The close flyby of 2004 BL86 gave researchers at the Planetary Science Institute (PSI) a chance to study the surface composition of the asteroid.
Funded by NASA's Near-Earth Object Observations Program through NASA Headquarters in Washington, D.C., Vishnu Reddy and Driss Takir remotely controlled the NASA Infrared Telescope Facility (NASA IRTF) on Mauna Kea, Hawai'I, according to a press release by PSI.
The research team used a study of infrared sunlight that was reflected by the asteroid. Astronomers around the world studied 2004 BL86.
"Our observations show that this asteroid has a spectrum similar to V-type asteroids," said Reddy. "V-type asteroids are basalt, similar in composition to lava flows we see in Hawai'i. The principal source of V-type asteroids is thought to be ancient basin-forming impacts on the south pole of the large, main-belt asteroid (4) Vesta. These impacts gave rise to the Vesta asteroid family spanning the inner part of the main asteroid belt, and some of those fragments in turn were transported to Earth-crossing orbits."
Vesta was the first target of NASA's Dawn mission, which has just sent back the sharpest images of the dwarf planet Ceres we have ever seen.
Other astronomers used photometric and radar observations. 2004 BL86 has been classified as a binary asteroid - an arrangement of two asteroids orbiting a common center of mass, according to the press release. 2004 BL86 has a diameter of 300-meters and missed the Earth by 745,000 miles.
An asteroid won't be that close to the Earth for another 200 years.
