Protecting Earth

When a double asteroid swings close to Earth in 2024, it just might get a nasty reception. NASA is studying a mission that would slam a spacecraft into the smaller of the two bodies. Astronomers would then measure how much the impact affected the orbit of the two asteroids around each other — vital information that could help us deflect an asteroid on a collision course with Earth.

An impact by a large asteroid could have devastating effects across a region or even the entire planet. But with enough lead time, it could be possible to nudge an asteroid onto a safe course. One way to provide the nudge might be to ram into the asteroid, changing its speed and direction by a tiny bit.

The new mission, known as DART, would test that technique.

The current concept calls for it to target Didymos, a system of two asteroids that orbit the Sun as a pair, bound by their mutual gravitational pull. The larger body is about half a mile in diameter, while the other is only about 500 feet across.

DART would hit the smaller asteroid at about 13,000 miles per hour. That should alter the asteroid’s orbit around its companion just enough for astronomers to measure the change.

NASA gave the okay to begin preliminary design work on the mission back in June. If DART is launched, it could be a first step in developing a way to protect our planet from potentially deadly space rocks.

Tomorrow: odd but beautiful Capricornus, the sea-goat.

Script by Damond Benningfield