Mission Design and Analysis of European Astrophysics Missions

Paper number

IAC-11,C1,2,2,x10292

Author

Dr. Markus Landgraf, European Space Agency (ESA), Germany

Coauthor

Dr. Florian Renk, European Space Agency (ESA), Germany

Coauthor

Mr. Bram de Vogeleer, Germany

Coauthor

Mr. Johannes Schoenmaekers, European Space Agency (ESA), Germany

Year

2011

Abstract

Understanding the history and evolution of our universe in general and
of stellar and planetary systems in our Galaxy requires the collection
of photons in all wavelength bands utilising high-performance space
observatories. Those observatories require a benign environment in
order to achieve the required performance. The environmental requirements
typically constrain stray-light, thermal, and dynamic parameters. In
order to fulfil the different environmental requirements of these
missions, the diversity of the family of libration orbits around the
night-side co-linear Lagrange point L\small 2 of the Sun-Earth three-body
system is exploited. Here a general overview is given of that
diversity and how it is mapped to the conditions at the perigee for
transfers with and without deterministic manoeuvres. Free transfers
always lead to large-amplitude orbits around L\small 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 geometry and different strategies of sharing
the apogee raising between launcher and spacecraft propulsion for
Soyuz (with circular parking orbit or direct injection) and Ariane 5
launches from French Guiana will be discussed. 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 limited. In both
cases the exponential nature of the state transition matrix has to be
considered. If the equivalent velocity error in the unstable direction
becomes too large, the orbit can become unrecoverable, leading to a
departure from the environment of the Lagrange point within a few
months. Here an analysis of the predictability of a libration orbit
with controlled velocity in the unstable direction is also presented.

Abstract document

IAC-11,C1,2,2,x10292.brief.pdf

Manuscript document

IAC-11,C1,2,2,x10292.pdf (🔒 authorized access only).

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