Volume 11, Number 1 • Spring 2003 • Aerospace Technology Development

Demonstrating Practical Use of UAV Technology

Ripe coffee "cherries" being processed after picking. Photo courtesy of Clark University, Worcester, MA. Professor Stanley Herwitz.

A solar-powered unmanned aerial vehicle (UAV) successfully completed a NASA remote-sensing applications demonstration. The Pathfinder-Plus airplane loitered more than four hours over Hawaii’s largest coffee plantation on the island of Kauai, taking digital images to make a “clear-sky” mosaic.

The NASA team combined preplanned, fixed flight lines with spontaneous, remotely controlled maneuvers to guide the UAV into cloud-free areas over the coffee fields. Despite an often 80-percent cloud cover, the project demonstrated how a solar-powered UAV, equipped with a ground-controlled aerial-imaging system, could aid coffee growers by informing them of the ripest fields for daily harvest. This type of technology may eventually aid farmers and lead to more efficient harvesting methods.

“Our flight demonstrated the viability of this type of UAV for practical applications,” said Cheryl Yuhas, Suborbital Airborne Sciences Program Manager, NASA Headquarters. “NASA is committed to taking new technologies, developed for Earth Science research, and showing their practical applications — integrating our technologies into decision-support systems that provide a return on the taxpayers’ investment,” she said.

“This type of aerial platform will ultimately allow for accurate and timely Earth observations over large regions for extended periods of time. They also could provide for the opportunity to upgrade payloads as technology develops at the end of an observation period — something not possible when using satellites,” Yuhas explained.

“The mission demonstrated the capability of this type of aircraft, with downsized digital-imaging systems, to collect and quickly deliver high-resolution imagery over localized regions, overcoming the challenging conditions of tropical cloud dynamics,” said Dr. Stan Herwitz, professor of earth sciences at Clark University in Worcester, MA. Herwitz is the Principal Investigator for the UAV coffee project. “An additional significant achievement of this mission was that we were flying in national airspace, and the UAV was treated like any conventionally piloted plane by air traffic controllers in Honolulu,” he said.

“During the flight, we assembled clear-sky images, even though the plantation was never
completely cloud-free,” Herwitz said. “I never thought I’d be this excited on a cloudy day in Kauai. We achieved everything we set out to do and much more,” he said.

There is a significant difference in the value of ripe coffee “cherries” compared to unripe or overripe. Choosing the fields with the highest percentage of ripe coffee cherries is crucial, because harvest machines shake off coffee cherries, ripe or not, in each field. “The main variety of coffee grown on this plantation ripens to a yellow color,” Herwitz said. The color of the cherries, which contain the coffee beans, is a guide to the degree of ripeness.

“We had a product available for immediate viewing by the coffee harvest manager. Each of the more than 300 high-resolution images taken during the mission was transmitted wirelessly to the ground station in less than 30 seconds, and four minutes after receiving an image, we could generate glossy prints showing the ripening coffee fields,” Herwitz said. For part of the mission, an undergraduate student 2,500 miles away at California State University in Monterey Bay, CA, controlled one of the digital cameras remotely. Herwitz added, “With the benefit of a downward-looking video on the underside of the UAV, we could direct the aircraft to cloud openings as they were developing.”

“The mobile satellite capability this UAV provides is very impressive,” said Herwitz. “When we observed an opening, we adjusted our flight path to acquire the clear-sky image,” he explained. The loitering capability of Pathfinder-Plus made it possible to acquire cloud-free imagery over virtually all of the plantation’s harvestable acreage.

During the NASA demonstration, the Pathfinder-Plus was based at the US Navy’s Pacific Missile Range Facility at Barking Sands on Kauai. AeroVironment, Inc., a California company, built and operated the aircraft. Q

For coffee project information, visit http://www.clarku.edu/faculty/herwitz. For more information, contact Dr. Stanley R. Herwitz, Professor of Earth Science at Clark University, T: 650/604-2192, F: 650/604-4680. Please mention you read about it in Innovation.

NASA Official: Jonathan Root • Web Design: Printing & Design Office, NASA Headquarters • Credits