Dr. Karl Szekeilda spoke to our group tonight about some research that he’s involved in.  In fact he came to talk about two projects. One involved a piece of technology called the “Portable Hyperspectral Imager for Low-Light spectroscopy” or PHILLS. Hyperspectral Imagers are, in a way, extremely fancy digital cameras.  They collect light data over a range of spectra and wavelengths, which generates an image. This image and/or the raw data about the spectra can then be worked on by researchers to inform them about a variety of topics. If , for example, there’s a lot of plants in the image, there will be a drop in intensity of the wavelengths of light that are absorbed by Chrolophyll, the pigment in plants that allows them to photosynthesize. Different types of chrolophyll and related materials actually absorb light at characteristic wavelengths, so you can distinguish between, say, trees and cyanobacteria.  Spectral data can tell you what the distribution and even density of a set of organisms are.

The PHILLS device is able to do this while mounted on a jet screaming through the atmosphere at 10,000 feet of altitude. And even though it’s looking down at the ocean surface through a third of the planet’s atmosphere, it can still achieve three meters of resolution. That’s enough to identify objects in your backyard or see your car on the street. This technology was developed by the Naval Research Lab, but it wasn’t designed to peer at your patio. Rather it looks at the surface of the ocean and can detect potentially harmful blooms of  marine algae. It can give us some idea of what kind of algae it is based on the chlorophyll it contains, it can determine the density of the bloom, and importantly can determine the shape and track the movement of the bloom over time.

Dr. Szekeilda showed us a PHILLS  image of the ocean surface where Langmuir cells were clearly visible. Langmuir cells are rolling parcels of water driven by steady winds over the surface. If you’ve ever looked at the ocean on a windy day you may have noticed long parallel running strings of sea-foam on the surface; they’re generated by Langmuir cells. In the image Dr. Szekeilda showed us, instead of ‘normal’ seafoam, the strings were concentrations of  cyanobacteria.

 

So that’s PHILLS. The other project was called HICO; Hyperspectral Imaging for the Coastal Ocean. Putting an imager on a jet sounds high tech, but here an even more advanced imager was mounted onto the International Space Station (ISS).  Now the device is blasting through space at 17,200 miles per hour, at an altitude of 1,000,000 feet, looking through the entire atmosphere to detect signals from creatures that are smaller than a tenth of a centimeter. Dr. Szekeilda explained that HICO was sent to the ISS as an ‘experimental’ payload, just to demonstrate that this sort of thing could be done. The device has 100 meter resolution, which is something like an order of magnitude (10X) better than anything else up there, and cant detect light-wave difference of 6 nm (6 billionths of a meter), which Dr. Szekeilda described as ‘laboratory grade resolution’; on a device, hurtling through space.

Dr. Szekeilda showed us a HICO image of Long Island Sound, and you could clearly see all sorts of patterns and patches running across the water. Interestingly, they weren’t able to send a boat out onto the sound, or collect data from an oceanographic buoy, to verify what the imager detected. This was because, since they’re an experimental payload, they could never be sure in advance when the ISS would have electrical power available for them to use.  They’d get maybe a day’s notice when there was some free electricity for them, so they couldn’t have a boat or something like that, ready to leap into the water as the device passed by in orbit. They’d have to have boats spread across the entire world ‘just in case’ they went ‘live’ while overhead.

But they could compare their data to something. In  many testing circumstances, you’d like to calibrate your device using a ‘blank’, and then subtract the blank from your sample of interest, so that all you’re looking at is signal from whatever chemical you’re studying.  Here they did something similar, they compared the ‘interesting patches’ they found along the coast to parcels of wide open ocean. Using this they were able to see things like cyanobacteria and dinoflagellates (which are toxic and make it so you can’t eat things like shellfish during a bloom) floating in the surface coastal waters.

Dr. Szekeilda also showed us images from the Potomac river and off the coast of China, and it was really fascinating to see these high resolution patches of algae, fed by farm and lawn fertilizer runoff, forming and moving across the sea. Pretty impressive accomplishments, especially, again, considering that it’s strapped to an orbital space station.