The window for launches at NASA’s famed Kennedy Space Center (KSC) in Florida can often be as little as 10 minutes or less–and the cost of missing those windows is sometimes in the $1 million range–so it’s essential that the rocket scientists managing them leave nothing to chance. Not even the wind.
That’s why, as Fast Company is the first to report, NASA has rolled out an all-new high-tech antenna system to measure wind shear at KSC at altitudes of up to 65,000 feet. Given that the old system, in operation since 1990, had fallen into such disrepair that contractors trying to reverse-engineer it had resorted to buying parts on eBay, it’s no wonder that the space agency has finally turned to something more cutting-edge.
For years, KSC has operated two systems side by side to get current wind data. On one side is a system built in 1990, a 50 Megahertz Doppler radar wind profiler that even NASA called “aging.” On the other, NASA is employing a set of weather balloons.
“The balloons were the primary,” says Lisa Huddleston, the chief of the applied meteorology unit at KSC’s Weather Office, “And we were only allowed to use the [old] profiler as kind of a backup, kind of a check on the wind. If the launch people saw any huge differences between balloon and profiler, they could launch another balloon.”
During launch countdowns, NASA wrote in a 2014 document, winds below 60,000 can pose a major concern. Rockets have to climb through the atmosphere, and “launch team members need accurate data in order to program the vehicle’s guidance and steering commands to ensure the vehicle reaches its proper orbit without exceeding its aerodynamic wind load limits.”
The balloons are certainly capable of returning the proper data, but here’s the problem: They drift with the wind, and can quickly end up 100 kilometers downrange. Any data returned at that point is “not representative of what’s going on at the launch site,” according to Huddleston.
The new system, a large phased array radar installation built by DeTect that features 640 antennas, is all solid-state, and state-of-the-art. It was designed to return accurate launch-site wind measurement data every five minutes. Costing $11 million to install, the new system was put in place last December and, pending final certification from NASA, is expected to be the primary system for at least the next 20 years.
KSC has launched about nine rockets with the new technology since December, but until certification is complete, the space center is still employing the weather balloons.
“The plan is we’re going to do a comparison with weather balloons over an extended period of time,” said Thomas Brauer, an engineer who works on electrical ground systems at KSC, adding that the goal is to ensure data from the new profiler is confirmed by data from the balloons.
Once the new profiler is certified, Huddleston said, it will serve as the primary source of wind data for launches, although NASA would still send up balloons, both to gather information on temperature and humidity, and in case the high-tech system fails.
Launa Maier, the weather lead at KSC, is quick to add that they would need far fewer balloons for launches than in the past. Possibly, she said, controllers could get by with just one.
The new profiler is an up-to-date Doppler system, a one-of-a-kind phased array of 640 antennas spread over five acres north of KSC’s Shuttle Landing Facility.
Maier explained that signals from the phased array are used to measure wind speed, providing what she called “a full vector of the wind.”
According to Paul Hart, a senior vice president and general manager at Freescale (the provider of radio frequency technology for the new profiler) the implementation of all-new technology was key.
“Think of solid-state hard drives, which give far better performance that is faster and more reliable” than disk-based drives of the past, Hart said. “We’re essentially doing the same thing, [using] solid-state transistors…to amplify radar signals, and to handle very accurate pulse signals.”
The technology has been proven for years in the aviation industry, and is now “the staple for how air traffic control” gets wind data, Hart said.
But the KSC implementation is bigger and more ambitious than anything that’s been built before.
Hart said the new profiler was possible today thanks to continual improvements in radar signal amplification power levels. The technology was originally created for wireless communications systems, and was meant to be installed in places like cell towers. Over the years, he said, the transistors have gone from 100 watts to 1.5 kilowatts.
“By raising the power, we’re able to create systems that are far less complicated than in the past,” Hart said. “In the past, [it would have required] thousands and thousands of transistors. Now, we’ve reduced that by a factor of 10.”