Space agencies test asteroid sampling tools in weightlessness to prep for lunar missions
Japanese researchers conducted microgravity experiments to validate penetrometry—a technique for measuring how instruments sink into asteroid surfaces—ahead of upcoming missions to Phobos and other minor bodies. The work addresses a critical gap: lab tests can't replicate the near-zero gravity conditions on asteroids, potentially compromising mission success and the scientific value of samples collected.
Originaltitel: Microgravity penetrometry flight campaign in support of MMX sampler science exploitation
**Pentrometri valideras för asteroidsamlingar – Luleå tek ledande** Framtida rymduppdrag kräver precis förståelse av ytegenskaper på små himlakroppar. Pentrometri — mätning av motstånd när ett föremål tränger in i material — erbjuder väg att karakterisera regolits kornstorlek, porositet och kohesion. Problemet: laboratorieförsök på jorden påverkas av gravitation, vilket försvårar överföring till asteroidmiljöer. Luleå tekniska universitet genomförde paraboliska flygningar för att testa pentrometri under mikrogravitation. Experimentet undersökte asteroid-analoga prover med varierande kornfördelning och form, sedan jämfördes resultaten med 1g-försök för att isolera gravitationens roll. Samarbetet involverade Airbus, JAXA och japanska universitet. Databasen från kampanjen stödjer utvecklingen av instrumentdesign för JAXA:s Martian Moons eXploration-mission till Phobos. Resultaten reducerar osäkerheterna vid instrumentval för framtida landningsuppdrag.
<p>Characterising the mechanical properties of minor bodies is essential for understanding their origin and evolution. Past missions such as Hayabusa2 have landed on asteroids to sample and discover what these bodies are made of. However, there has been conflicting evidence and reports into the physical properties of the granular surface material of these bodies. With future missions such as Japan Aerospace eXploration Agency’s Martian Moons eXploration mission landing on Phobos, the understanding and identification of these physical properties is crucial to maximising the scientific output from these missions. Penetrometry, the determination of the reaction force that an object experiences as it penetrates a surface, can help to understand the essential properties of regolith, such as grain size, porosity and cohesion. Results of penetrometry experiments are largely analysed based on empirical models, which presents us with a challenge if we want to apply them to understand granular materials on asteroid surfaces because gravity cannot be eliminated in the laboratory. Hence, it is essential to verify penetrometry as a method and validate penetrometry instrument designs in microgravity. For this purpose, we conducted a microgravity experiment onboard a parabolic flight campaign. Our experiment tested the use of penetrometry in asteroid-analogue environments by investigating samples with varying properties, such as grain size distribution and shape, and then compared to 1 g experiments to understand the role microgravity plays. The experiment provided a substantial database for future analysis. This paper will focus on the design of the experiment and the parabolic flight campaign in which the experiments were conducted. The design decisions and the variables adjusted during the experiment will be discussed, evaluating how these influenced the campaign and its outcomes. We will also provide a snapshot of preliminary results of the data captured during this experiment. For example, we show the effect of cohesion on penetrometer reaction force, with more cohesive materials providing larger reaction forces nearly of the same magnitude of their 1 g counterparts. We also show that penetrometer tip shapes provide different reaction forces and that flat tips provide the largest reaction force compared to the others. The influence of penetration velocity will be investigated further with the aid of theoretical models. Early indications from the results seen so far are promising for future analyses and will provide key information for the analysis of penetrometry data on future missions.</p>