“That’s Professor Global Hawk”
A remote-piloted warrior starts flying for science.
- By Kara Platoni
- Air & Space magazine, May 2011
On an April morning last year beneath a bright desert sky, officials at NASA’s Dryden Flight Research Center in California unveiled their newest tool for studying the atmosphere: a Global Hawk. In fact, it was the very first Global Hawk, produced in 1998 as a demonstrator to show the capabilities of the unmanned military airplane.
Originally developed to provide field commanders with high-resolution surveillance imagery and produced by Northrop Grumman, Global Hawks fly high and long. They reach altitudes of 65,000 feet, and can surpass 30 hours and 11,000 nautical miles in a single flight. For Earth scientists, loading a Global Hawk up with sampling gear and sending it into the stratosphere suggests intriguing applications: measuring levels of pollutants and greenhouse gases like ozone; studying the formation of hurricanes and the shrinkage of ice sheets; monitoring the effects of natural disasters. “Northrop Grumman and the U.S. Air Force have proved that you can use this plane to do reconnaissance,” says NASA atmospheric scientist Paul Newman, who helped oversee Global Hawk’s first climate research mission. “Well, science is just a different kind of reconnaissance.”
The Global Hawk is no diminutive drone—its slender wings span 116 feet, and its V-tail reaches 15 feet high. With its white paint job, snub nose, humped radome, and single Rolls-Royce AE-3007H turbofan engine, the Global Hawk cuts a figure both elegant and strange; its profile gives the vague impression of a beluga wearing a jetpack.
Global Hawks are well established as military aircraft: The Air Force has deployed them since 2001; 30 have been built and 26 remain operational. But last April marked the first time a Global Hawk had been used for Earth science. As scientists and NASA officials gathered inside a Dryden hangar to admire Air Vehicle-1, the first Global Hawk made, its sister airplane, AV-6, was heading up the Pacific Northwest coast on a 24-hour tour, one of five flights planned as part of the Global Hawk Pacific (GloPac) mission, a joint effort between NASA and the National Oceanic and Atmospheric Administration to demonstrate the aircraft’s scientific utility.
NOAA commander Phil Hall was at the controls that day, although nowhere near the aircraft itself. Clad in a khaki flightsuit, he was controlling the airplane from inside a ground station housed in an ordinary-looking office building at Dryden. Using mouse and keyboard, he guided the Global Hawk on a path that would take it from off the Alaskan coast to near Hawaii. Along the way, the aircraft underflew a tracking satellite to calibrate instruments with it, sampled a chunk of polar air to measure its ozone content, and intercepted a dust plume drifting across the ocean from Asia.
A few months later, Hall was back on the team for another Global Hawk first: its maiden hurricane surveillance mission. Part of NASA’s Genesis and Rapid Intensification Processes (GRIP) experiment, the unmanned airplane was deployed during the August-September hurricane season to help scientists better understand the formation and behavior of these fierce storms.
Says Hall: “We’re doing a lot of things with the airplane that have never been done before.”
For many Earth science researchers, the moment they saw a Global Hawk, it was love at first sight.
Newman, who is normally based at NASA’s Goddard Space Flight Center in Maryland, first glimpsed a Global Hawk in 1999; he was at Dryden preparing one of the agency’s ER-2s for an ozone depletion study, and a group of scientists were invited across the runway to look at one. “Boy, were we wowed,” he recalls.
Researchers immediately grasped the promise. “With any conventional aircraft, it always seems that the phenomena you’re interested in sampling—a hurricane or the polar vortex up in the Arctic—is always just out of range of your plane,” says Newman. The two rides NASA atmospheric scientists have traditionally used for high-altitude research—the ER-2 (the agency’s version of the Lockheed U-2 spyplane) and the WB-57 (a variant of the B-57 bomber)—typically fly no more than eight- and 6.5-hour missions, respectively. The record for a Global Hawk flight so far is 33.1 hours. With that kind of endurance, an autonomous aircraft could let a crew stationed at a temperate location operate a mission that spanned from pole to equator in a single trip.
While atmospheric research has long been conducted with satellites, airplanes offer more flexibility: They can descend from altitude, take in situ as well as remote measurements, move in any number of directions (satellites are limited to either east-west or north-south), and loiter over a spot instead of just passing overhead once a day. Even better, scientists can easily swap instruments out for repairs or upgrades. With a satellite, says Chris Naftel, NASA’s Global Hawk project manager, “whatever you put in orbit, you’re stuck with that.”
The Global Hawk does have limitations. NASA’s ER-2 can carry 2,600 pounds; its WB-57, 6,000 pounds. The Global Hawk, by contrast, can carry a payload of 1,500 pounds. Scientists may have to choose a simpler payload than they would for a conventional airplane, says Newman.