Twin APL-Built Solar Probes Shipped to NASA Goddard for Pre-launch Tests

The Johns Hopkins University Applied Physics Laboratory
Office of Communications and Public Affairs

Media Contacts:
Kristi Marren (The Johns Hopkins University Applied Physics Laboratory)
(240) 228-6268
, or
Rachel Weintraub (NASA Goddard Space Flight Center)
(301) 286-0918

November 9, 2005

FOR IMMEDIATE RELEASE

Note: Photos available at
http://www.jhuapl.edu/newscenter/pre...005/051109.asp

COMING SOON: THE SUN IN 3-D
Twin APL-Built Solar Probes Shipped to NASA Goddard for Pre-launch
Tests

The first spacecraft designed to capture 3-D "stereo" views of the sun
and
solar wind were shipped today from the Johns Hopkins University Applied

Physics Laboratory (APL) in Laurel, Md., to NASA Goddard Space Flight
Center (GSFC) in Greenbelt, Md., for their next round of pre-launch
tests.

The nearly identical twin STEREO (Solar TErrestrial RElations
Observatory)
observatories, designed and built by APL, were recently tested in APL's

vibration lab where engineers used a large shake table to check the
structural integrity of the twin spacecraft. These tests simulate the
ride
into space the observatories will encounter aboard a Delta II launch
vehicle from Cape Canaveral Air Force Station, Fla., where they're
scheduled for launch in spring 2006.

"Delivery of the twin observatories to NASA is a program milestone,"
says
Ed Reynolds, APL STEREO project manager. "Building two nearly identical

spacecraft simultaneously was a technical and scheduling challenge, but
one
our team welcomed and tackled with extreme professionalism and
dedication.
With the design, construction and now delivery of the observatories to
NASA
Goddard, we're very excited to help NASA get one step closer to launch
and
capturing the first-ever 3-D images of the sun."

During the next three months at NASA GSFC, the twin observatories will
undergo additional pre-launch checks including a series of spin tests
to
check the spacecraft's balance and alignment; thermal vacuum tests to
duplicate the extreme temperature and airless conditions of space; and
acoustic tests that simulate the noise-induced vibrations of launch.
The
mission team plans to transport the STEREO observatories to Florida in
March 2006 for final launch preparations.

Swinging into Orbit
During the two-year STEREO mission, two nearly identical space-based
observatories 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 humans in space.

To obtain unique "stereo" views of the sun, the twin STEREO
observatories
must be placed into different orbits where they're offset from each
other
and the Earth. One observatory will be placed ahead of Earth in its
orbit
around the sun and the other behind. Just as the slight offset between
your
eyes provides you with depth perception, this placement will allow the
STEREO observatories to obtain 3-D images and particle measurements of
the sun.

"This is the first time lunar swingbys will be used to place multiple
spacecraft into their respective orbits," says APL's Andy Driesman,
STEREO
system engineer. "Mission designers at APL will use the moon's gravity
to
redirect the observatories to their appropriate orbits around the sun.
This
innovative mission design allows the use of a single launch vehicle."

After launch, the observatories will fly in an orbit from a point close
to
Earth to one that extends just beyond the moon. Approximately two
months
later, mission operations personnel at APL will synchronize spacecraft
orbits, directing one observatory to its position trailing Earth in its

orbit. Approximately one month later, the second observatory will be
redirected to its position ahead of Earth.

STEREO is the third mission in NASA's Solar Terrestrial Probes Program.

STEREO is sponsored by NASA's Science Mission Directorate in
Washington,
D.C. NASA GSFC's Solar Terrestrial Probes Program Office manages the
mission, instruments and science center. APL designed, built and will
operate the twin observatories for NASA during the mission.

###

For more information about STEREO and to download images of the twin
observatories, visit stereo.jhuapl.edu; click on "gallery" for images.

Video will be available today on NASA TV on the Web (see
http://www.nasa.gov/ntv) and at noon, 3, 6, and 10 p.m. EST on an
MPEG-2
digital signal accessed via satellite AMC-6, at 72 degrees west
longitude,
transponder 17C, 4040 MHz, vertical polarization. It's available in
Alaska
and Hawaii on AMC-7 at 137 degrees west longitude, transponder 18C, at
4060
MHz, horizontal polarization. A Digital Video Broadcast compliant
Integrated Receiver Decoder is required for reception.

The Applied Physics Laboratory (APL) is a not-for-profit laboratory and

division of The Johns Hopkins University. APL conducts research and
development primarily for national security and for nondefense projects
of
national and global significance. APL is located midway between
Baltimore
and Washington, D.C., in Laurel, Md.