FEATURE

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Earth Science Takes Flight

When the Global Hawk aircraft takes off from an airstrip at the Edwards Air Force Base in the high desert of Southern California this summer, the event will herald a new era for Earth scientists who now have access to an unpiloted, high-altitude platform on which to fly their experiments. It also culminates months of planning — especially for three Goddard scientists who are participating in the maiden scientific flight of NASA’s first unmanned aircraft system, which is capable of flying for longer intervals than piloted scientific aircraft, thereby increasing the amount of data scientists can collect.

Goddard scientist Paul Newman (left) and NOAA scientist Dave Fahey (right) share project management responsibilities for Global Hawk’s maiden scientific flight.

Over the next few weeks, the Northrop Grumman aircraft will make between four to five flights — each lasting about 24 hours in duration — to gather data over the Pacific and Arctic regions. The principal goal is gathering data to validate measurements by Aura, an A-train satellite that Goddard developed to study Earth’s ozone, air quality, and climate, said Goddard’s Paul Newman, who is serving as the project scientist for the Global Hawk Pacific (GloPac) mission.

With its suite of 12 instruments — provided by scientists from Goddard (see related story, page 5), the Jet Propulsion Laboratory, the National Oceanic and Atmospheric Administration (NOAA), Denver University, and the Ames Research Center — the mission also will address trace gases in the upper troposphere and lower stratosphere from the mid-latitudes into the tropics. In addition, the mission will sample the developing winter stratospheric polar vortex, volcanic plumes, and aerosols and measure dust, smoke, and pollution that originate from Asia and Siberia and cross the Pacific.

Science Not the Only Objective

Science, however, is not the only objective.

“This is the maiden science flight. We’ve never tried to do this before and we’re trying to figure out how to do this well,” said Newman, who is sharing project management responsibilities with Dave Fahey, a scientist with NOAA’s Earth System Research Laboratory, and Mike Craig, a mission expert with the Ames Research Center. “This is a complex aircraft system,” Newman added.

Developed originally for the U.S. Air Force to gather intelligence and surveillance data, the Global Hawk is remotely piloted. Before a flight begins, the crew chief starts the aircraft from a laptop and then transfers control to the pilot who works from an operations center at Dryden Flight Research Center, located on the Edwards Air Force Base.

Mission Begins Mid-August

During the GloPac mission, which will run for about six weeks beginning in mid-August, the mission’s 12 principal investigators will work from an adjoining room where they will activate their instruments and begin gathering data as the Global Hawk ascends to its operational altitude of 65,000 feet (nearly twice as high as a regular commercial airliner). Throughout the mission, principal investigators will have immediate access to their data and will be able to command their instruments from their computer consoles.

“In many respects, the Global Hawk is more like a satellite than an airplane,” Newman said.

Global Hawk Offers Enhanced Capabilities

The addition of the Global Hawk to NASA’s fleet of research aircraft affords scientists a new capability, he added. The aircraft, which is distinguished by its bulbous nose and 116-foot wingspan, can travel 10,000 nautical miles for up to 31 hours, carrying 2,000 pounds of instrument payload. In contrast, NASA’s manned research aircraft, the ER-2, can fly for only eight hours. Furthermore, researchers do not have access to their data until after the ER-2 aircraft lands.

NASA decided nearly a decade ago to begin transitioning to unmanned aircraft. In 2007, the Air Force gave Dryden two of its seven Global Hawk Advanced Concept Technology Demonstrators built as part of the Advanced Concept Technology Demonstration program sponsored by the Defense Advanced Research Projects Agency. Last year, Dryden entered into a Space Act Agreement with Northrop Grumman to share in the use of the aircraft. In exchange, Northrop Grumman provides support for each flight.

Referring to the new platform, Newman put it this way: “This will be cool.”

For Goddard scientist Matt McGill, the maiden flight of NASA’s Global Hawk unmanned aircraft system “was a long time coming.” Four years ago, McGill asked a very simple question shortly after NASA announced that it would transition aircraft-based scientific investigations to unmanned systems: Did NASA even have any instruments that could fly on these platforms? Not content to wait for an answer, he competed for and received Internal Research and Development and Headquarters funding to modify his Cloud Physics Lidar to fly on an unmanned platform. He now gets his first chance to fly. Cloud and Aerosol Measurements During the Global Hawk Pacific (GloPac) mission, McGill’s instrument will gather cloud and aerosol measurements to validate Aura data. It is the first time that McGill has collected this type of data over the Arctic, he said. The instrument functions like the original. However, McGill modified the mechanical interface to make it compatible with the Global Hawk’s payload area. He also installed an Ethernet-based downlink capability so that the instrument could download data as it received it.

Goddard scientist Matt McGill used Internal Research and Development funds to modify his Cloud Physics Lidar for use on an unmanned aircraft system.

Another Goddard scientist, Scott Janz, will be measuring nitrogen dioxide, dust, smoke, and ozone with his Ultraviolet-Visible Spectrometer, again to help validate Aura measurements. But he has other reasons for flying on GloPac as one of 12 experimenters.

Spectrometer Measurements Important to Proposed GEO-CAPE Mission

His experiment covers some of the science topics important to the proposed Geostationary Coastal and Air Pollution Events (GEO-CAPE) mission, which the National Research Council has recommended for the 2015 timeframe. Janz would like to use lessons learned from the GloPac experience to build a next-generation instrument that might be suitable for GEO-CAPE, he said.

“This mission will help us refine science requirements,” he said. “We’re getting data at higher spatial resolution that will help bound the requirements.” The next step would be to build another aircraft-based instrument that might serve as the prototype for a future satellite mission.