Aware of parallel Canadian and Japanese interest, ESA policy, clarified at 
the Rome Ministerial meeting in January, is to cooperate in the US Space 
Station Programme provided it is to their mutual technical and financial 
advantage. The European policy is that ESA by the turn of the century 
should have a capability not only to provide its own transportation service 
to Columbus elements flying with the US station but also to operate, if 
necessary, totally autonomously. 
As a first step in ESA's Spacelab follow-on development programme aiming 
towards a COLUMBUS space station, and unmanned European Retrievable Carrier 
called EURECA is being developed. 
Based on the experience gained with Spacelab, EURECA has been designed to 
provide prolonged flight durations, retrievability, and reusability. In 
addition, EURECA provides a less contaminated environment than Spacelab, and 
smaller residual accelerations since it operates like a satellite in a 
free-flying mode away from the launcher or a future space station. 
Being on the other hand designed as an autonomous system with 
state-of-the-art technology, EURECA will also provide the Agency with 
valuable early experience in the development, utilisation, and operation of 
future large platforms in low Earth orbits. 
Scheduled for launch in March 1988, EURECA will be delivered by the Space 
Shuttle into an orbit of 296 km and will, by means of its own propulsion 
system, ascend to an operational altitude of about 500 km. From there it 
will be brought down to the lower orbit after 6 to 9 months to rendezvous 
with and to be returned to earth by the Shuttle. 
Parallel to the development of EURECA and its first microgravity payload, 
further studies in close collaboration with the Space Science and Earth 
Observation Communities are on the way to define the required flight 
configurations of EURECA in support of space-and-solar physics missions, 
remote sensing, as well as further microgravity dedicated missions. 
The present stage of the Space Station studies conducted separately by the 
US and ESA includes Polar Platform elements. These studies aim at defining 
candidate platforms to satisfy model payload requirements which have been 
provided separately by the US and ESA as driving inputs for their own 
studies. It turns out that the Polar Plarform users are predominantly from 
Earth Observation. 
As a first step towards improving the model payload generic requirements for 
further Polar Plarform studies, ESA set up the Earth Observation Polar 
Orbiting Plarform Element (POPE) Requirements Working Group. The Working 
Group examined the requirements and priorities in the different areas of 
Earth Observation, in order to make a first assembly of payload groupings 
and to derive the resulting generic requirements for both initial and later 
Polar Platform configurations. 
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