New Doppler Radar Wind Profiler Will Replace Old System Near Shuttle Landing Facility

Linda Herridge NASA's John F. Kennedy Space Center

As NASA moves forward next year to place instruments on the International Space Station to take ocean-surface wind speed and direction measurements, the Ground Systems Development and Operations Program office at the agency's Kennedy Space Center in Florida has plans of its own to upgrade decades-old wind measurement equipment near the center’s Shuttle Landing Facility (SLF).The 50 megahertz Doppler Radar Wind Profiler (DRWP) Project team successfully completed a preliminary design review on Jan. 18. The team, working under Kennedy's Engineering Support Contract, has members from NASA, QuinetiQ North America (QNA) and its subcontractor, DeTect Inc. of Panama City, Fla.The DRWP currently is used to warn launch operators of potentially hazardous upper-air wind conditions not detected by weather balloons that are used as the primary day-of-launch wind system.According to Dr. Frank Merceret, the director of research for Kennedy’s Weather Office, the DRWP accurately measures wind speed and direction at 500-foot intervals from 6,000 to 60,000 feet in altitude every five minutes.“The profiler has the advantage that it measures the winds 12 times faster than the balloons, and the measurements also are closer to the flight path of the vehicle,” Merceret said.The current system, built in the 1980s near the north end of the SLF on the east side, supports all launches on the Eastern Range. Its antenna comprises more than 100 wire dipoles and occupies about 3.7 acres of ground surrounded by an eight-sided fence.The system’s electronic components include the radar transmitter, receiver and computers which are housed in a trailer adjacent to the antenna. Merceret said that hardware in the system has become difficult to maintain because spare parts are no longer manufactured or available.The existing profiler cannot be used as the primary upper-air wind instrument, Merceret explained, because it is not certified for that application. Because of its age, it cannot meet the stringent reliability and maintainability requirements for certification. Installation of the new instrument will permit launch operators who want to use the wind profiler, rather than balloons, as their primary wind source to certify it for that purpose.The new system’s antenna will replace the large array of wire dipoles with 640, three-element Yagi sensors in a staggered antenna array. Each Yagi will be mounted on a 10-foot-high pole and consist of three, 10-foot-long aluminum tubes at right angles to the mounting pole.The hardware and associated software systems will be designed, constructed and installed by DeTect Inc., which is building the National Wind Profiler Network for the National Oceanic and Atmospheric Administration (NOAA). Kennedy’s system will largely be based on the NOAA design.Merceret said this will ensure there will be off-the-shelf components to support its maintenance for many years. The new system will replace the obsolete electronics with state-of-the-art equipment. The software will be replaced with modern, wind-finding algorithms, including an upgrade to the NASA-designed Median Filter First Guess wind-finding algorithm used on the existing DRWP.“This is a major project,” Merceret said. “The purpose is to provide the same or better, reliable and accurate wind profile data to Range Weather Operations and launch customers.”A critical design review will be completed by mid-April. The new system will take seven months to install, with work to remove the old system starting in March 2014. Installation of the DRWP will be completed by October 2014.Much of the old system hardware and spares will be shipped to Vandenberg Air Force Base in California, where an identical system is in use.