Over 50 years after the first human lunar landing, humanity is preparing to return to the Moon. Materials to be used in those missions will have to withstand the lunar environment over longer periods of time. Future Extravehicular Activities (EVAs) on the lunar surface will require improved suit concepts compared to previous systems of the Apollo era. PExTex is an ESA-funded project, implemented by the consortium of DITF (German Institutes of Textile and Fiber Research) and OeWF under the coordination of COMEX SA. The objectives of PExTex are:

• … to identify (novel) materials for future EVA space suit developments in Europe.
• … to propose a testing strategy to verify that such materials meet the conditions of future missions to the lunar surface.

The project aims to identify and test textiles to fulfil the requirements posed by the lunar environment. Some of those are:

The Austrian Space Forum performed computer simulations and tests targeting the issues of ionizing radiation and microbial growth.

Radiation Simulations and Tests

Ionizing radiation is a major environmental factor to be considered in lunar missions. As the Moon is not protected by a magnetic field, like the Earth, it is constantly being bombarded by highly energetic charged particles. This radiation can cause material fatigue and severe health effects. The most important radiation sources are Galactic Cosmic Rays (GCR) and energetic particles emitted by the Sun in solar particle events (SPEs). In numerical simulations, the OeWF modelled how this radiation would interact with the spacesuit textiles, and which radiation dose this would cause for the astronaut wearing such a suit.

The simulations were verified by two real-life tests at the MedAustron center for ion therapy and research in Wiener Neustadt. The facility features four irradiation rooms, where three are used for patient treatment and one for non-clinical research. The testing campaign at MedAustron was split into two basic subtests:

Radition Test – Material Fatigue

In this test a high radiation dose, about 50 Gy, was deposited in the fabric. The aim of the test was to determine to what extent the textiles are damaged by radiation. The test was performed on multiple samples of each investigated material. After the irradiation, the materials’ tensile strength was quantified at DITF – for that the textile is stretched until it breaks, and the maximum force measured. This value was compared to the tensile force achieved by a non-irradiated textile

Radition Test – Shielding

Um die Gefahren durch Strahlung im Weltall zu minimieren, wäre es wünschenswert, dass ein Raumanzug solche Strahlung abschirmt. Während Kopf und Rumpf des Astronauten durch die festen Teile des Anzugs (Helm, Lebenserhaltungsrucksack, feste Oberkörperteile) geschützt sind, sind Arme und Beine nur durch Textilien bedeckt. Aus diesem Grund untersuchte das Projekt die getesteten Stoffe auf deren Eignung zur Abschirmung eines Protonenstrahls. Dafür wurde der Dosimeterwert durch den Strahl ohne Textil verglichen mit den Ergebnissen, die mit verschiedenen Materialien vor dem Detektor erreicht wurden.

Microbial Growth Tests

During future lunar missions, the spacesuits will be used for long durations. In use, they will inevitably be exposed to microorganisms living e.g. on the human skin. Uncontrolled microbial growth on or inside the spacesuit could lead to material degradation, foul odours and even health risks for the astronauts. For that reason, the Austrian Space Forum, together with the Institute of Microbiology of the University of Innsbruck, tested the textiles for how well microbes (bacteria, fungi, etc.) could adhere to and grow on them. The tests also included investigations whether the microbes would propagate through the potential spacesuit layers. This can be important for planetary protection purposes; propagation from the inside out can lead to the contamination of samples, propagation from the outside in would mean that hypothetical extra-terrestrial life forms could enter the spacesuit.

For More Information See:

• ESA seeking dust-proof materials for lunar return

PEER MOHAMED, Mohamed Makthoum, Małgorzata HOŁYŃSKA, Peter WEISS, Thibaud GOBERT, Yann CHOUARD, Nisheet SINGH, Theo CHALAL, Nina SEJKORA, Gernot GRÖMER, Sibylle SCHMIED, Matthias SCHWEINS, Thomas STEGMAIER, Götz T. GRESSER und Shumit DAS, 2020. Planetary Exploration Textiles (PExTex) – Materials Selection Procedure for Surface EVA Suit Development. In: 71st International Astronautical Congress (IAC) [online]. The CyberSpace Edition: International Astronautical Federation (IAF). 12 Oktober 2020. IAC-20-A1.VP.57714.

WEISS, Peter, Makthoum PEER MOHAMED, Thibaud GOBERT, Yann CHOUARD, Nisheet SINGH, Theo CHALAL, Sibylle SCHMIED, Matthias SCHWEINS, Thomas STEGMAIER, Götz T. GRESSER, Gernot GROEMER, Nina SEJKORA, Shumit DAS, Riccardo RAMPINI und Małgorzata HOŁYŃSKA, 2020. Advanced Materials for Future Lunar Extravehicular Activity Space Suit. Advanced Materials Technologies. 26 Juni 2020. S. 2000028. DOI 10.1002/admt.202000028

About COMEX:
The Compagnie Maritime d’Expertises (COMEX) was founded in 1961 by Henri Germain Delauze (1929-2012). It is a globally active pioneer in deep sea diving and the development of technologies for manned intervention and robotics in extreme environments. COMEX has participated in numerous ESA projects targeting the return of humans to the Moon. comex.fr

About DITF:
The German Institutes of Textile and Fiber Research (DITF) form the largest textile research center in Europe. The three research areas textile chemistry and chemical fibers, textile and process engineering and management research cover the entire textile value chain, from the molecule to the finished product. DITF houses several testing laboratories for testing fibers, yarns, surfaces, and textiles. www.ditf.de

About MedAustron:
MedAustron in Wiener Neustadt, Austria, is one of the world’s most cutting-edge centers for cancer treatment and research. MedAustron uses ion beam therapy, where patients get irradiated with charged particles – protons or carbon ions. This form of therapy is optimal for treating tumors close to radiation sensitive organs. Side effects can be reduced significantly. Besides the treatment of patients in clinical trials, the MedAustron accelerator facility offers the opportunity for performing non-clinical research; for this purpose, the MedAustron center features a separate irradiation room. www.medaustron.at

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