Tethers as sustainable space transportation: implications from the YES2 tethered SpaceMail development and flight results
- Paper number
IAC-08.D4.2.3
- Author
Mr. Michiel Kruijff, Delft University of Techonology (TU Delft), The Netherlands
- Coauthor
Prof. Wubbo J. Ockels, Delft University of Techonology (TU Delft), The Netherlands
- Coauthor
Mr. Erik J. van der Heide, Delta-Utec SRC, The Netherlands
- Year
2008
- Abstract
Tethers provide a unique outlook for sustainable space transportation, because energy and momentum are not lost through exhaust gases. A step-by-step development of applications is necessary to achieve this final goal. Over the past decade, the authors have been involved in a sustained effort including mission analysis of various possible tether applications, simulations, ground tests, parabolic flight tests and the construction of the tethered first Young Engineers' Satellite. A focus evolved on tethered SpaceMail, a concept for a low-cost, safe and accurate sample return. Key factors in this application are accuracy and deployment controllability which are enhanced by a two-stage deployment. The mission of the second Young Engineers' Satellite, YES2, was developed as SpaceMail's first implementation, and as such as the first true application of tethers to date. In September 2007, the YES2 piggybacked on the Russian-built Foton-M3 microgravity platform, successfully performed a deployment of a record-breaking 32 km tether, and subsequent released a science-packed capsule accurately into a re-entry trajectory. Although the capsule is not (yet) retrieved, each of the contributing novel tether technologies could be demonstrated, including the complex tether deployment in two stages and its controllability. This paper identifies lessons learned from the development effort and the mission results. Implications are then analyzed such that some more light can be shed on possibilities and limitations for sustainable orbital transfer. The YES2 tether deployer is designed with a broad range of near-term tether applications in mind and is therefore suitable for novel near-term possibilities, such as launch assist, thermospheric multipoint investigations, multiple cubesat release into a constellation, balancing of the International Space Station from Progress for minimization of drag losses etc. A simulation and test approach was developed for effective flight preparation of tether systems and hardware characterization that allows robust and accurate control in flight. Furthermore, tether safety issues were for the first time taken into careful consideration and this effort proved critical to the project success. Finally, the rich mission data has allowed for an improved understanding of tether dynamics and tether physics as well as a comparison between tether deployment simulation and flight results. This paper provides first a brief overview of analysis and tests performed, the tether deployer system, safety features, the YES2 mission design and the measurement systems available. The mission results are presented, including comparison between deployment simulations and YES2's measurements of length, length rate, tension and (indirectly) deployment angle and conclusions on controllability. Observations of tether stiffness, damping, sound waves and lateral waves are analyzed including conclusions on scope of validity of simulation and test. Finally, implications of the design and results on feasibility of selected next-step applications are discussed.
- Abstract document
- Manuscript document
IAC-08.D4.2.3.pdf (🔒 authorized access only).
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