FROM OBSERVATIONAL GEOMETRY TO PRACTICAL SATELLITE DESIGN: ASTEROIDFINDER/SSB 1 st IAA Planetary Defense Conference: Protecting Earth from Asteroids 27-30 April 2009 Granada, Spain Jan Thimo Grundmann (1) , Stefano Mottola (2) , Volodymyr Baturkin (6) , Jörg Behrens (1) , Bernd Biering (3) , Max Drentschew (2) , Martin Drobczyk (1) , Sam Gerené (5) , Gerhard Hahn (2) , Marcus Hallmann (1) , Jens Hartmann (1) , Ansgar Heidecker (1) , Bobby Kazeminejad (1) , Ekkehard Kührt (2) , Matthias Lieder (4) , Horst-Georg Lötzke (3) , Harald Michaelis (2) , Markus Schlotterer (1) , Nicole Schmitz (2) , Martin Siemer (1) , Peter Spietz (1) (1) DLR German Aerospace Center - Institute of Space Systems Robert-Hooke-Straße 7, 28359 Bremen, Germany Email: jan.grundmann@dlr.de, joerg.behrens@dlr.de, martin.drobczyk@dlr.de, marcus.hallmann@dlr.de, jens.hartmann@dlr.de, ansgar.heidecker@dlr.de, bobby.kazeminejad@dlr.de, markus.schlotterer@dlr.de, martin.siemer@dlr.de, peter.spietz@dlr.de (2) DLR German Aerospace Center - Institute of Planetary Research Rutherfordstraße 2, 12489 Berlin, Germany Email: stefano.mottola@dlr.de, maximilian.drentschew@dlr.de, gerhard.hahn@dlr.de, ekkehard.kuehrt@dlr.de, harald.michaelis@dlr.de, nicole.schmitz@dlr.de (3) DLR German Aerospace Center - Institute of Space Systems, Department of System Conditioning Rutherfordstraße 2, 12489 Berlin, Germany Email: bernd.biering@dlr.de, horst-georg.loetzke@dlr.de (4) DLR German Aerospace Center - Institute of Robotics and Mechatronics, Department of Optical Information Systems Rutherfordstraße 2, 12489 Berlin, Germany Email: matthias.lieder@dlr.de (5) JAQAR Concurrent Design Services Witte de Withstraat 19-c, 3012 BL Rotterdam, The Netherlands Email: sam.gerene@j-cds.nl (6) National Technical University of Ukraine Kyiv Polytechnical Institute Peremogy Pr., 37, Kyiv 03056, Ukraine Email: vladimir.baturkin@dlr.de INTRODUCTION A small solar system body (SSSB) is presently classified as a Near-Earth Object (NEO) if it approaches the Sun to 1.3 Astronomical Units (AU) or less. Most of these objects are difficult to observe due to their minute size, their highly variable apparent motion relative to the background of stars, and their location in the sky relative to the Sun. Objects that cross the Earth’s orbit at ~1 AU, when seen from the Earth and moving in its vicinity, are increasingly backlit as they approach the Sun. The closer they approach the Sun’s position in the sky, the more the visible part of their sunlit side is by geometry reduced to an ever slimmer tiny crescent. This applies to all Earth-crossing asteroids, certainly to the Aten class of asteroids which orbit the Sun in less than one year but still have the most distant parts of their orbit outside the Earth’s, and in particular to the Inner Earth Objects which orbit the Sun completely Interior to Earth’s Orbit (IEO). Only ten mostly Aten-like IEOs have been found so far, of which two are classified as Potentially Hazardous Asteroids (PHA). A third IEO’s orbit comes closer to the Earth’s orbit than required for PHA status; although it does not quite have the size to be classified as a PHA, it still is similar in scale to the Tunguska object. Presently, only one ‘deep’ or ‘real’ IEO is known, 2008 EA 32 , which orbits the Sun in a fairly inclined and eccentric orbit at distances similar to the planets Venus and Mercury. Ground-based observations of Atens and IEOs are severely constrained by the presence of the Earth’s body and atmosphere between the target object and an observatory situated on the Earth’s night side within the circle of