The revolutionary mission which measured speed and direction of winds over global oceans for 10 years has been turned off.

The SeaWinds Scatterometer of NASA was an Earth observation satellite which was launched primarily for measuring the speed and direction of surface wind over the ice-free global oceans. The launch of the Quick Scatterometer took place in 1999 following a sudden failure of the NASA Scatterometer (NSCAT). NSCAT was supposed to measure surface winds over water for a number of years but the project was terminated much before its expected date. Despite its failure, NSCAT showed promising signs of success which urged the authorities at NASA to replace it with another satellite. Consequently, the QuikSCAT satellite was constructed on an emergency basis and was ready to be launched within a year, making it the fastest NASA mission since the 1950s.

The NSCAT team joined forces with the Jet Propulsion Laboratory to complete the construction in such a short time. Originally, the budget of this mission was set at $93 million but an increment of $5 million was needed to complete the project due to a series of rocket failures in 1998. The SeaWinds Scatterometer, a new instrument, was the major payload of the satellite which has a specialized Microwave Radar System. A pair of radars and a spinning antenna provided it the ability to record data across nine-tenths of the oceans of the world in a single day. It used to make 400,000 wind measurements every day and each of these measurements covered an area of 1,800 kilometers in width.

QuikSCAT was launched with an initial 3-year mission requirement. However, it exceeded all the expectations and created a massive record of the speed and direction of winds at the ocean surface over a decade before encountering a failure in its antenna motor. This did stop QuikSCAT from determining the vital information about surface wind but it continued to serve for another 9 years as the gold standard of accuracy for calibrating new spaceborne scatterometers. It was turned off recently on the 2^nd of October after completing its mission plan.

The authorities at NASA acknowledged that this unique national resource achieved much more than expectations. A lot of weather forecasting agencies of the world used the measurements of QuikSCAT to monitor storms and hurricanes far out in the open seas. Similarly, the data of winds over the global ocean surface was used for researching, modeling, monitoring, and forecasting the ocean, ice, atmosphere, and climate. Michael Freilich, the original Principal Investigator of the QuikSCAT who is currently working as the Director of the Earth Science Division of NASA, praised the scatterometer in the following words:

“QuikSCAT operated in space for nearly two decades, and we are certain that its impact and legacy will last much longer.”

The significance of QuikSCAT is clearly indicated by the fact that its decommissioning was postponed twice. The reason for this was the exceptional stability and accuracy of the satellite. Scientists wanted to launch and calibrate new scatterometers with respect to QuikSCAT before ending the mission. Satellite instruments need to be calibrated regularly in order to ensure that their readings are accurate. The Quick Scatterometer of NASA has been invaluable in assuring that all the new missions from different space agencies of the world are providing accurate measurements. Rob Gaston, the Project Manager of QuikSCAT said,

“It’s a testament to the research community’s commitment to climate research that QuikSCAT’s intercalibration mission has continued to receive the highest possible marks for science relevance in the reviews that NASA follows to establish funding priorities for missions like QuikSCAT. The intercalibration mission has enabled research that would not have been possible but for the remarkable stability of the SeaWinds instrument and the exceptional reliability and longevity of the QuikSCAT spacecraft.”

QuikSCAT has made some amazing discoveries over the years but some of them were extremely critical. Firstly, it observed that hurricane-strength winds develop regularly in the North Atlantic and North Pacific oceans. Similarly, it was critically important for a number of industries other than forecasting and research. For example, it helped in planning new offshore winds farms, assisted search-and-rescue operations at sea, and facilitated the identification of efficient shipping routes. Ernesto Rodriguez, a Project Scientist of QuikSCAT summed it up beautifully by saying,

“The decommissioning of QuikSCAT marks the passing of an era. Many scientists and forecasters have built their careers over the last 20 years using QuikSCAT. Its data led to major discoveries on the interaction between the ocean and the atmosphere.”