Cosmic Collision

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The Comet Tempel-1 is 9 miles long and 3 miles wide. It travels at 66,880 m.p.h., circling the sun between the orbits of Mars and Jupiter once every 51/2 years. It’s the solar wind, not the comet’s motion, that creates the tail

•Nucleus

•Tail

•Manhattan

•A slice lengthwise through the middle of Tempel-1 would reveal a face of roughly the same surface area as Manhattan

WHAT YOU CAN LEARN FROM A CRATER Making a crater is more than digging a hole. It’s an elaborate process that lets scientists peek inside an otherworldly object. In general, the deeper the crater and the bigger the debris field, the more porous and pristine the material that makes up the object

COMPRESSION STAGE The impactor punctures the surface of the comet, releasing heat and kinetic energy but sending up little debris

•Impactor

•Comet surface

EXCAVATION STAGE 1 The violence of the collision causes debris to be flung up in a cloud of so-called ejecta – a storm of vapor, mist and droplets

•Ejecta

•Shock waves

EXCAVATION STAGE 2 The debris is dispersed and begins to drift down in an ejecta blanket. The lip of the crater settles to form a characteristic rim

•Rim

•Fracture system

MODIFICATION STAGE Loose material slides down the crater wall. On larger bodies, ejecta material at the center of the crater can form a small peak

•Crater

•Ejecta blanket

Sources: Ball Aerospace & Technologies Corp.; NASA; J.P.L