The LunarSat Project
by Luisa Spairani
LunarSat, a European project, targeted to research the possibility of making a permanent human habitat on the Moon, offers new perspectives for human exploration. The aim of the project is to verify and study the Lunar South Pole ice resources as well as radar investigations to investigate the pristine lunar environment with respect to its plasma and exosphere. If the project can achieve this, we may be one step closer to moon colonization.
LunarSat is a proposal for the first European lunar micro-orbiter mission by 2001. LunarSat is designed by young engineers, scientists, and students from around Europe, with support from numerous institutions and space industry. It shall be launched as an auxiliary payload on an Ariane 5 ASAP platform and will have a mass of 100 kg in GTO.LunarSat will orbit the Moon on a highly elliptical polar orbit with its perigee above the lunar south pole area. This orbital strategy yields the possibility to obtain images of the lunar south pole region with a resolution never achieved before. The lead institution for this ambitious project is the ESA-ESTEC Office for Educational Project Outreach Activities.
Some of the technical objectives are:
In order to reduce the propellant mass, an innovative alternative is under investigation. A bi-elliptic shaped trajectory is chosen which crosses through the Earth-Sun Weak Stability Boundary (WSB). In this region, the gravitational attraction of the Earth and the Sun are approximately of the same magnitude. Strong solar perturbations combined with small correction maneuvers permit for significant propellant savings. The fuzzy boundary region is located at a distance of about 1.5 million km in the vicinity of the Earth-Sun line. Compared to the classical three-impulse transfer orbit, the apogee maneuver is replaced by solar perturbations, what permits a maximum propellant saving of more than 300 m/s.
The total velocity requirement has been determined to be within the range of 1180 m/s to 1280 m/s. The time of flight required to transfer from GTO to lunar orbit reaches 90 days at maximum. Departing from the Ariane-5 GTO, WSB transfers have been found feasible without restrictions concerning the launch date.
Apart from science and mission operations aspects, the selection of the operational lunar orbit must be mainly based on stability considerations. In order to reach the proposed lifetime of 180 days, only a 4 hour lunar orbit appears to be reasonable. The velocity requirement estimate for orbit maintenance is 140 m/s for the entire operational lifetime and has been calculated taking into account third-body perturbations imposed by the Earth and the Sun. The investigations of the lunar eclipse phases for the selected orbit resulted in a maximum eclipse duration of 65 minutes.
One of LunarSat's objectives is to gain data on the lunar south pole regions as well as to do measurements of the magnetospheric environment of the Moon. Additionally the probe will create an illumination chart of the south pole.
What about the LunarSat project "social" objectives?
Main objectives are :
Who is involved?
There are several european research communities that are part of this initiative but the main activities come from the University of Munich ( German), from the university of Uppsala and from some universities of Austria. Official sponsors from indutsry, even if they already are present with some minor subsidiary, should arrive. It should be very important not only the sponsorship but also an involvement of R&D industry departments. When will this happen?
Visit the Lunarsat website, at: http://www.lunarsat.de/
[LS - TDF 3/2000 - 14/10/00]