encounter period. Asteroid 449 Hamburga is about in diameter and is thought to be a carbonaceous type asteroid. CRAF's planned cometary target was Comet Kopff. This was named for August Kopff, who discovered it on August 22, 1906, during an observing session at Koenigstuhl Observatory near Heidelberg, Germany. Ninety-four years after Kopff's discovery, CRAF would arrive at the rendezvous point with Comet Kopff — in August 2000. Comet and spacecraft would be at the distance of Jupiter's orbit, and 850 days before closest approach to the Sun, or perihelion. CRAF would fire its penetrator/lander at the comet in August 2001, then would continue to fly beside Kopff. The spacecraft would take data for a total of two and two-thirds years, until about 109 days after they pass closest to the Sun and are outward bound again. It was to be the first time a spacecraft would have flown in formation with a comet, though a U.S. spacecraft, International Cometary Explorer (ICE), flew by Comet Giacobini-Zinner in 1985, spacecraft from several countries encountered Comet Halley in 1986, and the Giotto spacecraft flew past Comet Grigg-Skjellerup in 1992. The comet rendezvous would allow study of matter that scientists think is the original, relatively unchanged material left behind when a cloud of dust and gas collapsed to form the Solar System 4.6 billion years ago. Scientists believe comets now reside in a distant region of the Solar System called the Oort cloud. Current theory holds that gravitational nudges from stars in the Sun's neighborhood send some comets from the Oort cloud falling toward the Sun. The CRAF spacecraft would fly extremely close to the comet's nucleus, within . The close-up exploration would take place before the coma and tail begin to build, it would observe the nucleus as it becomes active in the growing sunlight and begins to have its lighter elements boil off and form a coma and tails. Later the spacecraft would move in and out through the coma and down the tail to study their properties and the complex processes occurring in them, and to collect samples of dust for detailed analysis on board the spacecraft. In December 2002 the spacecraft and the comet would make their closest approach to the Sun. They would then head outward again toward aphelion near Jupiter's orbit. On March 31, 2003, the Comet Rendezvous Asteroid Flyby, first primary mission of Mariner Mark II, would