 03:46 amI have no such argument. Jorge is right. Set a goal out to far, and it's meaningless, including an advanced upper stage. Proponent, you're right that that means no BLEO exploration. The only answer (to allow BLEO exploration) is to use a cheap upper stage, which basically means one we already have. That's what I think OV-106 has been hinting at. Is that correct?I tend to agree with this. Use what is available until flight rates and proposed payloads require/mandate the development of something more optimal.
[This is intended to be the continuation of a discussion that has been quite rightly booted out of an L2 forum for being OT.]The Senate's FY2011 authorization bill specifies that SLS is to be flown into earth orbit by 2016. It also specifies that an upper stage, enabling SLS to go beyond earth orbit, is to be developed but sets no timetable. This wishiwashiness about building a beyond-earth-orbit-capable vehicle leaves me concerned about the following scenario. Circa 2016, SLS does indeed fly to LEO. The necessary trio of presidential will, Congressional sentiment and economic reality, however, fails to coalesce behind building an upper stage anytime soon. Key SLS constituencies being well served by SLS's existence, regardless of whether it flies much or ever leaves LEO, SLS languishes without an upper stage for years, all the while consuming limited funds. If this goes on too long, SLS's lack of accomplishment may ultimately even catch up with its political benefits, the result being termination.That's my nightmare. I'd be less worried if the Senate bill at least specified a date for an upper stage. That not being the case, I'll be a happier space cadet if someone can convince me that my fears are unjustified.
Quote from: MickQ on 10/08/2010 04:16 amQuote from: Robotbeat on 10/08/2010 03:46 amI have no such argument. Jorge is right. Set a goal out to far, and it's meaningless, including an advanced upper stage. Proponent, you're right that that means no BLEO exploration. The only answer (to allow BLEO exploration) is to use a cheap upper stage, which basically means one we already have. That's what I think OV-106 has been hinting at. Is that correct?I tend to agree with this. Use what is available until flight rates and proposed payloads require/mandate the development of something more optimal.Heh. The irony of this is delicious. It's also kind of amusing that Ross and the other DIRECT guys, who keep hammering on "build only one vehicle because its probably the only one you're going to get" are banking on effectively a second round of development to upgrade their vehicle. It *is* a huge improvement over CxP, which had almost nothing in common between vehicles. But, it's still a similar leap of faith--you're spending a huge amount of money right now building a vehicle that gets you half-way to enabling BEO exploration, in the hopes that you'll be given a new batch of money down the road to develop the actual BEO capable vehicle...Maybe I'm just not getting it.~Jon