France in Space No 187 30 Nov 2001
1: WORLD PREMIERE : TWO SATELLITES COMMUNICATE VIA A LASER
On November 20th, an optical communication between two European satellites
was established by a laser link for the first time ever. The ESA (European
Space Agency) satellite ARTEMIS is equipped with the SILEX (Semiconducteur
Intersatellite Link Experiment) system. SILEX provides a link for data
transmissions with SPOT 4, the Earth observation satellite of the French
space agency (CNES). This connection starts with an acquisition phase
through a laser beacon sent by ARTEMIS and received by SPOT 4 before
tracking. Pointing precision is superior to one microradian – an
exceptional result given that the two satellites were moving at relative
speeds of several kilometers per second and were separated by more than
30000 km. The SILEX program was launched in 1998 by the ESA, in cooperation
with CNES under Astrium contractor authority working with over twenty
European subcontractors. [CNES Press Release and Astrium Press Release, 11/22/2001]
2: ARIANESPACE SUCCESSFULLY ORBITED DIRECTV-4S
The Ariane 4 launcher successfully orbited the DIRECT-4S direct broadcast
satellite for the American operator DIRECTV, Inc. The Ariane 4 took off
from the French Guyana Spaceport at 9:35 p.m. local French Guyana time, and
the 4,257-kg satellite separated from the launcher about 21 minutes later.
Flight 146 is Arianespace’s third launch for DIRECTV and marked the 107th
mission of an Ariane 4 vehicle. Previous Ariane-missions carried the
DIRECTV-1 spacecraft in December 1993 and DIRECTV-3 in June 1995. The
satellite DIRECTV-4S is a Boeing Space Systems 601 HP platform. Once in
operation, the satellite will be used by California-based DIRECTV to
provide digital television service with more than 300 channels of
additional capacity. [Arianespace Press Release, 11/26/2001]
3: UPGRADED ARIANE 5 SOLID PROPELLANT BOOSTER TEST FIRED
An Ariane 5 solid propellant booster was successfully test fired today, as
part of the Ariane 5 Research and Technology Accompaniment (ARTA) program
to increase the heavy-lift launcher’s payload capability and reduce its
production costs. The static test firing was performed with a full-sized
booster on a fixed test stand at the Guyana Space Center. The test lasted
125 seconds, the normal burning time for an Ariane 5 booster during flight.
The objective was to test a redesigned nozzle that will reduce the solid
rocket booster’s production costs. The new nozzle will be used on all
Ariane 5 launchers as of 2004. ARTA is a project of the European Space
Agency, which delegates the program’s technical and financial management to
CNES (French space agency).
[Arianespace Press Release, 11/20/2001]
4: NASA/FRENCH OCEAN-OBSERVING SATELLITE READY TO BE LAUNCHED
The French-American ocean-observation satellite JASON-1 will be launched on
December 7, aboard a Boeing DELTA 2 launcher from Vandenberg, California.
The satellite, a joint project between NASA and CNES (French space agency),
will continue the mission started by Topex/Poseidon to monitor global
climate interactions between the sea and the atmosphere. Jason 1 will
monitor the circulation of the world oceans, study interactions between the
oceans and the atmosphere, improve climate forecasts, and observe natural
phenomenon such as El Nino. JASON 1 is the first stage of a permanent ocean
observatory. Satellites, such as TOPEX/POSEIDON, are the result of an
international cooperation involving space agencies, industrials and data
users.
[CNES Press Release] [From Arianespace Press Release, Astrium Press Release (Astrium), CNES
Press Release]
