Future spacecraft could use dead stars to navigate

By David Szondy
October 10, 2012

The European Space Agency (ESA) wants to know if it’s possible to use dead stars as a navigational aid for traveling in deep space. To answer that question, ESA has contracted Britain’s National Physical Laboratory (NPL) and the University of Leicester to investigate whether pulsars can serve as navigational beacons in the far-flung reaches of the outer Solar System or interstellar space.

With GPS, smartphones and online maps, navigation has become so simple that we hardly give it a thought anymore – unless a software glitch has the satnav telling us to drive into a lake. For probes heading into deep space, it’s another matter. Currently, spacecraft are guided by radio signals from ground stations on Earth or other spacecraft, but the farther out one goes, the less reliable radio signals become. Radio beams can take hours within the Solar System and days, months or years outside of it. Also, the power needed for ground stations to punch a signal so far soon becomes uneconomical.

The alternative is to use navigation beacons much as terrestrial sailors use lighthouses, buoys and RDF stations. Unfortunately, space is insanely large and installing manmade beacons would be expensive, impractical and involve problems of its own. NPL and the University of Leicester have a different approach. They plan to use natural beacons that can be used by spacecraft to fix their positions.

In this case, the substitute is X-ray pulsars. A pulsar is a kind of neutron star. That is, a star that blasted its outer shell of gas away in a supernova explosion. These dead star remnants have collapsed in on themselves so tightly that gravity has squeezed the electrons and protons in their atoms together to form neutrons. This creates a unique substance called neutronium, which consists only of neutrons and no atoms. This neutronium is so dense that a teaspoon of it would weigh as much as Mount Everest. Not surprisingly, the gravitational pull of a neutron star is so great that a mountain located on one would be shorter than a paper crease.

Read more: Future spacecraft could use dead stars to navigate — gizmag.

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