Pioneer Anomaly Test – Jo nathan Fitt 1 Design Assessment of Lunar, Planetary and Satellite Ranging Applied to Fundamental Physics Jonathan Fitt Monday, June 13, 2022 http://www.sr.bham.ac.uk/yr4p asr/project05/pioneer_anomaly / A mission to test the Pioneer Anomaly
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Design Assessment of Lunar, Planetary and Satellite Ranging Applied to Fundamental Physics
Design Assessment of Lunar, Planetary and Satellite Ranging Applied to Fundamental Physics. Jonathan Fitt Thursday, 23 October 2014 http://www.sr.bham.ac.uk/yr4pasr/project05/pioneer_anomaly/. A mission to test the Pioneer Anomaly. Contents. What are Lunar/Planetary/Satellite ranging? - PowerPoint PPT Presentation
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Pioneer Anomaly Test – Jonathan Fitt
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Design Assessment of Lunar, Planetary and Satellite Ranging Applied to Fundamental Physics
• What are Lunar/Planetary/Satellite ranging?• Background to Pioneer Mission• Tracking the Pioneer craft• The Pioneer Anomaly• Exploring the Pioneer Anomaly• Direction & Summary
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Lunar Ranging
Lunar Ranging has been an experiment ongoing since the Apollo missions.
Pulses of laser light are sent to the moon and are reflected back by retro-reflectors left behind after landings.
The round trip light time (RTLT) of the pulse fundamentally defines the distance to the point on the moon.
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Planetary Ranging
Planetary ranging works on the same principle as Lunar Ranging but uses radio waves instead.
Radio waves are sent out from the Earth towards a planet and are either reflected back (Venus) or transponded back from a Lander (Mars).
The RTLT gives the distance information and the Doppler shift of the radio wave gives velocity information.
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Satellite Ranging
Earth orbiting satellites reflect laser light back down to Earth.
The LAGEOS mission uses passive retro-reflector satellites.
Active satellites can transmit their own signal and wait for it to be reflected off of the planet; Mars Global Surveyor.
The LAGEOS satellites provided valuable information about the structure and composition of the Earth.
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Satellite Ranging
Ranging does not have to be confined to craft orbiting planetary bodies.
Craft on interplanetary and outer solar system trajectories can also be tracked using ranging and Doppler methods.
Notable examples are Pioneer 10 & 11, the Voyager craft and Cassini.
Whilst the Pioneer craft were being tracked their Doppler information began to exhibit an un-modelled deceleration.
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Pioneer 10
Pioneer 10 was launched on 2nd March 1972 from Cape Canaveral. It was launched on board an Atlas/Centaur rocket.Pioneer 10 successfully encountered Jupiter on 4th December 1973
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Pioneer 10 & 11
In June 1983 Pioneer 10 was the first spacecraft to leave the solar system.
Pioneer 10 was also the first craft to enter the edge of interstellar space.
Pioneer 11 encountered Saturn and then left the solar system on a similar trajectory to Pioneer 10 but in the opposite direction
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Pioneer Orbits
20 A.U.
12.2 Km/s
’97
2000
67 A.U.75 A.U.
Modified from Anderson, J.D., et al., 2002, Phys. Rev. D 65
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Pioneer 10 – Layout
Anderson, J.D., et al., 2002, Phys. Rev. D 65
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Tracking The Pioneer Spacecraft
As the Pioneer craft got further into deep space the larger dishes of the Deep Space Network were needed to keep track of them
The DSN provided phase coherent tracking, telemetry and control (TT&C) at S-band
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Radio Science – Doppler Tracking
Doppler experiment: radio signal transmitted from the Earth to the spacecraft, coherently transponded and sent back to the Earth.
The frequency change of the received signal is measured with great accuracy.This is done over an integration time. And the craft is monitored over an observation time.
The observable is the received frequency.
The result is a ‘range rate’ of the spacecraft.
TfcvRf )1(
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Doppler Residual/Drift
caf
tff pobs 0mod DriftDoppler
2
f)( ResidualDoppler 20
mod
ctaf p
DSNobsff
For Pioneer 10 at S-band over 60s integration time.
Hzf 71070.7
210 )10168.8( msa p
19 )1099.5(Drift Doppler Hzs
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Doppler Velocity
The Doppler residual can be converted into a Doppler velocity
For S-band: 1 Hz = 68.2 mm/sTf
fc2
vlocity,Doppler ve D
Pioneer Anomaly Doppler velocity over 60s is 5.24x10-5 mm/s
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The Pioneer Anomaly
Beginning in 1987 and up until 1998 the Doppler data showed a constant residual deceleration in the range rate of the craft.
The Pioneer craft were tracked throughout their mission life.Doppler Velocity at S-band of Pioneer 10 between 1987 to 1998
-250
-200
-150
-100
-50
00 500 1000 1500 2000 2500 3000
Time (days)
Dopp
ler V
eloc
ity (m
m/s
)
Over this time Pioneer 10 moved 57 500 Km out of position.
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The Pioneer Anomaly
Actual plot of the data used to detect the Pioneer Anomaly between 1987 and 1998.
Anderson, J.D., et al., 2002, Phys. Rev. D 65
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A Mission to Test the Pioneer Anomaly
• The project is based on the proposal: A Mission to Explore the Pioneer Anomaly, http://arxiv.org/abs/gr-qc/0506139
• The proposal outlines key features needed for such a mission
• Can these requirements be realised• What limits does the mission science place
on the craft• With these requirements will the Pioneer
Anomaly be tested
Spacecraft Requirements
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Pioneer Collaboration Proposal
•Spin stabilised•Passive retro-reflector test mass•Symmetric design•Radio ranging from the Earth to the mother craft•Laser ranging to the test mass from the mother craft•Remove common mode noise
Is this design to complicated?Can the required accuracy be achieved with current radio Doppler ranging?
A Mission to Explore the Pioneer Anomaly
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The Experiment
• The mother craft will follow the test mass at a distance of 1 Km
ydx
The Earth/proof mass range is unaffected by mother craft motion
Penanen and Chui, arxiv: gr-qc/0406013
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Current Project Work
Doppler Errors
Link Budget
Power Source
Mass/power budget
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Doppler Errors – jitter
To ensure that the observed Doppler velocity is due to the Pioneer Anomaly and not the Doppler jitter the craft needs to be tracked for a period of 2/5 of a day.
TransmittedEIRP (dBW) 96.00ponting loss (dB) -0.20atmospheric loss (dB) -0.15Receivedspreading loss (m -̂2) 4.44E-27 -263.52free space loss (m 2̂) 1.11639E-05 -49.52antenna gain (dB) 42.00amp gain (dB) 0.00antenna efficiency 0.6 -2.22Received Power (dBW) 1.67E-18 -177.76
Values taken from current work, design related to Doppler errors, link budget and power source
3 RTGs for symmetry about the spin axis
Max mass 300 Kg
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Future work
• Add to the power/mass budget for the Anomaly Test mission
• Work on the error budget for the Doppler radio link
• Create a design for the laser ranging link• Work on a laser link error budget• Design characteristics for the laser detector• Look into dimensions for the Test mission
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Summary
• Ranging techniques are used to test gravity theory
• The Pioneer Mission was simple yet effective
• Doppler tracking techniques are well developed
• Doppler velocity is crucial observable
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Summary
• Pioneer Anomaly deceleration is (8.74±1.33)x10-10 ms-2
• Characteristics for a mission to test the Anomaly – problem with velocity/range measurement integration
• Learn from the Pioneer Mission
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End
Any questions?
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Questions about the design
• High level of accuracy achievable with Doppler measurement of anomaly, 9.13x10-15 ms-2
• Earth/primary – Doppler measurement• Primary/test mass – range measurement• Radio ranging Earth/primary accurate to