When astronauts return to the moon, they have a lot of work to do, the most important of which is to look for ice. They need to navigate precisely to where the ice is. But there are no Earth-like navigation satellites like GPS in lunar orbit. So can the SIGNAL of a GPS satellite launch in Earth orbit be used on the moon?
Kar-Ming Cheung and Charles Lee of NASA JPL did some calculations that they thought was possible. Navigation satellites in Earth orbit include 81 GPS in the United States, Galileo in Europe and GLONASS in Russia, most of which have directional antennas that transmit signals to the Earth’s surface, but these signals radiate into space, strong enough to be received by spacecraft near the moon.
A spacecraft in lunar orbit can receive signals from 5 to 13 navigation satellites at any time, with positioning accuracy of 200 to 300 meters. The researchers believe that the accuracy of multiple methods could be further improved.
But navigation can be difficult after an astronaut lands, and signals can be blocked by barriers such as hills. NASA scientists believe the relay satellite in lunar orbit could be used as a positioning beacon.