Southwest Research Institute 2000 Annual Report, Space Science

SwRI continues its research in space science and the development of innovative spacecraft instrumentation and systems. Institute scientists collaborate on the design and fabrication of scientific instruments, spacecraft computers, and power supplies for flight on interplanetary probes, Earth-orbiting spacecraft, and sounding rockets. Strong theoretical and observational research programs are maintained in the fields of solar physics, space physics, planetary science, and stellar astronomy.

The Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) spacecraft, with a payload of eight instruments, is providing the first global images of the tenuous plasmas that populate the Earth's magnetosphere and that are invisible to traditional observation techniques. Scientists are using these imaging instruments to study, in ways never before possible, the structure and dynamics of the inner magnetosphere. They are also tracking the development of "space weather" as the magnetosphere responds to sometimes violent disturbances caused by solar storms. The spacecraft was launched in March 2000 from Vandenberg Air Force Base, California. SwRI leads the mission for NASA and is responsible for its overall management. SwRI also provided a neutral atom imager, the payload, and spacecraft computers and integrated and tested the payload at an Institute clean facility.

In collaboration with the Los Alamos National Laboratory, SwRI is developing a modified version of the IMAGE medium-energy neutral atom (MENA) imager for the Two Wide-angle Imaging Neutral-atom Spectrometers (TWINS) mission. During this NASA program, two widely separated spacecraft will fly in high-inclination orbits to provide stereoscopic viewing of energetic neutral atoms within the Earth's magnetosphere. SwRI is also providing the flight detectors, high-voltage power supplies, and front-end electronics for the mission. Substantial progress has been made on the hardware development, with the first two sets of flight detectors delivered in October 2000.

Solar physics studies are rapidly growing at the Institute. Using data from the Michelson Doppler Imager aboard the Solar and Heliospheric Observatory, SwRI scientists produced the highest-quality magnetic maps ever made of the solar poles. NASA also funded an in-depth analysis of the relationship between the magnetic field and the two-million degree (F) plasma in the solar corona. This work uses "field-line relaxation," an innovative SwRI-developed technique for extrapolating magnetic fields, to solve problems that are inaccessible by more conventional techniques.

SwRI is providing two experiments for the European Space Agency (ESA) Rosetta mission to be launched in 2003 for a rendezvous with comet Wirtanen in 2011. The Ion and Electron Spectrometer, one of a suite of in situ instruments, will measure the charged particle environment of the comet and study its interaction with the solar wind. The engineering qualification model has been completed and tested, and the protoflight model is under development. The ALICE ultraviolet spectrograph, a remote-sensing instrument, will investigate the release of gases from the comet nucleus, which forms the cometary coma. ALICE saw its "first light" recently when it was tested in preparation for delivery to ESA. In addition to providing these instruments, SwRI is supplying the waveform capture subsystem for the ROSINA high-resolution mass spectrometer instrument under development at the University of Bern, Switzerland.

SwRI researchers are conducting investigations of the stability of Venus' climate. Advanced planetary climate models and data from NASA's Pioneer, Magellan, and Galileo missions were used to calculate the influence of volcanism on the climate history of Venus. They have theorized that Venus' ubiquitous cloud cover is most likely a product of ongoing volcanism. Additionally, computer simulations indicate that massive climate changes have altered the planetary environment. Working with colleagues from the Carnegie Institution of Washington, SwRI scientists have also explained enigmatic geologic features such as the globally extensive network of ridges that crosshatch the planet. Researchers now believe the wrinkling of Venus' surface resulted from rapid and tremendous climate changes.

MEDUSA^TM, a miniaturized ion and electron electrostatic analyzer developed at SwRI, launched in November 2000 aboard MUNIN, a Swedish "nanosatellite" that is roughly the size of a shoe box. The instrument has a mass of 1.5 kilograms and a power requirement of only 4 watts. The electron spectrometer (ELS) component of MEDUSA will also fly as part of the Swedish ASPERA-3 experiment on the ESA Mars Express mission, expected to launch in June 2003 and to arrive at Mars later that year. In addition to the ELS, SwRI is developing miniaturized packaging for the Mars Express ion mass analyzer sensor system. An SwRI scientist serves as a team member for the Mars Express ultraviolet spectrometer.

Institute scientists are involved in the ESA Cluster II project as co-investigators for the Plasma Electron and Current Experiment (PEACE). Cluster II is a four-spacecraft mission for investigating plasma processes occurring in key regions of the Earth's magnetosphere, at the boundary between the Earth's magnetosphere and the solar wind, and at the bow shock that is formed in the solar wind flow upstream of the Earth. The first pair of spacecraft was launched in July 2000, followed by the second pair a month later. In addition to participating in the PEACE science team, SwRI designed, implemented, and will run an archival system for data from the PEACE electron analyzers.

The moon's current orbital inclination has been a dynamical mystery for more than 30 years. Institute researchers discovered that a single gravitational resonant interaction between the moon, as it formed, and its remnant precursor disk around the Earth can explain the inclination. This finding reconciles the moon's current orbit with the generally accepted giant-impact theory on the formation of the Earth-moon system.

Institute scientists recently discovered argon in comet Hale-Bopp. The finding, resulting from a NASA high-altitude suborbital research rocket flight, constitutes the first detection of a noble gas in a comet. The presence of argon provides a method for measuring the thermal history of comets and, in this case, indicates that the comet likely formed in the deep outer reaches of the solar system - beyond its once-suspected birthplace in the somewhat-warmer Jupiter zone.

From a NASA F-18 aircraft, SwRI astronomers successfully observed an asteroid, 308 Polyxo, occulting a star. The aircraft was outfitted with the Southwest Ultraviolet Imaging System-Aircraft (SWUIS-A), designed and built at the Institute. The occultation will reveal the size of the asteroid, which is too small for even the Hubble Space Telescope to resolve. Performed in cooperation with the NASA Dryden Flight Research Center, the observation occurred above the cloud cover that would have obscured observations from the ground. Data will also be combined with ground-based observations to deduce the shape of the asteroid. Future SWUIS-A missions, from aboard high-altitude U-2s, will help NASA and U.S. Air Force researchers study meteor showers and search for Vulcanoids, a theorized population of small asteroids circling the sun inside Mercury's orbit.

SwRI scientists are developing tools to automatically detect and categorize craters in planetary surface images. This capability, developed with the Jet Propulsion Laboratory, addresses a growing crisis in planetary image data analysis. Currently, the inventory of NASA imagery exceeds that which humans can process, by a factor of thousands. At this time, measurement of crater sizes and distributions is the only method for determining the ages of surface regions on bodies in the solar system, short of returning a sample to Earth.

Copyright© 2001 by Southwest Research Institute. All rights reserved under U.S. Copyright Law and International Conventions. No part of this publication may be reproduced in any form or by any means, electronic or mechanical, including photocopying, without permission in writing from the publisher. All inquiries should be addressed to Communications Department, Southwest Research Institute, P.O. Drawer 28510, San Antonio, Texas 78228-0510, phone (210) 522-2257, fax (210) 522-3547.