2012.A.2.1 Increasing Interplanetary CubeSat Mission Science Return with Model Based Transmission Reduction

Author(s)

Jeremy Straub (1)

University of North Dakota

Session

A.2 – Technology – Communications, Planning, Operations, and Computing Issues for Interplanetary CubeSat Missions

Keywords

data transmission reduction, autonomy, mission ROI

Abstract

An interplanetary CubeSat faces a fundamental communications problem. Given its small size, it must use a lower transmission rate (compared with larger interplanetary spacecraft) in order to achieve reliable communications with an Earth-based ground station. However, the reduction of the transmission rate dramatically decreases the amount of scientific data that can be sent back to Earth. While there are clearly ways to increase the effective data transfer rate somewhat (e.g., expandable antennas, increasing ground receiver gain, compression, etc.) it is likely that the CubeSat will generate significantly more data than it can send. This is, of course, highly problematic as the science return for missions conducted under the prevailing communications model is clearly a function of the scientific data returned to Earth.

This paper proposes and evaluates a new paradigm for increasing mission science return as a function of data transfer. Instead of transmitting raw data, the proposed approach begins with the creation of a model (either mission specific, or quasi-generic) that is then evaluated in-situ by the spacecraft. The craft control software directs the collection of data that serves to validate or refute the model. This data is evaluated onboard and elements of the model are deemed to be validated or refuted (with an associated level of confidence). Model updates, validation confidence reports and supporting data for both are then sent over the limited communications link to ground controllers and Earth-based scientists for review and further analysis. Depending on the accuracy of the original model and the relative size of model-messages versus the data that must be transmitted in raw form for their creation, the data transmission savings could be several orders of magnitude.

This paper presents a detailed overview of the proposed approach, the application of both Dempster-Shafer and classical probability to model confidence characterization and an evaluation of the proposed approach in the context of the transmission of planetary science data. It demonstrates an analytical method for characterizing the decreased data transmission requirements and increased science returns possible. It also comments, qualitatively, on the mission concept possibilities facilitated by the proposed approach – specifically focusing on greater-distance-from-Earth missions.