NASA captures moment 'killer' space objects come close to Earth

NASA captured a rare event as two large asteroids, described by scientists as "planet killers", passed very close to Earth last week.

Scientists at NASA's Jet Propulsion Laboratory (JPL) in Southern California tracked the two space rocks with the Goldstone Solar System Radar, which also measured the objects' dimensions.

Pics or it didn't happen!
JPL scientists tracked two asteroids that safely flew past Earth recently and used the Deep Space Network to capture images, including this view of Asteroid 2024 MK.

Asteroid 2024 MK, which was first spotted by scientists just 13 days before its closest approach to Earth, was imaged as a 500-foot-long object on Saturday.

Asteroid 2011 UL21, a roughly mile-wide object, was seen passing close to Earth on Thursday at 58,000 mph and turned out to have a small moon orbiting about two miles from its surface.

None of the NEOs was at risk of hitting our planet, but the radar observations made during these two close approaches will provide valuable training for planetary defense, as well as information about their sizes, orbits, rotations, surface details, and clues about their composition.

Asteroid 2011 UL21 will pass Earth on June 27 at a distance of 4.1 million miles (6.6 million kilometers), or about 17 times the distance between the moon and Earth, and was discovered in 2011 by the Catalina Sky Survey, in Tucson, Ariz. But this is the first time the probe has come close enough to Earth to be imaged with radar.

While the roughly mile-wide (1.5 km) object is classified as "potentially hazardous," calculations of its future orbits show it will not pose a threat to our planet in the foreseeable future.

Using the Deep Space Network's 230-foot (70 m) Goldstone Solar System Radar (DSS-14), near Barstow, California, JPL scientists sent radio waves to the asteroid and received the reflected signals with the same antenna.

In addition to determining that the asteroid is roughly spherical, they discovered that it is a binary system: a smaller asteroid, or moon, orbiting it from a distance of about 1.9 miles (3 km).

“About two-thirds of asteroids this size are thought to be binary systems, and their discovery is particularly important because we can use measurements of their relative positions to estimate their orbits, masses and mutual densities, which could provide key information about how they formed,” said Lance Benner, a principal scientist at JPL who helped lead the observations.