Nasa tests a 'space GPS' that uses X-rays from rapidly spinning stars to help spacecraft explore the far reaches of the galaxy

  • Sextant apparatus uses X-rays from pulsars to work out an object's position
  • It takes measurements from the spinning stars taken by the Nicer tool on the ISS
  • Sextant can locate an object moving at thousands of miles per hour in space
  • The breakthrough could lead to robots being sent to explore deep space

Nasa is using X-rays from distant stars to navigate the Milky Way.

Mapping a path in space has long been a challenge for space agencies because there are very few obvious landmarks. 

Nasa's new experiment aboard the International Space Station has come up with a solution in the form of a 'cosmic GPS'.

This new type of GPS using X-rays sent out by pulsars, which are spinning stars that emit electromagnetic radiation.

These X-rays guides spacecraft in the same way GPS satellites are used to triangulate a position here on Earth.

The breakthrough could lead to robotic vehicles being sent out into the depths of the galaxy, sending back never before seen images and data.

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Exploring the mind-boggling distances between the stars just took a step closer to becoming a reality, thanks to a 'space GPS' system developed at Nasa. Experts at the space agency have successfully tested the world's first fully autonomous x-ray navigation apparatus

Exploring the mind-boggling distances between the stars just took a step closer to becoming a reality, thanks to a 'space GPS' system developed at Nasa. Experts at the space agency have successfully tested the world's first fully autonomous x-ray navigation apparatus

HOW NASA'S SEXTANT NAVIGATION SYSTEM WAS DEMONSTRATED 

During the demonstration, the Sextant team selected four millisecond pulsar targets and directed Nicer to orient itself so it could detect X-rays within their sweeping beams of light. 

The millisecond pulsars used by Sextant are so stable that their pulse arrival times can be predicted to microsecond accuracy for years into the future.

During the two-day experiment, the payload generated 78 measurements to get timing data.

Sextant fed this into specially developed onboard algorithms to autonomously stitch together a navigational solution that revealed the location of Nicer in its orbit around Earth as a space station payload. 

The team compared that solution against location data gathered by Nicer's onboard GPS receiver.

The goal was to demonstrate that the system could locate Nicer within a 10-mile radius as the space station sped around Earth at slightly more than 17,500 mph (28,000 km/h). 

Within eight hours of starting the experiment on November 9, the system converged on a location within the targeted range of 10 miles and remained well below that threshold for the rest of the experiment

In fact, a 'good portion' of the data showed positions that were accurate to within three miles, according to the Nasa team.

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Pulsar emit X-rays from their poles. 

Whenever their poles point toward us, we see a pulse of X-ray light, like a 'cosmic lighthouse'.

The new GPS, dubbed SEXTANT is designed to detect these X-ray signals from relatively close pulsars.

SEXTANT Is attached to the ISS, and the timings of the pulsar signals changes, depending on the position of the space station. 

This mirrors how the Global Positioning System (GPS), provides positioning, navigation, and timing services to users on Earth with its constellation of 24 operating satellites. 

GPS is able to locate a receiver's position by measuring distance, using the travel time of radio signals between three satellites to 'triangulate' where it is coming from. 

The technology was developed at Nasa's Goddard Space Flight Center in Greenbelt, Maryland.

It uses the 52 X-ray telescopes and  detectors that make up the Neutron-star Interior Composition Explorer (Nicer).  

Nasa first demonstrated the technology in November, but has only just made the results public.

Project Manager Jason Mitchell, an aerospace technologist at Nasa, said: 'This demonstration is a breakthrough for future deep space exploration.

'As the first to demonstrate X-ray navigation fully autonomously and in real-time in space, we are now leading the way.' 

During the demonstration, the Sextant team selected four millisecond pulsar targets and directed Nicer to orient itself so it could detect X-rays within their sweeping beams of light. 

The millisecond pulsars used by Sextant are so stable that their pulse arrival times can be predicted to microsecond accuracy for years into the future.

During the two-day experiment, the payload generated 78 measurements to get timing data.

Sextant fed this into specially developed onboard algorithms to autonomously stitch together a navigational solution that revealed the location of Nicer in its orbit around Earth as a space station payload. 

The team compared that solution against location data gathered by Nicer's onboard GPS receiver. 

The experimental new system, called Sextant, uses the Nicer  mirror assemblies on the International space station to gather data on  pulsars

The experimental new system, called Sextant, uses the Nicer mirror assemblies on the International space station to gather data on pulsars

Pulsars (artist's impression) are spinning stars that emit electromagnetic radiation, including the X-rays used by the apparatus

Pulsars (artist's impression) are spinning stars that emit electromagnetic radiation, including the X-rays used by the apparatus

The Nicer observatory, about the size of a washing machine, is currently studying neutron stars and their rapidly pulsating relatives, called pulsars

The goal was to demonstrate that the system could locate Nicer within a 10-mile radius as the space station sped around Earth at slightly more than 17,500 mph (28,000 km/h). 

Within eight hours of starting the experiment on November 9, the system converged on a location within the targeted range of 10 miles and remained well below that threshold for the rest of the experiment

In fact, a 'good portion' of the data showed positions that were accurate to within three miles, according to the Nasa team.

WHAT ARE PULSARS? 

Pulsars are essentially rotating, highly magnatised neutron stars.

These stars are made of matter much more densely packed than normal and which give the entire star a density comparable to an atomic nucleus.

The diameter of our sun would shrink to less than 18 miles if it was that dense. These neutron stars also have extremely strong magnetic fields which accelerate charged particles.

These give off radiation in a cone shaped beam which sweep across the sky like the light from a lighthouse as the star rotates.

When the beam sweeps over earth, it becomes visible as a pulsar, producing light that cycles every few seconds to just a few milliseconds.

Their rotational period is so stable that some astronomers use it to calibrate instruments and have proposed using it to synchronise clocks.

British astronomer Dame Jocelyn Bell Burnell was the first person to discover a pulsar in 1967 when she spotted a radio pulsar.

Since then other types of pulsars that emit x-rays and gamma rays have also been spotted.

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Nasa will now focus on updating and fine-tuning both flight and ground software in preparation for a second experiment later in 2018.

The ultimate goal, which may take years to realise, is to develop detectors and other hardware to make pulsar-based navigation readily available on future spacecraft.

Teams will focus on reducing the size, weight, and power requirements and improving the sensitivity of the instruments. 

 A version to support human spaceflight may also be developed.

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