Their names are a mouthful, but the global perspective satellites provide has revolutionized our view of the Earth.
TRMM. Landsat 7. Terra. ACRIMSAT. EO-1. Jason 1. GRACE (twice). Aqua. ICESat. SORCE. Aura. CloudSat. CALIPSO. Jason 2. And, as of June 2011, Aquarius. None of the acronym-heavy Earth-observing satellites seen in the visualization below have achieved the name recognition of big-ticket NASA missions like Apollo or Hubble. But unmanned probes are quietly beaming down information that has transformed our understanding of how the Earth works and what we know of the human fingerprint on climate. Together they represent a mission to planet Earth as ambitious as any NASA has made to the Moon or Mars. One of the oldest functioning satellites in the fleet, TRMM, monitors precipitation; the newest, Aquarius, measures the salinity of the ocean. The next to launch in October 2011—NPP—will continue a suite of atmospheric, ocean, and land surface records initiated decades ago. The visualization shows the precise orbit tracks of twenty current and former Earth-observing satellites (not including Aquarius), as well as the International Space Station and Hubble.