The Jet Propulsion Laboratory's (JPL) Deep Space Network
(DSN) provides two-way communications between the Stardust
spacecraft and the mission operations team at JPL. Also,
the DSN generates radio navigation data used to track
and guide the spacecraft to its destination.
To assure continuous communication with spacecraft and
compensate for Earth's rotation, three DSN complexes
are located 120 degrees apart around the world - in
Goldstone, California; Madrid, Spain; and Canberra,
Australia. One complex always has Stardust within view.
Data from Stardust, called telemetry, is received as
a coded bitstream, then forwarded to the Deep Space
Operations Center at JPL for processing and distribution
to the mission managers and mission scientists.
By the time Stardust's radio signal reaches a DSN antenna,
it can be of extremely low wattage. Separating the spacecraft's
faint signal frombackground "noise" requires
sophisticated techniques that involve both the use of
"low-noise" receivers to amplify the signal
and also telemetry coding to reduce signal distortion.
DSN antennas have parabolic reflector dishes, some as
large as 70 meters (230 ft.) in diameter, to capture
the signal. Typically, Stardust signals are received
on a 34-meter (112 ft) antenna.
The Mission Operations team generates commands for uplink
to Stardust. A "packet" of data, called a
"sequence" is pre-pared and forwarded by the
Deep Space Operations Center to the appropriate complex
for transmission to the spacecraft. The antenna is then
pointed precisely at the spacecraft and the data are
sent using powerful transmitters, the largest of which
is capable of generating up to 400 kilowatts.
Additional information is available at
|Last updated November