In 2029, an asteroid will pass close to Earth; if it passes through "the keyhole," it will collide with Earth in 2036. A rocket will push it off icourse; collision would be catastrophic.
Solar System Shooting Gallery (04:47)
Jupiter's gravitational pull and large cross section make it a frequent target; there is an asteroid belt between it and Mars. In 1994, the Shoemaker Levy 9 comets strike the gas giant; impacts occur again in 2009 and 2010.
Asteroid Belt (03:19)
Ceres is the largest object in the field between Jupiter and Mars; its impact with Earth would be devastating. We are more likely to be hit by a smaller body; they are less detectable and more common.
Consequences of Impact (03:19)
A 100 foot wide asteroid delivers the energy of a 500 megaton nuclear blast; it can create a crater and eject debris. Collision survivors will compete for resources. In 1908, an object's atmospheric airburst leveled hundreds of square miles in Siberia.
Space Rocks (01:55)
Meteoroids are smaller objects that frequently hit Earth's atmosphere; most burn up on entry.
Historic Impacts (06:04)
Earth's largest crater was created 2 billion years ago in South Africa. Approximately 65 million years ago, dinosaurs were wiped out by a strike in Mexico; Chesapeake Bay formed 35 million years ago.
Human Exploration (03:48)
NEAR spacecraft was set to orbit Eros; it landed and gathered geologic data. The Hayabusa rover landed on an asteroid and returned; data is still being examined. In 2007, Dawn launched to Vesta and Ceres.
Geology and Survival (04:50)
Asteroid composition and size varies; they often travel in binaries and many have moons. Knowing the chemistry of a threatening body helps to prevent or prepare for impact; comets are difficult to anticipate since they arrive from the outer solar system.
Future Exploration (03:50)
In April 2010, plans for deep space exploration are announced. Due to weak gravity of asteroids, travel will require less fuel, and anchoring.
Asteroids often contain water, which can be broken down to oxygen and hydrogen. Rare elements, such as platinum and titanium, may be present.
Recent Threats (04:04)
In 2009, the WISE mission launches to map asteroids and comets. In 2009 and 2010, objects pass only thousands of miles from Earth. In 1972, a body on a collision course skips off the atmosphere; in 2008, fragments land in Sudan. (Credits)
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