Pluto Through Stained Glass: First Movie from the Edge of the Solar System
When New Horizons recently flew by Pluto, it recorded images of the surface using the LORRI and MVIC cameras. It recorded the plasma and dust environments with the PEPSSI, SWAP, and SDC instruments. But one instrument, designed to measure the composition of Pluto and Charon's surfaces, recorded the first movies from the edge of the solar system. The instrument is LEISA, New Horizons' infrared imaging spectrometer. It takes 2D images like a normal camera, but it takes them through a linearly-varying filter. One side of the camera can only see light of one specific wavelength of infrared light (light that has longer wavelengths than can be seen by our eyes), and each row of pixels can see a subtly different wavelength. The effect is much like looking through a stained glass window designed for infrared eyes. By scanning this image sensor with its linear filter across a scene and quickly recording many images during the scan (like a movie), LEISA builds up a two-dimensional map of the scene in front of the camera with a measurement of the infrared spectrum (the brightness versus wavelength) at every location in the image. It makes this complex measurement with exactly zero moving parts - highly reliable for deep-space operations. The side-effect of collecting this scientifically-important data set, capable of measuring the composition of every location on the surface of Pluto and Charon that is imaged, is that LEISA collected low frame rate infrared color movies of Pluto and Charon as seen by New Horizons during its flyby.