NASA could soon watch the Sun's
violent behavior when the star's magnetic field becomes unstable shooting plasma
and high-energy particles deep into space.
Almost
identical twin probes, dubbed Solar
TErrestrial RElations Observatory (STEREO) and scheduled to be launched
aboard a Delta Rocket II on Aug. 31, will embark on a two-year mission to provide
three dimensional views of the Sun.
The satellites
will provide perspective on the origin, evolution and consequences of coronal
mass ejections (CMEs).
CMEs are giant
explosions on the Sun, caused by
magnetic field lines annihilating one another, release a tremendous amount of
energy. If directed the right way, ejected mass from CMEs can actually reach the Earth, explained Michael Kaiser, STEREO project scientist at NASA's Goddard
Space Flight Center.
"Now
we're very interested in this because these storms can cause all sorts of
electrical disturbances on Earth
particularly on spacecraft that are very sensitive to small changes in current
and voltage levels," Kaiser said in a STEREO Pre-Launch Teleconference
today. "They can also affect power on the ground."
A solar
storm in the late 1980's was responsible for a famous outage of the entire Quebec power grid in Canada.
The
energetic particles associated with such outbursts from the Sun can also harm
astronauts when they leave the Earth's magnetic field to go into free space and
on to long duration missions, such as a journey to Mars.
The data
from the spacecraft will also help scientists determine how the Sun affects
space weather.
"In
terms of space-weather forecasting, we're where weather forecasters were in the
1950s," Kaiser said. "They didn't see hurricanes until the rain
clouds were right above them. In our case, we can see storms
leaving the Sun, but we have to make guesses and use models to figure out if
and when they will impact Earth."
In order to
create a multidimensional view of the Sun and provide depth perception, the two
probes will be placed in different orbits of the Sun. Spacecraft "A"
will be in orbit moving ahead of Earth and probe "B" will lag behind
as the planet orbits the Sun. Each probe will sport imaging telescopes and
equipment to measure solar wind particles and radio waves.
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