Keeping space free of debris: CNES shows the way with decision to de-orbit SPOT-1 (Forwarded)

Centre National d'Etudes Spatiales (CNES)
Toulouse, France

PRESS RELEASE: November 13th 2003

Keeping space free of debris

CNES shows the way with decision to de-orbit SPOT-1

On 22 February 1986, a European Ariane 1 launcher orbited SPOT 1, the first 
satellite of the Earth observation programme decided by the governments of 
Belgium, Sweden and France. Initially designed to operate for three years, SPOT 
1 has since supplied commercial operator Spot Image with more than 2.7 million 
high-quality satellite images. Now at the end of its service lifetime, SPOT 1 is 
set to be de-orbited by engineering teams at CNES' Toulouse Space Centre 
starting on 17 November, to lower the satellite into an orbit below 600 kilometres.

Although still capable of acquiring high-quality imagery after 18 years in 
service, SPOT 1 has reached the end of its operating lifetime. Consequently, 
CNES has decided to use the satellite's last reserves of fuel to place it in a 
lower orbit. If the satellite was left alone at its current altitude, it would 
continue to orbit the planet for another 200 years before re-entering the 
atmosphere, gradually breaking up over the years and leaving a trail of debris 
in its wake. Guidelines laid down in October 2002 by the Inter Agency Space 
Debris Coordination Committee (IADC) are designed to avert such situations by 
requiring all satellites in low-Earth orbit to be de-orbited within no more than 
25 years. CNES is lending its full support to these guidelines at international 
level, since they are geared to mitigating the risks and costs of using space 
for future generations. Although the guidelines do not in fact apply to SPOT 1, 
which was built well before they came into effect, CNES has decided to set an 
example by voluntarily de-orbiting the satellite.

In readiness for de-orbiting operations, teams have been working with industrial 
prime contractor Astrium to make changes to the flight software. Basically, 
de-orbiting will involve configuring the satellite so that its attitude is 
controlled by its thrusters, then lowering the perigee to about 550 kilometres 
by performing daily braking manoeuvres for two weeks, then shutting down power 
to its systems. In this lower orbit, SPOT 1 will be subjected to higher drag 
that will cause it gradually to lose altitude and break up naturally in the 
atmosphere after about 15 years, thus posing no danger to populations on Earth.

CNES' network of tracking stations-at Issus Aussaguel (France), Hartebeesthoek 
(South Africa), Kerguelen and Kourou (French Guiana)-and the ground station in 
Kiruna, Sweden, will track and control SPOT 1 through every phase of 
de-orbiting, assisted by Norway's ground station in Svalbard.

"The de-orbiting of SPOT 1 illustrates the engineering expertise of CNES teams 
and, more besides, it shows that space activities remain closely governed by 
international guidelines, which guarantee that space will be used sustainably by 
and for future generations," said CNES President Yannick d'Escatha.

The other three SPOT satellites-SPOT 2, SPOT 4 and SPOT 5-will continue to 
deliver imagery, which is marketed by Spot Image. SPOT 5's enhanced performance 
has confirmed the remarkable imaging capability of the SPOT Earth observation 
system in service since 1986. The recent contract awarded to EADS Astrium to 
build two Pleiades satellites carrying high-resolution instruments supplied by 
Alcatel Space assures continuity of service for the next decade.