In order to both simplify the AO/Cat-I product quota system and to provide Principal Investigator's with a high flexibility in ordering the products, ESA has introduced the concept of product equivalence. This document describes what is entailed in product equivalence with respect to ERS and Envisat users.
Polar Orbit Earth Observation requirements have been considered for the Space Station era. Candidate model payload groupings (both an initial set and an evolutionary growth) have been derived assuming the availability of serviceable permanent polar platforms, e.g. a "morning" platform provided by ESA, and an 11 afternoon" one by NASA.