Tag Archives: pulsars

China’s FAST radio telescope discovers 93 new pulsars

The research team running China’s FAST radio telescope, the largest single dish such telescope in the world, have announced that they have discovered 93 new pulsars since October 2017.

China might still be having trouble finding a big name astronomer to run the telescope, but in the meantime it looks like their own people are taking advantage of the situation to use the telescope establish their own names.

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China successfully tests navigation in space using pulsars

Using the X-ray space telescope Insight it launched in 2017, China has successfully tested an autonomous navigation system using pulsars.

The time interval of two adjacent pulses emitted by the pulsar is constant. If a spacecraft moves toward the pulsar, the received pulse interval will be shortened, and vise versa. Thus the observed pulse profile will change as the spacecraft moves in space. The relative arrival times of pulses also indicate the relative position of the spacecraft with respect to the pulsar. Therefore, by analyzing the characteristics of the pulsar signals received by the spacecraft, the three-dimensional position and velocity of the spacecraft can be determined, Zheng explained.

From Aug. 31 to Sept. 5, 2017, Insight observed the Crab pulsar for about five days to test the feasibility of pulsar navigation. The research team had also proposed an algorithm for X-ray pulsar navigation, according to Zhang Shuangnan, lead scientist of the Insight space telescope.

The research team further improved the algorithm and applied it in the processing of the observation data of the three detectors onboard Insight. The satellite’s orbit was determined successfully, with the positioning accuracy within 10 km, comparable to that of a similar experiment conducted on the International Space Station, Zhang said.

This is not the first such test. U.S. scientists did something similar using an X-ray telescope on ISS in 2017.

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Scientists demonstrate first space navigation on ISS using pulsars

The stars are ours! Scientists using an x-ray telescope installed on ISS have demonstrated it is possible to pinpoint the location of a spaceship and thus navigate through space using pulsars.

In the SEXTANT demonstration that occurred over the Veteran’s Day holiday in 2017, the SEXTANT team selected four millisecond pulsar targets — J0218+4232, B1821-24, J0030+0451, and J0437-4715 — 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 accuracies of microseconds for years into the future.

During the two-day experiment, the payload generated 78 measurements to get timing data, which the SEXTANT experiment fed into its 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. “For the onboard measurements to be meaningful, we needed to develop a model that predicted the arrival times using ground-based observations provided by our collaborators at radio telescopes around the world,” said Paul Ray, a SEXTANT co-investigator with the U. S. Naval Research Laboratory. “The difference between the measurement and the model prediction is what gives us our navigation information.”

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. 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, Mitchell said. In fact, “a good portion” of the data showed positions that were accurate to within three miles. “This was much faster than the two weeks we allotted for the experiment,” said SEXTANT System Architect Luke Winternitz, who works at Goddard. “We had indications that our system would work, but the weekend experiment finally demonstrated the system’s ability to work autonomously.”

I think everyone who is interested in interstellar space travel has assumed since the discovery of the first pulsars that they would end up serving as the future north star for interstellar travelers. This experiment shows us how it will be done.

Well read science fiction fans should recognized the literary reference in the tagline.

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A pulsar that’s eating a galaxy

The uncertainty of science: Astronomers have discovered a pulsar emitting energy at a rate far greater than ever predicted and which is believed caused by the very fast in-fall of matter into the neutron star.

Astronomers have found a pulsating, dead star beaming with the energy of about 10 million suns. This is the brightest pulsar – a dense stellar remnant left over from a supernova explosion – ever recorded. The discovery was made with NASA’s Nuclear Spectroscopic Telescope Array, or NuSTAR. “You might think of this pulsar as the ‘Mighty Mouse’ of stellar remnants,” said Fiona Harrison, the NuSTAR principal investigator at the California Institute of Technology in Pasadena, California. “It has all the power of a black hole, but with much less mass.”

More here. The galaxy where this pulsar resides, M82, has been known for decades to be one of the most interesting, with evidence of vast explosions tearing it apart. This pulsar is at its center, and appears to be sucking in matter at a rate previously believed impossible, suggesting that the supermassive black holes found at the center of many galaxies could form much faster that any theory predicted.

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