According to foreign media, NASA wants to use the existing GPS system to navigate the spacecraft or its crew on the moon without the need to rebuild additional infrastructure on the moon.
"NASA has been promoting high-altitude GPS technology for years," Luke Winternitz, an MMS systems architect, said at a NASA news conference. "GPS around the moon is the next boundary."
In fact, four years ago NASA successfully extended GPS services to space hundreds of thousands of kilometers above the ground. In 2015, NASA launched four spacecrafts (mission code MMS) to study the phenomenon of "magnetic reconnection". Through precise positioning of GPS system, the four satellites are kept in a tetrahedral structure at all times, and the longest distance is about 150,000 kilometers from the earth.
But the moon is more than 380,000 kilometers from Earth. To receive signals on the moon, some parameters of the receiver need to be further enhanced based on MMS, such as high-gain antennas, enhanced clocks and more sophisticated electronic equipment.
It is reported that NASA has commissioned the Goddard Space Center in Maryland to build a prototype of a lunar GPS receiver and is preparing to send it to the International Space Station for testing in the near future. If the reliability of the system is verified, the relationship between the moon and the Earth will be even closer in the future.
In addition, NASA is pushing ahead with experiments on deep-space atomic clocks, which will change the way spacecraft navigate to Mars or beyond. At present, deep space atomic clocks have entered space aboard Falcon Heavy Rockets. This means that the navigation mode of deep space travel in the future will be dominated by the ground, and gradually transit to the mode of global positioning system-led or autonomous navigation.
In the future, with the new Deep Space Atomic clock, the aircraft will be able to transition to one-way tracking. The spacecraft will use the clock it carries to measure the time it takes for the tracking signal to arrive from Earth to the spacecraft without the need for the atomic clock to send the signal back to the ground for measurement. This will enable the aircraft to judge its own orbit.
With more efficient navigation, the aircraft can be self-positioned, space exploration can be more flexible to carry out operations, more timely response to unexpected situations.