A “revolution in remote sensing” took place in the mid-1980s, when Dr. Alexander F.H. Goetz and his colleagues at the Jet Propulsion Laboratory developed a powerful instrument called AVIRIS (Airborne Visible InfraRed Imaging Spectrometer), according to Dr. Nicholas Short, author of NASA’s online Remote Sensing Tutorial. AVIRIS extended the capabilities of ground-based spectrometers, enabling the spectrum-detecting instruments to be used in the air on moving platforms.
In the early era of remote sensing, limitations in technology prevented spectrometers from being used on moving platforms mounted on aircraft and spacecraft. Essentially, the high speeds of a moving vehicle did not allow spectrometers sufficient time to accurately focus on sample features of the Earth or atmospheric targets (water vapor, cloud properties, aerosols, and absorbing gasses). All of this changed with AVIRIS. The airborne spectrometer helped to open the door for a remote sensing imaging method known as hyperspectral imaging, according to Short.
Hyperspectral imaging yields continuous spectral signatures that are captured in high-spectral resolution; this surpasses multispectral imaging methods that collect data at slower rates and in low-spectral resolution. The continuous spectral signatures, or spectral “curves,” measure reflectance from the ground, water, or the atmosphere, in the wavelength region responding to solar illumination. The method is especially useful for classifying material types on the Earth’s surface in fine detail, such as rockforming minerals, soil, vegetation, and water.
Two decades after its development, AVIRIS continues to fly on aircraft today. The airborne instrument is identifying, measuring, and monitoring constituents of the Earth’s surface and atmosphere in order to facilitate advancements in the fields of oceanography, limnology (the study of lakes, ponds, and streams), snow hydrology, environmental science, geology, volcanology, soil and land management, atmospheric and aerosol studies, and agriculture.
Meanwhile, even higher above the Earth, NASA also has a hyperspectral instrument called Hyperion onboard the Earth Observing-1 satellite. Launched in 2000, Hyperion is providing a whole new class of Earth-observation data for improved Earth surface characterization.
Beginning with AVIRIS and continuing with Hyperion, hyperspectral imagery is helping to broaden NASA’s understanding of the natural and man-made influences that contribute to the ever-changing Earth.
A service-disabled veteran-owned small business concern, SpecTIR LLC is recognized for innovative sensor design, on-demand hyperspectral data collection, and image-generating products for business, academia, and national and international governments. William Bernard, SpecTIR’s vice president of business development, has brought a wealth of NASA-related research experience to the company in the past few years.
Prior to joining SpecTIR, Bernard was the principal investigator on a NASA-sponsored hyperspectral crop-imaging project. This project, made possible through a Small Business Technology Transfer (STTR) contract with Goddard Space Flight Center, aimed to enhance airborne hyperspectral sensing and ground-truthing means for crop inspection in the Mid-Atlantic region of the United States. With Goddard’s support and access to a wealth of the Center’s hyperspectral resources, Bernard and his research team established a program to collect crop imagery from an aerial-mounted hyperspectral sensor and to correlate this imagery with ground-truthed field data to further define crop classifications and create spectral signature data libraries.