Learn how Pulsars are used for navigation in space

In our day to day commuting, we travel in 2D paths and navigate using landmarks. But in space, your navigation happens in 3D, and there aren’t close landmarks because space is vast and mostly empty. When talking about space drives, we will need a highly reliable navigation system. In this article, we will explore using pulsars for space navigation.


When a massive star dies, it either forms a neutron star or a black hole. A pulsar is a neutron star with light beams at both its poles. You can think of it as a lighthouse and every time the beam passes through our line of sight we see a signal. Since pulsars rotate rapidly with great stability and precision close to that of atomic clocks in long time scales, they are an excellent candidate for a ‘Galactic Positioning System’.


Animation of the lighthouse model of pulsar by Michael Kramer (JBCA, University of Manchester)
Animation of the lighthouse model of pulsar by Michael Kramer (JBCA, University of Manchester)

Let’s first understand how regular GPS works. A Global Positioning System needs a minimum of 4 satellite signals that transmit radio signals and a receiver that has a model of the signals without delay. Using the delay between the signals and their direction, we calculate the location of the receiver.


In space, radio waves aren’t reliable because of ‘dispersion’ due to dust. We have a solution for that - replace satellites with pulsars that emit in X-rays! We have timing models for pulsars that can predict the arrival time of pulses at any point in space. The Neutron Star Interior Composition Explorer (NICER) instrument aboard the International Space Station (ISS) conducted the first demonstrations of the concept of X-ray Navigation (XNAV) achieving lower than 1 km error.


Pictured:  An illustration of pulsar navigation. Credits: Keith Gendreau
An illustration of pulsar navigation. Credits: Keith Gendreau

Recently, using data from NICER, astronomers have created pulsar surface-emission models that challenge our standard bipolar lighthouse model. Developing our understanding of pulsar emission and changes that occur in the ‘steady’ signals because of physical reasons like starquakes can help us better our timing models for pulsar signals. Along with improved X-ray instruments, Pulsars have the potential to be the cosmic lighthouses for our future space sailors




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