TECHNOLOGY ADVANCEMENTS


High-density digital tapes were used to store Landsat


data in the 1980s and 1990s. Photo: Jennifer Oeding, contractor to the USGS EROS


tasks was to move two large, dusty racks full of high-density digital tapes containing old Landsat data into a storage room and build a new high-performance computing cluster. We used this cluster to process satellite data from the Terra and Aqua satellites that had been recently launched by NASA. These satellites provided a global look at the Earth twice daily.


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Today, using just a laptop and a web browser, my students can process far more data and answer questions I could only dream of asking 20 years ago, even with two racks full of computers and disk arrays.


How was satellite imagery used 20 years ago?


Over the past two decades, we have witnessed a number of key advances in the use of satellite data within agriculture. In 2001, the primary use of satellite data in day-to-day agricultural operations was through the use of GPS-enabled tractors for precision agriculture. Use of multispectral and thermal satellite imagery in agriculture was largely limited to retrospective analyses and mapping


16 Irrigation TODAY | Summer 2021 irrigationtoday.org


hen I first started working at the NASA Ames Research Center in 2003, one of my first


WHAT HAS CHANGED IN THE LAST TWO DECADES? By Forrest Melton


of crop type and productivity, as well as evaluation of evapotranspiration and crop water stress.


Use of satellite-based evapotranspiration by agricultural engineers for irrigation system evaluation and design was just emerging, and scientists would spend months processing data for a single region. Highly accurate data products could be produced, but analyses were usually conducted using high-end workstations or local computing clusters, and the initial data compilation and processing often required months of work.


We’ve come a long way


In the past 10 years, advances in instrument and spacecraft design, cloud computing and data processing, coupled with scientific advances, have facilitated rapid growth in the availability and utility of remote sensing from a constellation of public and private sources. UAVs, aircraft and commercial satellites provide a wide range of data at spatial scales from a few centimeters to a few meters.


Satellite data from NASA, the U.S. Geological Survey and the European Space Agency are widely and freely available, increasingly within 24 to 72


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