Space Architecture

Sunday, June 12, 2005

Mobile Lunar Base Concepts

Just read Mobile Lunar Base Concepts [pdf], by Marc M. Cohen. It goes over three types of Mobile Bases: a Rover concept by John Frassanito, a Habot concept by John Mankins, and the Mobitat concept [pdf] that I had covered earlier.

When you click on the "Mobile Lunar Base Concepts" link above, you might find to the left on the screen a menu with more .pdf links. When you click on them, you'll get an error message. Also, from now on, for any links that contain files that take more than 30 seconds to load (for those who don't have high speed connections), I will label the file type in brackets. I.e., [pdf].

The document does a fair job of explaining the three concepts. All of them have the purpose of mitigating the problem of sending astronauts out to collect rocks (or whatever), and having their rover break down sometime during the trip. If a break-down occurred, then another team in another rover would have to be sent out. One can see how the problem of unreliable rovers could ruin a mission.

However, the article does not describe what happens if one of these moving bases breaks down. Maybe another team would have to be sent (maybe in one of the aforementioned unreliable rovers?) to rescue the team. I saw "maybe", since the astronauts aboard the broken base have radiation shielding, to a certain extent. The people on the rover have very little. The shielding would provide more time to fix whatever problem is afflicting the base.

The best reason for having mobile lunar bases, which is given in the article, is to protect the bases from ejecta when something else lands. Also, presumably, to protect the bases when something else takes off. I'm thinking that there are only so many good places to land on the Moon, so one may want to dedicate those places to landing/launching activities. In this respect, the mobile base is great, because after landing, it could move away, and protect itself when another base is sent down. A chain, or sequence, of landing, moving, and joining up with other bases allows for a standardization of parts and predicting reliability over a larger sample size.

As for what system I think is best, I favor a combination of the Frassanito rover with the Mobitat. The Mobitat solves one of the biggest problems of the Habot, in that the Habot is a hexagonally-organized, with six moving legs. Cohen says that there is no method yet for a six-legged transportation system to move about while "keeping the vessel level and stable". The restriction of the Frassanito rover is its geometry. Cohen says that "the number of berthing ports
are proportional to the length of the central berthing and EVA module". That is, there is a central hub at which the rovers dock. However, there is no reason why these hubs cannot be design such that they themselves link up. Or, if a non-orthoganol system is needed, the hubs can link up with the Mobitats. Granted, one's angles are no longer on 90-degree intervals; with Mobitat, one gets 60-degree intervals, because of the hexagonal shape in the Mobitat.

Sunday, June 05, 2005

The Mobitat

I finished the rest of "Plug-in Hardware Concepts for Mobile Modular Surface Habitats". It's not all acronyms and definitions -- there are pictures of what the proposed Mobitat should be. In fact, the title of the piece is mis-leading: the piece is about the Mobitat concept. The Mobitat in and of itself is far more interesting.

Essentially, it's a rover with a hexagonal pressurized vessel in the center. The idea is that it can be deployed from a vessel in, say, lunar orbit, land on the surface, move about the surface, and set up shop. A greater number of Mobitats can be launched, descend, and then connect the pressurized vessels, to create a chain. Unfortunately, as the authors point out, the design of the Mobitat doesn't allow for egress loops. That is, creating a loop of pressurized vessels, versus a linear chain. Loops are desirable in the event of a failure in one of the vessels, so that the greater base isn't divided into two (or three...) inaccessible parts, save for EVA.

Oh, and I found out what MESR (the article explains, well after page three) means: Modular, Extensible, Scaleable, Reconfigurable. In other words, Four Words For Flexible. MESR, in the article, was linked to ECLSS, which stands for Environmental Control and Life Support Systems. All together, MESR-ECLSS stands for a flexible way of keeping people alive. While the article provided the definition of MESR, the Hamilton-Sunstrand Space Vehicles [link broken 12/23/2005] website provided the meaning of ECLSS.