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
Image credit: (2018/Charles O’Neill)
I will be presenting “Benefits of Tracking Aids on a 1U CubeSat,” on Thursday, April 13 at the 2017 ESPRMC Graduate Research Symposium. Dr. O’Neill was my co-author. I hope to see you there.
Incoporating active/passive tracking aids into the design of a university/high school CubeSat mission promotes good space stewardship. Tracking aids are necessary for improved tracking covariance of CubeSats. Tracking aid support and design-space cost are covered. Reflectarrays, patch array(s), and deployable antennas show the potential benefit of transmitting data over S-band frequencies and tracking aids that enhance the mission capabilities. Passive and active tracking aids with low impact on the mission provide reduced covariance of CubeSats orbit tracks shown through use of modeling tools.
I presented Tuesday at the Center for Orbital Debris Education and Research on “CubeSat Network for Prediction and Tracking of Orbital Debris.” The key points:
- Conceptual Stage of Development
- LIDAR ~700W and CubeSat ~200 W
- Assuming UV laser, 355 nm, resolution of 1 mm would require a 2 m telescope diameter for a range of 5 km
Presentation is attached here: simpson_v2
Several topics that are of interest specifically to my presentation:
- Research that suggests that the satellite operators that do not follow good practices will be the primary source of new collisions in the future. Roger Thompson, The Aerospace Corporation, spoke to this on my panel.
- Space is about to get a lot more crowded. To put it in context their have been 56 launches this year. SpaceX filed for 4400 satellites with the FCC Wednesday.
- There is a strong need for knowledge of conjunctions and good covariance analysis. I.E. there seems to be the need for secondary analysis for conjunction warnings from JSpOC. On my panel Don Greiman, Schafer Commercial Space Situational Awareness Team, spoke to this from the commercial side and Ryan Shepperd as analysis in-house for Iridium.
Talk about a huge learning experience. I hope to take what I’ve learned back to The University of Alabama and disseminate this knowledge among our academic community. I also plan to stay in touch with the contacts I’ve made to help expand my horizons.
CODER is the Center for Orbital Debris for Education and Research. CODER is having a Workshop and accepted our, Dr. O’Neill and I, abstract for CubeSat Network for Orbital Debris Tracking and Prediction. I will be a presenter for the Space Situational Awareness Session. Here’s the link for my session and bio: CODER 2016 Sessions
The conference is hosted at the University of Maryland on November 15-17. If you’re headed to the conference hope to see you there!