Is there an EDS backup option up DIRECT's sleeve? So that if/when NASA shoot down the numbers, you can fall back to something more robust. Even if that means accepting a performance hit.In fact, IMHO, since the lunar mission requirements were essentially arbitary, there ought be nothing wrong with proposing a scaled down lunar mission if the cost is reduced appropriately. The whole point of DIRECT is about having a 'sweet spot' where we are tied into a certain performance level by the infrastructure and hardware that already exists. If that sweet spot can only support 3 men on the surface rather than four, but costs less than 75% as much, then what's the problem?
Actually, this is an interesting discussion. How far, and in what depth, should DIRECT plan?I can see an argument in favour of keeping things simple: a single, simple message "Build a single vehicle which can reuse existing facilities, to save lots of money, and use some of that money to fly it often enough to offset any performance losses."However I can also see the argument in favour of a more expansive approach- e.g. trying to get the space science crowd onboard with the promise of cheap heavy lift.
Is there an EDS backup option up DIRECT's sleeve? So that if/when NASA shoot down the numbers, you can fall back to something more robust. Even if that means accepting a performance hit.In fact, IMHO, since the lunar mission requirements were essentially arbitary, there ought be nothing wrong with proposing a scaled down lunar mission if the cost is reduced appropriately.
Keep in mind that the maximum number of Jupiter launches per year is limited, (16 to 22, IIRC?), without incurring huge additional infrastructure costs. Better to use them for the big payloads that can't be easily sub-divided. Propellant can be.Also, drastically increasing the flight rate of smaller launchers, and encouraging the development of new, cheaper launchers, can only reduce the cost to orbit for everyone else.
Quote from: Kaputnik on 12/25/2008 01:00 pmIs there an EDS backup option up DIRECT's sleeve? So that if/when NASA shoot down the numbers, you can fall back to something more robust. Even if that means accepting a performance hit.In fact, IMHO, since the lunar mission requirements were essentially arbitary, there ought be nothing wrong with proposing a scaled down lunar mission if the cost is reduced appropriately. But part of the attraction of DIRECT is that it can launch the currently planned hardware items like Orion and Altair, where as the Ares 1 can't. Getting rid of Ares 1 and Ares V will be difficult for NASA, even if it's a no-brainer to everyone else. Getting rid of Orion will be an even harder sell.
No one wants to get rid of Orion. In fact, one of the biggest criticisms of Ares-I is that its limited lift capacity has been adversely affecting development of Orion. Switching launchers from Ares-I to Jupiter-120 will allow the Orion team to restore a lot of functionality that was dropped due to problems with Ares-I. Little things like landing on land instead of in the ocean.
Is it just me.. or does this SSME based Ares V with smaller tank and 5-seg sound more and more like some early "heavy" variants of DIRECT?For all those DIRECT "nay-sayers"(Griffin's groupies?) on this board.. How many real design issues with Ares/Orion(many that have forced NASA to change design direction.. for example: Base Heating).. were brought up on this board as issues(by the DIRECT team).. and solutions already incorporated into DIRECT.. well before the issues were fully addressed by NASA?
Quote from: TrueBlueWitt on 12/27/2008 04:30 pmIs it just me.. or does this SSME based Ares V with smaller tank and 5-seg sound more and more like some early "heavy" variants of DIRECT?For all those DIRECT "nay-sayers"(Griffin's groupies?) on this board.. How many real design issues with Ares/Orion(many that have forced NASA to change design direction.. for example: Base Heating).. were brought up on this board as issues(by the DIRECT team).. and solutions already incorporated into DIRECT.. well before the issues were fully addressed by NASA?It is taking on a more Direct-esq feel. However, hold your horses, it's a trade study at the moment, not a new baseline!
Quote from: Mark S on 12/27/2008 01:28 pmNo one wants to get rid of Orion. In fact, one of the biggest criticisms of Ares-I is that its limited lift capacity has been adversely affecting development of Orion. Switching launchers from Ares-I to Jupiter-120 will allow the Orion team to restore a lot of functionality that was dropped due to problems with Ares-I. Little things like landing on land instead of in the ocean. Given that Orion is pretty much the way to go, one would think that this argument alone would be the one that would tip the scales, so that means that there is some other reason, one the general public is unaware of, one that has been held closely, and one that if it got out, would cause serious problems, there has to be some other reason why limiting Orion is being permitted, and why there is such a push to "stay the course."Haven't we learned anything over the last 8 years? 20 years? 30 years? 50 years?
Have the dangers of an ocean spash-down been added to the Ares-I LOC numbers? All kinds of things can go wrong with an ocean splash-down, such as the capsule capsizing or sinking, or the flotation devices could malfunction. Surely that would have an adverse affect on the safety ratings of the mission. I can't imagine that there could be 2000 splash-downs without a serious event taking place at least once.Mark S.
Quote from: Mark S on 12/27/2008 05:17 pmHave the dangers of an ocean spash-down been added to the Ares-I LOC numbers? All kinds of things can go wrong with an ocean splash-down, such as the capsule capsizing or sinking, or the flotation devices could malfunction. Surely that would have an adverse affect on the safety ratings of the mission. I can't imagine that there could be 2000 splash-downs without a serious event taking place at least once.Mark S.To the best of my knowledge, Ares-I LOM/LOC numbers do NOT include any spacecraft recovery events or milestones. IIRC, they are limited to the spacecraft launch. Someone please correct me if that is not right.
Didn't one of the Mercury capsules actually sink, and nearly take the astronaut down with it?
Quote from: clongton on 12/27/2008 05:41 pmQuote from: Mark S on 12/27/2008 05:17 pmHave the dangers of an ocean spash-down been added to the Ares-I LOC numbers? All kinds of things can go wrong with an ocean splash-down, such as the capsule capsizing or sinking, or the flotation devices could malfunction. Surely that would have an adverse affect on the safety ratings of the mission. I can't imagine that there could be 2000 splash-downs without a serious event taking place at least once.Mark S.To the best of my knowledge, Ares-I LOM/LOC numbers do NOT include any spacecraft recovery events or milestones. IIRC, they are limited to the spacecraft launch. Someone please correct me if that is not right.So, the Columbia accident should not count towards Shuttle LOC numbers, in that case. Sure, the trigger event was during the launch, but they actually survived the launch, completed their science mission, and had left orbit. Clearly, that line of logic does not hold up.I would say that LOC/LOM numbers have to account for and include any possible loss while riding in, on, or around any NASA vehicle. Once they are safely on board the Nimitz (or whatever), then NASA can be absolved of responsibility.Didn't one of the Mercury capsules actually sink, and nearly take the astronaut down with it?Mark S.
Quote from: Mark S on 12/27/2008 06:01 pmDidn't one of the Mercury capsules actually sink, and nearly take the astronaut down with it?Yep, the second manned Mercury/Redstone. I don't think it was ever established whether the LOV was caused by a crew error (Grissom hitting the 'hatch eject' lever too early) or by an equipment malfunction. As the Liberty Bell 7 is at the bottom of a fairly deep ocean, I can't see it ever being resolved.
Quote from: Mark S on 12/27/2008 06:01 pmDidn't one of the Mercury capsules actually sink, and nearly take the astronaut down with it?Yep, the second manned Mercury/Redstone. I don't think it was ever established whether the LOV was caused by a crew error (Grissom hitting the 'hatch eject' lever too early) or by an equipment malfuction. As the Liberty Bell 7 is at the bottom of a fairly deep ocean, I can't see it ever being resolved.
Quote from: clongton on 12/27/2008 05:41 pmQuote from: Mark S on 12/27/2008 05:17 pmHave the dangers of an ocean spash-down been added to the Ares-I LOC numbers? All kinds of things can go wrong with an ocean splash-down, such as the capsule capsizing or sinking, or the flotation devices could malfunction. Surely that would have an adverse affect on the safety ratings of the mission. I can't imagine that there could be 2000 splash-downs without a serious event taking place at least once.Mark S.To the best of my knowledge, Ares-I LOM/LOC numbers do NOT include any spacecraft recovery events or milestones. IIRC, they are limited to the spacecraft launch. Someone please correct me if that is not right.So, the Columbia accident should not count towards Shuttle LOC numbers, in that case.
Sure, the trigger event was during the launch, but they actually survived the launch, completed their science mission, and had left orbit. Clearly, that line of logic does not hold up.
The only controversy is which subsystem: ET or orbiter. The ET routinely violated debris requirements; the orbiter TPS was designed for the required debris environment rather than that actual debris environment.