Survival and operations of a micro-lander during the night in the dark side of the moon

Paper number

IAC-05-E2.3.02

Author

Dr. Nicola Baggio, Politecnico di Milano, Italy

Coauthor

Mr. Giovanni Binet, European Space Agency (ESA)/ESTEC, The Netherlands

Coauthor

Mr. Fabio Pignata, Politecnico di Milano, Italy

Coauthor

Ms. Concetta Clemente, Politecnico di Milano, Italy

Coauthor

Mr. Andrea Falzone, Politecnico di Milano, Italy

Year

2005

Abstract

The Moon is an extremely interesting planet to explore: the more and more affordable space technologies, make it a target reachable with small and cheap missions affordable by Universities as well.
The following paper illustrates part of a project developed from a group of students, supervised by a professor and aims to demonstrate the feasibility of a mission to the surface of  the dark side of the Moon.
The objective of this research is the realization of a net of three micro-landers (about 20 kg each) which have to operate during the 14-days-long lunar night and that are capable to survive this severe environment using a thermal control system as much passive as possible and installing a conventional power supply system of solar cells and batteries.
Additional requirements are that the transmission of the telemetry has to be provided each 12 hours during the eclipse periods and the scientific payload is required to operate for an effective total duration of 6 months.
Considering these demands, the power, thermal and telecommunication subsystems have been developed.
Concerning the EPS, it is shown that it is possible to realize a system that can guarantee a minimal power supply to feed the spacecraft only using technologies that are already available on the market and avoiding the installation of non-conventional devices as the RTGs.
This important advantage can be better evaluated if compared to the other landers that up to now have been operating in similar conditions (i.e. on Mars): these spacecrafts had to stand much shorter periods of darkness or, in case of long eclipses, they were equipped with RTG devices.
The landers have to communicate with an orbiter which is orbiting about the libration point L2 of the Earth-Moon system. The orbiter is a micro-satellite as well and operates as a data relay bridge between the landers and the Earth. The landers have to cooperate as well. 
These particular restrains required the design of complex telecommunication system in order to reduce the power consumptions as much as possible.
In particular two distinct operational modes were designed in order to manage the power consumption during the lunar night: one is capable to handle the data transmission to the orbiter, the other assures the lander survival (and namely the batteries) maintaining the temperature within an acceptable range.
In order to achieve this result, the architecture of each lander has been designed considering the thermal requirements as well: all the vital instruments (computer, battery) are packed in a central box, on the upper face an MLI blanket insulates the inner from the outer environment, the lateral faces is covered with an irradiating surface.  
The external instruments, such as the antenna and all the instruments that operate on the robotic arm are white painted. 
A particular solution had to be investigated for the batteries that are attached to one of the lateral radiating surfaces and are kept all together to increase their the thermal inertia. 
An insulator layer reduces the conduction between the structure and the battery: however an heat source is needed therefore some heaters that provide 0.4W continuously during lunar nights are used. 
Alternatively, a backup solution would be a PCM (phase change material) jacket for the battery, making the TCS completely passive.
The limited total weight, the versatility in performing several scientific experiments, the standardization and the cost reduction philosophy that leaded the choice of the components make this project a valid example of how a modern space mission is developed. The project is totally consistent with the modern trend of investing in small and cost reduced missions with low risks.

Abstract document

IAC-05-E2.3.02.pdf

Manuscript document

IAC-05-E2.3.02.pdf (🔒 authorized access only).

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