The "Mars" part of the CEV mission confuses me....

• #20 by mong' on 30 Jul, 2006 10:58
• Quote

  lmike - 30/7/2006  5:30 AM
  
  My take is we can't possibly mount a Mars expedition until we can *massively* send humans into space.  "Space" as LEO or the Moon.  Otherwise it's dice roll.  What government organizations would stand for such a dice roll?  We'd need a Mars bent strong willed dictator.

  
  I disagree. every spaceflight has a great deal of risk, people have died doint it and people WILL die doing it, that's a given. the most detaield mars mission sudies (i.e:NASA DRM's) may sound a little tricky with a small hab, 2.5 years missions and ISRU, but you can build in a great deal of safety options. the most challenging system will probably be a life support system capable of running for years without a glitch, it's a challenge but merely an engineering challenge, I'm confident it will be overcome by the engineers of 2020.
  as for public opinion, I, for one believe the prospect of a mission to mars will generate more wonder than criticism, call me naive but I feel any danger of such a mission will only strengthen the public's respect for astronauts and the space program in general
• #21 by MATTBLAK on 30 Jul, 2006 11:31
• Thank you, Mong for your compliments.
  
  Actually the original and 'traditional' Mars Direct architecture is still my favourite. Perhaps a larger, combined Mission Module/Lander would probably be ideal: maybe the MM could be reduced to a simple food & water pantry/storm shelter, with the crew living in the Habitat Lander both outbound and on the Martian surface. Using the MM consumables would save the Hab/Landers supplies for Mars and less mass would be jettisoned before arrival at Mars.
  
  And your statements about risks and challenges of spaceflight are bang on.
• #22 by mong' on 30 Jul, 2006 11:56
• I agree about Mars Direct, it is also my favorite for its simplicity, but I am afraid such a mission will be very tight wrt to supplies and living space, if it worked with the numbers given (and that is a "if") there would not be much room left for scientific instruments and redundant systems. I think something along the lines of the DRM III, even if it means more launches (and thus more complexity) would have a higher scientific payoff, 6 people with the adequate scienntific payload could get the most out of the 1.5 year stay.
• #23 by MATTBLAK on 31 Jul, 2006 06:57
• Agreed. I've always thought the DRM-3 gives extra safety by having extra vehicles that also provide more living volume. Also, I think a crew of 5 would be the best number for a Mars mission. Why? Extra redundancy over 4 persons and about 16% percent less comsumables needed than for 6 persons.
• #24 by mong' on 03 Aug, 2006 21:56
• recent comment by Griffin:
  "Next year, I hope to make plans as to how to carry out manned missions to Mars, building on the heavy-lift launch vehicles, landers, and other capabilities from the lunar exploration architecture."
  
  Full transcript here: http://www.spaceref.com/news/viewsr.html?pid=21597
• #25 by lmike on 04 Aug, 2006 05:04
• Quote

  mong' - 30/7/2006  3:45 AM
  
  

  Quote

  lmike - 30/7/2006  5:30 AM
  
  My take is we can't possibly mount a Mars expedition until we can *massively* send humans into space.  "Space" as LEO or the Moon.  Otherwise it's dice roll.  What government organizations would stand for such a dice roll?  We'd need a Mars bent strong willed dictator.

  
  I disagree. every spaceflight has a great deal of risk, people have died doint it and people WILL die doing it, that's a given. the most detaield mars mission sudies (i.e:NASA DRM's) may sound a little tricky with a small hab, 2.5 years missions and ISRU, but you can build in a great deal of safety options. the most challenging system will probably be a life support system capable of running for years without a glitch, it's a challenge but merely an engineering challenge, I'm confident it will be overcome by the engineers of 2020.
  as for public opinion, I, for one believe the prospect of a mission to mars will generate more wonder than criticism, call me naive but I feel any danger of such a mission will only strengthen the public's respect for astronauts and the space program in general

  
  It's great wishful thinking (in the good sense), and I wish you were right, but as it currently stands every human lost even in LEO resounds as "NASA's kaput" on the ground.  And results in a 3 year delay in manned space operations.  So a single Mars expedition with no chance for the crew to survive (as ephemeral as it would be) would be a big no-no in the current environment.
  
• #26 by publiusr on 18 Aug, 2006 19:45
• Quote

  mong' - 3/8/2006  4:43 PM
  
  recent comment by Griffin:
  "Next year, I hope to make plans as to how to carry out manned missions to Mars, building on the heavy-lift launch vehicles, landers, and other capabilities from the lunar exploration architecture."
  
  Full transcript here: http://www.spaceref.com/news/viewsr.html?pid=21597

  
  I look forward to more. Mike Griffin is the best NASA Chief we've had in a generation.
• #27 by Jim on 18 Aug, 2006 19:48
• That is debatable.  Just because he advocates a big booster doesn't qualify him as the 'Best".  He may end up damaging the agency more by cutting the R&D
• #28 by publiusr on 18 Aug, 2006 20:39
• J-2 is R&D too. He is helping replace the damage done to propulsion under that fool Goldin.
• #29 by Zoomer30 on 18 Aug, 2006 22:31
• Persoanlly I would like the "faster" idea myself.  the shorter the trip to Mars the less time you spend outside the Earth mag field and the less chance you have of getting nailed by a CME.  Does not matter what kind of solar storm protection you have then, a good sized CME can ruin your whole weekend.  
  
  Its like that show they had on Discovery a few months back.  It was a BBC program about a "grand tour" of the solar system.  One of the crew developed cancer and died during the trip, presumbly due to cosmic rays.  Once issue discussed was the TREATMENT he had to undergo to try and save him.  The chemo drugs contaminated the water so the crew had to take medications to counter-act that.  Pretty good show, cant remember the name of it.
• #30 by Spacely on 19 Aug, 2006 00:42
• Quote

  publiusr - 18/8/2006  1:26 PM
  
  J-2 is R&D too. He is helping replace the damage done to propulsion under that fool Goldin.

  Isn't the RS-68 for CaLV use going to be an upgraded/uprated version of the current model? Yeah, it's not as flashy as some cleansheet heavy lift engine, but it's still going to be innovative and advanced as far as chemical engines go.
• #31 by publiusr on 22 Aug, 2006 22:43
• I would like to See Ares V with a wide-body core--but I'll take DSD to nothing.
• #32 by tom nackid on 24 Aug, 2006 21:38
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  PurduesUSAFguy - 29/7/2006  8:17 AM
  
  The CEV really wouldn't be any use on a manned mission to Mars other then providing Earth to LEO transport to get to the assembled Mars craft and for rentry. I can't imagine taking the CEV all the way to Mars and back as it would represent ~25tons of dead weight to push into TMI. It would just make more sense to launch the crew and then have the CEV return to earth unmanned and then launch another to pick the crew up upon their return.
  
  (Since all it is providing is Earth to LEO transportation it would make as much sense to use a COTS provider if and when they materialize)

  
  Have you calculated the mass of the fuel needed for a returning Mars ship to rendezvous with a ferry in LEO? I haven't, but I would bet that it is a lot more than the mass of a CEV capable of reentering Earth's atmosphere from a Mars return trajectory. Rendezvousing with ferries or space stations in LEO sounds great but in space it takes as much fuel to slow down as it did to accelerate in the first place.
• #33 by Avron on 25 Aug, 2006 05:02
• Quote

  tom nackid - 24/8/2006  5:25 PM
  
  

  Quote

  PurduesUSAFguy - 29/7/2006  8:17 AM
  
  The CEV really wouldn't be any use on a manned mission to Mars other then providing Earth to LEO transport to get to the assembled Mars craft and for rentry. I can't imagine taking the CEV all the way to Mars and back as it would represent ~25tons of dead weight to push into TMI. It would just make more sense to launch the crew and then have the CEV return to earth unmanned and then launch another to pick the crew up upon their return.
  
  (Since all it is providing is Earth to LEO transportation it would make as much sense to use a COTS provider if and when they materialize)

  
  Have you calculated the mass of the fuel needed for a returning Mars ship to rendezvous with a ferry in LEO? I haven't, but I would bet that it is a lot more than the mass of a CEV capable of reentering Earth's atmosphere from a Mars return trajectory. Rendezvousing with ferries or space stations in LEO sounds great but in space it takes as much fuel to slow down as it did to accelerate in the first place.

  
  
  Not quite true... there is always aerobraking and trust levels in or out of the soup (i.e. vacuum rating vs sea level)... and good old gravity.. but yes, a lot fuel is required for chemical engines.. these is always the Nuclear   option...
• #34 by punkboi on 25 Aug, 2006 05:20

• Quote

  Avron - 24/8/2006 9:49 PM

  Quote

  tom nackid - 24/8/2006 5:25 PM

  Quote

  PurduesUSAFguy - 29/7/2006 8:17 AM The CEV really wouldn't be any use on a manned mission to Mars other then providing Earth to LEO transport to get to the assembled Mars craft and for rentry. I can't imagine taking the CEV all the way to Mars and back as it would represent ~25tons of dead weight to push into TMI. It would just make more sense to launch the crew and then have the CEV return to earth unmanned and then launch another to pick the crew up upon their return. (Since all it is providing is Earth to LEO transportation it would make as much sense to use a COTS provider if and when they materialize)

  Have you calculated the mass of the fuel needed for a returning Mars ship to rendezvous with a ferry in LEO? I haven't, but I would bet that it is a lot more than the mass of a CEV capable of reentering Earth's atmosphere from a Mars return trajectory. Rendezvousing with ferries or space stations in LEO sounds great but in space it takes as much fuel to slow down as it did to accelerate in the first place.

  Not quite true... there is always aerobraking and trust levels in or out of the soup (i.e. vacuum rating vs sea level)... and good old gravity.. but yes, a lot fuel is required for chemical engines.. these is always the Nuclear option...

  And then the Global Network Against Weapons & Nuclear Power will come in to rain on the parade...

• #35 by kevin-rf on 25 Aug, 2006 13:09
• Quote

  tom nackid - 24/8/2006  4:25 PM
  
  Have you calculated the mass of the fuel needed for a returning Mars ship to rendezvous with a ferry in LEO? I haven't, but I would bet that it is a lot more than the mass of a CEV capable of reentering Earth's atmosphere from a Mars return trajectory. Rendezvousing with ferries or space stations in LEO sounds great but in space it takes as much fuel to slow down as it did to accelerate in the first place.
  
  

  
  Actually, it would take less fuel to deccelerate since you have to also accelerate your decceleration fuel. Anyway, it is still a fair amount of fuel that you don't need if you go straight for reentry or aero breaking.
  
  
• #36 by tom nackid on 25 Aug, 2006 13:30
• And for aerobraking you still need to bring along a heat shield anyway, why not just make it reentry capsule and save fuel and avoid the dangers of a rendezvous in LEO?
• #37 by Avron on 25 Aug, 2006 16:21
• Quote

  tom nackid - 25/8/2006  9:17 AM
  
  And for aerobraking you still need to bring along a heat shield anyway, why not just make it reentry capsule and save fuel and avoid the dangers of a rendezvous in LEO?

  
  EH.... reentry capsule without a heat shield is deadly....
• #38 by imfan on 25 Aug, 2006 17:53
• :-) he was talking about heatshield for the whole battlestar galactica needed for mars trip. not to mention structural limits that would probably prevent such a violent treating to big structure like that. heatshield for capsule is nothing compared to previous
• #39 by tom nackid on 25 Aug, 2006 18:46
• Yes. A sturdy little capsule capable of reentering the Earth's atmosphere from a Mars return trajectory would seem (to me anyway) as being a lot lighter, cheaper, and safer than trying to slow down the whole "Battlestar Galactica" to rendezvous with a ferry or station in LEO.
  
  Of course things like nuclear propulsion and reusable "cycler" spacecraft change everything. But I don't see these happening until AFTER we start our exploration of Mars. Lewis and Clark didn't wait for highways and railroads after all.