Over the last 40 years, images from Landsatsatellites have been painting a portrait of global changes in agriculture, forestry, urban development, wetlands, and soil and water resources. Open access is a milestone for a movement that seeks ways to exploit best the scientifically useful portion of the over 1,000 exabytes of data now existing in the world (one exabyte equals one billion gigabytes). But, as a recent symposium found, there are other hurdles to overcome before open access actually delivers.

Recent developments, including the laying of three submarine cables along the coast of Africa in the past year, have boosted data speeds four-fold and reduced prices by 90 per cent. This suggests that the hardware challenge is increasingly being met and will likely be overcome in the years ahead.