Scientists from Wrocław are co-creating a navigation system on the Moon

Moonlight is the name of a new navigation system being developed by the European Space Agency (ESA). It is to enable precise positioning on the surface of the Moon and its vicinity. Scientists from the University of Environmental and Life Sciences in Wrocław are participating in the project.

In a statement sent on Tuesday, the Wrocław university announced that it plans to place four lunar orbiters (satellites), receivers in landers, rovers and satellites, as well as deploy a ground network – reference stations, telescopes and laser stations.

"The entire mission is to be launched in 2031. But before that happens, algorithms must be developed that will allow for precise determination of the position of the satellites and the user. This is where Polish scientists come into play," we read in the release.

The team from the University of Environmental and Life Sciences in Wrocław consists of Dr. Grzegorz Bury, Dr. Radosław Zajdel and Prof. Krzysztof Sośnica; he was responsible for testing models describing the motion of satellites around the Moon.

"The biggest challenge in developing and testing the models was to take into account the real, dynamic conditions in which the satellite moves with the parameters set by ESA," explain the Wrocław scientists quoted in the release.

The designed orbit around the Moon is highly elliptical, meaning that the satellite moves much faster when it is closest to the surface (i.e. at periapsis), and slower when it is farthest from it (at apoapsis). The problem is that it is at periapsis that the satellite's motion becomes most unpredictable - it is affected by local gravitational disturbances (such as mascons - mass concentrations of higher density than average, located relatively shallow below the surface of the celestial body), non-gravitational forces, and also variable flight speed.

"The parameters proposed by ESA determined the shape of the orbit as a strongly flattened ellipse, which means that in the periapsis region the satellite's speed is significantly higher. Moreover, the shape of the orbit is not a perfect ellipse, but strongly deformed by forces disturbing the curve. These forces change more dynamically the faster the satellite moves. This means that during the flyby in the periapsis region it is very difficult to correctly model deviations from its motion. The changes are dynamic and less predictable," we read in the release.

As the researchers explain, in this situation, we may not lose contact with the satellite, but we will know its location much worse than elsewhere. That is why the orbit was designed so that the satellite spends the shortest possible time over the problematic region near the surface, and spends most of its time at apocenter, where conditions are more stable.

However, ESA set the bar higher – it wanted maximum positioning accuracy throughout the orbit, even in the most difficult conditions. Because only then will the system be able to provide precise navigation data to all users, regardless of their location or mission stage.

One of the biggest obstacles to extraterrestrial missions is cosmic radiation. Earth's satellites are partially protected from the solar wind and cosmic radiation by our planet's magnetic field. In the case of lunar orbiters, this protection is much weaker, making electronics, processors, and especially atomic clocks very vulnerable to cosmic radiation, solar flares, or magnetic storms on the Sun.

"Without atomic clocks, a navigation satellite cannot function, so there must be several such clocks on board (at least two) to ensure an adequate reserve. Cosmic radiation was also important. The moon has no magnetic field, so on-board electronics are exposed to solar storms and flares," we read in the release. (PAP)

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