H. Fragner1, P. Beck2, A. Dielacher1, O. Koudelka3, C. Tscherne2, M. Wenger3, M. Wind2
1 RUAG Space GmbH, Stachegasse 16, 1120 Vienna, Austria
2 Seibersdorf Laboratories, TFZ Seibersdorf, 2444 Seibersdorf, Austria
3 Graz University of Technology, Inffeldgasse 12, Graz 8010, Austria
The PRETTY (Passive Reflectometry and Dosimetry) mission is an Austrian Cubesat mission currently under development in a Phase B study for the European Space Agency (ESA). The platform will host two different scientific payloads: A passive reflectometer, exploiting signals of opportunity for passive bistatic radar measurements and a reference dosimeter system, continuously assessing the ionizing dose on-board the PRETTY spacecraft.
The exploitation of signals from global navigation systems for passive bistatic radar applications has been proposed and implemented within numerous studies. The planned implementation is focusing on very low incidence angles whereby the direct and reflected signal will be received via the same antenna and RF front end. Apart from the reflection geometry the new aspect of the PRETTY reflectometer is the interferometric approach. The processing power intense task of correlating the two signal paths will be done in the digital domain using an FPGA. The demonstration of a passive reflectometer without the use of local code replica will implicitly show that also signals of unknown data modulation can be exploited for this purpose.
There is a great interest to correlate the satellite’s radiation environment with the status of all other electronic systems of the satellite itself and its payloads. The objectives of the reference dosimeter payload are to assess the radiation mission dose during the whole CubeSat space mission and in particular at three geographic regions of interest with elevated radiation levels, such as the South Atlantic Anomaly (SAA), North Pole and the South Pole. The proposed dosimeter system is based on RADFET which is made of silicon and therefore its response can be used as reference dose for total ionizing dose (TID) effects. This measurement is representative for other silicon-based electronic systems e.g. during reliability testing of electronic components, in particular commercial components of-the-shelf (COTS) on-board CubeSat.
 J. Wickert, et al, “GEROS-ISS: GNSS Reflectometry, Radio Occultation, and Scatterometry Onboard the International Space Station” IEEE Journal of selected topics in applied earth sciences and remote sensing, Vol. 9, No. 10, pp. 4552-4580, October 2016
 P. Beck, M. Latocha, M. Wind, Space Radiation Environment Phase-A Study Report Austrian CubeSat Mission (PRETTY), SL-LD-002/17, 2017.
 A. Dielacher, H. Fragner, „PARISCorrelator Final Report“ P-11281-RP-0006-RSA, 30 Jan 2015
 Koudelka, O., D.Evans, The OPS-SAT Nanosatellite Mission- A Flexible Platform for On-Board Experiments, 11th IAA Symposium on Small Satellites for Earth Observation, Berlin, 2017.
The Phase B study for the PRETTY mission is funded by ESA GSTP Programme. The according Phase A study was funded by ASAP/FFG.