YADMI (Yet Another Dark Matter Idea)

Ars Technica said:

When a theoretical astrophysicist looks up at the nighttime sky, he or she will see the stars shining overhead. But what concerns the physicist is not what he or she sees but rather what is unseen. Based upon different kinds of observations, such as how galaxies rotate and how they are flying apart from one another, scientists know that 95 percent of the of the universe is made of up stuff we cannot see. Of the universe's mass, physicists say 27 percent is dark matter, and 68 percent is dark energy. And researchers have no idea what this stuff is or where to find it.

Yet a scientist at NASA’s Jet Propulsion Laboratory has now provided a clue about where dark matter—and lots of it—might be found. In a new study published in the Astrophysical Journal, Gary Prézeau has proposed that Earth and other planets and stars in the Milky Way galaxy are surrounded by theoretical filaments of dark matter called "hairs.” By finding the roots of these hairs, he reports, physicists could uncover a trove of dark matter.

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So far, all of this searching has been to no avail. And while the experimental physicists have flailed about in the dark searching for dark matter, theoretical physicists have turned to their computer simulations. During the 1990s, theoretical physicists performed simulations and found that this dark matter could orbit galaxies like the Milky Way in fine-grained streams. Now Prézeau has taken this idea a step further and modeled what happens to this dark matter when it passes through star systems like our own solar system.

What he found is a bit like light coming into a telescope, Nick Suntzeff, an astrophysicist at Texas A&M University, told Ars. When a telescope points at a star, light still comes into the instrument from every direction, but the light coming from the star is moving along parallel lines with a strong signal. When a telescope focuses on a star, it is simply collecting only this parallel light. In his paper, Prézeau says the same thing happens with dark matter.

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Wikipedia said:

Gravitational assists are valuable techniques for Solar System exploration. Because the success of these flyby maneuvers depends on the geometry of the trajectory, the position and velocity of a spacecraft is continually tracked during its encounter with a planet by the Deep Space Network (DSN).

The flyby anomaly was first noticed during a careful inspection of DSN Doppler data shortly after the Earth-flyby of the Galileo spacecraft on 8 December 1990. While the Doppler residuals (observed minus computed data) were expected to remain flat, the analysis revealed an unexpected 66 mHz shift, which corresponds to a velocity increase of 3.92 mm/s at perigee. An investigation of this effect at the Jet Propulsion Laboratory (JPL), the Goddard Space Flight Center (GSFC) and the University of Texas has not yielded a satisfactory explanation. No anomaly was detected after the second Earth-flyby of the Galileo spacecraft in December 1992, because any possible velocity increase was masked by atmospheric drag of the lower altitude of 303 km.

On 23 January 1998 the Near Earth Asteroid Rendezvous (NEAR) spacecraft experienced an anomalous velocity increase of 13.46 mm/s after its Earth encounter. Cassini–Huygens gained ~0.11 mm/s in August 1999 and Rosetta 1.82 mm/s after its Earth-flyby in March 2005.

An analysis of the MESSENGER spacecraft (studying Mercury) did not reveal any significant unexpected velocity increase. This may be because MESSENGER both approached and departed Earth symmetrically about the equator (see data and proposed equation below). This suggests that the anomaly may be related to Earth's rotation.

In November 2009, ESA's Rosetta spacecraft was tracked closely during flyby in order to precisely measure its velocity, in an effort to gather further data about the anomaly, but no significant anomaly was found.[2][3]

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