Source: ANFR

Auto-translated from French


In recent weeks, the conquest of space has occupied the news a lot with the success of the flight of the first drone on Mars, Ingenuity and the arrival of the French astronaut Thomas Pesquet in the international space station where he will stay 6 months. This media interest is particularly aroused, beyond technological prowess, by the publication of photos taken and sent during these events. The ANFR deciphers how, thanks to frequencies, these extraterrestrial missions can keep in contact with the Earthlings that we are.

From space, Thomas Pesquet gives his news by sometimes calling Earth but, above all, by regularly posting texts and images on social networks. However, inside its International Space Station, there is neither WiFi nor 5G. How then are the data transfers carried out? It is in fact a communication via the internet! But to come back down to Earth, the texts and images are first transmitted far from Earth: to a geostationary satellite of the TDRS data relay system of NASA, which orbit 36,000 km, 90 times farther from us, than the ISS. This data is then sent back to us by this satellite. This inter-satellite link uses the 26 GHz band, identified at the 2019 World Radiocommunication Conference ( WRC-19) for 5G, and which should be deployed in the coming years in France. The protection of space receivers vis-à-vis 5G base stations is also the subject of specific regulatory studies with a view to WRC -23. On the side of ESA (European Space Agency), it will soon implement its new COLKA system to communicate with the International Space Station. It will also operate in the 26 GHz band and will use the European data relay system, EDRS, operated by Airbus D&S.

As for Ingenuity, the first motorized and controlled machine to fly on a planet other than Earth, it also uses frequencies for its communications. This little helicopter takes pictures of the surface of Mars. To send them to us, it must first transfer them to the rover. For this, it uses the 914 MHz frequency, used in France and in a large part of the world by mobile networks. This frequency is part, in Region 2 of the ITU (the American continent), of a free band (902-928 MHz) where there are many communicating objects using the Zigbee protocol, which is particularly energy efficient and which NASA has adapted for its mission. NASA has also chosen to use a commercial chip known for its low consumption, which is found in many smartphones. In any case, don’t worry about interference between our mobile networks and Ingenuity, Mars is far away! Of course, Ingenuity’s images don’t stop at the NASA rover – they’re going to have to make a long trip to Earth afterwards. These communications then use the attributions of the Radio Regulations for the space research service (deep space).

A future article will tell you all about this service and explain how the images travel from Mars to Earth.

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