West Virginia’s Green Bank Telescope teamed up with two other powerful radio telescopes to produce observations showing that an asteroid discovered late last year is actually two objects, each about 3,000 feet long, that orbit each other as they travel through space.
The discovery, announced last week by NASA, marks only the fourth time that two near-Earth asteroids nearly identical in size and orbiting together have been observed. Near-Earth asteroid 2017 YES was first observed during a Moroccan university’s sky survey conducted late last December. On June 21, the asteroid made its closest approach to Earth for the next 170 years or so, passing within 3.7 million miles of our planet
NASA’s Goldstone Solar System Radar in California, on June 21 and 22, detected the first signs that 2017 YES could be a binary system by revealing two distinct lobes in the asteroid. But Goldstone observers could not discern whether or not the two lobes were joined or separate.
Scientists at the Arecibo Observatory in Puerto Rico, home of a 305-foot diameter radio telescope, teamed up with their counterparts at the Green Bank Observatory, where the world’s largest fully steerable radio telescope is located, to try to solve the mystery.
On June 24, the Arecibo Telescope transmitted radar signals that bounced off 2017 YES and were received by the Green Bank Telescope. An analysis of the observations made by the Goldstone, Arecibo and Green Bank telescopes confirmed that 2017 YES consists of two distinct objects that revolve around each other every 20 to 24 hours.
According to NASA, further analysis of the observations may allow scientists to estimate the densities of the 2017 YES objects, allowing them to learn more about their composition, internal structure and how they were formed.