The APL-built and -operated twin STEREO observatories
have made the first 3-D
measurements of solar explosions, known as coronal mass
ejections, enabling scientists to see their
size and shape, and to image them as they travel
approximately 93 million miles from the sun to Earth.
Scientists will be able to use this information to help
determine how these strong solar storms will
impact Earth's atmosphere.
The Solar TErrestrial RElations Observatory's science
data is enhanced, in part, due to the
STEREO guidance and control team at the Johns Hopkins University
Applied Physics Laboratory. The
team is helping mission scientists more easily reconstruct
3-D imagery by very accurately pointing the
spacecraft and reducing its jitter or movement.
"By tuning each spacecraft's control software —
much like a race car's control system is tuned
for optimal performance on the track — spacecraft
system performance is now approximately five
times better than at launch and seven times better than
specifications require," said Andy Driesman,
STEREO's system engineer at APL.
Since STEREO's launch in 2006, the APL team has been
proactively tuning spacecraft and
ground systems, maximizing data return and optimizing
contact with satellites used to downlink data.
The APL-based mission operations center downloads six to
nine gigabytes of data each day —
approximately 20 percent to 80 percent more data than the
science team expected.
Coronal mass ejections, or CMEs, are powerful solar
explosions that can have damaging effects
when hitting Earth's upper atmosphere at speeds of nearly 1
million miles per hour. These giant clouds
of electrically charged gas called plasma can disrupt
satellite communications, including GPS and/or
cell phone signals, or induce large currents in power
grids, which can cause power disruptions or
"Using STEREO observations, we can extract a CME's
properties and are able to determine
when it will reach Earth, at what speed and with how much
energy it will impact Earth's
magnetosphere," said Angelos Vourlidas, of the Naval
Research Laboratory and project scientist for
STEREO's SECCHI (Sun Earth Connection Coronal and
Heliospheric Investigation) imaging suite.
Disruptions to the magnetic envelope surrounding Earth can
often trigger auroras. These bright bands
of light, often visible at night in northern and southern
regions, can interfere with communications
between air-traffic controllers and pilots flying near
Earth's polar regions.
STEREO is sponsored by NASA Headquarters' Science
Mission Directorate. NASA Goddard
Space Flight Center's Solar Terrestrial Probes Program
Office manages the mission, instruments and
science center. APL designed and built the spacecraft and
is operating the twin observatories for
NASA during the mission.
For more on the mission, go to: