Flyby anomaly

The fly-by- abnormality refers to a phenomenon so far unexplained gravity research. It is a small additional increase in speed, which have undergone several space probes at a fly-by to Earth.

Observation

After the launch of space probes so-called fly-by maneuvers are performed frequently. In these maneuvers, the probes fly partially several times past the earth and the path of the emissions before and after a fly-by is detected with high accuracy. Deviations from the predicted velocity were first measured in 1990 the Galileo spacecraft.

The first flyby of the Galileo spacecraft on December 8, 1990 959.9 kilometers altitude an increase in the Doppler shift of the signal transmitted by Galileo from 5 GHz to 66 mHz was found that an unexpected increase in speed of 3.92 mm / s corresponded. Extensive studies at the Jet Propulsion Laboratory, Goddard Space Flight Center and the University of Texas could find neither measurement error nor other explanations for the deviations. As Galileo approached the Earth at the second Earth swing on 8 December 1992 up to 303.1 kilometers, the spacecraft flew through the already high atmosphere. Suitable measurements to confirm discovered the first flyby deviations were therefore not possible.

Further deviations were observed in the order in case the spacecraft NEAR Shoemaker and Rosetta. As on 23 January 1998, the NEAR Shoemaker probe passed by the Earth in 538.8 kilometers away, an unexpected increase in the Doppler shift of 730 mHz, what / s corresponds to a speed increase of 13.46 mm showed. This was the strongest observed deviation. As the Rosetta spacecraft on 4 March 2005 flew past Earth in 1954 km altitude, resulted from the Doppler measurements, an unexplained increase in speed of 1.82 mm / s The data from the space probe Cassini -Huygens in this regard are useless, because the probe has accelerated over their own engines during the fly-by. When the spacecraft Messenger, however, was not measured fly-by anomaly in August 2005.

Changes in airspeed 10 and 11 are observed since the 1980s, even in the space probes Pioneer. Here, the phenomenon is referred to as Pioneer anomaly. It has been speculated that this is the same phenomenon. Meanwhile, the mystery of the Pioneer anomaly, however, seems solved, which means that the fly-by anomaly would have to have another reason.

Attempts to explain

The currently unexplained discrepancy is small enough to be neglected in satellite missions can, however, leads to doubts whether the gravitational physics of the solar system is fully understood. The predicted by general relativity Lense- Thirring effect is not sufficient for the observations. Meanwhile an empirical formula to calculate the fly-by anomaly has been developed by researchers at the Jet Propulsion Laboratory, after this depends on the approach and departure angle relative to the equator. At the flyby of the Rosetta spacecraft in November 2007, but a determined on the basis of this formula deviation could not be confirmed.

A hypothesis of Jean -Paul Mbelek by the French nuclear research center CEA- Saclay proposes to explain the anomaly with the special theory of relativity. In his view, the anomaly is due no physical effect in the strict sense, but only to the inadequate because nonrelativistic consideration of the phenomenon.

Since the fly-by anomaly in the second and third fly-by the Rosetta spacecraft did not occur, keep researchers of the " International Flyby Collaboration " at the International Space Science Institute ( ISSI ), Bern, explores the fly-by anomaly, now also an inaccuracy in dating from the 1960s algorithm might consider using all the computer programs for the calculation of fly- bys.