17 research outputs found
Thermal recoil force, telemetry, and the Pioneer anomaly
Precision navigation of spacecraft requires accurate knowledge of small
forces, including the recoil force due to anisotropies of thermal radiation
emitted by spacecraft systems. We develop a formalism to derive the thermal
recoil force from the basic principles of radiative heat exchange and
energy-momentum conservation. The thermal power emitted by the spacecraft can
be computed from engineering data obtained from flight telemetry, which yields
a practical approach to incorporate the thermal recoil force into precision
spacecraft navigation. Alternatively, orbit determination can be used to
estimate the contribution of the thermal recoil force. We apply this approach
to the Pioneer anomaly using a simulated Pioneer 10 Doppler data set.Comment: 10 pages, 3 figures. Published versio
The Pioneer Anomaly
Radio-metric Doppler tracking data received from the Pioneer 10 and 11
spacecraft from heliocentric distances of 20-70 AU has consistently indicated
the presence of a small, anomalous, blue-shifted frequency drift uniformly
changing with a rate of ~6 x 10^{-9} Hz/s. Ultimately, the drift was
interpreted as a constant sunward deceleration of each particular spacecraft at
the level of a_P = (8.74 +/- 1.33) x 10^{-10} m/s^2. This apparent violation of
the Newton's gravitational inverse-square law has become known as the Pioneer
anomaly; the nature of this anomaly remains unexplained. In this review, we
summarize the current knowledge of the physical properties of the anomaly and
the conditions that led to its detection and characterization. We review
various mechanisms proposed to explain the anomaly and discuss the current
state of efforts to determine its nature. A comprehensive new investigation of
the anomalous behavior of the two Pioneers has begun recently. The new efforts
rely on the much-extended set of radio-metric Doppler data for both spacecraft
in conjunction with the newly available complete record of their telemetry
files and a large archive of original project documentation. As the new study
is yet to report its findings, this review provides the necessary background
for the new results to appear in the near future. In particular, we provide a
significant amount of information on the design, operations and behavior of the
two Pioneers during their entire missions, including descriptions of various
data formats and techniques used for their navigation and radio-science data
analysis. As most of this information was recovered relatively recently, it was
not used in the previous studies of the Pioneer anomaly, but it is critical for
the new investigation.Comment: 165 pages, 40 figures, 16 tables; accepted for publication in Living
Reviews in Relativit