Or, build nearer the launch site. An 8M module might be better than a 4 meter module for some applications, especially landers, since it shouldn't be as tall, as Zubrin pointed out. It's not the module itself, but the guts.
Or, build nearer the launch site. An 8M module might be better than a 4 meter module for some applications, especially landers, since it shouldn't be as tall, as Zubrin pointed out. It's not the module itself, but the guts.
14ft(about 4meters) was all that the Apollo lunar lander used to land on the moon. Anyway the size of an lander should be determined by function. Building near the launch site just adds costs that NASA alone would bear in full.
Consider the case of a spherical habitat. The surface area is given by 4πr². The volume is given by (4/3)πr³. The ratio of the volume compared to the surface area, a measure of the resulting mass efficiency, is therefore (4/3)πr³/4πr² or r/3. In other words, if you double the radius from 4m to 8m, the ratio of surface area(a mass analogue) to habitable volume goes down by a factor of 2. It doesn't really matter if the deep space habitat just sits there in a set orbit. On the other hand, if you want this to be a basis for an MTV that does the considerable TMI, Mars orbit insertion, TEI and earth capture maneuvers, the extra mass is going to increase the IMLEO of the architecture considerably.
Consider the case of a spherical habitat. The surface area is given by 4πr². The volume is given by (4/3)πr³. The ratio of the volume compared to the surface area, a measure of the resulting mass efficiency, is therefore (4/3)πr³/4πr² or r/3. In other words, if you double the radius from 4m to 8m, the ratio of surface area(a mass analogue) to habitable volume goes down by a factor of 2.
That doesn't work with pressurised vessels, where the mass of the pressure vessel is proportional to its volume, and not its surface area. See
https://en.wikipedia.org/wiki/Pressure_vessel
14ft(about 4meters) was all that the Apollo lunar lander used to land on the moon.
The Lunar Module diameter, not including the legs was 4.2 m. In its stowed configuration it was about 6.5 m diameter and 9.4 m diameter with the legs deployed.
https://www.hq.nasa.gov/alsj/LM04_Lunar_Module_ppLV1-17.pdf
My impression was that the cutoff for routine road & rail transport was ~14ft, about 4.25m, with practical fully encumbered numbers being more like 3.5-3.8m. Falcon 9 is spoken of as the thing they built as large as possible which still fits on the freeway system.
You're right. I was generalizing too much. The ISS modules like Destiny are 4.2m in diameter, and that is close to the largest you can transport by road or by air (I think the C-5C can carry Shuttle sized 4.6m diameter payloads).
So once you get above the size of existing ISS modules you have to rely on factories that have water access. And while there are probably a number of those that could do space hardware if needed (and some might already do space hardware), it eliminates the already existing ones not with water access that already do space hardware - it reduces choice/competition.
Aircraft like the Super Guppy or the 747 LCF and airbus Beluga can handle wider diameter cargo then the C-5C.
Another option modify a 747 to carry out sized cargo like the VM-T Atlant.
Might be a good reason to pull the Shuttle carriers out of retirement.
Or, build nearer the launch site. An 8M module might be better than a 4 meter module for some applications, especially landers, since it shouldn't be as tall, as Zubrin pointed out. It's not the module itself, but the guts.
ie. build at Michoud where the infrastructure exists including the giant welding tool. And the barge transportation already exists.
Or, build nearer the launch site. An 8M module might be better than a 4 meter module for some applications, especially landers, since it shouldn't be as tall, as Zubrin pointed out. It's not the module itself, but the guts.
ie. build at Michoud where the infrastructure exists including the giant welding tool. And the barge transportation already exists.
This is precisely why the MSFC group wanted to use SLS sized module - existing infrastructure already being used.
Or, build nearer the launch site. An 8M module might be better than a 4 meter module for some applications, especially landers, since it shouldn't be as tall, as Zubrin pointed out. It's not the module itself, but the guts.
ie. build at Michoud where the infrastructure exists including the giant welding tool. And the barge transportation already exists.
This is precisely why the MSFC group wanted to use SLS sized module - existing infrastructure already being used.
I agree. It makes a lot of sense for Skylab II DSH. Will be interesting to see a trade-off study.
Or, build nearer the launch site. An 8M module might be better than a 4 meter module for some applications, especially landers, since it shouldn't be as tall, as Zubrin pointed out. It's not the module itself, but the guts.
ie. build at Michoud where the infrastructure exists including the giant welding tool. And the barge transportation already exists.
This is precisely why the MSFC group wanted to use SLS sized module - existing infrastructure already being used.
Only part of the infrastructure - just the shell manufacturing. No infrastructure for everything that goes inside of it.
Plus, if the destination for this DSH is beyond Earth's radiation protection, then an aluminum shell is not going to be the preferred material since aluminum has bad secondary radiation effects.
The preferred material is plastics of some type.
If the design of the DSH were to be opened for bid, and the diameter specifications were left open (just the base requirements), then it's possible that one of the airliner manufactures could bid for building a composite shell at one of their facilities that could be moved using their existing transportation infrastructure. For instance, Boeing's 787 composite fuselage is 5.48m in diameter (18ft), and they already have a transportation system to move substantial lengths of that around the world by air using the Boeing 747-LCF.
I know there is an effort to find additional uses for the SLS tooling, but what you make rockets out of is not necessarily what you want to make spaceships out of. Completely different requirements.