The ISHTAR Mission: Probing the Internal Structure of NEOs

ISHTAR (Internal Structure High-resolution Tomography by Asteroid Rendezvous) is a mission developed through ESA General Studies programme. The study led by Astrium in cooperation with several scientific institutes throughout Europe has produced a spacecraft design capable of performing multiple asteroid rendezvous and to characterize them with a focussed set of instruments. The ISHTAR concept is centred around a Radar Tomography payload able to probe the internal structure of a small asteroid to depths of 300-1000m. This instrument uses low-frequency radio waves that can penetrate deep inside solid rock and records the reflected echoes caused by changes in the internal structure (permittivity). By combining these echo signals it is possible to reconstruct a 3D image of the asteroid interior. The radar payload is combined with a multispectral imager for measurement of the surface properties & surface geology an IR spectrometer for mineralogical characterization and a radio science experiment for accurate mass and density determination. The ISHTAR mission is designed to visit at least 2 NEOs one stony and one carbonaceous in composition the most common among the NEO population. This unique combination of instruments and multiple rendezvous will allow the first detailed physical characterization of the NEO population.