The Tracking and Data Relay Satellite System
The Tracking and Data Relay Satellite
System
is a
communication signal relay system which provides tracking and data
acquisition services between spacecraft in low-Earth orbit and
spacecraft control, or data processing, facilities.
The
TDRSS
space segment consists of seven on-orbit Tracking and Data Relay
Satellites (TDRSs) located in geosynchronous orbit. The spacecraft
constellation is distributed to provide global coverage.
The
TDRSS
ground segment is located near Las Cruces, New Mexico and consists of
two functionally identical ground terminals collectively known as the
White Sands Complex. Commands and data for Swift are uplinked
from the MOC
to the
TDRSS
and then from the
TDRSS
to Swift. Return data are downlinked from Swift via the
TDRSS
to the MOC
at PSU.
- TDRSS
is used to track the spacecraft and to transmit State of Health
telemetry for the spacecraft and its instruments from Swift to the ground.
- TDRSS
is used to send burst alert messages to the ground. Swift
will be in nearly-constant contact with the
TDRSS
so that burst alerts can be received when Swift is not in
contact with its ground stations.
The
TDRSS
link is used to download
BAT
localizations of transient sources approximately 12 seconds after
initial detection by the
BAT,
XRT
localizations (approximately 90 seconds after the initial
detection), and an optical finding chart (approximately 300
seconds after the initial detection).
- TDRSS
can also be used to upload commands that allow Swift to
observe ToOs. This capability is intended to allow Swift
to rapidly observe transients that occur outside the field of view of the
BAT,
but are detected by other satellites.
Eleonora Troja
2016-08-08