DOCSLIB.ORG

The Constancy of the Pioneer Anomalous Acceleration

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Constancy of the Pioneer Anomalous Acceleration A&A 463, 393–397 (2007) Astronomy DOI: 10.1051/0004-6361:20065906 & c ESO 2007 Astrophysics The constancy of the Pioneer anomalous acceleration Ø. Olsen Institute of Theoretical Astrophysics, University of Oslo, PO Box 1029 Blindern, 0315 Oslo, Norway e-mail: [email protected] Received 26 June 2006 / Accepted 8 November 2006 ABSTRACT Aims. The temporal evolution of the Pioneer anomalous acceleration is studied to determine its correlation with solar activity. Methods. Bayesian Weighted Least Squares algorithms and Kalman filters are used to study the temporal evolution of the Pioneer anomalous acceleration. Doppler data for Pioneer 10 and 11 spanning respectively 11 and 3.5 years were used in this study. Results. The Doppler data itself can not be used to distinguish between a constant acceleration model and acceleration proportional to the remaining plutonium in the radioisotope thermoelectric generators. There are significant short term variations in the anomalous acceleration. These are shown to be consistent with radio plasma delay from coronal mass ejections. Key words. celestial mechanics – ephemerides 1. Introduction transmission time at the receiving and transmitting electronics. The integration limits t and t are the beginning and end of The Pioneer 10 and 11 missions were the two first spacecraft to 3s 3e 1 each count interval at the receiving station, while t1s and t1e are explore the outer Solar System. Anderson et al. (2002) found the start and end times of the corresponding interval at the uplink a small unmodeled acceleration acting on the spacecraft. The station. t and t can be found from t and t and the precision magnitude of the acceleration is approximately 8 × 10−8 cm/s2 1s 1e 3s 3e round-trip light time solutions ρe and ρs. The precision round- with a direction towards the inner Solar System. Explanations of trip light times were computed from this anomaly range from the new physics to overlooked conven- tional forces. Scheffer (2003) argues for non-isotropic radiation r r ρ = 23 + RLT + 12 + RLT of spacecraft heat as the most likely candidate. In this Paper I c 23 c 12 study the temporal variations of the anomalous acceleration to −∆Tt3 − ∆Tt1 see if any model can be excluded. 1 PA together with its references provide comprehensive de- + ∆Aρ(t3) +∆SCρ23 +∆Aρ(t1) +∆SCρ12 , (2) scriptions of the Pioneer spacecraft and the Deep Space Network c (DSN) communications system. This will not be repeated in this where RLTij is the Shapiro delay on the upleg and downleg light paper. time solutions. r23 is the distance between receiver at reception time and the spacecraft at retransmission time. Similarily, r12 2. Analysis of the data is the distance between transmitter at transmission time and the spacecraft at retransmission time. c is the speed of light. ∆Aρ(ti) Moyer (2000) provides the formulation for observed and com- are the off-axis antenna corrections to the receiving and trans- puted values of DSN data types for navigation. Only a cursory mitting station on Earth. The values used to calculate these cor- description for doppler data is provided in this paper as the Orbit rections where taken from Imbriale (2002). ∆SCρ3 and ∆SCρ1 are Data File (ODF) tracking data consists of time series of observed the solar corona corrections on the down and up leg. The Cassini doppler counts, which can be converted to time series of doppler model was used for this study, but as pointed out by PA, the net frequencies with given count intervals, TC. effect of the solar corona is small and can ultimately be ignored. Moyer designates the transmission time from Earth as t1,the The model itself is given by PA. ∆T3 and ∆T1 are the differences epoch of retransmission as t2 and the reception time as t3.At between Coordinated Universal Time (UTC) and Barycentric each of these epochs the Solar System Barycentric (SSB) po- Dynamical Time (TDB) at transmission and reception time. sition of the uplink station r1, spacecraft r2 and downlink sta- Troposphere and ionosphere corrections were not included tion r3 must be calculated. The range rij is defined as the mag- in the light time solution, but added as a media correction to the nitude of the vector r j − ri. Computed values for two-way and Doppler observable. Media corrections for two-way and three- three-way doppler observables are then found from way computed Doppler observables are given by t3e t1e M2R M2 F , = f (t )dt − f (t )dt , (1) M2 2 3 T 3 3 T 1 1 ∆F , = ( f (t )∆ρ − f (t )∆ρ ) . (3) TC t TC t 2 3 T 1e e T 1s s 3s 1s TC M = M = / S where 2R 2 240 221 for -band communication. ∆ρ ∆ρ f (t )and f (t ) are the transmitter frequencies at reception and e and s are the correction to the precision round-trip light T 3 T 1 times at the end and beginning of the transmission interval. The 1 Herafter denoted as PA. frequencies at the start and end of the transmission interval must Article published by EDP Sciences and available at http://www.aanda.org or http://dx.doi.org/10.1051/0004-6361:20065906 394 Ø. Olsen: The constancy of the Pioneer anomalous acceleration be known. Media corrections are computed both for the up-leg To study the variation of the anomalous acceleration, I imple- and down-leg part of the light time solution. mented a Kalman filter with stochastical variables. The anoma- Finally, partials of the computed Doppler observables with lous acceleration was modeled as a first order Markow process respect to solve-for parameters q are required: with colored noise: ∂F , M ∂ρ ∂ρ p + = m(t + , t )p + e (5) 2 3 = 2 f (t ) e − f (t ) s · (4) k 1 k 1 k k k ∂q T T 1e ∂q T 1s ∂q C and − − /τ , = (tk+1 tk) , 2.1. Relativistic equations of motion m(tk+1 tk) e (6) The spacecraft ephemeris is generated by numerically integrat- where τ is the correlation time. tk+1 and tk are the time-tags ing the equations of motion using the Bulirsh-Stoer method of observation number k and k + 1. A correlation time of zero (Press et al. 1996). The equations of motion were represented corresponds to a white noise process while an infinite correla- by the β-andγ-parameterized post-Newtonian (PPN) approx- tion corresponds to a random walk process. The evolution of the imation formulated in the solar system barycentric frame of stochastic parameter is dependent on the correlation time and the reference (Moyer 2000). General relativity corresponds to β = standard deviation, σe, of the noise vector ek. Some care must γ = 1 which were chosen for this study. Relativistic equations be taken when selecting σe. A too large value of σe allows ab- of motion are not necessary to analyze the Pioneer anomalous sorbing all of the doppler-noise into the anomalous acceleration, acceleration as demonstrated by Markwardt (2002). They are while a too small value forces the stochastic parameter to re- more than four orders of magnitude smaller than the anomalous main constant. Guided by the results of PA, σe = a0τe was cho- acceleration. sen. This preserves short-term structures and the general noise A natural choice for this study is the International Celestial level of the doppler data. The estimate of the anomalous accel- Reference Frame (ICRF) with the SSB as origin. The coordi- eration at a given time tm is based only on the preceding data- nates of the uplink station, spacecraft and downlink station (r1, points, and is therefore not optimal estimates. Hence, after for- r2 and r3) must all be expressed in the same coordinate system. ward processing of the data-sets, the results were smoothed with r2 was interpolated from the spacecraft ephemeris and therefore the Rach-Tung-Striebel (RTS) algorithm (Rauch et al. 1965). already in the desired frame of reference. The station coordi- nates had to be transformed from the International Terrestrial Reference Frame (ITRF) to the ICRF and then transformed 3. Results and discussion from the geocentric to barycentric coordinates. The International The dataset spans the time-interval from January 1987 to Earth Rotation and Reference Systems Service (IERS) 2003 con- July 1998, which is the same interval analyzed in PA. I report vention (McCarthy & Petit 2003) and Moyer (2000) covers these best fit values corresponding to each of the three intervals de- transformations. fined by PA. Interval I spans January 1st 1987 to 17 July 1990, The coordinates of the Sun, the planets and the Moon with Interval II spans July 17th 1990 to July 12th 1992 and Interval III respect to the SSB were interpolated from the Jet Propulsion continues up to July 21st 1998. Laboratory (JPL) DE405 planetary ephemeris, which uses the The parameters included in the fitting model were the ini- ICRF. The time argument of DE405 is TDB (Standish 1998), tial SSB position and velocity, a constant anomalous acceler- which was used while integrating the equations of motion. ation and instantaneous velocity increments along the Earth- spacecraft line for each maneuver. Because of the Pioneer spin, 2.2. Parameter estimation algorithms these maneuvers are only important along the Earth-spacecraft line, and I chose to use the same model as Markwardt (2002) The parameters were estimated using an ordinary Bayesian for the maneuvers. PA models the maneuvers as instantaneous Weighted Least Squares (BWLSQ) algorithm, although I ini- velocity increments along the three spacecraft axes. The timing tially used a Kalman filter to check the numerical accuracy and of each maneuver was provided by Slava Turyshev.
Load more

Recommended publications
  • The Quest to Understand the Pioneer Anomaly
    The quest to understand the Pioneer anomaly I Michael Martin Nieto, Theoretical Division (MS-8285) Los Alamos National Laboratory Los Alarnos, New Mexico 87545 USA E-mail: [email protected] +a l1 l I l uring the 1960's, when the Jet Propulsion Laboratory (JPL) Pioneer 10 was launched on 2 March 1972 local time, aboard D first started thinking about what eventually became the an Atlas/Centaur/TE364-4launch vehicle (see Fig. l).It was the "Grand Tours" of the outer planets (the Voyager missions of the first craft launched into deep space and was the first to reach an 1970's and 1980's),the use of planetary flybys for gravity assists of outer giant planet, Jupiter,on 4 Dec. 1973 [l, 21. Later it was the first spacecraft became of great interest. The concept was to use flybys to leave the "solar system" (past the orbit of Pluto or, should we now of the major planets to both mowthe direction of the spacecraft say, Neptune). The Pioneer project, eventually extending over and also to add to its heliocentric velocity in a manner that was decades, was managed at NASAIAMES Research Center under the unfeasible using only chemical fuels. The first time these ideas were hands of four successive project managers, the legendary Charlie put into practice in deep space was with the Pioneers. Hall, Richard Fimrnel, Fred Wirth, and the current Larry Lasher. While in its Earth-Jupiter cruise, Pioneer 10 was still bound to the solar system. By 9 January 1973 Pjoneer l0 was at a distance of 3.40 AU (Astronomical Units'), beyond the asteroid belt.
    [Show full text]
  • Pioneer Anomaly: What Can We Learn from Future Planetary Exploration Missions?
    56th International Astronautical Congress, Paper IAC-05-A3.4.02 PIONEER ANOMALY: WHAT CAN WE LEARN FROM FUTURE PLANETARY EXPLORATION MISSIONS? Andreas Rathke EADS Astrium GmbH, Dept. AED41, 88039 Friedrichshafen, Germany. Email: [email protected] Dario Izzo ESA Advanced Concepts Team, ESTEC, Keplerlaan 1, 2200 AG Noordwijk, The Netherlands. Email: [email protected] The Doppler-tracking data of the Pioneer 10 and 11 spacecraft show an unmodelled constant acceleration in the direction of the inner Solar System. Serious efforts have been undertaken to find a conventional explanation for this effect, all without success at the time of writing. Hence the effect, commonly dubbed the Pioneer anomaly, is attracting considerable attention. Unfortunately, no other space mission has reached the long-term navigation accuracy to yield an independent test of the effect. To fill this gap we discuss strategies for an experimental verification of the anomaly via an upcoming space mission. Emphasis is put on two plausible scenarios: non-dedicated concepts employing either a planetary exploration mission to the outer Solar System or a piggybacked micro- spacecraft to be launched from an exploration spacecraft travelling to Saturn or Jupiter. The study analyses the impact of a Pioneer anomaly test on the system and trajectory design for these two paradigms. Both paradigms are capable of verifying the Pioneer anomaly and determine its magnitude at 10% level. Moreover they can discriminate between the most plausible classes of models of the anomaly. The necessary adaptions of the system and mission design do not impair the planetary exploration goals of the missions. I.
    [Show full text]
  • Max-Planck-Institut Für Sonnensystemforschung Max Planck Institute for Solar System Research Tätigkeitsbericht 2011 Activit
    Max-Planck-Institut für Sonnensystemforschung Max Planck Institute for Solar System Research Tätigkeitsbericht 2011 Activity Report 2011 Inhalt Contents 1 Inhalt Contents 1 Wissenschaftliche Zusammenarbeit 2 Scientific collaborations 1.1 Wissenschaftliche Gäste 2 Scientific guests 1.2 Aufenthalt von MPS-Wissenschaftlern an anderen Instituten 4 Stay of MPS scientists at other institutes 1.3 Projekte in Zusammenarbeit mit anderen Institutionen 5 Projects in collaboration with other institutions 2 Vorschläge und Anträge 22 Proposals 2.1 Projektvorschläge 22 Project proposals 2.2 Anträge auf Beobachtungszeit 23 Observing time proposals 3 Publikationen 25 Publications 3.1 Referierte Publikationen 25 Refereed publications 3.2 Doktorarbeiten 45 PhD theses 4 Vorträge und Poster 46 Talks and posters 5 Seminare 69 Seminars 6 Lehrtätigkeit 73 Lectures 7 Tagungen und Workshops 74 Conferences and workshops 7.1 Organisation von Tagungen und Workshops 74 Organization of conferences and workshops 7.2 Convener bei wissenschaftlichen Tagungen 74 Convener during scientific meetings 8 Gutachtertätigkeit für wissenschaftliche Zeitschriften 75 Reviews for scientific journals 9 Herausgebertätigkeit 76 Editorship 10 Mitgliedschaft in wissenschaftlichen Gremien 76 Membership in scientific councils 11 Auszeichnungen 77 Awards Wissenschaftliche Zusammenarbeit / Scientific collaborations 2 1. Wissenschaftliche Zusammenarbeit / Scientific collaborations 1.1 Wissenschaftlich Gäste (mit Aufenthalt ≥1 Woche) Scientific guests (with stay ≥1 week) Jaime Araneda (University of Concepcion, Chile), 1 Jul - 15 Aug (host: E. Marsch) Ankit Barik (Indian Institute of Technology, Kharagpour, India), 19 May - 15 Jul (host: U. Christensen) Alexander Bazilevsky (Vernadsky Institute, Russian Academy of Sciences, Moscow, Russia), 1 Aug - 26 Aug (host: W. Markiewicz) Jishnu Bhattacharya (Indian Institute of Technology, Kanpur, India), 10 May – 18 Jul (host: L.
    [Show full text]
  • Estimating the Thermally Induced Acceleration of the New Horizons Spacecraft
    Estimating the thermally induced acceleration of the New Horizons spacecraft André G. C. Guerra,1, ∗ Frederico Francisco,1, y Paulo J. S. Gil,2, z and Orfeu Bertolami1, x 1Departamento de Física e Astronomia and Centro de Física do Porto, Faculdade de Ciências, Universidade do Porto, Portugal 2CCTAE, IDMEC, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal (Dated: November 3, 2017) Residual accelerations due to thermal effects are estimated through a model of the New Horizons spacecraft and a Monte Carlo simulation. We also discuss and estimate the thermal effects on the attitude of the spacecraft. The work is based on a method previously used for the Pioneer and Cassini probes, which solve the Pioneer anomaly problem. The results indicate that after the encounter with Pluto there is a residual acceleration of the order of 10−9 m=s2, and that rotational effects should be difficult, although not impossible, to detect. I. INTRODUCTION mination of the γ parameter of the parametrised post- Newtonian (PPN) formalism so far [9], but also led to The first probes aimed at the planets beyond the aster- the detection of a similar anomalous acceleration of ther- oid belt were launched in the 1970s, starting with the ap- mal origin, just like the Pioneer spacecraft [10]. propriately named Pioneer 10 and 11. These two space- The New Horizons mission has undergone some “hiber- craft visited Jupiter and Saturn and paved the way for nation” periods, where no thruster was fired. Therefore, the two much heavier and more sophisticated Voyager 1 it is very likely that a similar thermal origin accelera- and 2, which completed the round through all four gas gi- tion might show up in the radiometric data.
    [Show full text]
  • A Route to Understanding of the Pioneer Anomaly
    The XXII Texas Symposium on Relativistic Astrophysics, Stanford University, December 13-17, 2004 1 A Route to Understanding of the Pioneer Anomaly aSlava G. Turyshev, bMichael Martin Nieto, and cJohn D. Anderson∗ a,cJet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, USA bTheoretical Division (MS-B285), Los Alamos National Laboratory, University of California, Los Alamos, NM 87545 The Pioneer 10 and 11 spacecraft yielded the most precise navigation in deep space to date. However, while at heliocentric distance of ∼ 20–70 AU, the accuracies of their orbit reconstructions were limited by a small, anomalous, Doppler frequency drift. This drift can be interpreted as a −8 2 sunward constant acceleration of aP =(8.74 ± 1.33) × 10 cm/s which is now commonly known as the Pioneer anomaly. Here we discuss the Pioneer anomaly and present the next steps towards understanding of its origin. They are: 1) Analysis of the entire set of existing Pioneer 10 and 11 data, obtained from launch to the last telemetry received from Pioneer 10, on 27 April 2002, when it was at a heliocentric distance of 80 AU. This data could yield critical new information about the anomaly. If the anomaly is confirmed, 2) Development of an instrumental package to be operated on a deep space mission to provide an independent confirmation on the anomaly. If further confirmed, 3) Development of a deep-space experiment to explore the Pioneer anomaly in a dedicated mission with an accuracy for acceleration resolution at the level of 10−10 cm/s2 in the extremely low frequency range.
    [Show full text]
  • The Non-Gravitational Accelerations of the Cassini Spacecraft and the Nature of the “Pioneer Anomaly”
    Dipartimento di Ingegneria Astronautica e Aerospaziale Dottorato di ricerca in Ingegneria Aerospaziale Ciclo XXIII The non-gravitational accelerations of the Cassini spacecraft and the nature of the “Pioneer anomaly” Dottorando: Relatore: Mauro Di Benedetto Ch.mo Prof. Luciano Iess Anno Accademico 2010-2011 Table of Contents Introduction vi 1 The Pioneer anomaly 1 1.1 Pioneer 10 & 11 mission . 2 1.2 Spacecraft design . 3 1.3 Discovery of the anomalous acceleration . 4 1.4 Status of current investigations . 8 1.5 Contribution from this work . 9 2 CassiniteststhePioneeranomaly 10 2.1 Cassinimission .......................... 11 2.1.1 The interplanetary cruise phase . 11 2.1.2 The Saturnian phase . 12 2.2 Spacecraft design . 13 2.2.1 Cassini coordinate system . 16 2.3 Experimental method to test the Pioneer anomaly . 17 2.3.1 Inner cruise phase . 18 2.3.2 Radio science experiments in the outer cruise phase . 18 2.3.3 Multi arc method on the Saturnian phase . 20 2.3.4 Disentangling RTG and Pioneer like acceleration . 22 3 Theorbitdeterminationmethod 24 3.1 The orbit determination problem . 25 3.2 Method of differential correction . 26 3.2.1 Linearization procedure . 28 3.2.2 The weighted least squares solution . 29 3.2.3 A priori information . 31 3.3 TheODPfilter:SIGMA .. .. .. .. .. .. .. .. .. 34 3.3.1 Householder transformations . 36 3.4 Consider parameters: definition . 38 3.4.1 Mathematical formulation . 38 3.5 The multi arc method . 42 i TABLE OF CONTENTS ii 4 Radio metric observables 44 4.1 Range and range-rate observables . 45 4.1.1 Data information content .
    [Show full text]
  • The Study of the Anomalous Acceleration of Pioneer 10 and 11
    The Study of the Anomalous Acceleration of Pioneer 10 and 11 SlavaSlava G.G. Turyshev,Turyshev, JohnJohn D.D. AndersonAnderson ((JetJet PropulsionPropulsion Laboratory,Laboratory, CaltechCaltech)) MichaelMichael MartinMartin NietoNieto ((LosLos AlamosAlamos NationalNational Laboratory,Laboratory, UU ofof CaliforniaCalifornia)) Journées du GREX 2004 Nice, France, 29 October 2004 THETHE STUDYSTUDY OFOF THETHE PIONEERPIONEER ANOMALYANOMALY Conclusions & Outline: The Pioneer 10/11 anomalous acceleration: −82 aP =±(8.74 1.33) ×10 cm/s A line-of-sight constant acceleration towards the Sun: –We find no mechanism or theory that explains the anomaly – Most plausible cause is systematics, yet to be demonstrated Phys. Rev. D 65 (2002) 082004, gr-qc/0104064 Possible Origin? Conventional Physics [not yet understood]: – Gas leaks, heat reflection, drag force, etc… New Physics [many proposals exist, some interesting] Both are important − a “win-win” situation: – CONVENTIONAL explanation: improvement of spacecraft engineering for precise navigation & attitude control – NEW physics: would be truly remarkable… THETHE STUDYSTUDY OFOF THETHE PIONEERPIONEER ANOMALYANOMALY Pioneer 10/11 Mission – Built: TRW (Northrop-Grumman Space Technology) – Navigation: Jet Propulsion Laboratory, Caltech – Project management: NASA Ames Research Center Position of Pioneer 10 on 29 October 2004: Last successful precession maneuver to point the spacecraft to Earth was accomplished on 11 Feb 2000 (distance from the Sun of 75 AU) THETHE STUDYSTUDY OFOF THETHE PIONEERPIONEER
    [Show full text]
  • A Study of Anomalous Acceleration of the Pioneer 10 and 11
    The Study of the Anomalous Acceleration of the Pioneer 10 and 11 SlavaSlava G.G. Turyshev,Turyshev, JohnJohn D.D. AndersonAnderson ((JetJet PropulsionPropulsion Laboratory,Laboratory, CaltechCaltech)) MichaelMichael MartinMartin NietoNieto ((LosLos AlamosAlamos NationalNational Laboratory,Laboratory, UU ofof CaliforniaCalifornia)) The XXII Texas Symposium on Relativistic Astrophysics Stanford University, December 13-17, 2004 THETHE STUDYSTUDY OFOF THETHE PIONEERPIONEER ANOMALYANOMALY Conclusions and Outline: The Pioneer 10 and 11 anomalous acceleration: −82 aP =±×(8.74 1.33) 10 cm/s A line-of-sight constant acceleration towards the Sun: –We find no mechanism or theory that explains the anomaly – Most plausible cause is systematics, yet to be demonstrated Phys. Rev. D 65 (2002) 082004, gr-qc/0104064 Possible Origin? Conventional Physics [not yet understood]: – Gas leaks, heat reflection, drag force, etc… New Physics [many proposals exist, some interesting] A “win-win” situation, as both are important: – CONVENTIONAL explanation: improvement of spacecraft engineering for precise navigation & attitude control – NEW physics: would be truly remarkable… THETHE STUDYSTUDY OFOF THETHE PIONEERPIONEER ANOMALYANOMALY Pioneer 10/11 Mission – Built: TRW (Northrop-Grumman Space Technology) – Navigation: Jet Propulsion Laboratory, Caltech – Project management: NASA Ames Research Center Position of Pioneer 10 on 15 December 2004: Last successful precession maneuver to point the spacecraft to Earth was accomplished on 11 Feb 2000 (distance from the
    [Show full text]
  • The Pioneer Anomaly
    The Pioneer Anomaly José A. de Diego and Darío Núñez Instituto de Astronomía, Universidad Nacional Autónoma de México Ciudad Universitaria, 04510 México, D.F., México [email protected] ABSTRACT Analysis of the radio-metric data from Pioneer 10 and 11 spacecrafts has indicated the presence of an unmodeled acceleration starting at 20 AU, which has become known as the Pioneer anomaly. The nature of this acceleration is uncertain. In this paper we give a description of the effect and review some relevant mechanisms proposed to explain the observed anomaly. We also discuss on some future projects to investigate this phenomenon. RESUMEN El análisis de datos radiométricos de las naves espaciales Pioneer 10 y 11 ha indicado la presencia de una aceleración inexplicada a partir de 20 UA, que se ha dado en denominar la anomalía del Pioneer. La naturaleza de esta aceleración es incierta. En este artículo damos una descripción del efecto y hacemos una reseña de los mecanismos más relevantes que se han propuesto para explicar la anomalía observada. También discutimos algunos proyectos a futuro para investigar este fenómeno. INTRODUCTION Radiometric data from the Pioneer 10 and 11, Galileo, Ulysses and Cassini spacecrafts have Revista Mexicana de Ciencias Geológicas Ciencias de Mexicana Revista brought out the existence of an anomalous acceleration towards the Sun with a value of -10 2 aA = (8.74±1.33)×10 m/s (Anderson et al.. 2002a; 2003). The phenomenon has resisted any attempt for explanation invoking either failures in the tracking algorithm, engineering causes or external forces acting upon the space probes.
    [Show full text]
  • Gravitational Solution to the Pioneer 10/11 Anomaly
    Gravitational solution to the Pioneer 10/11 anomaly J. R. Brownstein and J. W. Moffat Perimeter Institute for Theoretical Physics, Waterloo, Ontario, N2L 2Y5, Canada Department of Physics, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada E-mail: [email protected], [email protected] Abstract. A fully relativistic modified gravitational theory including a fifth force skew symmetric field is fitted to the Pioneer 10/11 anomalous acceleration. The theory allows for a variation with distance scales of the gravitational constant G, the fifth force skew symmetric field coupling strength ω and the mass of the skew symmetric field µ =1/λ. A fit to the available anomalous acceleration data for the Pioneer 10/11 spacecraft is obtained for a phenomenological representation of the “running” constants and values of the associated parameters are shown to exist that are consistent with fifth force experimental bounds. The fit to the acceleration data is consistent with all current satellite, laser ranging and observations for the inner planets. Published Class. Quantum Grav. 23 (2006) 3427-3436 1. Introduction The radio tracking data from the Pioneer 10/11 spacecraft during their travel to the outer parts of the solar system have revealed an anomalous acceleration. The Doppler data obtained at distances r from the Sun between 20 and 70 astronomical units arXiv:gr-qc/0511026v5 16 Jan 2007 (AU) showed the anomaly as a deviation from Newton’s and Einstein’s gravitational theories. The anomaly is observed in the Doppler residuals data, as the differences of the observed Doppler velocity from the modelled Doppler velocity, and can be represented as an anomalous acceleration directed towards the Sun, with an approximately constant amplitude over the range of distance, 20 AU <r< 70 AU [1, 2, 3]: −8 −2 aP = (8.74 ± 1.33) × 10 cm s .
    [Show full text]
  • SCIENTIFIC AMERICAN 69 Onito Arth's Lit
    Should Dying Patients Get Unproved Drugs? (page 92) Saving Nature That SCIENTIFIC -WORKS FOR pagePEOPLE50 AMERICAN October 2007 $4.99 www.SciAm .co m SPECIAL REPORT The Future of " A Preview of the Orion Spaceship " 5 Essential,Things to Do Up There Consciousness Scientists Debate How Neurons Make Us Aware Diamond Chips Sparkling Processors Spin Quantum Logic Diagnosis to Go New Portable Microlabs ESSENTIAL THINGS TO DO IN SPACE Planetary scientists have articulated goals for exploring the solar system TO A CHILD OF THE SPACE AGE, system, from Mercury to Pluto. But budget cuts, books about the solar system from cost overruns and inconsistency of purpose before 1957 are vaguely horrifying . have cast long shadows over NASA. At the very How little people knew. They had least the agency is going through its most unset- no idea of the great volcanoes and tled period of transition since Nixon shot down canyons of Mars, which make the Apollo moon missions 35 years ago. Mount Everest look like a worn hill- "NASA continues to wrestle with its own iden- ock and the Grand Canyon like a road- tity," says AnthonyJanetos of the Pacific North- side ditch. They speculated that Venus west National Laboratory, a member of a Na- beneath its clouds was a lush, misty jungle, or tional Research Council (NRC) panel that scru- maybe a dry, barren desert, or a seltzer water tinized NASA's Earth observation program. "Is ocean, or a giant tar pit-almost everything, it it about exploring space? Is it about human ex- seems, but what it really is: an epic volcanic ploration, is it about science, is it about explor- wasteland, the scene of a Noah's flood in molten ing the outer universe, is it about exploring the rock.
    [Show full text]
  • Preliminary Design of an Advanced Mission to Pluto
    ISTS 2004-k-10 PRELIMINARY DESIGN OF AN ADVANCED MISSION TO PLUTO Torsten Bondo, Roger Walker, Andrew Willig*, Andreas Rathke, Dario Izzo and Mark Ayre ESA/ESTEC Advanced Concepts Team, *ESA/ESTEC Earth Observation Department Keplerlaan 1 2200 AZ, Nordwijk ZH, The Netherlands www.esa.int/act (E-mail: [email protected], [email protected] ) Abstract A technology assessment and feasibility study is being In this paper we present a system engineering study of performed within the ESA Advanced Concepts Team on POP (Pluto Orbiter Probe) a spacecraft of 830 kg that sending a small-to-medium (700-900 kg) Nuclear requires ~1 kW of nuclear power to feed its electric Electric Propulsion spacecraft into orbit around Pluto propulsion system. The preliminary spacecraft system with a mission launch in 2016 using existing or design, example payload and overall mission design is emerging space technology. The objective of the study is presented in detail. This includes a low thrust capture at to examine which technologies are needed to achieve Pluto and spiral down to low altitude orbit via Charon. this objective and to understand how current technology Furthermore it is pointed out that at no cost in ∆V trends can modify this scenario in the future. tracking data on the coast phase towards Pluto can investigate the anomalous deceleration reported from It is found that a feasible mission, that includes a pioneer Pioneer 10 and 11. anomaly test on the cruise phase, can be accomplished if technologies such as gridded ion engines coupled to 2. POP Mission Analysis - Cruise Phase and orbit multiple Radioisotope Thermal Generators, composite insertion at Pluto structures and miniaturised avionics/payload are For a spacecraft below 1000 kg a direct transfer to Pluto considered.
    [Show full text]