Pulsar Navigation

Golden Record​

The Voyager 1 Spacecraft, currently the farthest human-made object from Earth ever created, contains a so-called "Golden Record" that contains music, images of humans, and other depictions of humanity. The record also contains a 2D map of space (there is a dashed line between the sun and the center of the galaxy to center Earth in space), with a number of dots with lines drawn inward towards a center point. This center point is the sun, and the outer points are pulsars. This is because pulsars are a useful navigational tool for humans or any other intelligent, spacefaring, and extraterrestrial life. 

 

It is relatively straightforward to track pulsars, as each pulsar has its own signature rate of pulse, much like a lighthouse has a unique flash characteristic. The record counts time by the time needed for a hydrogen atom to change compared to a proton (hyperfine period of hydrogen) instead of seconds because hydrogen is the most abundant element in the universe. Assuming there was intelligent life that intercepted the Voyager Spacecraft, they would be able to locate the pulsars and then Earth using the pulsar map.

 

Pulsar navigation is useful because it allows intelligent species to determine their "absolute position" (that is, they can determine exactly where they are in space as opposed to where they are relative to their initial launch point). It also allows spacecraft to track time, as pulsars are extremely accurate clocks.

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The NICER mission is a project by NASA on the International Space Station to track neutron stars through X-rays. Using pulsars, scientists can attempt for the first time pulsar navigation though the use of X-ray Timing and Navigation Technology, scanning neutron stars to determine the location of spacecraft within the universe. The X-rays can also tell scientists about the interior structure and origins of the pulsars. The instrument to measure the pulsars is located aboard the ISS and was launched in 2017 through a SpaceX Falcon 9 rocket.

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The X-ray Timing Instrument used in the NICER mission will utilizes 56 X-ray "concentrator" optics (XRC) and silicon drift detector (SDD) pairs. The XRC's take the data from the sky and funnel this data onto a Focal Plane Module (there are 56) which includes a SDD. The SDD analyzes individual photons and the time they are collected, thus allowing the instrument to analyze the pulsars.

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In short, the X-ray Timing instrument features and XRCs, which intern include focal Plane Modules which include SDD's. See the diagram to the right.

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Sources: 

https://voyager.jpl.nasa.gov/golden-record/

https://www.nasa.gov/nicer

https://heasarc.gsfc.nasa.gov/docs/nicer/mission_guide/

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Listen to the Podcast Interview BELOW for more information about NICER!

*Interview with Keith Gendreau, Principal investigator of NASA's NICER mission

Music: Spacetrack by Chad Crouch