Los Alamos to Ride on NASA Mission to Collect Solar Material

Los Alamos National Laboratory
John Gustafson, 505-665-9197 / [email protected]

LOS ALAMOS TO RIDE ON NASA MISSION TO COLLECT SOLAR MATERIAL

LOS ALAMOS, N.M., Oct. 27, 1997 -- Los Alamos National Laboratory scientists will provide three key instruments and other scientific input for a mission that will spend two years in space collecting material that blows off the sun, then return to Earth where the captured solar samples will be analyzed in detail.

The $216 million National Aeronautics and Space Administration mission, called Genesis, is scheduled for launch in 2001. NASA announced last week that the mission had been selected for NASA's Discovery program of relatively low-cost spacecraft focused on specific scientific goals.

Genesis will travel out about a million miles and orbit about a gravitationally stable point between Earth and the sun for two years. There it will collect charged atomic particles, or ions, traveling outward from the sun. These particles form part of the solar wind, which blows at about a million miles an hour and carries occasional energetic disturbances that can create storms of activity in Earth's magnetosphere and knock out electrical systems on satellites.

Solar wind particles can't easily be captured by Earth-orbiting satellites because Earth's magnetic field deflects most of the solar wind.

Los Alamos, whose Genesis contribution represents a total effort of about $10 million, will provide a concentrator to create an enhanced sample of oxygen ions, the mission's most important science goal. Los Alamos also will build an ion monitor and an electron monitor to determine what the ambient solar wind conditions are while particle collections are being made.

"We are woven throughout this whole mission," said Los Alamos' Dave McComas, a co-investigator on Genesis. "The concentrator addresses the mission's primary scientific objectives, the monitors will be used to guide the mission's operations, and we'll be involved in selecting materials for the collectors and analyzing them on their return. We're providing a large fraction of the scientific capability for the mission; it's an exciting role."

When the collected materials -- which will total only a few millionths of a gram -- are back on Earth, scientists can do detailed studies to determine accurately the true composition of the sun.

"This will be the first mission since the days of Apollo to return extraterrestrial material for study," said Los Alamos space physicist Roger Wiens.

Current and earlier space missions have measured the most abundant elements in the solar wind, which are hydrogen and helium.

For Genesis, though, "we're interested in the one percent of solar material that hasn't been studied that well," principally different forms of the elements oxygen, carbon and nitrogen, Wiens said. "Some of the most interesting science will come from studying these isotopes."

The most important element to be studied is oxygen, which when bound with two hydrogen atoms forms water, critical for life.

Studies of materials from planets and asteroids show wide variability in the relative amounts of the different oxygen isotopes. This variability is thought to reflect conditions in the cloud of gas and dust that condensed to form the sun and planets. Measuring the oxygen composition of the sun, described in Genesis project literature as the mission's "highest priority objective," would let scientists sort out the different theories of how the solar system formed.

"Genesis will provide a meter stick for interpreting all these other samples and help us understand in detail the composition of oxygen in the primordial solar nebula," McComas said.

The concentrator is essential for the oxygen studies because anything built on Earth will carry oxygen contamination into space with it. If the measurement is not made properly, Genesis will only sample Earth's oxygen concentration. The concentrator uses a series of electrically charged grids to repel unwanted ions and concentrate oxygen ions onto a specially developed diamond surface.

The monitors, whose development is being led by Bruce Barraclough, will tell scientists the conditions in the solar wind so they can expose the appropriate collectors to the wind.

"Los Alamos has been developing and flying space instruments such as these since the 1960s, so we've got a long track record of success," McComas said. "For Genesis, we will provide solar wind instruments very similar to what we put on the Advanced Composition Explorer and Ulysses missions."

ACE currently is traveling to the stable gravitational point called L1, the same location where Genesis will park. Ulysses is nearing completion of its first full orbit out of the plane of Earth's orbit and around the sun's poles.

The Los Alamos instrument design uses pairs of closely spaced, curved plates that are electrically charged. By varying the voltage on the plates, ions and electrons of differing energies can transit the curved pathways without colliding with the plates. Those that successfully travel the arch are counted by detectors.

These measurements tell researchers the number of particles in the solar wind, their energy and their direction of travel -- essentially a weather report on the wind.

Wiens, who has worked on the Genesis proposal for about seven years, will help Genesis principal investigator Donald Burnett of the California Institute of Technology investigate and select the material for the arrays of collectors that will absorb solar wind particles.

Barraclough, McComas and Wiens work in Los Alamos' Nonproliferation and International Security Division. Ron Moses, from the Laboratory's Theoretical Division, is helping with the solar wind concentrator design.

Los Alamos National Laboratory is operated by the University of California for the U.S. Department of Energy. -30-