Nav: Home

NASA continues to study pulsars, 50 years after their chance discovery

August 01, 2017

A little bit of "scruff" in scientific data 50 years ago led to the discovery of pulsars -- rapidly spinning dense stellar corpses that appear to pulse at Earth.

Astronomer Jocelyn Bell made the chance discovery using a vast radio telescope in Cambridge, England. Although it was built to measure the random brightness flickers of a different category of celestial objects called quasars, the 4.5 acre telescope produced unexpected markings on Bell's paper data recorder every 1.33730 seconds. The pen traces representing radio brightness revealed an unusual phenomenon.

"The pulses were so regular, so much like a ticking clock, that Bell and her supervisor Anthony Hewish couldn't believe it was a natural phenomenon," said Zaven Arzoumanian of NASA's Goddard Space Flight Center in Greenbelt, Maryland. "Once they found a second, third and fourth they started to think differently."

The unusual stellar objects had been previously predicted but never observed. Today, scientists know of over 2,000 pulsars. These rotating "lighthouse" neutron stars begin their lives as stars between about seven and 20 times the mass of our sun. Some are found to spin hundreds of times per second, faster than the blades of a household blender, and they possess enormously strong magnetic fields.

Technology advances in the past half-century allowed scientists to study these compact stellar objects from space using different wavelengths of light, especially those much more energetic than the radio waves received by the Cambridge telescope. Several current NASA missions continue to study these natural beacons.

The Neutron star Interior Composition Explorer, or NICER, is the first NASA mission dedicated to studying pulsars. In a nod to the anniversary of Bell's discovery, NICER observed the famous first pulsar, known today as PSR B1919+21.

NICER launched to the International Space Station in early June and started science operations last month. Its X-ray observations - the part of the electromagnetic spectrum in which these stars radiate both from their million-degree solid surfaces and from their strong magnetic fields - will reveal how nature's fundamental forces behave within the cores of these objects, an environment that doesn't exist and can't be reproduced anywhere else. "What's inside a pulsar?" is one of many long-standing astrophysics questions about these ultra-dense, fast-spinning, powerfully magnetic objects.

The "stuff" of pulsars is a collection of particles familiar to scientists from over a century of laboratory studies on Earth -- neutrons, protons, electrons, and perhaps even their own constituents, called quarks. However, under such extreme conditions of pressure and density, their behavior and interactions aren't well understood. New, precise measurements, especially of the sizes and masses of pulsars are needed to pin down theories.

"Many nuclear-physics models have been developed to explain how the make-up of neutron stars, based on available data and the constraints they provide," said Goddard's Keith Gendreau, the principal investigator for NICER. "NICER's sensitivity, X-ray energy resolution and time resolution will improve these by more precisely measuring their radii, to an order of magnitude improvement over the state of the art today."

The mission will also pave the way for future space exploration by helping to develop a Global Positioning System-like capability for the galaxy. The embedded Station Explorer for X-ray Timing and Navigation Technology, or SEXTANT, demonstration will use NICER's X-ray observations of pulsar signals to determine NICER's exact position in orbit.

"You can time the pulsations of pulsars distributed in many directions around a spacecraft to figure out where the vehicle is and navigate it anywhere," said Arzoumanian, who is also the NICER science lead. "That's exactly how the GPS system on Earth works, with precise clocks flown on satellites in orbit."

Scientists have tested this method using computer and lab simulations. SEXTANT will demonstrate pulsar-based navigation for the first time in space.

NICER-SEXTANT is the first astrophysics mission dedicated to studying pulsars, 50 years after their discovery. "I think it is going to yield many more scientific discoveries than we can anticipate now," said Gendreau.
NICER-SEXTANT is a two-in-one mission. NICER is an Astrophysics Mission of Opportunity within NASA's Explorer program, which provides frequent flight opportunities for world-class scientific investigations from space utilizing innovative, streamlined, and efficient management approaches within the heliophysics and astrophysics science areas. NASA's Space Technology Mission Directorate supports the SEXTANT component of the mission, demonstrating pulsar-based spacecraft navigation.

More about NICER:

Read about five famous pulsars from the past 50 years:

By Clare Skelly
NASA's Goddard Space Flight Center, Greenbelt, Md.

NASA/Goddard Space Flight Center

Related Pulsar Articles:

Observatories combine to crack open the Crab Nebula
Astronomers have produced a highly detailed image of the Crab Nebula, by combining data from telescopes spanning nearly the entire breadth of the electromagnetic spectrum.
Image release: Telescopes team up for dramatic new look at the crab nebula
Multiwavelength image with VLA, Spitzer, Hubble, XMM-Newton, and Chandra observatories shows the 'whole picture' of the famous Crab Nebula supernova remnant, and provides astronomers with new insights into the object's complex physics.
Astrophysicists studied the 'rejuvenating' pulsar in a neighboring galaxy
The Lomonosov Moscow State University scientists published the results of a study of the unique ultra-slow pulsar XB091D.
Astronomers hazard a ride in a 'drifting carousel' to understand pulsating stars
What sounds like a stomach-turning ride at an amusement park might hold the key to unraveling the mysterious mechanism that causes beams of radio waves to shoot out from pulsars -- super-magnetic rotating stars in our galaxy.
Mysterious white dwarf pulsar discovered
An exotic binary star system 380 light-years away has been identified as an elusive white dwarf pulsar -- the first of its kind ever to be discovered in the universe -- thanks to research by the University of Warwick.
Amateur astronomer helps uncover secrets of unique pulsar binary system
A professional astrophysicist and an amateur astronomer have teamed up to reveal surprising details about an unusual millisecond pulsar (MSP) binary system comprising one of the fastest-spinning pulsars in our Galaxy and its unique companion star.
NASA's Fermi satellite detects first gamma-ray pulsar in another galaxy
Researchers using NASA's Fermi Gamma-ray Space Telescope have discovered the first gamma-ray pulsar in a galaxy other than our own.
11-year cosmic search leads to black hole rethink
One hundred years since Einstein proposed gravitational waves as part of his general theory of relativity, an 11-year search performed with CSIRO's Parkes telescope has failed to detect them, casting doubt on our understanding of galaxies and black holes.
Gravitational constant appears universally constant, pulsar study suggests
Astronomers produced the best constraint ever of the gravitational constant measured outside of our Solar System.
Astronomers predict fireworks from rare stellar encounter in 2018
Astronomers are gearing up for high-energy fireworks coming in early 2018, when a stellar remnant the size of a city meets one of the brightest stars in our galaxy.

Related Pulsar Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Do animals grieve? Do they have language or consciousness? For a long time, scientists resisted the urge to look for human qualities in animals. This hour, TED speakers explore how that is changing. Guests include biological anthropologist Barbara King, dolphin researcher Denise Herzing, primatologist Frans de Waal, and ecologist Carl Safina.
Now Playing: Science for the People

#SB2 2019 Science Birthday Minisode: Mary Golda Ross
Our second annual Science Birthday is here, and this year we celebrate the wonderful Mary Golda Ross, born 9 August 1908. She died in 2008 at age 99, but left a lasting mark on the science of rocketry and space exploration as an early woman in engineering, and one of the first Native Americans in engineering. Join Rachelle and Bethany for this very special birthday minisode celebrating Mary and her achievements. Thanks to our Patreons who make this show possible! Read more about Mary G. Ross: Interview with Mary Ross on Lash Publications International, by Laurel Sheppard Meet Mary Golda...