A GPS for the Moon will soon no longer be science fiction. Astronauts should soon be able to geolocate themselves on the Moon. All the major international space agencies, led by NASA, are trying to meet this astronomical challenge, which is essential for establishing a future lunar base.
« You have arrived at your destination on the South Pole of the Moon »: this is the objective of the future international mission Artemis of NASA. But to get there, to establish an exploration and research base at the South Pole of the Moon, so that astronauts can carry out their mission on the surface, the basic communication relays used until now for lunar missions will not be enough.
We will have to move to a much higher speed of communication and precision in localization. Like our famous GPS, an acronym for Global Position Systemwhich has become essential in all areas of our interconnected lives thanks to the constellations of satellites around the Earth. But now, it is the Moon that will have to be studded with satellites so that astronauts can also geolocate themselves. Which poses huge questions for scientists.
How to design a GPS that works on the Moon?
First, we need to answer the following basic question: what time is it on the Moon? And the answer is not simple. Although we know that the day/night cycle on the Moon corresponds to two weeks on Earth, there is still no international convention on lunar time equivalent to our universal time on Earth. However, we know how essential the precision of atomic clocks and their synchronization are to the proper functioning of global satellite navigation systems (GNSS) whether they are American like GPS, Chinese like BeiDou, Russian like Glonass or Galileo for Europe. They all depend on extremely precise measurements, down to the nanosecond.
But because of relativity, the Moon is less massive than the Earth, so the atomic clocks on its surface tick faster. But by how much? By 56 microseconds per day, exactly. That’s the calculation that two physicists from the American Institute of Standards and Technology have just made, in a study published last month in the journal Astronomical Journal : 56 microseconds more per day, that’s one second more every 50 years, between lunar time and Earth time.
We will therefore also have to synchronize our clocks and agree on a universal lunar time, which is what all the space agencies on the planet are working on, in collaboration rather than in competition. Because in space, there is really no other choice, given the extent of the task and the means implemented to make this spatial and technological leap.
While NASA, the American agency, ESA, the European agency and Jaxa, the Japanese agency, each work on specific programs, they are all brought together in a consortium called Lunanet, that China and other space powers could join. And this knowing that China is also developing a program of constellations of lunar navigation satellites and actively participates in all international forums on the subject.
Rather than a new race to make the first lunar version of GPS, we can hope for international cooperation, following the recent congress of the International Astronomical Union, in August in Cape Town, South Africa, which voted a joint resolution emphasizing the importance of such a union to establish a universal lunar time and collaborate on future lunar navigation and communication systems. GPS on the Moon? It could be soon!
Source : Wired
