I'm going to make a specific appeal to all of our supporters:Can we all please try to refrain from any "confrontation" with CxP from here onwards. It isn't helping things.
Quote from: adamsmith on 06/05/2009 02:53 pm With propellant depots a lunar architecture is cheaper. ( please review appropriate section in Direct v2.0 presentation.Not being antagonistic, but much like I have asked the DIRECT guys, prove this statement.
With propellant depots a lunar architecture is cheaper. ( please review appropriate section in Direct v2.0 presentation.
Keys to any organization are a clear vision, effective direction and delegation.
Quote from: mars.is.wet on 06/05/2009 02:59 pmQuote from: adamsmith on 06/05/2009 02:53 pm With propellant depots a lunar architecture is cheaper. ( please review appropriate section in Direct v2.0 presentation.Not being antagonistic, but much like I have asked the DIRECT guys, prove this statement.Its not. Well, not exactly...What the Depot allows you to do is increase the number of missions each year. By amortizing costs over a larger number of elements each year that helps reduce the cost *OF EACH MISSION*.A secondary effect is that the cost of all the systems reduces, so other uses for them become more affordable. For example, if a dozen Atlas-V's were added to the annual launch manifest, the cost to DoD, NOAA, NASA and commercial customers would drop -- which would likely increase business a bit in all those different areas. So the cost savings would ultimately also feed back into places like SMD and that would help to perpetuate more science missions as one of the side-effects.Ultimately, you will still spend the same amount of total money.But *overall* you will get greater returns for it -- and not just in NASA's back yard, but also across many areas of the whole industry.Ross.
Quote from: adamsmith on 06/05/2009 03:16 pmNow, what about my point concerning no Mars without PD.NASA HSF budget would need to increase 4-5x to enable Mars mission (NR is $100-$400B, RE is at least $7B) so the point is effectively moot.
Now, what about my point concerning no Mars without PD.
NASA HSF budget would need to increase 4-5x to enable Mars mission (NR is $100-$400B, RE is at least $7B) so the point is effectively moot.
If I were going to recommend a name convention change, which I'm not really inclined to, I would probably suggest using the simplest descriptions of just the "Jupiter" vehicle and the "Jupiter with Upper Stage".
Quote from: mars.is.wet on 06/05/2009 02:14 pmConcepts are judged by their weakest link. Propellant depots are a non-starter IMO, and simply weaken the DIRECT presentation and distract from the main message.I agree with this. Don't even mention depots as having anything to do with Direct at this time. Direct 3.0 gets us to the moon without them. Depots are very high risk and need lots of development at this time. I think the idea should be brought forward to the Commission, but not tied to Direct.Danny Deger
Concepts are judged by their weakest link. Propellant depots are a non-starter IMO, and simply weaken the DIRECT presentation and distract from the main message.
snipMaybe this would make a good subject for a separate presentation, depots & the whole of DIRECT phase 2. Gives you another bite at the cherry.snipcheers, Martin
3) Without Propellant depots, it is impossible to go to mars.
Except it isn't as obvious an upgrade path for Ares, because you'd have to upgrade Altair to get much extra performance out of a depot with a one-launch Ares V mission - Ares V already lofts 90% of the payload, and they don't seem to want to launch crew on the thing anyway.With Jupiter, a PD turns two J-246 launches into one. All the pieces are there on the crew launch; all you have to do is refill the upper stage, and presto - instant EDS...If you do want to upgrade Altair later, then the difference between the two launch architectures WRT PD blurs a bit...
Quote from: 93143 on 06/05/2009 05:48 pmExcept it isn't as obvious an upgrade path for Ares, because you'd have to upgrade Altair to get much extra performance out of a depot with a one-launch Ares V mission - Ares V already lofts 90% of the payload, and they don't seem to want to launch crew on the thing anyway.With Jupiter, a PD turns two J-246 launches into one. All the pieces are there on the crew launch; all you have to do is refill the upper stage, and presto - instant EDS...If you do want to upgrade Altair later, then the difference between the two launch architectures WRT PD blurs a bit...Interesting point I hadn't thought much about on PD's.How do PD's really help Ares? The idea of Ares is to have a small, man-rated launcher for just the crew, and then a large, non-man rated stack for everything else. Ares 1 can only carry the crew, and Ares V wouldn't be able to launch the crew unless they later decided to man-rate it, and basically make a Saturn VI out of it. But the vast majority of an Ares Moonshot is the Ares V iteself, and you are still launching it, so yea, I don't think a PD helps the Ares architecture much at all. You are still expending 80% of your launch hardware.With Direct you're cutting your launch hardware down by half. So it becomes a very appearling upgrade path for Direct, but not much of a benefit for Ares.Hmmm.... interesting.