Two new-generation Earth observation satellites, NASA's Aqua and  Spot Image's Spot 5, will be launched into sun-synchronous polar orbits next month.

Aqua, the latest NASA Earth Observing System (EOS) programme spacecraft, will be launched by a Delta II from Vandenberg AFB, California, on a $952 million mission.

The TRW-built craft, equipped with six instruments, will study the hydrological cycle which sustains life on Earth. Aqua will complement observations made by the recently launched Jason 1 and Grace satellites, developed with France and Germany, respectively, to study the effect of hydrology on the climate.

The 3t Aqua is equipped with an atmospheric infrared sounder, microwave sounding unit and radiometer, a cloud and Earth radiant energy sensor, a humidity sounder, and a moderate resolution imaging spectro-radiometer.

French space agency CNES-led commercial remote sensing satellite company Spot Image, meanwhile, will launch Spot 5, its fifth sun-synchronous orbiting satellite, on board an Arianespace Ariane 4 booster from Kourou on 3 May.

Built by a consortium led by the former Matra Marconi Space, now Astrium, Spot 5 is based on the spacecraft bus developed for French Helios 2 reconnaissance satellites, and is equipped with three new 270kg (600lb) visible and infrared cameras with a maximum resolution of 2.5m (8.2ft).

This resolution was designed to meet commercial market requirements as perceived in 1993 when the satellite's development began. But this has been overtaken in some applications by commercial high-resolution satellites, such as Digital Globe's QuickBird with a resolution of less than 1m.

A US Air Force Defense Meteorology Space Programme (DMSP) satellite, grounded since 1999, has been delayed again. The Lockheed Martin Titan II booster has malfunctioned several times - and in 2001, the satellite, also built by Lockheed Martin, sprang a propellant leak. Another Titan II is due to launch the National Oceanic and Atmospheric Administration's NOAA M satellite - based on the same spacecraft bus as a DMSP - on 24 June, also from Vandenberg.

Source: Flight International