Science

The BisonSat science mission is an Earth science mission. BisonSat carries a SKC-designed visible light camera that will be used for a variety of scientific studies.The camera uses a CMOS Bayer pattern filter detector similar to the image detectors used in consumer cameras and cellphone cameras. Each pixel on the detector has a small filter covering the pixel that allows either green, blue, or red light through. When an image is acquired there are effectively three images taken, the scene as seen through the green filter pixels as well as through the blue and red pixels. A color image is created by combining the green, blue, and red images.

 BayerPattern

One BisonSat science goal is to perform land cover classification using the three Bayer pattern filters on the detector as broad band visible light filters. Space-based land cover classification has long been performed with large satellites with many narrow band filters spanning the visible spectrum and into the infrared. The Landsat series of satellites has provided 40 years of narrow band image data that is used extensively for land cover classification. BisonSat will test the capability of using a low cost small satellite carrying a Bayer pattern filter detector for land cover classification. Of special interest is using BisonSat image data for land classification on the Flathead Indian Reservation.

An additional science goal is measuring the height of large tropical storm clouds. Cloud heights measured with satellites are usually inferred from measurements of the temperature at the top of the cloud. BisonSat uses passive magnetic stabilization to point the camera. BisonSat has several small permanent magnetics aligned along the camera optical axis. As BisonSat moves along its orbit the satellite aligns with the direction of Earth’s magnetic field at that location much like a compass needle. Over the northern hemisphere Earth’s magnetic field points mainly downward so the BisonSat camera is pointed downward over that part of its orbit. Over tropical areas Earth’s magnetic field points close to horizontal so the camera is pointed close to horizontal. By taking images a few seconds apart and using some trigonometry the height of a large cloud can be measured directly. These height measurements will be correlated with measurements from NOAA satellites to assess the utility of using CubeSats for augmenting NOAA satellite data.