We're not ignoring the other 20mT launchers, they're just not germaine to the discussion. Assuming VSE continues to be an all-US endeavor, it makes sense to rule out non-US launchers. In another thread (God knows which one), there was a discussion of world wide launch capacity that looked at what you could do with EELVs, Ariane V, H2, Proton, etc.
By the way, IIRC some parts of ISS were lugged up by Proton, and wasn't the Russian airlock lugged up by a Soyuz (the rocket, not the capsule)?
As far as ISS not being 5 parts propellant 1 part hardware, what difference does it really make? You still have to get the pieces and parts to one spot in LEO and make them work together, whether its berthing bits of ISS together and hooking up electricals or docking tankers to a fuel depot and pumping fuel/oxydizer. ISS is the only example we have of orbital assembly, unless you want to count Mir.
It'd be a lot easier to embrace the EELV architecture if the EELV flight rate were already high. Remember that's the same sales tool was used to promote STS. EELV proponents are certain it can be brought to a high flight rate, but then most people believe the thing we believe in will work the way we hope. What if it doesn't?
yinzer - 24/1/2008 2:50 PMISS can still be very instructive.Your typical Shuttle assembly flight requires turning around the orbiter, producing a more or less unique 20 ton chunk of aerospace hardware, training a crew in how to install that hardware via EVA, configure it, and troubleshoot it, and then carrying off a two-week mission. Your typical Progress flight involves building the 10th consecutive copy of a 4000kg spacecraft, filling it with a bunch of fuel, air, and food, carrying out the 100th consecutive launch of a medium-lift LV, an automated docking to a space station, then some valve reconfiguration. The interfaces, procedures, and hardware in the latter case are just much, much, simpler.Depending on your EELV lunar architecture, the majority of the flights should be at least as simple as a Progress, albeit with larger propellant tanks.
yinzer - 24/1/2008 7:02 PMI think your reading is off. NASA is required by law to use elements from the space shuttle program to the maximum extent possible consistent with a successful development program.Furthermore, the authorization does not get created out of thin air. It's the result of collaboration between NASA, the president, and congress. They frequently get amended and updated. After O'Keefe retired, Griffin came in with his existing architecture including the Stick and a SDHLV. Hence, this is what got authorized.
yinzer - 24/1/2008 5:02 PMI think your reading is off. NASA is required by law to use elements from the space shuttle program to the maximum extent possible consistent with a successful development program.
William Barton - 24/1/2008 1:31 PMAs for using a single EELV to put up ISS in a year, I certainly have not suggested that. As far as I know, the manufacturing infrastructure couldn't produce 25 Delta IVH's in a year. And how many have been flown since the beginning of the program? Two? Besides which, having a rocket that can lug 20mT to LEO doesn't build a space station. One of the handy things about Shuttle is, you don't need a space tug because it is a space tug.
William Barton - 24/1/2008 1:42 PMIt'd be a lot easier to embrace the EELV architecture if the EELV flight rate were already high. Remember that's the same sales tool was used to promote STS. EELV proponents are certain it can be brought to a high flight rate, but then most people believe the thing we believe in will work the way we hope. What if it doesn't?
tankmodeler - 24/1/2008 12:50 PMQuoteSMetch - 24/1/2008 2:02 PMPaul, no disrespect but I have been to the 9th floor and let me assure you that even when we are blessed with comparatively open mind leadership it’s the exact opposite of the “It’s a Small World” ride at Disneyland.Wow, you sound more cynical then I am & I teach grad level cynicism courses here at work! Seriously, no disrespect taken at all and I am more than willing to belive you are correct in this assessment. However, such an open letter as Ross has written really isn't for the NASA HQ staff anyway. It's for Congress and the press and should be posted to any press outlets you can think that might be interested. It is the press who really don't need an incentive to go looking for interpersonal dirt that may or may not exist to spice up a story. Get it out to Congress and let them see if they can get a response out of the NASA Administration that jives with the letter & the speach.That's where the hope lies. Not, really, with senior NASA HQ, whose ability to remove their rectally emplaced craniums I am seriously in doubt of. At least not without Congress' help.Paul
SMetch - 24/1/2008 2:02 PMPaul, no disrespect but I have been to the 9th floor and let me assure you that even when we are blessed with comparatively open mind leadership it’s the exact opposite of the “It’s a Small World” ride at Disneyland.
david-moon - 24/1/2008 12:17 PMRoss, that's an excellent open letter, very well written. I just have one suggestion, concerning this paragraph:While I have previously been a vocal and sometimes bitter critic of both Dr. Griffin and .... While there has been vitriol aplenty, I actually find I support NASA's Administrator far more than I oppose him.The natural reaction of anyone inside NASA to this would be "who are you and why should I care whether you support or oppose my plans." That reaction might even stop some from reading the rest of the letter, which would be unfortunate.I suggest that you edit down the discussion of your personal history and just focus on your point about two separate launch vehicles versus one launch vehicle with two configurations. I would limit the personal stuff to at most an apology for any intemperate comments you may have made in the past. Actually as far as I can remember, the intemperate vitriol on these forums came from other fans of DIRECT, not from you.
William Barton - 24/1/2008 11:42 AMAs far as ISS not being 5 parts propellant 1 part hardware, what difference does it really make? You still have to get the pieces and parts to one spot in LEO and make them work together, whether its berthing bits of ISS together and hooking up electricals or docking tankers to a fuel depot and pumping fuel/oxydizer. ISS is the only example we have of orbital assembly, unless you want to count Mir.
kraisee - 24/1/2008 9:03 PMJon, I disagree.From where I sit, Congress has made it profoundly clear that it intends to protect the existing workforce as its first and overriding priority.
khallow - 24/1/2008 9:49 PMQuoteWilliam Barton - 24/1/2008 1:31 PMAs for using a single EELV to put up ISS in a year, I certainly have not suggested that. As far as I know, the manufacturing infrastructure couldn't produce 25 Delta IVH's in a year. And how many have been flown since the beginning of the program? Two? Besides which, having a rocket that can lug 20mT to LEO doesn't build a space station. One of the handy things about Shuttle is, you don't need a space tug because it is a space tug.I'm sorry. I thought when you said infrastructure to support 25 launches per year, you meant it. Manufacture is part of the launch support infrastructure. But at a glance, one can always expand infrastructure if the money is there. At 25 launches a year, it would be.QuoteWilliam Barton - 24/1/2008 1:42 PMIt'd be a lot easier to embrace the EELV architecture if the EELV flight rate were already high. Remember that's the same sales tool was used to promote STS. EELV proponents are certain it can be brought to a high flight rate, but then most people believe the thing we believe in will work the way we hope. What if it doesn't?There's a difference. EELV launches now and doesn't require a high flight rate to be economical to NASA.
savuporo - 25/1/2008 12:38 AMQuoteWilliam Barton - 24/1/2008 11:42 AMAs far as ISS not being 5 parts propellant 1 part hardware, what difference does it really make? You still have to get the pieces and parts to one spot in LEO and make them work together, whether its berthing bits of ISS together and hooking up electricals or docking tankers to a fuel depot and pumping fuel/oxydizer. ISS is the only example we have of orbital assembly, unless you want to count Mir.The difference it really makes is first, you are NOT limited to 20-ton launchers for propellant. If a 10-ton or 5-ton works out cheaper or is politically more convenient over a range of launches, then by all means use it. Just a possibility, but a basic Dragon 9 is likely to be pretty cheap per pound delivered.. And ISS and Mir are not the only examples of orbital assembly. There was a certain alternative to Apollo program that sucessfully docked manned capsules and propulsion stages together, and had laid the entire path to lunar surface out using ~10 mT or smaller launchers at some point in history. Just because Apollo approach won out thanks to congressional wallets being wide open, does not mean that the alternative would not have worked.