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China Space Communications Earth NASA Transportation Technology

China Launches World's First Pulsar Navigation Satellite (ibtimes.com) 46

hackingbear writes: After launching the world's first quantum communication satellite this year, China today successfully launched the world's first pulsar-based navigation satellite (Warning: may be paywalled, alternate source), which will conduct in-orbit experiments using pulsar detectors to demonstrate new technologies. The X-ray pulsar navigation satellite XPNAV-1 was sent skyward at 7:42 AM (local time) atop a Long March 11 solid-fueled rocket from the Jiuquan Satellite Launch Center in China's northwest. China's new system is expected to be a significant improvement over the earth-based systems currently used by spacecraft as it would eliminate the time delay with sending signals back to Earth and processing.
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China Launches World's First Pulsar Navigation Satellite

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  • Pulsars! How do they work?

    • It will blow your mind, but they're basically giant magnets. Now we've reduced it to a known problem, so you know what to do next.
  • by MancunianMaskMan ( 701642 ) on Friday November 11, 2016 @03:40AM (#53263541)
    From TFA:

    X-ray pulsars consist of a magnetized neutron star that draws gas from a companion normal star, forming a rotating disk that channels the gas to its magnetic polls, resulting in the generation of intense energies

    hope they get these right...

  • How can they do that when they are still limited by the speed of light?

    • by dinfinity ( 2300094 ) on Friday November 11, 2016 @04:16AM (#53263629)

      FTA:
      "The X-ray pulsar captures X-ray signals emitted from pulsars. By mapping those signals, they can be used to determine spacecraft location in deep space, which will eliminate the hours-long delays incurred in using ground-based navigation like the Deep Space Network and European Space Tracking network." (my emphasis)

      • FTA:
        "The X-ray pulsar captures X-ray signals emitted from pulsars. By mapping those signals, they can be used to determine spacecraft location in deep space, which will eliminate the hours-long delays incurred in using ground-based navigation like the Deep Space Network and European Space Tracking network." (my emphasis)

        Replying here because it's highest-Modded.

        This is a brilliant way to coordinate deep-space travel. Pulsars have not only a known position, but also a know frequency of pulsing.

        Man, do I wish I had thought of this! It's nominally just like GPS, only using the periodicity of a known pulsar, rather than a human-launched GPS satellite. Genius!

        • Well, the Voyagers carried plates that showed the elative position of the Sun to the center of the Galaxy and 14 pulsars, so there pulsars were already linked to position in deep space (from the aliens point of view).
        • by Anonymous Coward

          Man, do I wish I had thought of this! It's nominally just like GPS, only using the periodicity of a known pulsar, rather than a human-launched GPS satellite. Genius!

          There are some differences from GPS satellites. A GPS bird does not send a completely monotonous signal. They actually tell time. So comparing to a known good clock, you immediately know the exact distance to that satellite. A few more satellite distances, and you have a fix.

          A pulsar does not tell time. If you observe it continously, you can use deviation from the completely monotonous signal to infer that the spacecraft has moved towards or away from the pulsar. So you can start with a known position (eart

      • by dj245 ( 732906 )

        FTA: "The X-ray pulsar captures X-ray signals emitted from pulsars. By mapping those signals, they can be used to determine spacecraft location in deep space, which will eliminate the hours-long delays incurred in using ground-based navigation like the Deep Space Network and European Space Tracking network." (my emphasis)

        All good stuff, and it has many practical peacetime applications. I wonder about how much of this technology can be applied to military hardware. We often forget that the space race is often at least 50% military in nature. Could the same sensors detect nuclear detonations on earth? Could the navigation method be a useful secondary method for ICBMs to navigate in addition to other guidance systems?

      • Basically, pulsars "transmit" all the time. Coordinating signals from Earth are only transmitted as needed, so there's a delay due to the speed of light.
        • if time delay is an issue then "as needed" means continuously - and thus no time delay so long as you have enough stations broadcasting.
    • by bruce_the_loon ( 856617 ) on Friday November 11, 2016 @06:18AM (#53263907) Homepage

      At the moment the spacecraft need data fed to them from Earth about their position and that takes time because of the speed of light.

      With this system, the spacecraft itself can calculate its position using the pulsars as if they were GPS satellites. So no delay caused by the comms to and from Earth.

      • This launch is also to characterize the x-ray pulsar data as the signals cannot be studied from within the shielding atmosphere. It is unlikely that there is enough data currently to make the position calculation reliable.

  • Pulsar navigation may allow to determine the direction in which the spacecraft is traveling, but not the actual distance from Earth, unless the spacecraft has traveled very large distances.

    A simple example. Last time I checked, Voyager1 was 18 light-hours away from Earth. Now Alpha Centauri is 4 light-years away. Multiply 4 by 365 and then by 24 and divide by 18.
    That tells us that Alpha Centauri is about 2000 times more distant than Voyager1.

    Put two dots on a blackboard, 2 meters apart. The dots represent E

  • by Anonymous Coward on Friday November 11, 2016 @08:50AM (#53264231)

    Dear editors, please write better summaries.. Something such as below is much more informative...

    China today successfully launched the world's first pulsar-based navigation satellite. The X-ray pulsar navigation satellite XPNAV-1 was sent skyward at 7:42 AM (local time) atop a Long March 11 solid-fueled rocket from the Jiuquan Satellite Launch Center in China's northwest. Pulsar navigation allows the satellite to determine its position in space by using the periodic signal emitted from pulsars, much like earth-based GPS. This will eliminate time delays incurred using ground based navigation.

  • Isn't that the satellite that's raining debris all over Eur... err, Myanmar [bbc.com]?
  • Are the Iridium sats still up there and working?

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