Build an international observatory

ADEOS, called Midori, was a Japanese Earth-observation mission with international instruments. It combined observations relevant to environmental change with development of spacecraft and data-handling technology. Its payload included NASDA’s AVNIR and OCTS, NASA’s NSCAT and TOMS, France’s CNES POLDER, and Japanese instruments IMG, ILAS and RIS. These names identify different measurement roles, not eight copies of one camera.

A question about Earth’s environment often crosses disciplinary boundaries. Ocean conditions interact with winds, clouds and the exchange of heat and water. Combining different observations can make those connections testable. The benefit comes from knowing what each instrument measures and matching the records carefully, rather than simply counting how many sensors fit on a satellite.

Midori launched on H-II on August 17, 1996 at 01:53 UTC, or 10:53 in Japan. A contemporary JPL release described the same event at 6:53 in the evening on August 16 in Pacific time. Keeping the time zone explains the different calendar dates without inventing an extra launch. The archive keeps one spacecraft identity for that event.

ADEOS-II, called Midori II and recorded as Midori-2 in the archive, launched on H-IIA on December 14, 2002. Its instruments included AMSR, GLI, SeaWinds, ILAS-II and POLDER. NSCAT belongs to the first ADEOS, while SeaWinds belongs to ADEOS-II. A family relationship helps explain continuity of scientific work; it does not make the two spacecraft or their payload lists interchangeable.

Two spacecraft, connected scientific goals

Putting several instruments on a spacecraft lets them share an orbiting platform, power, pointing and communications. It also connects their continued operation to common spacecraft systems. An instrument can be scientifically valuable and mechanically intact yet stop supplying observations when those supporting services are lost.

Consider an original design exercise with two options. One platform carries three instruments; three separate platforms each carry one. The shared platform can simplify some coordination and avoid duplicating spacecraft services, but a common failure can affect all its payloads. Separate platforms change the costs, coordination and failure relationships. Neither layout is automatically best without specifying the mission’s goals and constraints.