Luna Hall: Sensors, rovers and astronauts explore "the moon" – in Cologne

A photo published by the German Aerospace Center (DLR) last week might at first glance give the impression that it shows gift packages, but it is actually a much more mundane "payload box". And despite the background of the picture, it was not taken on Earth's satellite, but in the Luna Hall in Cologne. DLR and the European Space Agency (ESA) have been simulating the surface of the moon and the conditions there for a few months now.

The aim of the current communication project is to research how cargo to be transported, sensors, rovers and astronauts can connect to form a network in a rather inhospitable environment without GPS & Co. According to the plan, all participants exchange signals that can be used for communication and navigation at the same time.

Each robot, human or measuring device passes on information "to its neighbors" in the network, explains project manager Emanuel Staudinger from the DLR Institute of Communications and Navigation. The distances between the participants and their exact position can be determined via the propagation time of the radio signal between them. The advantages: "The system works decentrally, requires no infrastructure and is designed for a large number of participants, among other things." The swarm navigation system developed for this purpose makes it possible to explore the surface of the moon, for example, which can be transferred to other planets such as Mars. It also works in lava caves or complex environments on Earth where conventional systems such as satellite navigation are not available.

700 square meters with craters

Staudinger and his team have already tested the swarm in recent years on the Etna volcano in Sicily and in a lava cave on Lanzarote. Now they are reporting the first successful test in the realistic lunar environment of the Luna Hall not far from the European Astronaut Center. The training facility, which has been planned since 2018 and was officially opened at the end of September after a delay of several years, houses a 700-square-metre simulated lunar environment. Astronauts or robots could be prepared there for use on Earth's satellite, explains Thomas Uhlig from the Luna project management team. The DLR institute based in Oberpfaffenhofen is "one of the first to conduct research in our facility".

The scientists have run through several scenarios in the hall. In one of them, a lander arrived on the moon and deployed two rovers. The first had the task of placing radio beacons around the spacecraft. These sensor units immediately took over the first navigation tasks. During its reconnaissance trips, the rover discovered a crater and realized that it could not drive down into it. It had to call the second rover for help. The crater was in an area of the facility where the ground had sunk by three meters. The second bot was able to find the crater on its own using the navigation system and carried out its scientific investigations. The first rover helped it find its way from the edge of the crater.

"Moon Village" is to be supported

Another scenario involved the deployment of sensor units in an area that was too steep for the unmanned vehicles. Up to 50 sensors were distributed and connected to form a network for navigation. The researchers also tested flying units or dropping probes into an inaccessible crater.

The team also created a 3D model of the hall and the ground for simulations and to check measurement data. A large part of the "Moon on Earth" is covered with a layer of regolith simulant ("moon dust"). The mixture has similar chemical, physical and geotechnical properties to the original that astronauts from the Apollo missions brought back to Earth. In the long term, ESA wants to build a Moon Village on the moon. The DLR researchers want to help ensure that robust decentralized navigation and communication is available to astronauts and robots during exploration. The experts now want to evaluate the data collected so far in detail and further develop the swarm system. (nen)