SCIENTIFIC AND TECHNICAL AEROSPACE REPORTS

A Biweekly Publication of the National Aeronautics and Space Administration
VOLUME 44, ISSUE 12 - JUNE 20, 2006

92 SOLAR PHYSICS
Includes solar activity, solar flares, solar radiation and sunspots.

For related information see 93 Space Radiation.

20060014032 Jet Propulsion Lab., California Inst. of Tech., Pasadena, CA, USA

Experimental Design for the LATOR Mission

Turyshev, Slava G.; Shao, Michael; Nordtvedt, Kenneth, Jr.; Proceedings of the 2004 NASA/JPL Workshop on Physics for Planetary Exploration; [2004]; 16 pp.; In English; See also 20060014017; Original contains black and white illustrations; No Copyright; Avail.: CASI: A03, Hardcopy; Available from CASI on CD-ROM only as part of the entire parent document

This paper discusses experimental design for the Laser Astrometric Test Of Relativity (LATOR) mission. LATOR is designed to reach unprecedented accuracy of 1 part in 10(exp 8) in measuring the curvature of the solar gravitational field as given by the value of the key Eddington post-Newtonian parameter gamma. This mission will demonstrate the accuracy needed to measure effects of the next post-Newtonian order (near infinity G2) of light deflection resulting from gravity s intrinsic non-linearity. LATOR will provide the first precise measurement of the solar quadrupole moment parameter, J(sub 2), and will improve determination of a variety of relativistic effects including Lense-Thirring precession. The mission will benefit from the recent progress in the optical communication technologies the immediate and natural step above the standard radio-metric techniques. The key element of LATOR is a geometric redundancy provided by the laser ranging and long-baseline optical interferometry. We discuss the mission and optical designs, as well as the expected performance of this proposed mission. LATOR will lead to very robust advances in the tests of Fundamental physics: this mission could discover a violation or extension of general relativity, or reveal the presence of an additional long range interaction in the physical law. There are no analogs to the LATOR experiment; it is unique and is a natural culmination of solar system gravity experiments. Author

Astrometry; Relativistic Effects; Laser Ranging; Solar Magnetic Field; Gravitational Fields; Experiment Design; Quadrupoles; Curvature; Relativity

20060014038 Northwest Analysis, Bozeman, MT, USA

LATOR Spacecraft Orbits

Nordtvedt, Kenneth; Proceedings of the 2004 NASA/JPLWorkshop on Physics for Planetary Exploration; [2004]; 11 pp.; In English; See also 20060014017; Original contains color illustrations; No Copyright; Avail.: CASI: A03, Hardcopy; Available from CASI on CD-ROM only as part of the entire parent document

The LATOR mission aims to make a major advance in the precision of testing for scalar field modifications of general relativity's pure tensor gravity. By using a laser interferometer to measure one angle of a light triangle, and laser ranging to measure the three sides of the triangle, and shaping the triangle so that two of its sides have the laser light pass close by the Sun, first-order gravitational deflection of light will be measured to part-in-a-hundred million precision. But such an accurate measurement of the theory's predictions would seem to require a correspondingly accurate knowledge of the light trajectores' impact parameters passing the Sun. This amounts to 10 meter or better knowledge of the light triangle's key transverse location coordinate. My study deals with this issue: How can the LATOR mission succeed in meeting its goals if traditional tracking and drag-free system methods cannot supply the better than 10 meter knowledge of spacecraft location in this key long-track direction and over the several-day time interval during which the mission's key data will be taken? Author

Spacecraft Orbits; Laser Ranging; Relativistic Effects; Gravitation; Tensors; Laser Outputs; Triangles; Scalars; Light Beams

20060016359 NASA Marshall Space Flight Center, Huntsville, AL, USA

Dynamic Aperture-based Solar Loop Segmentation

Lee, Jon Kwan; Newman, Timothy S.; Gary, G. Allen; [2006]; 1 pp.; In English; 7th IEEE Southwest Symposium on Image Analysis and Interpretation, 26-28 Mar. 2006, Denver, CO, USA; Copyright; Avail.: Other Sources; Abstract Only

A new method to automatically segment arc-like loop structures from intensity images of the Sun's corona is introduced. The method constructively segments credible loop structures by exploiting the Gaussian-like shape of loop cross-sectional intensity profiles. The experimental results show that the method reasonably segments most of the well-defined loops in coronal images. The method is only the second published automated solar loop segmentation method. Its advantage over the other published method is that it operates independently of supplemental time specific data. Author

Sun; Coronas; Segments; Coronal Loops; Solar Magnetic Field

20060016372 National Space Science and Technology Center, Huntsville, AL, USA

Solar Activity and Solar Eruptions

Sterling, Alphonse C.; [2006]; 1 pp.; In English; Total Solar Eclipse: Astronomy and Culture Conference, 27-31 Mar. 2006, Cape Coast, Ghana; No Copyright; Avail.: Other Sources; Abstract Only

Our Sun is a dynamic, ever-changing star. In general, its atmosphere displays major variation on an 11-year cycle. Throughout the cycle, the atmosphere occasionally exhibits large, sudden outbursts of energy. These 'solar eruptions' manifest themselves in the form of solar flares, filament eruptions, coronal mass ejections (CMEs), and energetic particle releases. They are of high interest to scientists both because they represent fundamental processes that occur in various astrophysical context, and because, if directed toward Earth, they can disrupt Earth-based systems and satellites. Research over the last few decades has shown that the source of the eruptions is localized regions of energy-storing magnetic field on the Sun that become destabilized, leading to a release of the stored energy. Solar scientists have (probably) unraveled the basic outline of what happens in these eruptions, but many details are still not understood. In recent years we have been studying what triggers these magnetic eruptions, using ground-based and satellite-based solar observations in combination with predictions from various theoretical models. We will present an overview of solar activity and solar eruptions, give results from some of our own research, and discuss questions that remain to be explored. Author

Solar Activity; Solar Flares; Coronal Mass Ejection; Astrophysics; Actuators; Energetic Particles

Source: NASA