NASA's Cassini probe is in the orbit of the planet Saturn. It arrived in June 2004 and, in addition to the planet, is studying closely the moons of the planet. In July it was the turn of the eighth largest moon, the so-called Hiperion. It is an irregular satellite of 300 kilometers in length that has a spongy appearance seen closely. The NASA probe approached 75 kilometers to take photos and, as far as possible, analyze the chemical composition of the moon. Astronomers have found ice, carbon dioxide and other unidentified compounds on the satellite surface.