Gravitational experiments on a solar probe mission: Scientific objectives and technology considerations

The concept of a solar impact probe (either solar plunger or sun grazer) led to the initiation of a NASA study at JPL in 1978 on the engineering and scientific feasibility of a Solar Probe Mission, named Starprobe, in which a spacecraft is placed in a high eccentricity orbit with a perihelion near 4 solar radii. The Starprobe study showed that the concept was feasible and in fact preliminary mission and spacecraft designs were developed. In the early stages of the Solar Probe studies the emphasis was placed on gravitational science, but by the time of a workshop at Caltech in May 1978 (Neugebauer and Davies, 1978) there was about an equal division of interest between heliospheric physics and gravitation. The last of the gravitational studies for Solar Probe was conducted at JPL in 1983. Since that time, the Committee on Solar and Space Physics (CSSP) of the National Academy of Sciences has recommended the pursuit of a focused mission, featuring fields and particles instrumentation and emphasizing studies of the solar wind source region. Such a solar probe mission is currently listed as the 1994 Major New Star candidate. In the remainder of this review, the unique gravitational science that can be accomplished with a solar probe mission is reviewed. In addition the technology issues that were identified in 1980 by the ad hoc working group for Gravity and Relativity Science are addressed

Pioneer Anomaly and the Helicity-Rotation Coupling

The modification of the Doppler effect due to the coupling of the helicity of the radiation with the rotation of the source/receiver is considered in the case of the Pioneer 10/11 spacecraft. We explain why the Pioneer anomaly is not influenced by the helicity-rotation coupling.Comment: LaTeX file, 1 figure, 6 pages, v2: note and figure added at the end of the paper, to be published in Phys. Lett.

Comparison of Hedging Cost with Other Variable Input Costs

Recent spikes in commodity prices have led to higher margin amounts and option premiums. For the most part, producers have always attributed their lack of use in reducing risk via futures and options markets to the high cost associated with the use of these markets. This study determines the relative costs of hedging with futures and options and compares these with the costs of other variable inputs. We find that with the exception of hedging corn with both tools and soybeans with options the costs of hedging has only increased at roughly the same rate as all other inputs.Hedging costs, Costs of production, Risk management, Agribusiness, Agricultural Finance, Demand and Price Analysis, Farm Management, Marketing, Risk and Uncertainty,

Producer Perceptions of Corn, Soybean and Cotton Price Risk

Risk is an inevitable part of agricultural production and all producers face various forms of risk. This study used the subjective price expectations and price distributions of survey participants to determine how producer’s expectations compare with that of the market. Data used for this study were gathered through survey responses from Mississippi State University Extension meeting and workshop participants. Individual respondent’s discreet stated price and price distribution information was fitted to a continuous distribution and an implied mean and standard deviation was determined. This was compared to market price and price risk data. Participants largely over-estimated price. Individual volatilities resulting from each fitted distribution were lower than that implied by the market.price risk, price perception, subjective probability elicitation, Production Economics, Q13,

Lessons Learned from the Pioneers 10/11 for a Mission to Test the Pioneer Anomaly

Analysis of the radio-metric tracking data from the Pioneer 10/11 spacecraft at distances between 20--70 astronomical units (AU) from the Sun has consistently indicated the presence of an anomalous, small, constant Doppler frequency drift. The drift is a blue-shift, uniformly changing with rate a_t = (2.92 +/- 0.44) x 10^(-18) s/s^2. It can also be interpreted as a constant acceleration of a_P = (8.74 +/- 1.33) x 10^(-8) cm/s^2 directed towards the Sun. Although it is suspected that there is a systematic origin to the effect, none has been found. As a result, the nature of this anomaly has become of growing interest. Here we discuss the details of our recent investigation focusing on the effects both external to and internal to the spacecraft, as well as those due to modeling and computational techniques. We review some of the mechanisms proposed to explain the anomaly and show their inability to account for the observed behavior of the anomaly. We also present lessons learned from this investigation for a potential deep-space experiment that will reveal the origin of the discovered anomaly and also will characterize its properties with an accuracy of at least two orders of magnitude below the anomaly's size. A number of critical requirements and design considerations for such a mission are outlined and addressed.Comment: 11 pages, invited talk given at ``35th COSPAR Scientific Assebly,'' July 18-24, 2004, Paris, Franc

Seeking a solution of the Pioneer Anomaly

The 1972 and 1973 launched Pioneer 10 and 11 were the first missions to explore the outer solar system. They achieved stunning breakthroughs in deep-space exploration. But around 1980 an unmodeled force of \sim 8 \times 10^{-8} cm/s^2, directed approximately towards the Sun, appeared in the tracking data. It later was unambiguously verified as not being an artifact. The origin remains unknown (although radiant heat remains a likely cause). Increasing effort has gone into understanding this anomaly. We review the situation and describe programs to resolve the issue.Comment: 7 pages, 1 figure, invited talk at the Fourth Meeting on CPT and Lorentz Symmetry, 8-11 Aug. 2007, held at Indiana Universit

Earth Flyby Anomalies

In a reference frame fixed to the solar system's center of mass, a satellite's energy will change as it is deflected by a planet. But a number of satellites flying by Earth have also experienced energy changes in the Earth-centered frame -- and that's a mystery.Comment: 5 pagea 3 figure

A Mission to Test the Pioneer Anomaly

Analysis of the radio tracking data from the Pioneer 10/11 spacecraft has consistently indicated the presence of an anomalous small Doppler frequency drift. The drift can be interpreted as being due to a constant acceleration of a_P= (8.74 +/- 1.33) x 10^{-8} cm/s^2 directed towards the Sun. Although it is suspected that there is a systematic origin to the effect, none has been found. The nature of this anomaly has become of growing interest in the fields of relativistic cosmology, astro- and gravitational physics as well as in the areas of spacecraft design and high-precision navigation. We present a concept for a designated deep-space mission to test the discovered anomaly. A number of critical requirements and design considerations for such a mission are outlined and addressed.Comment: Final changes for publication. Honorable Mention, 2002 Gravity Research Foundation Essay