NASA spacecraft show three dimensional anatomy of a
solar storm
Wednesday, April 15, 2009
Twin NASA spacecraft have provided scientists with their first view
of the speed, trajectory, and three-dimensional shape of powerful
explosions from the sun known as coronal mass ejections, or CMEs.
This new capability will dramatically enhance scientists' ability
to predict if and how these solar tsunamis could affect
Earth.
When directed toward our planet, these ejections can be
breathtakingly beautiful and yet potentially cause damaging effects
worldwide. The brightly colored phenomena known as auroras -- more
commonly called Northern or Southern Lights -- are examples of
Earth's upper atmosphere harmlessly being disturbed by a CME.
However, ejections can produce a form of solar cosmic rays that can
be hazardous to spacecraft, astronauts and technology on
Earth.
Space weather produces disturbances in electromagnetic fields on
Earth that can induce extreme currents in wires, disrupting power
lines and causing wide-spread blackouts. These sun storms can
interfere with communications between ground controllers and
satellites and with airplane pilots flying near Earth's poles.
Radio noise from the storm also can disrupt cell phone service.
Space weather has been recognized as causing problems with new
technology since the invention of the telegraph in the 19th
century.
NASA's twin Solar Terrestrial Relations Observatory, or STEREO,
spacecraft are providing the unique scientific tool to study these
ejections as never before. Launched in October 2006, STEREO's
nearly identical observatories can make simultaneous observations
of these ejections of plasma and magnetic energy that originate
from the sun's outer atmosphere, or corona. The spacecraft are
stationed at different vantage points. One leads Earth in its orbit
around the sun, while the other trails the planet.
Using three-dimensional observations, solar physicists can examine
a CME's structure, velocity, mass, and direction in the corona
while tracking it through interplanetary space. These measurements
can help determine when a CME will reach Earth and predict how much
energy it will deliver to our magnetosphere, which is Earth's
protective magnetic shield.
"Before this unique mission, measurements and the subsequent data
of a CME observed near the sun had to wait until the ejections
arrived at Earth three to seven days later," said Angelos
Vourlidas, a solar physicist at the Naval Research Laboratory in
Washington. Vourlidas is a project scientist for the Sun Earth
Connection Coronal and Heliospheric Investigation, STEREO's key
science instrument suite. "Now we can see a CME from the time it
leaves the solar surface until it reaches Earth, and we can
reconstruct the event in 3D directly from the images."
These ejections carry billions of tons of plasma into space at
thousands of miles per hour. This plasma, which carries with it
some of the magnetic field from the corona, can create a large,
moving disturbance in space that produces a shock wave. The wave
can accelerate some of the surrounding particles to high energies
that can produce a form of solar cosmic rays. This process also can
create disruptive space weather during and following the CME's
interaction with Earth's magnetosphere and upper atmosphere.
"The new vantage point of these spacecraft has revolutionized the
study of solar physics," said Madhulika Guhathakurta, STEREO
program scientist at NASA Headquarters in Washington. "We can
better determine the impact of CME effects on Earth because of our
new ability to observe in 3D."
STEREO is part of NASA's Solar Terrestrial Probes Program in NASA's
Science Mission Directorate in Washington. The program seeks to
understand the fundamental physical processes of the space
environment from the sun to Earth and other planets.
The Solar Terrestrial Probes Program also seeks to understand how
society, technological systems and the habitability of planets are
affected by solar processes. This information may lead to a better
ability to predict extreme and dynamic conditions in space, and the
development of new technologies to increase safety and productivity
of human and robotic space exploration.
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NASA/Goddard Space Flight Center
Thanks to NASA/Goddard Space Flight Center for this article.