Studio di Fattibilità del nuovo Lanciatore Luna-Terra ''David''
Andrea Migli - Politecnico di Milano - [2001-02]
Last year, in the summer of 2001, I took part to a parabolic flight experiment session, organized by the European Space Agency: an initiative under the name of SPFC, Student Parabolic Flight Campaign, which promoted 30 teams across Europe capable of conceiving and then to build an interesting experiment to be run in microgravity. When we first heard about the possibility of taking part to this astounding experience, my room mate, Nicola Baggio, and I asked ourselves the question: what could be really useful in space? We knew about the experiments carried through in the previous parabolic flight campaigns, and they were all interesting: not only about space technology, but also particle physics, botany, zoology. Someone even presented a special table to comfortably eat pizza without gravity! But, we said, let’s take a step further: today any space infrastructure (like the newborn ISS) depends strongly from our planet, the Earth; somewhen, in the future, this dependence will more and more loosen, with gaining growth of the space affair. A part of this step will be the production in situ of an always bigger percentage of hardware for maintenance, repairing, and for new construction. Right on this topic was eventually focused the experiment that Nicola and I proposed, an electrolytic process which produced oxygen from a solution of copper sulphate in zero-g conditions. Material processing in space starts from raw material of various kind (be it solid, liquid or even gaseous) to end with the finite element. Of course, until the time that the unique source of prime materials will be our planet Earth, there is absolutely no need of investing time and money in such a new and risky business as manufacturing in space: it is much more convenient, from here, to bring exactly what we need there, and no more: because every trip Earth to orbit is very expensive. A large part of space technology is nowadays absorbed by continuous studies on always more competitive launchers, aimed to be built exactly for the mass they are going to carry into orbit; at this regard, see the new launcher Vega, thought for the new trend of microtechnology applied on always smaller satellites; or the newest versions of the Ariane 5 rocket, conceived for carrying more satellites at the time, in a single launch. Unfortunately the intrinsic problem related to this kind of launcher remains, and that is the huge inefficiency due to the fuel to payload ratio: today the cost for sending one kilogram into Low Earth Orbit presents the prohibitive bill of 10000 US$ [Motordyne]. It appears now clear to everybody that technology in this field 3 has basically reached an optimum plateau; and this problem has no real or easy solution, and one is not expected any time soon. In the next chapters I’ll explain how the idea of David was born. However I anticipate that the main objective of this paper is to develop an idea for a new way of obtaining material for on-orbit use; we will see that we’ll suppose that this material will come from our natural satellite, the Moon; and we will try to conceive an idea for a new launcher’s conception, more competitive than the ones so far proposed. In particular detail we will study the problem of the space mechanics related to this launcher: first of all we will investigate the effective possibility of using this launcher, finding adequate launch windows and lunar sites where it could be placed. If this first try will be successfull, we will analyse David’s sensibility to the launch’s initial conditions concerning different launching targets. Moreover, we will shortly study the launcher’s mechanical behaviour in one of its most simple-to-study configuration, which is however also the dimensioning one.
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