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Space Dynamics Lab SmallSat Sees Big Picture

August 3, 2020

This May 3, 2020 composite image was taken by the Hyper-Angular Rainbow Polarimeter, or HARP, small satellite over Lake Titicaca that straddles the borders of Peru and Bolivia. The image is an example of HARP's three polarized image sensors surveying Earth and its atmosphere as the spacecraft orbits above. (Credit: UMBC Earth and Space Institute).

A small satellite built by Utah State University’s Space Dynamics Laboratory is providing scientists unprecedented images for a spacecraft of its size.

Measuring only 10 centimeters wide, 10 centimeters high and 30 centimeters long, the small satellite was designed, manufactured, integrated and tested by SDL and carries the Hyper-Angular Rainbow Polarimeter payload built by the Earth and Space Institute at the University of Maryland, Baltimore County. The program is funded by NASA and is under the direction of principal investigator J. Vanderlei Martins. HARP is designed to measure the microphysical properties of cloud and aerosol particles in Earth’s atmosphere. HARP was launched on Nov. 2, 2019, from a Northrop Grumman Antares rocket in its Cygnus cargo spacecraft. Following a three-month stay on the International Space Station, HARP was deployed into orbit on Feb. 19, 2020.

SDL also manages mission operations for HARP’s flight while UMBC manages the science operations.

“Dr. Martins and his team from UMBC are providing NASA with incredibly specialized images from low earth orbit of our atmosphere, further validating that Earth science from space can be achieved with small satellites,” said Tim Neilsen, SDL program manager for HARP. “The application of space-based Earth observation technology has historically been the domain of large satellites. HARP helps to confirm that miniaturized sensors on small satellites can provide a high degree of fidelity at a fraction of the cost and time it takes to build larger satellites.”

HARP isn’t just testing technology. It’s providing useful information to scientists.

Cloud and aerosol processes influence climate change, which affects our oceans, weather, ecosystems, and society at large. The largest impediments to estimating climate change are a lack of quantitative information about aerosol forcing, insufficient understanding of aerosol-cloud processes and cloud feedbacks in the climate system. New observations and a better understanding of aerosol-cloud processes will help to narrow climate change estimate uncertainties.

HARP, an imaging polarimeter with hyper-angular capability, can make a strong contribution to characterizing ice and water cloud properties. Polarization and an increased number of observation angles provides a much clearer picture of cloud droplet distribution, adding the width of the droplet distribution to the currently measured effective radius.

“HARP is the first ever instrument in space to perform moderate spatial resolution measurements of the cloud droplet size distribution using a hyperangular polarization capability,” said Martins. “HARP is also a precursor for future image polarimeters to perform global measurements of aerosol and cloud properties, including the HARP2 instrument that is currently being built at UMBC to fly in the NASA PACE mission.”

SDL has been solving the technical challenges faced by the military, science community and industry for six decades and supports NASA's vision to reveal the unknown for the benefit of humankind. As one of 14 University Affiliated Research Centers, SDL serves as a subject matter expert in its core research areas to the U.S. Government, ensuring that essential engineering and technology capabilities are maintained. SDL is a research laboratory headquartered in North Logan, UT, and has offices in Albuquerque, NM; Bedford, MA; Dayton, OH; Huntsville, AL; Houston, TX; Los Angeles, CA; Stafford, VA; and Washington, DC. For more information, visit


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