Space weather and earthly disturbances: Dartmouth researcher will help make predictions

Posted 11/10/98

From the cellular phone in your pocket or car to the detection methods that tracked Hurricane Mitch, satellite technology has been increasingly woven into modern life. A malfunction last May in a satellite called Galaxy Four froze the image of CBS anchorman Dan Rather on national television, stopped credit card systems at banks and gas pumps and blacked out an estimated 80 percent of the country's pagers -- a nightmare for physicians.

Professor Mary Hudson, chair of Dartmouth's Physics and Astronomy Department, is part of a new effort to study and predict changes in space weather that could prevent these satellite problems. She is participating in a $12.8 million project funded by the National Aeronautics and Space Administration (NASA) to build a satellite called the Inner Magnetosphere Explorer (IMEX).

When launched into orbit by the U.S. Air Force's Titan IV rocket in 2001, IMEX will transmit valuable data about the solar events that threaten satellite operations and likely caused the Galaxy Four mishap. Those events, coronal mass ejections, are streams of highly energetic charged particles that periodically burst from the sun toward Earth's protective magnetic field. A spectacular one occured in May, increasing radiation exposure in a way that has been shown to cause satellite failures.

"The sun is not a solid," Hudson explains. "It is a rotating fluid that gets twisted up. Every 11 years, that fluid untwists and changes direction." At that solar maximum, which will take place in 2001 and could last a year or more, the resulting changes in the sun's magnetic field configuration will cause explosions of hot ionized gas to escape the sun's magnetic field with greater frequency.

For a satellite, that can mean a tremendous rush of charged particles sweeping through like a freight train, wiping out computer memory. With the data from IMEX, scientists hope to predict where and when solar winds will travel so that satellites in their path might be put into "safe mode" or turned off entirely.

Astronauts on a space walk are also vulnerable to these radiation bursts. Next year, NASA will participate with an international team to begin construction on a new space station -- the first ever to be constructed during solar maximum. Dartmouth alumnus Jim Newman, Class of 1978, will be aboard one of these construction teams and IMEX data may help protect him and his fellow astronauts on future missions.

The last space mission exposed to the risks of solar maximum was the 1969 moon landing. "The orders were to go ahead with the mission," Hudson said, "because we had to land on the moon before the Russians."

The IMEX craft will be built at the University of Colorado and the University of Minnesota. Hudson is helping to determine the measurements the satellite will need to make and is developing models to predict and analyze the data.

The goal of IMEX is to transmit valuable data when it's most needed -- during the period of peak solar activity. "Right now," Hudson said, "we're like the weather service during the Second World War. We have some ability to see space weather, but we're trying to evolve to real-time detection capability." Without a satellite like IMEX specifically studying the problem, "There's a hole in the puzzle. And it's a big one."