Europe’s third Galileo satellite has
transmitted its first test navigation signals back to Earth. The two Galileo
satellites launched last October have reached their final orbital position and
are in the midst of testing. The third Galileo Flight Model, known as FM3,
transmitted its first test navigation signal in the E1 band on 1 December, the
band being used for Galileo’s freely available Open Service interoperable with
GPS.
Then, on the morning of 4 December, the
satellite broadcast signals across all three Galileo bands – E1, E5 and E6.
Galileo is designed to provide highly accurate timing and navigation services
to users around the world. So the testing is being carried out in addition to
the standard satellite commissioning to confirm that the critical navigation
payloads have not been degraded by the violence of launch.
Galileo satellites
While the satellites are run from Galileo’s
Oberpfaffenhofen Control Centre near Munich in Germany and their navigation
payloads are overseen from Galileo’s Mission Control Centre in Fucino, Italy, a
separate site is used for the in-orbit testing.
Located in the heart of Belgium’s Ardennes
forest, Redu is specially equipped for Galileo testing, with a 15 m-diameter
S-band antenna to upload commands and receive telemetry from the satellite, and
a 20 m-diameter L-band dish to monitor the shape and quality of navigation
signals at high resolution. “This marked the very first time that a Galileo
payload was activated directly from ESA’s Redu centre in Belgium,” explained
Marco Falcone, overseeing the campaign effort as Galileo’s System Manager.
First FM3 test navigation signal
“We have now established an end-to-end setup
in Redu that allows us to upload commands generated from Fucino’s Galileo
Control Centre to the satellite payload whenever the satellite passes over the
station, while at the same time directly receiving the resulting navigation
signal through its main L-band antenna.
“The result is our operations are much more
effective, shortening the time needed for payload in orbit testing.” Operating
at an altitude of 23 222 km, the Galileo satellites take about 14 hours to
orbit our planet, typically coming into view of Redu for between three to nine
hours each day.
FM3's test team
The fourth Galileo flight model, FM4, was
launched together with FM3 on 12 October. The two satellites shared the same
Soyuz launcher from French Guiana. Both have now been manoeuvred into their
operational orbits: at the same altitude but in a different orbital plane to
the first two Galileos, launched in 2011, in order to maximise the global
coverage.
Now that FM3’s payload has been activated,
FM4 is set to begin transmitting test navigation signals later this month. The
first two satellites have already passed their in-orbit testing.
For further information visit: http://www.esa.int/esaCP/SEM2R5F16AH_index_2.html
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