"DIRECT" Goes Live

[DMeader]

kraisee - 10/5/2007  1:43 PM
As for separate Cargo and Crew, that is only partially the story.   Mixing cargo and crew was ideally suited to accomplishing the Apollo missions.   It was also absolutely essential to accomplishing the Apollo/Soyuz rendezvous.   Shuttle had to have that capability to install a suitable docking module at MIR.   Every Gemini mission flew with a module on the rear containing useful "payload" cargo which was not part of the spacecraft itself.

I was under the impression that equipment needed to complete the goals of a mission was not considered "cargo".  Therefore, consumables in the Gemini adapter section, the ASTP docking module, and the Apollo LM,  not cargo.  Beans, blankets, toilet paper and t-shirts to the ISS, cargo. Correct? If we are going to make the "no cargo with crew" argument, we have to keep the  definitions consistent.

[sandrot]

kraisee - 10/5/2007  1:43 PM

For CEV, if any hardware needs to be launched it is going to require lifting on a second launch vehicle becasue it can not be lifted with the CEV on the Ares-I.   For example for future Hubble Servicing Missions, a payload module will have to be launched on something like a Delta-IV or Atlas-V, costing at least $150m for that flight.   Then the crew will have to rendezvous & dock with that module, and then rendezvous & dock with the Hubble.   Is this easier, safer or more logical than bringing up your tools with you when you fly the first time - especially when your flight costs are only $10m different from Ares-I - but you saved $20 billion by not having to develop Ares-V as well?

Or (my fingers crossed) we can launch mission packages with Falcon 9 at a lower $$$ per flight.

[SolarPowered]

My understanding of the origin of the "no crew with cargo" concept is that it comes from three basic points:

1.  It's really, really dumb to risk the lives of seven astronauts to launch a satellite that could just as well be launched by an unmanned launcher,

2.  It's kind of stupid and wasteful to keep launching this huge "truck" (Shuttle) into space when all it's ever re-entering with is the crew, and

3.  There are basically three categories of things that you are sending into orbit:
     i.  Human beings
     ii.  Expensive cargo, like Hubble telescopes and ISS modules, and
     iii.  Cheap cargo, like food, water, and propellents.
With category (i), you go to extreme lengths to reduce risk of loss.  For categories (ii) and (iii), you can make cost vs. risk tradeoffs.

None of these points argues for never launching cargo along with a crew.  Indeed, it would appear to often be safer to launch the cargo that is needed to carry out a mission along with the crew, avoiding an unnecessary rendezvous.

On the other hand, these points do argue for designing a vehicle for crew launch that is as safe as you can possibly make it, while possibly having other launch vehicles for launching things like moon or Mars mission stacks that make tradeoffs for greater launch capability at the expense of higher risk.  There is no reason why said crew-launch vehicle can't be designed with the capacity to carry more than just the crew.

[kraisee]

wiinum - 10/5/2007  2:18 PM

I see what you are saying Ross.

Do you think that Ares 1 will work if it is build?

And can you explan to me why NASA should defend Ares 1 so much if it didn't work?

What is you personal guess of the chances of NASA changing to DIRECT ? Honestly?

I think that if you belive so strongly in DIRECT you should contact the right people and do it real QUICKLY - I mean senators, poiliticians and my be even the White House.

Kasper

I think Ares-I could be integrated into a lunar program ultimately, but I believe that far too much money will be spent on it for the performance it will offer, and it will only serve to tie the hands of every other aspect of the program.

Already, because the CEV has to be so small, it can't perform the Lunar Orbit Injection burn to stabilise the CEV/LSAM into a lunar orbit before the crew descends.   This job has had to be passed to the LSAM Descent stage instead - which means it has heavier fuel tanks which have to be taken all the way to the lunar surface.   This is an horrifically wasteful use of the lunar downmass performance - which is what this is all about ultimately.   This change alone has cost about 2 tons of useful performance to the lunar surface on every mission.   That's a LOT of waste and I'm darn sure a lot of people could come up with far better uses for 2 tons of extra performance.   But Ares-I eliminates all chances of ever doing it a different way - because it simply can't lift a heavier (read: "more capable" in this context) CEV.

There are other issues with Ares-I, but that's a critical one "they" don't want to admit to.

Ross.

[Wolverine]

kraisee - 10/5/2007  3:39 PM

wiinum - 10/5/2007  2:18 PM

I see what you are saying Ross.

Do you think that Ares 1 will work if it is build?

And can you explan to me why NASA should defend Ares 1 so much if it didn't work?

What is you personal guess of the chances of NASA changing to DIRECT ? Honestly?

I think that if you belive so strongly in DIRECT you should contact the right people and do it real QUICKLY - I mean senators, poiliticians and my be even the White House.

Kasper

I think Ares-I could be integrated into a lunar program ultimately, but I believe that far too much money will be spent on it for the performance it will offer, and it will only serve to tie the hands of every other aspect of the program.

Already, because the CEV has to be so small, it can't perform the Lunar Orbit Injection burn to stabilise the CEV/LSAM into a lunar orbit before the crew descends.   This job has had to be passed to the LSAM Descent stage instead - which means it has heavier fuel tanks which have to be taken all the way to the lunar surface.   This is an horrifically wasteful use of the lunar downmass performance - which is what this is all about ultimately.   This change alone has cost about 2 tons of useful performance to the lunar surface on every mission.   That's a LOT of waste and I'm darn sure a lot of people could come up with far better uses for 2 tons of extra performance.   But Ares-I eliminates all chances of ever doing it a different way - because it simply can't lift a heavier (read: "more capable" in this context) CEV.

There are other issues with Ares-I, but that's a critical one "they" don't want to admit to.

Ross.

Ross, you have a great and knowledgeable grasp of this.  Kudos!

[Jim]

kraisee - 10/5/2007  3:39 PM

Already, because the CEV has to be so small, it can't perform the Lunar Orbit Injection burn to stabilise the CEV/LSAM into a lunar orbit before the crew descends.   This job has had to be passed to the LSAM Descent stage instead - which means it has heavier fuel tanks which have to be taken all the way to the lunar surface.   This is an horrifically wasteful use of the lunar downmass performance - which is what this is all about ultimately.   This change alone has cost about 2 tons of useful performance to the lunar surface on every mission.   That's a LOT of waste and I'm darn sure a lot of people could come up with far better uses for 2 tons of extra performance.   But Ares-I eliminates all chances of ever doing it a different way - because it simply can't lift a heavier (read: "more capable" in this context) CEV.

There are other issues with Ares-I, but that's a critical one "they" don't want to admit to.

Ross.

Ross,

Don't use that arguement.  It will be shot down quickly.  The intend was to always have the LSAM perform the LOI burn.  This was to allow for sortie LSAM missions without the CEV.  The LSAM would have to do the same maneuver by itself anyway.  The CEV propellant tanks were never sized for this nor was the engine thrust level.  That is why the CEV engine is sized around 5-15k lb thrust because it was never intended to be as big as the Apollo SPS.  Look at the ESAS.  Big engine like that is not needed for ISS or MTV mission neither.   Use of an EELV would not have changed this.

[kraisee]

Actually that misses the point that a cargo-only LSAM does not require braking of the CEV mass into LLO on top of the LSAM mass.   The dV requirements are much lower.   Optimizing for crew use is more worthwhile because it's the most common configuration we're going to fly.   For cargo-only flights, you "suck up" the 800kg or so of lost payload performance which you suffer from in that configuration (you're not braking the CEV and all it's propellant, and you've started with a smaller cargo than the Ascent Stage mass by doing a one-launch, no crew, flight anyhow).

The analysis actually shows that the difference is massively in favour of making CEV perform the LOI whenever possible.

Ross.

[Chris Bergin]

Thread locked, as this concept moves into Direct v2: http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=7868&start=1