Researches and developments of "Space version GPS" will be proceeding to know the current position of the spaceship, relying on signals from stars

GPS functions such as car navigation and smart phone map application can know their position by using radio waves sent from artificial satellites. A celestial object emitting regular radio waves with the same mechanism as thisPulsarOn the basis of the signal from "a system that can accurately grasp the location of the spacecraft even in the vast universe"Galactic Positioning System"Research and development is progressing.

NASA's Got a Plan for a 'Galactic Positioning System' to Save Astronauts Lost in Space
https://www.space.com/40325-galactic-positioning-system-nasa.html

Beyond knowing where you are on the earth, it is important that the spacecraft can grasp the location of your spacecraft in space. Especially in a spacecraft aiming for a star far from the earth and a spaceship that has become unable to receive radio waves from the earth for some reason, if you can know the current position only by yourself, It is possible to aim precisely and return home to the earth without guidance from the earth.

Aiming for realization NASA's R & D progress Galactic Positioning System observes and analyzes multiple radio waves from among the pulsers where 1,600 have been found so far, so that your aircraft can be monitored by triangulation It is a system for finding out which area it is in. Pulsar is a celestial body emitting pulsed visible light, radio waves, and X-rays with a period of several milliseconds to several seconds, and it is known that its cycle is kept extremely accurate.


NASA sends a signal from this pulser to the X-ray telescope "NICER(Neutron star Interior Composition Explorer) "to determine the position"SEXTANT(Station Explorer for X - Ray Timing and Navigation) "program.


In the experiment of November 2017 actually carried out by mounting NICER on the International Space Station (ISS), we successfully identified the position of ISS moving at a high speed of approximately 280,000 km at an accuracy of only 7 km It is. In other words, for the ISS flying at 7.6 km / h at a speed of about 27,600 km / h, 7 kmDistance that will pass by only 0.9 secondsIt will be how you can feel how high the accuracy of the space version GPS is. In the future NASA aims to increase the accuracy and aim to target "1 km".


When specifying the position, four pulsers emitting radio waves with millisecond period are used. Three of them are used for position measurement, and by calibrating the internal clock of NICER using the remaining one, we confirm that we observe the other three pulsers appropriately And that.

When NASA scientist Zaven Arzoumanian can figure out the exact position with this system, it will be possible to operate the spacecraft so accurately as possible in the future planet exploration . It is impossible with conventional technology to send a probe to orbit around a planet that revolves around a remotely located star, and even the moon (satellite), just like "thread through a needle hole" It will be possible to maneuver.

In addition, by being able to grasp the position of the spacecraft by itself, "Robot spacecraft" which does not require astronauts can also go to the destination precisely without assistance from the earth. As a principle, it can be said that "simple GPS" or "Deep space GPSHowever, it seems that technological development has finally reached the stage where practical application will come into view in the vast universe.