Franco-US satellite to make survey of Earth's water
A Franco-US satellite is due for launch this week on a mission to survey with unprecedented accuracy nearly all water on the Earth's surface for the first time and help scientists investigate its impact on the planet's climate. For Nasa and France's space agency CNES, which have worked together in the field for 30 years, it's a landmark scientific mission with a billion dollar budget. French President Emmanuel Macron went to Nasa's Washington headquarters at the end of November alongside US Vice President Kamala Harris. He highlighted the liftoff – scheduled for early Thursday on the US west coast – of the Surface Water and Ocean Topography (Swot) mission to monitor the levels of oceans, lakes and rivers, including in remote locations. Its predecessor, Topex/Poseidon, launched in 1992, was also a Franco-US joint venture that measured ocean surface to an accuracy of 4.2 centimeters. It aided the forecast of the 1997-1998 El Nino weather phenomenon and improved understanding of ocean circulation and its effect on global climate. The 2.2-tonne Swot mission will be put into orbit from Vandenberg Space Force Base in California atop a SpaceX Falcon 9 rocket. The satellite's primary payload is an innovative instrument to measure the height of water called KaRin, or Ka-band radar interferometer. Its two antennas, separated by a big boom, create paralleled swaths of data. "We're going to get ten times better resolution than with current technologies to measure sea-surface height and understand the ocean fronts and eddies that help shape climate," said Nasa Earth Science Division Director Karen St. Germain. "It's like looking at a car number plate from space when before we could only see a street," added Thierry Lafon, Swot project leader at the CNES. While the impact of major ocean currents such as the Gulf Stream is known, more local flows and eddies covering dozens of kilometres remain more of a mystery. But they too affect sea water surface temperatures and heat transfer as well as the absorption by the oceans of carbon dioxide from the atmosphere. Swot will improve weather and climate modelling, the observation of coastal erosion and help track how fresh and saltwater bodies change over time. (AFP)