GPS Constellations used to probe Earth's mass

Earth may be heaver than thought due to invisible belt of dark matter
no picture of dark matter available ;-)



In 2009, researchers at the Institute of Advanced Studies in Princeton, N.J., theorized that observed changes in the speeds of space probes as they flew past the Earth could be explained by dark matter bound by Earth's gravity.

Can the flyby anomaly be attributed to earth-bound dark matter?
Stephen L. Adler∗ Institute for Advanced Study, Einstein Drive, Princeton, NJ 08540, USA

We make preliminary estimates to assess whether the recently reported flyby anomaly can be attributed to dark matter interactions. We consider both elastic and exothermic inelastic scattering from dark matter constituents; for isotropic dark matter velocity distributions, the former decrease, while the latter increase, the final flyby velocity. The fact that the observed flyby velocity anomaly shows examples with both positive and negative signs, requires the dominance of different dark matter scattering processes along different flyby trajectories. 

The magnitude of the observed anomalies requires dark matter densities many orders of magnitude greater than the galactic halo density. Such a large density could result from an accumulation cascade, in which the solar system-bound dark matter density is much higher than the galactic halo density, and the earth-bound density is much higher than the solar system-bound density. We discuss a number of strong constraints on the hypothesis of a dark matter explanation for the flyby anomaly. These require dark matter to be non-selfannihilating, with the dark matter scattering cross section on nucleons much larger, and the dark matter mass much lighter, than usually assumed.

Ben Harris

Now Ben Harris at the University of Texas at Arlington used orbiting satellites to see if dark matter might be affecting them. Using data on the satellites in the U.S. GPS, Russian GLONASS and European Galileo groups, he calculated Earth's mass as "felt" by each satellite.

GPS satellites suggest Earth is heavy with dark matter - physics-math - 02 January 2014 - New Scientist

Harris has yet to account for perturbations to the satellites' orbits due to relativity, and the gravitational pull of the sun and moon. What's more, preliminary data from NASA's Juno probe, also presented at the AGU Fall meeting, suggests its speed was as expected as it flew by Earth, casting doubt on the earlier anomalies.

But if Harris's explanation is correct, satellites could reveal properties of dark matter, such as whether its particles interact with each other.

Ben Harris has fifteen years of R&D experience with navigation and telecommunication satellite systems. For the majority of that time he worked at Applied Research Laboratories, the University of Texas at Austin, on a project that enhanced the performance of the GPS system. During that period he helped establish the open source project the GPS Toolkit (www.gpstk.org). He has focused on how receivers can mitigate the impact of signal reflection (multipath). He is exploring a variety of techniques, including the application of software receivers and new antenna designs.

Earth May Have Dark Matter Halo - disinformation