SABIA: turn a shared observation goal into requirements

Brazil and Argentina agreed in 1996 to develop a remote-sensing satellite called SABIA. INPE’s retrospective chronology says that original project was not developed. An Argentine government account describes SABIA within cooperation among CONAE, AEB and INPE, associates it with the SAC-E designation and sets out goals for information about water, food and the environment in the MERCOSUR region. Those are stated purposes, not a catalog of observations returned by a flown satellite.

The later SABIA-Mar effort belongs to the continuing history of regional cooperation, but its instruments, mission scope and development milestones need their own dated account. A familiar acronym does not guarantee an unchanged spacecraft design. Preserve the link between related initiatives while identifying which version each document describes. In this lesson, SABIA means the earlier proposal; later ocean-observation work is a connected topic rather than an assumed flight outcome of the 1996 agreement.

A request for environmental imagery is incomplete until it names the decision to be supported. Mapping small agricultural fields, following a rapidly changing flood and distinguishing surface materials require different combinations of spatial, temporal and spectral information — open definition. Spatial detail concerns the ground area represented by measurements; temporal sampling — open definition concerns when usable observations are obtained; spectral information concerns the wavelength ranges measured. Improving one dimension does not automatically improve the others.

Consider an original planning exercise with two fictional data products. Product A records ten-meter samples every sixteen days; product B records one-hundred-meter samples daily. If the immediate task is following the regional progression of a flood, frequent observations may be valuable even though the individual samples are larger. If the task is separating narrow neighboring fields, the finer sampling may matter more. These values illustrate a tradeoff and are not specifications assigned to SABIA or any other spacecraft.

Translate a regional goal into a product

Both products still need suitable wavelength measurements, calibration, known locations and quality information. Cloud can prevent an optical observation from becoming a useful surface image even when the spacecraft passes on schedule. A planned revisit is therefore different from the interval between usable observations. A real design also needs receiving stations, processing, distribution and people able to interpret the results in their local environmental setting.

In a partnership exercise, assign one team to define the user’s question, another to specify measurements and another to deliver a documented product. Agree the interfaces and how a sample result will be checked. Then distinguish a signed cooperation agreement from a tested instrument, an operational satellite and a validated application. SABIA’s historical value includes the questions it posed about regional information needs; understanding those questions does not require inventing a successful flight for a proposal that did not reach that stage.