Goldin, O’Keefe and the International Space Station
- Paper number
IAC-04-IAA.6.15.4.05
- Author
Mr. W. Henry Lambright, The Maxwell School of Citizenship and Public Affairs, United States
- Year
2004
- Abstract
In the frame of the Cosmic Vision 2015-2025 programme of the European Space Agency new missions are analysed for feasibility and preparation of the industrial study phase. A number of the preselected missions of the programme are astronomy missions that target the night-side Lagrange point (L 2) of the Sun-Earth system for its benign environment, excellent sky accessibility, reasonable communication distance, and low transfer delta-v requirement. These missions are PLATO, a high precision photometry mission for exo-planet hunting and astroseismology, XEUS/XRO a formation-flying high-resolution x-ray telescope, SPICA, a large aperture infrared telescope, and EDEM, a combined mission for the detection of the signature of dark energy and dark matter in the early universe. In order to fulfil the different science requirements of these missions, the diversity of the family of libration orbits around L 2 is exploited. Here a general overview is given of that diversity and how it is mapped to the conditions at the perigee for transfers without any deterministic manoeuvres. These free transfers always lead to large-amplitude orbits around L 2, their properties (amplitudes, phases, non-linear behaviour) are related to the conditions at perigee. Launch scenarios with different degrees of freedom in the perigee geomery and different strategies of sharing the apogee raising between launcher and spacecraft propulsion for Soyuz (with circular parking orbit or direct injeciton) and Ariane 5 launches from Kourou will be discussed. In the latter case a transfer from the L 1 to the L 2 region may be required if the launch is shared with a commercial customer (midnight launch to GTO). Transfer solutions for that case are presented. Besides the orbit selection and transfer analysis, an important aspect of libration missions is the maintenance of the operational orbit. For some missions it is required to maximise the time between maintenance manoeuvres, and for some the thrust authority is very limited. In both cases the exponential nature of the state transition matrix has to be considered. It can lead to un-recoverable trajectories, if the equivalent velocity error in the unstable direction becomes too large, leading to a departure from the environment of the Lagrange point within a few months. Here an analysis of the dynamic noise environment is presented, together with the methods to model deterministic disturbances and calibrate stochastic disturbances with sufficiently long auto-correlation times. The application of these methods to the design of the new Cosmic Vision missions allows for longer times for science operations and/or higher operational flexibility.
- Abstract document
- Manuscript document
IAC-04-IAA.6.15.4.05.pdf (🔒 authorized access only).
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