Pioneer Anomaly Test – Jonathan Fitt 1 System Design Assessment for a Mission to Explore the Pioneer Anomaly Jonathan Fitt Monday, 15 June /pioneer_anomaly/

Pioneer Anomaly Test - Jonathan Fitt 2 Contents Pioneer Anomaly Components of Project Work Specific Details of Project Work Project Summary

Pioneer Anomaly Test - Jonathan Fitt 3 What is the Pioneer Anomaly? The Pioneer Anomaly can be interpreted as a constant radial deceleration of Pioneer 10 and 11s’ velocity in the direction of the sun which was identified in Doppler tracking data.

Pioneer Anomaly Test - Jonathan Fitt 4 Doppler Residuals – Doppler Velocity

Pioneer Anomaly Test - Jonathan Fitt 5 Pioneer Orbits 20 A.U Km/s ’ A.U. 90 A.U. Modified from Anderson, J.D., et al., 2002, Phys. Rev. D 65

Pioneer Anomaly Test - Jonathan Fitt 6 Project Components 1.Understanding the method behind discovering the Anomaly – updating to 21 st century 2.An improved method to explore the Pioneer Anomaly 3.A potential use of new data

Pioneer Anomaly Test - Jonathan Fitt 7 Design Requirements Explore the Anomaly to ms -2 level of accuracy Ability to distinguish between gravitational and non- gravitational origin of the Anomaly A craft on an escape hyperbolic trajectory A velocity significantly different to the Pioneer craft Communication in X-band A passive retroreflector test mass Radio ranging from the Earth to the primary craft Laser ranging from the primary craft to the test mass

Pioneer Anomaly Test - Jonathan Fitt 8 1. Understanding and Updating Interpretation of Doppler residuals Doppler measurement errors Solar corona phase scintillation Random number generation + Data analysis

Pioneer Anomaly Test - Jonathan Fitt 9 2. An Improved Method Bounds on planetary orbits New system architecture Range measurement & error Data rate Laser range measurement Radio communication link Position Control System Mass/power budget

Pioneer Anomaly Test - Jonathan Fitt Potential Behaviour of the primary/test mass system How to use data from the new system to differentiate between a gravitational and a non-gravitational origin of the Pioneer Anomaly.

Pioneer Anomaly Test - Jonathan Fitt 11 Understanding & Updating Doppler Errors Doppler Jitter:- Statistically inherent to the Doppler process Dependent on the characteristics of the radio link Constant Allan Deviation:- Due to instability oscillator Improves with extended observations Solar Corona Phase scintillation:- Caused by radio wave passing through the solar corona Randomly changes the phase of the carrier wave Manifested as an error in Doppler velocity Present for an SEP between 5 and 27 degrees Below 5 degrees too large to make measurement Doppler jitter: mm/s Allan deviation: mm/s Solar Corona: 0.6 mm/s (at its highest)

Pioneer Anomaly Test - Jonathan Fitt 12 Doppler Residual Model Summary

Pioneer Anomaly Test - Jonathan Fitt 13 Possible Mechanism The Anomaly could be explained by heat radiating un-symmetrically from the craft Although 21 st century offers better accuracy, it does eliminate this mechanism Need a new system

Pioneer Anomaly Test - Jonathan Fitt 14 An Improved Method Primary/Test mass System Earth Primary Test mass Use a system that uses a primary craft with a test mass – similar to a drag free spacecraft but with the test mass outside of the craft. By taking the vector addition of the Earth/primary range and the primary/test mass range any movement in primary position will not affect the overall result

Pioneer Anomaly Test - Jonathan Fitt 15 Range Residual

Pioneer Anomaly Test - Jonathan Fitt 16 Range Residual

Pioneer Anomaly Test - Jonathan Fitt 17 Uplink Link Budget

Pioneer Anomaly Test - Jonathan Fitt 18 Downlink Link Budget

Pioneer Anomaly Test - Jonathan Fitt 19 Perturbations on Primary

Pioneer Anomaly Test - Jonathan Fitt 20 Perturbations on Primary

Pioneer Anomaly Test - Jonathan Fitt 21 Positioning Control System

Pioneer Anomaly Test - Jonathan Fitt 22 Positioning Control System

Pioneer Anomaly Test - Jonathan Fitt 23 Mass/Power Budget

Pioneer Anomaly Test - Jonathan Fitt 24 A Potential Use of New Data 1.Both primary and test mass feel a force acting towards the sun due to solar gravity 2.Both craft can potentially experience any unknown forces (Pioneer Anomaly) 3.The primary craft will experience forces acting on it due to the local space environment (solar radiation pressure) 4.Any onboard systematic forces such as heat radiation will affect the primary 5.The test mass will not be affected by onboard systematic forces as it is passive 6.The test mass will not experience environmental forces because it is in an environmentally quiet position relative to the primary

Pioneer Anomaly Test - Jonathan Fitt 25 Equation of Motion of Primary Craft

Pioneer Anomaly Test - Jonathan Fitt 26 Equation of Motion of Test Mass

Pioneer Anomaly Test - Jonathan Fitt 27 Test Mass Motion Relative to the Primary The bracketed term describes the motion of the test mass relative to the primary craft due to any unknown forces acting on both the primary and the test mass, positive in the sun direction.

Pioneer Anomaly Test - Jonathan Fitt 28 The Origin of the Pioneer Anomaly These unknown forces could be the Pioneer Anomaly If the Pioneer Anomaly is gravitational in nature then there will be no relative motion If the Anomaly is due to a drag force or a radiation force then the primary will experience a smaller force than the test mass Observed as a change in primary/test mass distance over time.

Pioneer Anomaly Test - Jonathan Fitt 29 A Potential Use of Data

Pioneer Anomaly Test - Jonathan Fitt 30 System Behaviour Gravitational behaviour Non-gravitational behaviour

Pioneer Anomaly Test - Jonathan Fitt 31 Possible Results

Pioneer Anomaly Test - Jonathan Fitt 32 Summary Studied the Pioneer Anomaly – how it was discovered A model created Updates were explored A new system architecture was adopted System design requirements built up A potential of the new system highlighted

Pioneer Anomaly Test - Jonathan Fitt 33 Questions