About the STEREO Mission
Mission Design | The basics:
- Two Sun-pointed observatories with identical instrument
- Each in a heliocentric orbit drifting away from the
Earth, one leading and one lagging.
The most efficient and cost-effective method to place the twin
observatories, launched aboard a single rocket, into their respective
orbits was to use what is known as "lunar swingbys." This was the first
time this technique has been used to manipulate orbits of more than
one spacecraft at the same time. Mission designers use the
Moon's gravity to redirect the observatories to their appropriate
orbits - something the launch vehicle alone is not able to do.
For the first three months after launch, the two observatories
flew in highly elliptical orbits extending from very close to Earth to
just beyond the Moon's orbit. STEREO Mission Operations personnel at
the Johns Hopkins University's Applied Physics Laboratory (APL) in
Laurel, Maryland, synchronized spacecraft orbits so that about two
months after launch they encountered the Moon, at which time one of them
was close enough to use the Moon's gravity to redirect it to a position
"behind" Earth. Approximately one month later, the second observatory
encountered the Moon again and was redirected to its orbit "ahead"
Thus, the two STEREO spacecraft provide a stereoscopic view of
the Sun and its atmosphere, similar to the way our two eyes allow us
to see the three-dimensional world around us. When combined with data
from observatories on the ground and in low-Earth orbit, STEREO's data
allows scientists to track the buildup and lift-off of magnetic
energy from the Sun and the trajectory of Earth-bound CMEs in 3-D.
Last Revised: Thursday, 05-Jun-2008 10:22:29 EDT
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