ERS-1 SEEN FROM SPOT-4

Huston, Stu (A016174@MDCPO102.HB.MDC.COM)
Fri, 16 Oct 98 09:05:00 PDT

The following was posted to sci.space.news by Andrew Yee:

ERS-1 SEEN FROM SPOT-4

CNES has taken a shot of the European satellite ERS-1 from SPOT-4,   
launched
on March 24, which is a first in the history of space observation. From   
its
orbit at 820 km, SPOT4 has been built to distinguished 10m details on   
earth
at 24,000 km/h. ERS-1 covers an orbit 41km under SPOT's , which enables
SPOT 4 to see on ERS-1 50cm details. However, since ERS-1 flies lower, it
is faster and passes SPOT 4 at about 250km/h. Because of these
extraordinary conditions, CNES has had to reprocess the raw images to
distinguish ERS-1 real aspect. The conditions for this shot have been
calculated by CNES, which implied a thorough knowledge of both   
satellites'
position. SPOT 4 orbit is evaluated by the ground control center of SPOT
satellites, in CNES/Toulouse, while ERS-1's has been given by the
ESA/ESOC/Darmstadt center which monitors the satellite. SOPT 4   
telescopes,
thanks to their oblique viewing mirror, helped take the shot on May 6,   
1998
at 9:56 am UT above the Tenere desert (Niger). To see the images:
http://www.cnes.fr/actualites/news/cp_cnes_98_6_30.html [CNES Press
Release, 06/30/98]

Stu Huston