Future technology improvements
Satellite altimetry has proven to be a valuable source of data for a broad range of applications. Looking beyond the missions in operational service today, future satellites will need to provide better spatial and temporal coverage so that we can study further near the coasts or mesoscale variations and other phenomena more closely. For the medium term, consideration is now being given to altimetry missions capable of 'scanning' the ocean surface to acquire data at scales of a few tens of kilometres, passing over the same spots every few days. Other projects on the drawing board are based on constellations of dedicated, low-cost microsatellites. The use of 'opportunity signals' is also being considered, with the possibility of retrieving reflected signals transmitted by satellites in the Global Navigation Satellite System (GNSS).
An altimeter/interferometer would include several altimeters mounted on masts which would acquire measurements simultaneously, thus providing continuous, single- or multi-altimeter wide-area coverage. Further information
See also J.C Souyris, OSTST 2010, Upcoming altimeter measurments: explaining interferometric SAR, pdf
One of the ways to improve altimetry resolution is to use several satellites at the same time. Until now, this has been done with very different types of satellite. The use of several identical satellites in constellation could reduce costs (development costs, and launch costs too for micro-satellites launched by the same rocket).
One approach being pursued to achieve maximum altimetry data coverage is to receive reflected signals transmitted by satellites in the Global Navigation Satellite System (GNSS), in particular from the Global Positioning System (GPS) constellation and its European civil counterpart, Galileo. This concept is based on a satellite in near-polar orbit (at an altitude of 400 to 500 km) retrieving signals emitted by multiple satellites and reflected by the ocean surface, then analysing these signals to compute sea surface height. This concept is currently still only in the study phase.