Cubesat demonstrates Earth science instrument

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WASHINGTON — A cubesat launched earlier this year has successfully tested a version of an instrument that will fly on a larger NASA mission in development.

The Hyper-Angular Rainbow Polarimeter (HARP) cubesat was deployed from the International Space Station in February after being delivered to the station on a Cygnus cargo spacecraft. The cubesat carries an imaging polarimeter designed to measure properties of cloud and aerosol particles in the Earth’s atmosphere.

The three-unit cubesat is managed by the Space Dynamics Lab (SDL) of Utah State University, which built the spacecraft, while the payload was developed and is operated by the University of Maryland Baltimore County (UMBC). The payload achieved “first light” in April and took its first images in May.

Tim Neilsen, program manager for HARP at SDL, said the spacecraft demonstrates that cubesats can provide useful data in the Earth sciences. “The application of space-based Earth observation technology has historically been the domain of large satellites,” he said in a statement. “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.”

The instrument’s utility comes from its ability to measure the size distribution of cloud droplets, which can provide information on the properties of ice and water clouds. That can, in turn, improve modeling of aerosol processes and help reduce uncertainties in climate modeling.

HARP is a precursor for a similar instrument, called HARP2, that UMBC is developing for NASA’s Plankton, Aerosol, Cloud, ocean Ecosystems (PACE) mission. HARP2 will feature improved resolution and sensor performance, and will be able to provide global coverage every two days from PACE’s sun-synchronous orbit.

PACE has been the subject of repeated attempts at cancellation in the administration’s budget requests, including in the fiscal year 2021 budget proposal earlier this year. Congress, though, has rejected those proposals and continued to fund PACE’s development. The spacecraft is scheduled to launch on a SpaceX Falcon 9 in late 2022.