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When the next generation of crews land on the surface of the moon – perhaps as early as 2024 – NASA plans to use a lunar global positioning system (GPS) to help astronauts make their way. .
Such a system would prevent the repetition of the navigation problems that preoccupied Apollo astronauts in the 1960s and 1970s. It is notoriously difficult to navigate the moon because it is difficult to judge the distance and size of lunar landmarks only. in sight. There is no atmosphere to soften the horizon, as humans are used to the Earth; Apollo's astronauts sometimes had trouble determining the distance to the craters shown on their maps from orbital imagery. The crew of Apollo 14, for example, missed a crater he planned to visit from just 30 meters away.
Thus, since the agency is once again concentrating on crew missions on the moon, NASA is developing a special receiver capable of capturing GPS signals from the lunar orbit. The US GPS system is a military system that relies on 24 to 32 satellites orbiting the Earth at one time. It is a popular tool for everything from location devices to navigation systems.
Related: How does GPS work?
If all goes as planned, the new NASA system will build a lunar receiver to pick up signals from GPS satellites orbiting the Earth. This lunar GPS would support both surface missions and personnel flying the Orion Space Shuttle and the Gateway Lunar Space Station that NASA is planning to build.
"GPS is a system of three parts: satellites, ground stations and receivers, ground stations monitor satellites, and a receiver, like those found in a phone or car, is constantly listening to the signals from these satellites, and the receiver calculates the distance to four or more satellites to locate a location, "NASA said in a statement.
"Instead of navigating the streets of the Earth, a spacecraft equipped with an advanced GPS receiver could soon be associated with accurate mapping data to help astronauts track their position in the vast ocean of the Earth. space between the shores of the Earth and the Moon, or through the surface crater. "
NASA has sailed in many spacecraft near the moon in recent decades, but the directions still came from NASA's communications networks. GPS can support more satellites and free up valuable bandwidth from these other NASA networks that can be used for other spacecraft.
One of the technological challenges is that GPS is more accurate at low altitude, below the orbit of satellites (20 to 115 kilometers). But NASA has already extended GPS navigation to higher altitudes for missions such as Operational Geostationary Satellites for the Environment (GOES) and Multiscale Magnetospheric Mission (MMS), and the agency estimates that it is possible to go even higher.
"In fact, with MMS, we are already almost halfway to the moon," said Jason Mitchell, chief technologist of the mission engineering and systems analysis division of NASA Goddard Space Center, in the same statement. .
The team plans to rely on the MMS GPS Navigator system by developing better electronics, antenna technology and a more accurate clock. (The GPS uses atomic clocks to calculate the time required for signals to move between its satellites, signals are then triangulated to determine the position of an object.) Goddard is already working on a better GPS receiver that would not not only useful for lunar missions, but also for the proliferation of small satellites.
The latest in-orbit GPS receiver concept is currently NavCube, which combines the capabilities of the MMS GPS navigator and a flight computer platform called SpaceCube. A NavCube version recently launched on the International Space Station will test the processing of its GPS signal while showing how to perform high-speed X-ray communications in space.
"NavCube's GPS processing power, coupled with a receiver for lunar distances, should provide the capabilities needed to use GPS on the moon," NASA added. The team plans to complete work on the latest prototype later this year, and then launch prototype technologies for space testing.
Follow Elizabeth Howell on Twitter @howellspace. Follow us on twitter @Spacedotcom and on Facebook.
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