One thing I've been wondering, and I'm sure it's been discussed before:What about in-orbit rendezvous with a full Delta IV upper stage (launched on the latest Delta IV Heavy) and an Orion? Couldn't that get you to EML1/2 and back?
I don't think so, for three reasons: DIRECT looked at this. A DIVHUS will just barely push a 22mT fueled Orion through TLI. EML 1 & 2 are delta-v-i-er.
You also couldn't do rendezvous with the DIVHUS, unless you're amazingly quick, because the loiter time in LEO is quite low; even the GSO kit only gives, what, 6 hours?
Also, you can't quite lift a second, full DIVHUS on a DIVH, perhaps not even with RS-68A; it masses about 30mT (though adding GEMs would do it.) -Alex
We need a better upper stage!
The OP was asking about launch on a DIV-H. I think you'd need quite a lot of modifications to do EOR!
Quote from: 93143 on 10/05/2010 08:58 pmCorrection: reverse the order of the launches... sorry...A JUS is supposed to have 0.01% per day passive boiloff.Is that feasible? It seems obvious that it is a requirement.How fast could you cycle the launch pad? A month?Would a launch-on-need capability be required/desired?
Correction: reverse the order of the launches... sorry...A JUS is supposed to have 0.01% per day passive boiloff.
Quote from: yg1968 on 10/05/2010 05:37 pmI think that both are still possible under the bill. It will be up to NASA to make that decision later on. One of the concern that Augustine had was that commercial companies would have much less business opportunities once the ISS was deorbited. Thus the idea of space taxis. But the idea of space taxis could still work with SLS (even if it has a crewed version). If a mission can be done with a 1.5 structure (SLS plus commercial crew) instead of a 2.0 structure (SLS Cargo and another SLS with crew), why not use commercial companies for such missions? In regards to a 1.5 system relevant to this chain of posts (Taxi system to in orbit SLS components) I have not seen or been part of an analysis so I will reserve judgment. However, if SLS is to take up the multifunction vehicle it may make sense to put a crew in it. Unless, the desire is not to human rate SLS.This chain of post was partially pushed along by me since it was my belief that DIRECT members and others believed the bill required SLS to carry a crew. If the intent of Congress was to leave open the requirement for whether SLS is to carry a crew or not, then I understand.
I think that both are still possible under the bill. It will be up to NASA to make that decision later on. One of the concern that Augustine had was that commercial companies would have much less business opportunities once the ISS was deorbited. Thus the idea of space taxis. But the idea of space taxis could still work with SLS (even if it has a crewed version). If a mission can be done with a 1.5 structure (SLS plus commercial crew) instead of a 2.0 structure (SLS Cargo and another SLS with crew), why not use commercial companies for such missions?
Quote from: Mark S on 10/05/2010 07:28 pmI realize that many people use 1.5 in that capacity, I just do not agree with the underlying premise. You are selling yourself short. Was Mercury a 0.5 architecture? Or Gemini? By using fractional launch terminology, you are implying that any mission without an HLV component is incomplete. The 0.5 is especially misleading, since it looks like a 1 sig-fig decimalization of the non-quantitative human language use of "half". Going by mass alone, if an F9 or AV-x0x lifts around 10mT, then with the 5/5 vehicle it's a 1.1 launch, for the 4/3 it's a "1.14" launch. The latter is especially nice -Alex
I realize that many people use 1.5 in that capacity, I just do not agree with the underlying premise. You are selling yourself short. Was Mercury a 0.5 architecture? Or Gemini? By using fractional launch terminology, you are implying that any mission without an HLV component is incomplete.
27-28mT as opposed to 26mT for Ares I. Not much greater.
Quote from: marsavian on 10/06/2010 06:22 pm27-28mT as opposed to 26mT for Ares I. Not much greater.Make sure to compare apples to apples... With Ares I, the trajectory is suborbital.
Quote from: Robotbeat on 10/06/2010 06:25 pmQuote from: marsavian on 10/06/2010 06:22 pm27-28mT as opposed to 26mT for Ares I. Not much greater.Make sure to compare apples to apples... With Ares I, the trajectory is suborbital.The penalty for that is about the same as Delta IV having to follow a human rated 4g ascent profile so the relative performance difference is still the same i.e less than 10%.
Quote from: 93143 on 10/05/2010 08:58 pmA JUS is supposed to have 0.01% per day passive boiloff.The DIRECT guys used 0.35% per day boiloff in their Moon mission sims (just so it matched AVUS / CxP), but they reckoned 0.1% would be easily in reach for JUS. At ~130nmi, 0.01% is below station-keeping requirements (assuming you use boiloff for this), so that's unrealistic....ULA's ACES-based depots also have a different structure than their ACES upper stages & use sunshields to achieve 0.01% passive boiloff, and I'm not even sure they can achieve this in LEO.
A JUS is supposed to have 0.01% per day passive boiloff.
The JUS has a common bulkhead and is based on the WBC "Cold Technology". It has a passive boiloff rate of 0.01%. Active boiloff is significantly less than that. It is specifically designed for long-duration loiter.
WBC would essentially bring all the tanking technologies together in one unit to make a 0.1% boiloff stage. ICES then takes that excellent foundation and adds a few more specific features (like the VDMLI and vapor cooling) to improve the passive boiloff characteristics to the point where you really don't need any active cooling unless you're planning to hold the same fuel in one tank, without re-filling, for a period measured in years.
As for boiloff, we have more than enough margin built in for that. We've been publicizing the NASA rate at 0.35% per day, and that's the number used in the performance calculations, but in reality because of the JUS design it's 0.10% for the passive system, and when the active system becomes operational it'll be more like 0.01% per day.
Quote from: marsavian on 10/06/2010 06:34 pmQuote from: Robotbeat on 10/06/2010 06:25 pmQuote from: marsavian on 10/06/2010 06:22 pm27-28mT as opposed to 26mT for Ares I. Not much greater.Make sure to compare apples to apples... With Ares I, the trajectory is suborbital.The penalty for that is about the same as Delta IV having to follow a human rated 4g ascent profile so the relative performance difference is still the same i.e less than 10%.Show me.EDIT:My main point is that MP99 originally had implied (probably not intentionally) that Ares I would give greater performance than Delta IV Heavy, when the opposite is true.
Quote from: Robotbeat on 10/06/2010 06:39 pmQuote from: marsavian on 10/06/2010 06:34 pmQuote from: Robotbeat on 10/06/2010 06:25 pmQuote from: marsavian on 10/06/2010 06:22 pm27-28mT as opposed to 26mT for Ares I. Not much greater.Make sure to compare apples to apples... With Ares I, the trajectory is suborbital.The penalty for that is about the same as Delta IV having to follow a human rated 4g ascent profile so the relative performance difference is still the same i.e less than 10%.Show me.EDIT:My main point is that MP99 originally had implied (probably not intentionally) that Ares I would give greater performance than Delta IV Heavy, when the opposite is true.Actually it does if you bother to human rate it to the same accepted standard as Ares I as Aerospace did in their study.http://www.nasa.gov/pdf/377875main_081109%20Human%20Rated%20Delta%20IV.pdfp.30 (p17 in pdf)To ISS target--------------- (config 1) RS-68A D-IVH -> 25.8mT (config 6) human-rated D-IVH -> 18.3-23.6mT depending on whether you use the correct 75% human rating of RL10-A-4-2 or use it at 100% which is not strictly human rated. Ares I -> 23.1mTTo Lunar target----------------- (config 1) RS-68A D-IVH -> 27.5mT (config 6) human-rated D-IVH -> 20.4-25.3mT depending on whether you use the correct 75% human rating of RL10-A-4-2 or use it at 100% which is not strictly human rated. Ares I -> 25.5mT
Actually it does if you bother to human rate it to the same accepted standard as Ares I as Aerospace did in their study.http://www.nasa.gov/pdf/377875main_081109%20Human%20Rated%20Delta%20IV.pdf (config 1) RS-68A D-IVH -> 25.8mT (config 6) human-rated D-IVH -> 18.3-23.6mT depending on whether you use the correct 75% human rating of RL10-A-4-2 or use it at 100% which is not strictly human rated. Ares I -> 23.1mT
While I may dispute parts of that, I want to say: Thank you! I really appreciate it when people back up their opinions with numbers and reviewed analysis.
1) Baseline:- Orion + crew on HLV.2) Uncrewed Orion on HLV+ crew taxi ("1.1"):- HLV launches slightly more due to not needing LAS, taxi delivers negligible BLEO payload. Net IMLEO change: < 5mT?3) HLV + Orion on EELV ("1.5"):- HLV launches slightly more due to not needing LAS, plus Orion is docked into BLEO stack. Net IMLEO change: +15-25mT?