Quote from: Nathan on 01/02/2010 11:01 pmAnd no - we don't need 200mt rockets to do Mars. Just need a smart lightweight plan. Send 2 people at a time!2 persons is not viable to operate a complex mission for that length of time, at this point in our 'infancy'. Zubrin made a good case for 4, but NASA had insisted on 6, which is why the Orion was being designed for 6 to Mars.
And no - we don't need 200mt rockets to do Mars. Just need a smart lightweight plan. Send 2 people at a time!
Quote from: robertross on 01/02/2010 11:51 pmQuote from: Nathan on 01/02/2010 11:01 pmAnd no - we don't need 200mt rockets to do Mars. Just need a smart lightweight plan. Send 2 people at a time!2 persons is not viable to operate a complex mission for that length of time, at this point in our 'infancy'. Zubrin made a good case for 4, but NASA had insisted on 6, which is why the Orion was being designed for 6 to Mars.For Mars Missions, I'd hedge my bets and say 5 people: 5 crew uses about 16-to-18% percent less consumables than 6 and gives you, er, 25% percent more personnel redundancy in the case of a crewmember getting ill or dying -- the mission could still be fulfilled quite well with four folks. Because with a crew of four; if you lost one person the workload would be pretty high. Also, I've read that many psychologists reckon having uneven crew numbers means that during conflicts and arguments, its much harder for warring crewmembers to takes sides on very long, stressful missions.
It main problem is that its reliance on a sidemounted vehicle, this limits is expansion options and causes needless risk with the escape tower.
I feel that if the SD HLLV is designed to carry both crew and cargo, it will loose efficiency (kg to LEO). That's why I insist on separating crew and cargo. And separation gives more mission flexibility, as you can launch several cargo carriers and only one crewed capsule for a mission.
However, since the SD-HLV will be able of transporting 70 to 100 tonnes to LEO and up to 48 tonnes to lunar orbit, it would be a considerable waste only to use it only to launch a 22 tonne Orion into orbit.
While I'm strongly in favor of developing the Altair as a cargo vehicle for transporting unmanned payloads (lunar base modules, solar power plants, etc.), I think it might make for sense to develop a small 25 tonne single stage lunar shuttle to transport humans to the lunar surface and back into lunar orbit instead of developing an ascent stage for the Altair. Even though such a vehicle would weigh more than the 16 tonne lunar module of the Apollo era, there should still be enough room in a longer payload carrier for it to fit below the Orion. Therefore, just a single launch could take astronauts too the Moon and back-- reducing the cost of manned flights to the moon.
It actually doesn't when you do the analysis and examine all of the trades.The real key is not to compromise the design of the crew spacecraft in order to accommodate payload mass.As long as the spacecraft is not compromised in any way -- and especially the abort capabilities -- there is no danger from carrying secondary payloads.Where the line ought to be drawn is when contemplating launching unmanned satellites with a crew which really doesn't require any human participation.That is where the planning for Shuttle went wrong back in the 1970's -- they wanted it to do everything -- including launching with large stages filled with dangerously explosive fuels inside the crew re-entry vehicle!In hindsight, that was a pretty bad compromise to have included in the design In the case of Lunar and NEO missions, having the capability to launch the crew and their Lander/Hab Module together can actually increase overall safety as the crew immediately gains access to a safe haven upon reaching orbit. Ask the crew of Apollo 13 if having a Safe Haven was useful or not...1) Do not compromise the Crew Spacecraft design.2) Never compromise the Crew Abort capabilities.3) Only launch Secondary Payloads with a Crew if the Crew needs that Payload.Ross.
"My guess is you would need at least 3x SD-HLV launches to perform the mission you've described, or maybe 2x Ares V Heavy (300mT+ to LEO)."Or a '2.5 launch' scenario: 2x 70+ton HLVs +plus Orion on a Delta IV-Heavy. *FIRST: send Altair directly to lunar orbit or L-1.
Therefore, just a single launch could take astronauts too the Moon and back-- reducing the cost of manned flights to the moon.
Quote from: kraisee on 01/03/2010 06:07 amIt actually doesn't when you do the analysis and examine all of the trades.The real key is not to compromise the design of the crew spacecraft in order to accommodate payload mass.As long as the spacecraft is not compromised in any way -- and especially the abort capabilities -- there is no danger from carrying secondary payloads.Where the line ought to be drawn is when contemplating launching unmanned satellites with a crew which really doesn't require any human participation.That is where the planning for Shuttle went wrong back in the 1970's -- they wanted it to do everything -- including launching with large stages filled with dangerously explosive fuels inside the crew re-entry vehicle!In hindsight, that was a pretty bad compromise to have included in the design In the case of Lunar and NEO missions, having the capability to launch the crew and their Lander/Hab Module together can actually increase overall safety as the crew immediately gains access to a safe haven upon reaching orbit. Ask the crew of Apollo 13 if having a Safe Haven was useful or not...1) Do not compromise the Crew Spacecraft design.2) Never compromise the Crew Abort capabilities.3) Only launch Secondary Payloads with a Crew if the Crew needs that Payload.Ross.Absolutely spot on.
As for the lunar mission I am in with the MATTBLAK post above except I would use the ULA ACES derived Altair lander and ACES EDS on the side mount.side mount might allow for something larger then a ACES-71?Yep Orion on Delta but per the Augustine commission any cargo vehicle should be human rated as a back up to the EELV or for any future follow on heavy lifter.
Quote from: hydra9 on 01/03/2010 07:19 amHowever, since the SD-HLV will be able of transporting 70 to 100 tonnes to LEO and up to 48 tonnes to lunar orbit, it would be a considerable waste only to use it only to launch a 22 tonne Orion into orbit.I don't think the Heavy variant of Ares V can deliver 48mT to LLO, so there's no chance that SD-HLV could do this.I don't remember the exact figures for side-mount, but with 100mT (inc EDS?) to LEO, you'll push about 48mT through TLI including the EDS. Something under 40mT excluding the EDS.And don't forget that that 40mT then needs to include a stage which will brake itself & Orion through LOI. Presuming that you retain the EDS for this, that gives you something in the mid-20's mT payload, which is just going to be an Orion and not much else. Add in some manoeuvring to rendezvous with a lander and you'll be carrying the bare Orion and nothing else at all.To further this discussion, a pdf copy of NASA figures on the net payload capability of the Sidemount can be found at: http://www.orlandosentinel.com/news/space/orl-alternative-rocket-pdf,0,7079469.htmlpageBut I should note that the Apollo program was able to place over 46 tonnes into lunar orbit (command and service modules plus the lunar module) with a single launch. NASA argues the the SD-HLV with an EDS would have a gross TLI capability of 53 tonnes with a net payload capability of 47.8 tonnes. Marcel F. Williams
Does anyone really think that NASA is serious about about 200mt launcher? I don't.