Pioneer anomaly: What can we learn from LISA?

TL;DR

This paper investigates how the Pioneer anomaly, an unexplained blueshift in spacecraft data, could affect the LISA gravitational wave detector, concluding that the anomaly's impact is negligible for LISA's detection capabilities.

Contribution

It analyzes the potential influence of the Pioneer anomaly on LISA's measurements, providing insights into whether the anomaly could interfere with gravitational wave detection.

Findings

The anomalous blueshift could produce a frequency shift of 10E-16 in LISA.

Both the blueshift effect and its low-frequency component are undetectable by LISA.

The Pioneer anomaly does not impair LISA's ability to detect gravitational waves.

Abstract

The Doppler tracking data from two deep-space spacecraft, Pioneer 10 and 11, show an anomalous blueshift, which has been dubbed the "Pioneer anomaly". The effect is most commonly interpreted as a real deceleration of the spacecraft - an interpretation that faces serious challenges from planetary ephemerides. The Pioneer anomaly could as well indicate an unknown effect on the radio signal itself. Several authors have made suggestions how such a blueshift could be related to cosmology. We consider this interpretation of the Pioneer anomaly and study the impact of an anomalous blueshift on the Laser Interferometer Space Antenna (LISA), a planned joint ESA-NASA mission aiming at the detection of gravitational waves. The relative frequency shift (proportional to the light travel time) for the LISA arm length is estimated to 10E-16, which is much bigger than the expected amplitude of gravitational waves. The anomalous blueshift enters the LISA signal in two ways, as a small term folded with the gravitational wave signal, and as larger term at low frequencies. A detail analysis shows that both contributions remain undetectable and do not impair the gravitational-wave detection. This suggests that the Pioneer anomaly will have to be tested in the outer Solar system regardless if the effect is caused by an anomalous blueshift or by a real force.