GENESIS’ first year a success
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LOS ALAMOS, N.M., Dec. 10, 2002 - As scientists at Los Alamos National Laboratory begin analysis of first-year data from the solar wind probe GENESIS they have determined the spacecraft is working so well that they are considering possibilities for research beyond the planned 2004 mission completion date. Three of GENESIS' instruments were designed and built at Los Alamos.
Along with colleagues from NASA's Jet Propulsion Laboratory and the California Institute of Technology, Los Alamos scientists have been analyzing data from GENESIS to study solar wind in more detail than ever before and will eventually return solar wind particle samples to earth in September 2004.
"The two solar wind monitors aboard GENESIS, designed and built at Los Alamos, were turned on in August 2001, and have been working flawlessly ever since," says lead researcher Roger Wiens. The monitors instantaneously determine the speed, density, temperature and approximate composition of the solar wind and translate that knowledge into actions for the solar wind collector arrays - five meter-sized panels containing 55 coaster-sized tiles made of a variety of materials selected to trap specific elements in the solar wind.
The solar wind concentrator, also built at Los Alamos, is designed to collect high concentrations of oxygen and return the samples back to Earth for analysis. The concentrator takes solar wind and passes it through a series of electrically charged grids into a bowl-shaped mirror. The mirror reflects a filtered stream of elements heavier than hydrogen upward into a centrally poised collector tile, where oxygen and other elements embed themselves.
GENESIS will collect just 10 to 20 micrograms of the solar wind elements of interest- or the equivalent of a few grains of salt. The extraterrestrial material will return to Earth in the spacecraft's specially designed sample-return capsule for study over the next century by scientists around the world in search of answers to fundamental questions about the exact composition of the sun and solar system. The only other time solar wind particles were returned to Earth was during the Apollo lunar exploration missions of the 1970s. Those samples consisted of particles from only a few minutes of solar wind exposure, while the GENESIS mission will collect samples over two years of its three-year mission.
Working with Wiens on the early GENESIS data analysis program are Los Alamos' Bruce Barraclough, John Steinberg, Randy Bremmer, John Gosling and Daniel Reisenfeld together with JPL's Marcia Neugebauer and Caltech's Donald Burnett.
GENESIS began its solar observation orbit in November 2001, around the Lagrange 1, or L1 point, nearly one million miles from the Earth and 92 million miles from the sun, where the gravities of the Earth and sun are balanced. GENESIS will eventually complete five "halo" loops around L1 traveling a distance of about a million miles in each loop. GENESIS' instruments will collect samples of the solar wind to reveal the makeup of the cloud that formed the solar system nearly five billion years ago, and it will help scientists understand the origin of the solar system.
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Wiens and his collaborators plan to propose to NASA that the mission be extended beyond the originally designed three years. The researchers have determined that the spacecraft is working so well, and that it entered its L1 orbit so perfectly, that there is enough fuel on board to propel the ship even closer to the sun following its return trip to Earth and the delivery of the solar wind sample container. "We believe that after the sample container is returned to Earth, the spacecraft will be in good enough shape to enter a new solar observation orbit, a distant retrograde orbit, some four to six million miles from Earth, where it can continue to provide us with valuable solar wind data," says Wiens. "There's a lot of fuel left, the possibilities are really endless."
Wiens says early data analysis has yielded a surprise finding of sunward traveling electrons in high-speed "coronal hole" solar wind that mimics solar wind electrons from Coronal Mass Ejections (CMEs) that are sometimes responsible for communications blackouts and power interruptions on Earth. With CMEs, both ends of the magnetic field lines are connected back to the sun, forming a large loop along which electrons can travel in both directions. Coronal holes do not have such loops, leading to the question of why the electrons travel in both directions in this type of wind.
Wiens and his colleagues have determined that the sunward electrons have leaked from plasma heated at more distant shock waves. The shock waves are associated with the long spiraling arms of solar magnetic fields drawn out into space by the fast coronal hole solar wind. This phenomenon has been observed in the solar wind much further from the sun by another Los Alamos instrument on the Ulysses spacecraft. The new GENESIS observation is the first time that bi-directional flow in coronal holes has been observed near the Earth. The discovery now allows scientists to better differentiate between two very similar types of solar wind signals originating from two very dissimilar solar phenomena-potentially resulting in more accurate early warning of large solar events that could disrupt power and communications on Earth.
Los Alamos National Laboratory is operated by the University of California for the National Nuclear Security Administration (NNSA) of the U.S. Department of Energy and works in partnership with NNSA's Sandia and Lawrence Livermore national laboratories to support NNSA in its mission.
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By Kevin Roark