Prelaunch Performance of the 118 GHz Polarcube 3U Cubesat Temperature Sounding Radiometer
Abstract
The low cost PolarCube 3U CubeSat supports a 118.75 GHz imaging spectrometer for temperature profiling of the troposphere and surface temperature. It is a demonstrator for a constellation of LEO passive microwave sensors at V-band and other frequencies using 3U/6U CubeSats. Such a satellite constellation for weather forecasting will provide data at high spatial and temporal resolution to observe rapidly evolving mesoscale weather. The satellite's payload is an eight channel, double sideband passive microwave temperature sounder with cross-track scanning and will provide 18 km surface resolution from a 400 km orbit. The radiometer implements a two-point calibration using an internal PIN switch and view of cold space. Although the instrument is based on a well established classical design, the challenges lie in developing a sensitive spectrometer that fits in a 1.5U volume, is low cost, consumes 4 W power and satisfies the CubeSat weight and envelope constraints. PolarCube is scheduled for launch on a Virgin Galactic flight in summer, 2018. The estimated radiometer sensitivity, ΔTrms varies from 0.3 to 2 K across the eight channels. The 50 MHz to 7 GHz 8-channel filter bank (designed with surface mount capacitors and inductors) fits on a 9x5 cm2 RO4350B PCB and includes 2-stage amplification and detector circuitry. The scanning reflector with an 8 cm2 main aperture uses a 3D printed corrugated feed that includes a WR8 to WC8 waveguide transition with a 17° bend. Initial performance results from the instrument using the 3D printed feed and IF/VA board obtained from airborne measurements over Antarctica on the NASA DC8 in early November 2016 indicate a well-functioning radiometer. The end-to-end characterization of the payload with the satellite bus, performance results from vibration and thermal-vacuum tests and roof-top measurements will be presented.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2017
- Bibcode:
- 2017AGUFM.A41I2416P
- Keywords:
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- 0394 Instruments and techniques;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 3360 Remote sensing;
- ATMOSPHERIC PROCESSES;
- 7599 General or miscellaneous;
- SOLAR PHYSICS;
- ASTROPHYSICS;
- AND ASTRONOMY;
- 7999 General or miscellaneous;
- SPACE WEATHER