Entwicklung und experimentelle Validierung einer Marssimulationsanlage für astrobiologische Experimente

Abstract

The requirements of the diploma thesis consisted in building an experimentation chamber capable of producing Mars-like environmental conditions. The main focus resided in simulating the composition of the atmosphere, as well as its pressure, temperature and humidity. On the basis of this data, a regulating device was designed in order to measure and directly influence the environmental parameters. The aim of the thesis was to build a chamber which could later accommodate sample bowls with micro-organisms. Based on the products of their metabolism, one should be able to deduct whether or not micro- organisms can survive and metabolise under such extreme conditions. The main element of the Mars simulation chamber is a high-vacuum chamber, capable of accommodating the samples, and which can be evacuated via two vacuum pumps. A vacuum measurement device gauges the low pressure within the chamber and displays the results on the dials. A humidity sensor, capable of resisting vacuum conditions, registers the humidity within the chamber whereas PT-100 resistance thermometers show the temperature. Additionally, all measurement devices are connected to a data reception card that forwards them to a controlling processor. The control software, programmed in Labview, displays the received parameters on the screen and takes over the whole pressure regulation. With the help of this control software, cyclical pressure fluctuations, consistent with those on Mars, can be programmed as well. The regulation is carried out by two electromagnetic vacuum valves that are also connected to the NI-card. The desired amount of water is introduced manually into the atmosphere using a reservoir that leads water into the system and which can be closed by a hand valve once the designated water concentration has been achieved. The temperature regulation in the Mars chamber is controlled with a programmable external cryostat, attached to a copper spiral inside the chamber that reliably forwards the appointed temperature to the experimentation chamber.