For several decades, accelerators have been operated at the Chair of Astronautics, allowing small particles (micrometer to millimeter-sized) to be accelerated to several km/s. This makes it possible to simulate micrometeoroid impacts. Since the end of March, at least one of these facilities, the so-called electrothermal accelerator, has been operational again.

An electrothermal accelerator works like this: A large capacitor bank is charged via the normal power grid. Then, all the stored energy is conducted in a very short time through an aluminium wire located in an explosion chamber. The wire turns into plasma, which expands very strongly. This accelerates a projectile in the barrel. Our facility accelerates plastic projectiles of 2 or 4 mm in diameter and various thicknesses to up to 3 km/s (that’s over 10,000 km/h!).

With this facility, one can, for example, simulate the impacts of dust or debris particles on satellites in space. Here, we are interested in craters in loose rock, so-called regolith, as it occurs on asteroids. With our measurement technology, we can determine how much momentum is transferred from an impact to the target. This is relevant to the defence against asteroids that could threaten Earth.

The facility was operated for many decades at the Chair of Astronautics at the TU Munich in Garching. Last year, it was moved to the Professorship of Lunar and Planetary Exploration in Ottobrunn. Shortly before Christmas, we successfully fired the first shot. At the end of March, we conducted an experimental campaign with 16 shots in four days. During this process, various projectiles were fired into sand targets. The upper figure shows the experimental setup, including the measurement instrumentation. The lower figure shows a typical post-impact crater. We perform shots into so-called quarter-space targets, which essentially produce 'half-craters' and allow us to better observe the impact.

The main purpose of this campaign was to test the facility and ensure its functionality, which we successfully achieved.

The accelerator team consists of: Michael Frühauf, Martin Rott, Lara Schuberth (Chair of Spacecraft Systems), Robert Luther (Museum für Naturkunde, Berlin), and Detlef Koschny.