Imaging of extrasolar advanced terrestrial planets

The gravitational lens effect of the Sun would allow, by using a detector a t one of its foci, to obtain a "telescope" with gigantic amplification and resolution powers opening extraordinary perspectives far the detailed study of extrasolar planets, particularly technologically advanced ones. But, as tronautical challenges are raised by the necessity to align precisely and p ut in an efficient tracking and scanning mode the detector, necessarily mod est in size compared to the dimensions of the planet images and ranges of o rbital and rotational motions. In the frame of the FOCAL space mission subm itted to ESA, we present the dynamical geometry of the images for two typic al cases of observational wavelengths: 10 centimeters (radio) and 10 microm eters (infrared), for a solar-type stellar system 10 parsecs away. Plasma t hrusters could provide interesting solutions for the control of the detecto r for tracking and scanning the focal images. (C) 1999 Published by Elsevie r Science Ltd. All rights reserved.