While your right that standardized cargo modules that can be linked together to form habitats, your size is much too small. The BEAM module is a mere 2.36 m in diameter and 1.7 tall when compressed for a volume of ~7.5 m^3. ISS cargo has a fairly low average density so your looking at many dozens of such modules needing to be unloaded from each ship and then linked together. As these modules are already too large to be moved by anything other then cranes their is every incentive to go bigger as the usefulness of the modules increases as well as the speed of unloading.I favor a module size comparable to a TEU shipping container which is 6.1 m x 2.44 m x 2.59 m totaling 38.5 m^3 roughly 5 times larger then BEAM when compressed and about twice as large as BEAM when expanded. If a module this size expanded with the same ratio as BEAM the resulting interior space would be 80 m^3 a very generous and spacious habitat indeed.Containers this size will necessitate a side door and a cargo bay of around 500 m^3 in which containers can be stacked and secured by bolting them to structural hard-points as in modern containerized cargo on ships, planes, trains etc etc. This is very similar to the Space Shuttle which had 300 m^3 internal cargo bay and similar hard-point mountings. Cargo would be loaded/unloaded by a gantry crane in the roof of the cargo bay and extends out to clear the edge of the vehicle. First a flat bed truck is unloaded, then modules are unloaded onto the truck which take them away.Remember we need to think about the entire SYSTEM in MCT including logistics of ground transportation on Mars, we can't just dump stuff right at the landing site, we need the habitat a safe distance of a few miles away.
Yes, the BFR will most likely be 15 m diameter. However, BFS may not be 15 m diameter because of mass limitations. A 15 m diameter upper stage/BFS is a lot of dry mass, which mean more engines and more fuel.
Quote from: kaoru on 04/14/2016 05:09 pmYes, the BFR will most likely be 15 m diameter. However, BFS may not be 15 m diameter because of mass limitations. A 15 m diameter upper stage/BFS is a lot of dry mass, which mean more engines and more fuel.Que? A shorter, wider stage is closer to a sphere, therefore more mass-efficient than a longer narrower stage.
We have some evidence/conjecture for the notion that BFR is going to be 15m diameter. MCT is going to require lots of space for vacuum bell nozzles to achieve high Isp with enough engines for redundancy, so it will probably be about the same 15m diameter. A side-loading cargo dispenser at 15m overall diameter might have six <=5m diameter cargo pods arrayed along the outer edge, of indefinite length, around a central structural core + crane system. We know that ISS modules have already been designed at 4.1 to 4.5m diameter for 10 to 20 tons of mass, and that MCT is targeting 100 tons 'useful cargo' to the Martian surface. This provides a cargo footprint that is usefully similar to the Shuttle's payloads.Lower these standard cargo pods to the ground, and you can have vehicles drive out of their ends, just like a new automobile might drive out of an ISO container coming off the shipyard stacks in Baltimore. ISO containers are built of the cheapest materials that will take the load of intermodal shipping, and weigh about 10% of their rated maximum load.
It may not be part of the existing design plan, but why couldn't MCT have some temporarily expandable section, a la Bigelow, which could be temporarily expanded during transit to Mars in order to provide necessary interior space during the months-long journey, and which could then be un-expanded or jettisoned before Mars arrival?
Quote from: sanman on 04/18/2016 05:15 amIt may not be part of the existing design plan, but why couldn't MCT have some temporarily expandable section, a la Bigelow, which could be temporarily expanded during transit to Mars in order to provide necessary interior space during the months-long journey, and which could then be un-expanded or jettisoned before Mars arrival?Another alternative to using that would be to just launch it separately and have MCT dock with it in LEO before heading out.Would it then be possible to just leave it in orbit around Mars then pick it up again on the way back? (fully reusable and all that...)
I thought MCT is supposed to fly to Mars directly, with no stops in between (like what Zubrin originally suggested)
The Moon MethaLOX ISRU thread got me thinking about the MCT as passenger service vehicle from Earth to Moon surface. For a short trip < 1week the volume needed per passenger is lot less than the volume per passenger needed for a Mars trip. If The MCT is designed for a crew volume area of 2000-3000 m^3 to support the transport of 100 passengers to Mars how many person could be sent on a short trip to just the Moon?My estimate was numbers of passengers as low as 250 and as high as 750.2000m^3/8m^3(per person) = 2503000m^3/4m^3(per person) = 750