JPL Sensor on Space Station Eyes Contamination off California Coast

An instrument built at Jet Propulsion Laboratory in Pasadena has revealed a breakthrough in water quality monitoring. The Earth Surface Mineral Dust Source Investigation, launched in July 2022, was originally designed to map minerals but has now demonstrated an unexpected ability to detect sewage contamination from its orbit high above Earth’s surface.

A recent study examined a large wastewater plume at the mouth of the Tijuana River near San Diego. Every year, millions of gallons of treated and untreated sewage enter the river, carrying pollutants through communities and a national reserve before emptying into the Pacific Ocean. Contaminated coastal waters can impact human health and harm marine ecosystems, fisheries, and wildlife.

The instrument orbits Earth aboard the International Space Station, using advanced optical components to split visible and infrared wavelengths into hundreds of color bands. This allows scientists to discern molecules based on their unique spectral “fingerprint” — a method more sophisticated than traditional satellite monitoring.

“From orbit you are able to look down and see that a wastewater plume is extending into places you haven’t sampled,” said Christine Lee, a scientist at Jet Propulsion Laboratory. “It’s like a diagnostic at the doctor’s office that tells you, ‘Hey, let’s take a closer look at this.'”

Scientists compared the instrument’s observations with ground-based water samples. Both detected a spectral fingerprint of phycocyanin, a pigment in cyanobacteria that can sicken humans and animals.

Lead author Eva Scrivner, a doctoral student at the University of Connecticut, noted that the findings “show a ‘smoking gun’ of sorts for wastewater in the Tijuana River plume.” She added that the instrument could be useful for filling data gaps around polluted sites where traditional water sampling is time-consuming and expensive.

Scrivner was surprised that an instrument initially designed to explore land could reveal insights about water. “The fact that the findings over the coast are consistent with field measurements is compelling to water scientists,” she said. “It’s really exciting.”

To learn more about the Earth Surface Mineral Dust Source Investigation, visit: https://earth.jpl.nasa.gov/emit/