Press Release

Optical Ground Station has sights set on Artemis

By SpaceRef Editor

March 5, 2001

Filed under Europe, European Space Agency

Completion of a new Optical Ground Station (OGS) in Tenerife marks the
latest stage in the preliminary launch preparations for Artemis — ESA’s
new data relay communication satellite.

Artemis is due for launch into geostationary orbit in June 2001 and will
be the first data relay satellite to use a ‘free-space’ laser beam for
communication purposes.

The satellite will receive data via a laser link from low Earth orbiting
satellites and re-transmit it in ‘real-time’ via a microwave link to a
ground station.

Two laser communication terminals have been developed for the Semiconductor
Laser Inter-satellite Link Experiment (SILEX), one of which is aboard
Artemis, with the second one on the French Spot 4 Earth observation
satellite (launched in March 1998).

The OGS, located at the Instituto de Astrofisica de Canarias’ (IAC)
Observatorio del Teide in Tenerife, will be used for the commissioning and
later for periodic checkouts of the laser communication terminal onboard
Artemis.

To perform laser communication from ground to space, the sky must be
perfectly clear, without any clouds, and the path through the atmosphere
must be as short as possible. Both conditions are satisfied at the
Observatorio del Teide, which is situated above cloud level at 2400 metres
altitude and is the closest point to the equator in an ESA member state.

Artemis, like all geostationary satellites, is located some 36,000 km above
the equator (over central Africa) and the path of the laser beam through
the atmosphere is therefore minimised.

The OGS consists of an observatory building with a dome and associated
infrastructure, a one-metre diameter Zeiss telescope including control
system and special optical test equipment.

Built specifically for the commissioning of the laser communication
terminal on-board Artemis, the OGS is also operating as Europe’s first
post for observing space debris in geostationary and geostationary transfer
orbits. For that purpose, a sophisticated liquid nitrogen cooled CCD camera
and focal reducer are part of the system.

In addition, the OGS forms part of the IAC’s comprehensive infrastructure
for astronomical studies.

The Instituto de Astrofisica was contracted by ESA to develop, integrate
and test the main control system of the OGS. Representatives from the
Institute presented their final overview of the control system to ESA on
1 March at ESTEC in Noordwijk, The Netherlands.

“Alongside other space agencies, ESA has been working on space laser
communications for more than 20 years and it is exciting to see this
technology finally being demonstrated,” said ESA’s OGS Project Manager,
Zoran Sodnik.

“After the launch and commissioning of Artemis, inter-satellite laser
communication will be performed for the first time. We hope it will go a
long way to convince satellite operators of the many advantages of laser
communication compared to microwave communications. These advantages
include smaller terminals, higher data rates, lower power consumption
and regulation and interception-free service,” he added.