Comparison of second and third generation 135.6 nm ionospheric photometers using on-orbit and laboratory results

The second generation Tiny Ionospheric Photometer (TIP) is a compact, high-sensitivity, nighttime ionospheric photometer designed for small satellites. TIP launched February 19, 2017 to the International Space Station as part of the GPS Radio Occultation and Ultraviolet Photometry—Colocated (GROUP-C) experiment to test advanced sensing objectives. The TIP optical design improves upon previously-flown photometers and employs a filter wheel to measure signals. The third generation sensor is a 1U Cubesat-compatible Triple Tiny Ionospheric Photometer (Tri-TIP), manifested to fly on the dual 6U Coordinated Ionospheric Reconstruction CubeSat Experiment (CIRCE) in early 2020. The Tri-TIP design builds upon several technologies demonstrated aboard TIP, but utilizes a beam splitter to simultaneously monitor signal, red-leak, and background signals. This paper compares the pre-flight and on-orbit performance of TIP with pre-test theoretical results for Tri-TIP.