NASA's STEREO spacecraft — en route as the first
mission to capture the sun in 3-D — successfully
launched on Oct. 25 aboard a single Delta II vehicle from
Cape Canaveral Air Force Station, Fla., at 8:52 p.m.
The two nearly identical spacecraft, designed, built
and operated by the Johns
Hopkins Applied Physics Laboratory for NASA, separated
from the launch vehicle 25 minutes after liftoff. After
receiving the first signal from the spacecraft 63 minutes
after launch, mission control personnel at APL confirmed
each observatory's solar arrays successfully deployed and
were providing power to the spacecraft. The initial radio
signals were forwarded to the APL-based mission operations
center from NASA's Deep Space Network antennas in Canberra,
Australia.
During its two-year mission, the twin observatories
(named STEREO for Solar TErrestrial RElations Observatory)
will explore the origin, evolution and interplanetary
consequences of coronal mass ejections. These powerful
solar eruptions are a major source of the magnetic
disruptions on Earth and a key component of space weather,
which can greatly affect satellite operations,
communications, power systems and the lives of astronauts
in space.
For the next few weeks, the spacecraft will fly in an
elliptical orbit that extends from Earth to just beyond the
moon. During this time, mission operations personnel at APL
will place the spacecraft in flight mode, turn on and check
out all instruments and subsystems, and ensure all systems
are operating nominally in preparation to begin their data
collection efforts.
In approximately two months, the APL team will
synchronize spacecraft orbits and direct one observatory to
its position ahead of Earth; about a month later, it will
redirect the second observatory to its position trailing
Earth. Just as the slight offset between your eyes provides
you with depth perception, this placement will allow the
observatories to obtain 3-D images and particle
measurements of the sun.
Lunar swingbys will take advantage of the moon's
gravity to redirect the observatories to their appropriate
orbits, something the launch vehicle alone can't do. This
is the first time lunar swingbys have been used to
manipulate orbits of more than one spacecraft.
Each observatory is carrying two instruments and two
instrument suites, providing more than a dozen instruments
per observatory. APL designed and built the spacecraft
platform housing the instruments. When combined with data
from observatories on the ground or in space, STEREO's data
will allow scientists to track the buildup and liftoff of
magnetic energy from the sun and the trajectory of
Earth-bound coronal mass ejections in 3-D.
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