The proposals will help the agency develop the broad outlines of commercial use of the station. "We are still in the brainstorming phase," says Jorg Feustel-Buechl, ESA's director of manned spaceflight and microgravity.

In June, ESA asked major aerospace companies for ideas on how they -- whether jointly or singularly -- could manage station operations and logistics. Five companies have been asked to present ideas: Daimler Chrysler Aerospace (DASA), Aerospatiale, Matra Marconi, Alenia Aerospazio, and Arianespace. ESA is expecting responses in mid-September.

In addition, ESA is asking a broad range of companies for "utilization" ideas -- suggestions about specific payloads and experiments.

Companies making proposals must meet three conditions, says Feustel-Buechl. "They must take their share of the risk. They must do it in a technologically adequate way. And they must do it cheaper than ESA can."

The companies' input will be placed into a policy paper to be submitted to ESA's Council of Ministers, the agency's highest policy-making body, next spring. After approval of a general policy, ESA will issue a formal request for proposals from companies seeking management contracts.

The station's major European component, the Columbus laboratory, is scheduled for launch in 2004. Columbus will be used for experiments in materials processing, life sciences, and other areas.