Pulsars May be GPS of the Cosmos: New Method for Spacecraft Navigation

Pulsars may become the new GPS of the cosmos. Scientists have discovered that these small spinning stars that deliver occasional pulses of either X-rays or radio waves can help astronomers determine the positions of telescopes, leading to a new way to navigate the universe.

Usually, astronomers are interested in measuring when pulsar pulses arrive in the solar system. Slight deviations from the expected arrival times of these pulses can give clues about the behavior of the pulsar itself, or whether it's orbiting another star. Yet the researchers can also work backwards, using information from pulsars to precisely determine the location of spacecraft.

So how could pulsars be used as a cosmic GPS? It would require observations of at least four pulsars every seven days.

"Each pulsar would have to be observed for about an hour," said George Hobbs, one of the researchers, in a news release. "Whether you can do them all at the same time or have to do them one after the other depends on where they are and exactly what kind of detector you use."

It's certainly possible to use pulsars to navigate, but why would we want to? Currently, spacecraft in the solar system are tracked and guided from the ground. Yet the further away the spacecraft travels from Earth, the less accurately we can measure their locations. Being able to have another system to track certain telescopes could give scientists more accurate information about where data is being collected.

Pulsars could also be used for deep-space navigation beyond our solar system. Because position information from on-board instruments, such as gyroscopes and accelerometers, becomes less accurate over time, using pulsars could help scientists with these deep-space missions.

In order to test how navigating with pulsars might work, the researchers made a detailed simulation of a spacecraft navigating autonomously to Mars using a combination of technologies and their TEMPO2 software. In the end, they found that the spacecraft could determine its position to within about 20 km and its velocity to within 10 cm per second--that's the best accuracy anyone has ever been able to demonstrate.

"Unlike previous work, we've taken into account that real pulsars are not quite perfect, they have timing glitches and so on," said Hobbs. "We've allowed for that."

The new findings could allow spacecraft to better navigate to the far reaches of space. In addition, it could allow scientists to better keep track of instruments that travel through our solar system.

The findings are published in the journal Advances in Space Research.