THE ARTEMIS PROJECT
PRIVATE ENTERPRISE ON THE MOON
Aerobraking to Earth Surface
Section 4.1.1.7.2.
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Possible Aerobraking Method

Aerobraking for the first mission has been considered, but it was decided that using a direct rocket braking for LEO rendezvous would be safer, cheaper, and less massive than the fuel needed.

The point does warrant a detailed study, however. There are new technologies which could be applicable to Artemis, if they ended up being less massive then the rocket fuel needed for braking. It is unlikely, but possible, especially if a less massive method is devised.

For example, there was a paper presented in the fall of 1995 about a replacement for parachutes. Here is a side view cutaway. The upper portion is an inflated torus. The "V" shape is a conical webbing (stiffened with inflated struts). The lower rectangle is an inflated cylinder, used like an automobile air-bag to cushion the landing, and the interior rectangle is the cargo. It closely resembles a large shuttlecock.

         ___ _________________________________ ___
        /   \                                 /   \
       (     )      inflated torus           (     )
        \___/_________________________________\___/
           \                                   /
            \                                 /
              \                             /
               \                           /
                 \                       /  <--  conical web and
                  \       _______       /     inflated struts
                    \    |       |    /
                     \   | Cargo |   /
                       \ |       | /
                        \|_______|/
                         |       |
                         |airbag |
                         |       |
                         |_______|

The idea is that the bigger the area of the webbing, the lower the terminal velocity. The presentation included a video of this thing being dropped (successfully) out of airplanes. The interesting part of this was that one of the applications they proposed was to use it as a re-entry vehicle. In crude terms, the energy you have to lose to re-enter is proportional to the mass of the vehicle, and the surface temperature of the windward side of the vehicle is inversely proportional to the surface area. So, just like a parachute, area density (m/A) is important, and they claimed they could make a re-entry structure for a minute fraction of the mass of a traditional reentry heat shield.

If anyone would like to conduct a study as to the feasibility of using an aerobrake such as this for the Reference Mission, contact <Boise Pearson>.

In any event, aerobraking is a frequently suggested "Better Idea", and umpteen man-hours have been spent comparing the virtues of rocket braking and aerobraking. Having a detailed study which confirms the results of the preliminary study would eliminate the need for discussion every time the idea is suggested.

Aerobraking to Earth Surface

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