[Previous] | [Session 77] | [Next]
R. Arrell, P. Gurfil, J. Kasdin (Princeton University), S. Seager (Institute for Advanced Study), S. Nissanke (Cambridge University)
Out-of-the-ecliptic trajectories that are beneficial to space observatories such as the Terrestrial Planet Finder and other potential mid-IR missions are introduced. These novel trajectories result in significantly reduced background noise from the zodiacal dust and therefore allow a reduction in the necessary size of the telescope collecting area. The reduced size of the mirrors allows for a considerable reduction in payload mass and manufacturing costs. Two types of optimal trajectories that are energetically feasible were derived using genetic algorithms. These are highly inclined non-Keplerian heliocentric orbits.
We use the zodiacal dust model from the COBE data (Kelsall et al. 1998) to determine how well the orbits mitigate the zodi dust interference. The first optimal trajectory can use existing launch technology and yields a maximum decrease of 67% in the zodiacal cloud brightness. The zodi brightness for this trajectory is reduced by at least 50% for 60% of the mission lifetime. The second optimal trajectory requires planned improvement in launch technology but it renders a dramatic 97% maximum noise decrease. The zodi brightness is reduced by at least 70% for 82% of the mission lifetime for this trajectory.
Heliocentric orbits at 5 AU have been discussed because the zodi dust concentration is extremely low there. Unfortunately such orbits are exceedingly impractical because of high cost, power source constraints (inability to use solar cells), and a long travel time before science return.