STANFORD UNIVERSITY
EE 350 RADIOSCIENCE SEMINAR
Professor Antony Fraser-Smith
Fall 2000-2001
Date: Wednesday, June 6, 2001
Time: 4:15-5:30 PM; Refreshments at 4:00 PM
Location: Bldg. 200, Rm. 34
Study of the Anomalous Accelerations of Pioneer 10 and 11
Drs. Slava G. Turyshev and John Anderson
NASA Jet Propulsion Laboratory
Abstract
Our previous analyses of radio Doppler and ranging data from distant
spacecraft in the solar system indicated that an apparent anomalous
acceleration is acting on Pioneer 10 and 11, with supporting data from the
Galileo and Ulysses spacecraft.The data implied an anomalous,
constant acceleration with a magnitude a_P ~ 8 x 10^-8 cm/s^2, directed towards the Sun.Much effort
has been expended looking for possible systematic origins of the
residuals.We provide a detailed investigation of effects both
external to and internal to the spacecraft, as well as those due to
modeling and computational techniques.Our analyses strongly suggest
that it is difficult to understand how any of these mechanisms can
explain the magnitude of the observed behavior of the Pioneer
anomaly.
There are now further data for the Pioneer 10 orbit determination. The
extended Pioneer 10 data set spans 3 January 1987 to 22 July 1998.[For Pioneer 11 the shorter span goes from 5 January 1987 to the time of
loss of coherent data on 1 October 1990.]With these data sets
and more detailed studies of all the systematics, we
can now give a total error budget for our analysis and a result
a_P = (8.76 a_P = (8.76+/-0.92)x10^8 cm/s^2.