One of the world's most powerful radio telescopes is back online months after sustaining hurricane damage. The 1,000-ft (305-m) Arecibo Observatory only received minor structural damage when Hurricane Maria made landfall on the island of Puerto Rico on September 20, but the commercial electrical grid needed to power the giant antenna was only recently re-established. Though it resumed radio observations after a few days, it wasn't until December that it was able to restart its Arecibo Observatory Planetary Radar, which scans potentially dangerous asteroids.

According to NASA, Arecibo's first major task after resuming normal operations was to complete a radar survey of the near-Earth asteroid 32000 Phaeton as it made its closest approach to Earth this month. The high-resolution images with a resolution of 250 ft (75 m) per pixel show that it is spheroidal in shape with a dark circular area at one of its poles.

Since Phaeton not only passes close to Earth, but has a diameter of 3.6 mi (6 km), it is classed as a potentially hazardous Near Earth Object, though its current orbit does not pose a near-future threat to our planet. However, NASA's Planetary Defense Coordination office routinely uses radar to assess such asteroids' size, shape, rotation, surface features, roughness, and trajectory.

"Arecibo is an important global asset, crucial for planetary defense work because of its unique capabilities," says Joan Schmelz of USRA and deputy director of Arecibo Observatory. "We have been working diligently to get it back up and running since Hurricane Maria devastated Puerto Rico."