Environmental satellites today are designed to meet the most requirements possible within the constraints of budget, reliability, availability, robustness, manufacturability, and the state of the art in affordable technology. As we learn more and more about observing and forecasting, requirements continue to be developed and validated for measurements that yearn for advances in technology. The goal is to incorporate new technologies into operational systems as quickly as possible. Technologies that exist or are being developed in response to growing requirements can be categorized as ”requirements pull” whereas technologies rooted in basic research and engineering exploration fall in to a ”technology push” category.

NOAA is exploring technologies for future NOAA satellite systems. Unmet requirements exist that drive the need to locate, explore, exploit, assess, and encourage development in several technologies. Areas needing advanced technologies include: atmospheric aerosols; cloud parameters; precipitation; profiles of temperature, moisture, pressure, and wind; atmospheric radiation; trace gas abundance and distribution; land surface; ocean surface; and space weather components such as neutral density and electron density.

One of the more interesting ideas in the technology push category is a constellation of satellites at Medium Earth Obit (MEO) altitudes, here described as circular orbits at 11,000 km altitude. Consider the vision of being able to observe the environment anywhere on the Earth, at anytime, with any repeat look frequency, and being able to communicate these measurements to anyone, anywhere, anytime, in real time. Studies suggest that a constellation of MEO satellites occupying equatorial and polar orbits (inclination = 90 degrees) could, in principle, accomplish this task.

Also new on the horizon is solar sail technology. NOAA has been looking at solar sails as providing a propulsive system that could be used to maintain a satellite in a position closer to the Sun than L1. L1 is that point between the Earth and the sun where the gravitational forces of the Earth and the sun are equal. The sail would allow the increased gravitational force from the Sun to be balanced by the propulsive force of the solar sail. This capability could increase the lead time for measuring and predicting the impact of solar events. Solar sails could also allow a satellite to be positioned over the Earth's polar regions continuously, filling a critical gap in current orbital observations and services.

This paper will focus primarily on current studies of MEO orbits and solar sail technology, and report briefly on other technologies of interest.