In March 2008 anomalous behavior in spacecraft flybys of Earth was reported in Physical
Review Letters, Volume 100, Issue 9, March 7, 2008, in an article entitled "Anomalous
Orbital-Energy Changes Observed during Spacecraft Flybys of Earth".
The data indicate unaccounted for changes in spacecraft speed, both increases and
decreases, for six different spacecraft involved in Earth flybys from December 8, 1990 to August
2, 2005. The article states that, "All ... potential sources of systematic error .... [have been]
modeled. None can account for the observed anomalies.... Like the Pioneer anomaly ... the
Earth flybys anomaly is a real effect .... Its source is unknown."
In this article it is shown that the Earth flybys anomaly is caused by a very small centrally
directed acceleration, [in addition to that of natural gravitation], the same effect as that which
produces the Pioneer anomaly. How that effect operates to produce the observed results is
analyzed. A common cause of the centrally directed accelerations is presented.