In the early solar system, comets bombarded the planets, repeatedly and often. The space object which impacted Earth 65 million years ago, causing the dinosaurs to become extinct, may have been a comet. Most particles from a comet are smaller than the diameter of a human hair. Comet particles will be captured relatively gently by using a sponge-like cushioning material, called aerogel. Aerogel is a special type of foamed glass, made so light weight that it is barely visible and almost floats in air.
Comet particles make carrot-shaped tunnels in the aerogel as they are stopped.
At the pointed tip of each tunnel is where a tiny particle can be found. Less than one-thousandth of an ounce of cometary dust will be collected. But more than 1,000 of the particles collected will be large enough for complete scientific analysis, plus millions of smaller particles that can be analyzed as groups. Some of the powerful scientific instruments on Earth that will be used to study the cometary material are more than 100 times larger and heavier than the spacecraft itself. Scientists also hope to collect more than 100 particles from a newly discovered beam of particles streaming into our solar system from other stars in outer space.