The CubeSat Radiometer Radio Frequency Interference Technology Validation (CubeRRT) Mission

The CubeSat Radiometer Radio Frequency Interference Technology Validation (CubeRRT) mission has developed a 6U CubeSat to demonstrate radio frequency interference (RFI) detection and mitigation technologies for future Earth remote sensing missions. Anthropogenic sources of RFI can degenerate important geophysical retrievals from spaceborne passive microwave radiometers. Real-time on-board RFI processing is therefore an important technology needed for future radiometry missions. CubeRRT will perform microwave radiometry observations in 1 GHz channels tunable from 6-40 GHz and will demonstrate on-board real-time RFI processing. The CubeRRT payload consists of a wideband antenna subsystem developed at Ohio State, a tunable analog radiometer subsystem developed at Goddard Space Flight Center, and a digital backend processor for real-time RFI mitigation developed at the Jet Propulsion Laboratory. The spacecraft bus was developed and integrated at Blue Canyon Technologies. The enabling CubeRRT technology is a digital Field-Programmable Gate Array-based spectrometer with 1 GHz bandwidth that implements advanced RFI filtering algorithms based on real-time kurtosis and cross-frequency techniques. CubeRRT was manifested on the OA-9 International Space Station resupply mission and launched on May 21, 2018. This talk will describe the assembly and test of the flight system as well as the status of on-orbit operations

Real-Time Detection and Filtering of Radio Frequency Interference On-board a Spaceborne Microwave Radiometer: The CubeRRT Mission

The Cubesat Radiometer Radio frequency interference Technology validation mission (CubeRRT) was developed to demonstrate real-time on-board detection and filtering of radio frequency interference (RFI) for wide bandwidth microwave radiometers. CubeRRT’s key technology is its radiometer digital backend (RDB) that is capable of measuring an instantaneous bandwidth of 1 GHz and of filtering the input signal into an estimated total power with and without RFI contributions. CubeRRT’s on-board RFI processing capability dramatically reduces the volume of data that must be downlinked to the ground and eliminates the need for ground-based RFI processing. RFI detection is performed by resolving the input bandwidth into 128 frequency sub-channels, with the kurtosis of each sub-channel and the variations in power across frequency used to detect non-thermal contributions. RFI filtering is performed by removing corrupted frequency sub-channels prior to the computation of the total channel power. The 1 GHz bandwidth input signals processed by the RDB are obtained from the payload’s antenna (ANT) and radiometer front end (RFE) subsystems that are capable of tuning across RF center frequencies from 6 to 40 GHz. The CubeRRT payload was installed into a 6U spacecraft bus provided by Blue Canyon Technologies that provides spacecraft power, communications, data management, and navigation functions. The design, development, integration and test, and on-orbit operations of CubeRRT are described in this paper. The spacecraft was delivered on March 22nd, 2018 for launch to the International Space Station (ISS) on May 21st, 2018. Since its deployment from the ISS on July 13th, 2018, the CubeRRT RDB has completed more than 5000 hours of operation successfully, validating its robustness as an RFI processor. Although CubeRRT’s RFE subsystem ceased operating on September 8th, 2018, causing the RDB input thereafter to consist only of internally generated noise, CubeRRT’s key RDB technology continues to operate without issue and has demonstrated its capabilities as a valuable subsystem for future radiometry missions