5. Not so, we are already flying our astronauts on Soyuz, they aren't complaining about that. An engine is minor compared to that
snip1. No dice? You don't know enough to say that. Where is the requirement that it has to be fully redundant? Where is your data for that? Anyways, Atlas is only missing one box that doesn't have redundancy and the new version has gone through CDR. D-IV is no where near redundant.snip5. Not so, we are already flying our astronauts on Soyuz, they aren't complaining about that. An engine is minor compared to thatsnip
To be fair, we aren't flying our astronauts on Soyuz as the primary, much less sole, method of getting them to ISS. Though, as long as we ramp up domestic RD-180 at some point, I don't think it will shift the cards in favor of Delta IV.
Can you post a link to the latest NASA man rating requirement document stating single fault tolerant is no longer a requirement? The latest I can find states it is still a requirement. Here is a quote from the May 2008 version:3.2.2 The space system shall provide failure tolerance to catastrophic events (minimum of one failure tolerant), Is there a later version where a "minimum of one failure tolerant" is not required?
Quote from: strangequark on 04/26/2009 03:02 pmTo be fair, we aren't flying our astronauts on Soyuz as the primary, much less sole, method of getting them to ISS. Though, as long as we ramp up domestic RD-180 at some point, I don't think it will shift the cards in favor of Delta IV.We will during the gap. NASA just sent out a solicitation for Soyuz rides
Quote from: Danny Dot on 04/26/2009 03:07 pmCan you post a link to the latest NASA man rating requirement document stating single fault tolerant is no longer a requirement? The latest I can find states it is still a requirement. Here is a quote from the May 2008 version:3.2.2 The space system shall provide failure tolerance to catastrophic events (minimum of one failure tolerant), Is there a later version where a "minimum of one failure tolerant" is not required?Redundancy is method of meeting fault tolerance, it isn't a requirement in itself
Quote from: Jim on 04/26/2009 03:10 pmQuote from: Danny Dot on 04/26/2009 03:07 pmCan you post a link to the latest NASA man rating requirement document stating single fault tolerant is no longer a requirement? The latest I can find states it is still a requirement. Here is a quote from the May 2008 version:3.2.2 The space system shall provide failure tolerance to catastrophic events (minimum of one failure tolerant), Is there a later version where a "minimum of one failure tolerant" is not required?Redundancy is method of meeting fault tolerance, it isn't a requirement in itselfDo you agree this requirement for "minimum of one failure tolerant" is the current requirement?Danny Deger
We will during the gap. NASA just sent out a solicitation for Soyuz rides
Delta IV-H keeps getting mentioned because, well, it's actually flown. If it pulled the Ares I "SM as a third stage" trick, a current Delta IV-H could probably work for ISS/LEO. With planned (and IIRC, already funded) upgrades it could handily do Lunar Orion. So, it's understandably the most mentioned second choice.Simon
Quote from: Jim on 04/26/2009 03:07 pmQuote from: strangequark on 04/26/2009 03:02 pmTo be fair, we aren't flying our astronauts on Soyuz as the primary, much less sole, method of getting them to ISS. Though, as long as we ramp up domestic RD-180 at some point, I don't think it will shift the cards in favor of Delta IV.We will during the gap. NASA just sent out a solicitation for Soyuz ridesAnd they just dropped the minimum number of seats from 18 to 3. Something is afoot to not buy as many seats from Russia. Does KSC know something about the Delta we don't know?
The real question with Delta IV-H is how to transition from LEO to the point of the VSE, exploration. If Delta IV-H were to be chosen to fly Orion, then the eventual lunar vehicle(s) would most likely use RS-68Bs, but not necessarily SRBs...Simon
Quote from: Danny Dot on 04/26/2009 03:12 pmQuote from: Jim on 04/26/2009 03:07 pmQuote from: strangequark on 04/26/2009 03:02 pmTo be fair, we aren't flying our astronauts on Soyuz as the primary, much less sole, method of getting them to ISS. Though, as long as we ramp up domestic RD-180 at some point, I don't think it will shift the cards in favor of Delta IV.We will during the gap. NASA just sent out a solicitation for Soyuz ridesAnd they just dropped the minimum number of seats from 18 to 3. Something is afoot to not buy as many seats from Russia. Does KSC know something about the Delta we don't know?I doubt the change in the Soyuz solicitation had anything to do with Delta. The change notice specifically mentioned commercial providers (e.g. SpaceX).
err, wouldn't a ULA Delta based system qualify as commercial?
ULA doesn't have a spacecraft
Quote from: Jim on 04/26/2009 05:45 pmULA doesn't have a spacecraftThis will probably annoy Jim (it usually does when I start weaving 'what if...?' scenarios with ULA) but I have to ask.I know that Lockheed-Martin was co-operating with SpaceDev with on their DreamChaser space-plane. Does anyone know what is the current status of those interactions? I must say that I haven't seen any updates recently.Just look at what these arrangements potentially gives them:1) Atlas-V - Flexible ELV; I'm sure Boeing wouldn't begrudge them a Delta-IV if they asked either;2) DreamChaser - Essentially COTS-D-ready crew vehicle;I'm not saying that they are planning anything right now. However, if CxP crashes and burns, there is a nice big gap into which they (through the offices of ULA) could jump, if they have done their prepartory work correctly and can get moving quickly enough.Don't forget that Lockheed have the Centaur (single and twin-engine variants) that is a good EDS. They also did some work on various lander concepts. Don't forget that they have also been talking to Bigelow, giving them access, if required, to a long-duration, large-capacity crew vehicle. If MSFC completely drops the ball, they have the chance to 'save' the US manned space program.