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A new scientific technique could significantly improve the frames of reference that millions of people rely on every day when using GPS navigation services, according to a recently published article in Radio Science.
For the first time, researchers from the University of Texas at Austin’s Applied Research Laboratories and NASA’s Goddard Space Flight Center have formed a radio interferometer between a GPS antenna and receiver and a large radio telescope. The new technique uses a type of radio interferometer, a device that measures the difference in arrival time of radio waves emitted from distant astronomical sources, with antennas that detect and record the emission.
The team used an approach called Very Long Baseline Interferometry to use the sensitivity of the radio telescope to increase the sensitivity of the GPS receiver. This extra sensitivity allowed them to extend the range of the receivers and observe powerful beams of radiation and particles generated by supermassive black holes up to 5 billion light-years away.
The discovery will improve a variety of critical scientific measurements, from tracking small land movements in earthquake-prone areas to understanding sea level changes.
“The ability to point new sources directly to GPS antennas paves the way for improvements in geodetic reference frames, which underpin modern navigation in applications from smartphones to national security,” said Johnathan York, research scientist at Applied Research Laboratories. “Improving reference frames to meet the millimeter-level consistencies required by a variety of important Earth science applications is critical to taking the next steps in robust precision positioning.”
Using data collected at the Very Long Baseline Array facility in Fort Davis, Texas, and the nearby McDonald Geodetic Observatory, the researchers were able to demonstrate multiple detections of these powerful extragalactic jets. The detections extend the distance of signals pointing to a GPS antenna, from satellites about 20,000 kilometers away to astronomical objects 5 billion light-years from Earth. This distance is equivalent to flying to a GPS satellite approximately 1 trillion times (a 1 followed by 18 zeros), or an increase of 18 orders of magnitude.
“Extending the range of a scientific instrument is common – scientists are always trying to push their instruments to the limit – but a jump of 18 orders of magnitude is certainly extraordinary,” said Leonid Petrov, chief scientist of the Space Geodesy Project at NASA Goddard . Space Flight Center.
Observations using this new combination of antennas and receivers will improve the accuracy of geodetic reference frames, which use a large number of locations measured with positioning techniques such as GPS to establish a common coordinate frame.
Future research will investigate the connections between GPS positioning and the positioning based on observations of distant astronomical sources performed by radio telescopes. Uniting these techniques will further help researchers improve the geodetic reference frames that determine how positions are measured relative to Earth.
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