I attended the 2018 International Geoscience And Remote Sensing Symposium (IGARSS 2018) in July; presenting on the recently proposed 50 CubeSat constellation to sound the Antarctic ice sheets. There are still large gaps in ice thickness data despite more than 50 years of airborne radar sounding. A satellite mission presents an opportunity to gain complete coverage of the ice sheets. Some key features of the constellation include a 50 m and 1 m along-track and cross-track separation, respectively, a Ka-band radar and downlink device, and a 150 MHz sounder.

Abstract-In spite of more than 50 years of airborne radar soundings of Antarctic ice by the international community, there are still large gaps in ice thickness data. We propose a CubeSat satellite mission for complete sounding and imaging of Antarctica with 50 CubeSats integrated with a VHF radar system to sound the ice and image the ice-bed. One of the major challenges in orbital sounding of ice is off-vertical surface clutter that masks weak ice-bed echoes. We must obtain fine resolution both in the along track and cross track directions to reduce surface clutter. We can obtain fine resolution in the along track direction by synthesizing a large aperture by taking advantage of the forward motion of a satellite. However, we need a large antenna-array to obtain fine resolution in the cross track direction. We propose a train of 50 CubeSats with optimized offset position to obtain a 500-m long aperture and also coherently combine data from multiple passes of the train to obtain a very large aperture of 1-2 km in the cross track direction. Our initial analysis shows that we can obtain measurements with horizontal resolution of about 200 m and vertical resolution of about 20 m. The CubeSat will carry a transmitter and receiver with peak transmit power of about 50 W. We will synchronize all transmitters and receivers with a Ka-band system that serves as a communication link between the earth and Cubesats to downlink data and as command and control for the CubeSats.

Paper: A CubeSat Train for Radar Sounding and Imaging of Antarctic Ice Sheet

Presentation: Simpson_CubeSatTrain_Presentation_IGARSS2018

Image credit: (2018/Charles O’Neill)