The asteroid 2014 RC swooped by Earth at a distance of only 34,000 km (21,000 miles) on Sunday, September 7. The close approach allowed scientists to make some observations of the small asteroid.
While 2014 RC was in no danger of colliding with the Earth, it highlighted a deficiency in asteroid early warning systems: it was discovered by the Catalina Sky Survey only a week before its closest approach. That was a week more warning time than was available for the damaging Chelyabinsk explosion, which was caused by an asteroid roughly the same size as 2014 RC, but it’s still uncomfortably little time.
The late detection is due to the small size of these objects. Teetering on the edge of undetectability even during the best of times, discovery and tracking small asteroids require highly specialized survey telescopes. Follow-up observations for new or interesting discoveries are made more difficult by the lack of observing time available on non-survey telescopes. With NASA attempting to get backing for a mission to retrieve an asteroid less than 5m (15 feet) in diameter, understanding how small asteroids look and behave is a vital piece of groundwork that needs to be laid.
Fortunately, 2014 RC’s close approach allowed for some observations that otherwise wouldn’t have been possible. Here’s what those observations turned up:
2014 RC is an Sq-type asteroid. In lieu of samples, the composition of an asteroid can be determined by observing its spectrum. Measurements of 2014 RC’s infrared spectrum by R. P. Binzel (MIT), D. Polishook (MIT) and S. J. Bus (University of Hawaii) at NASA’s Infrared Telescope Facility (IRTF) place the asteroid in a group known as Sq-type asteroids. The Sq classification is intermediate between the S-type (stony meteorites) and Q-type (stony-iron meteorites). This means that 2014 RC is probably a large rock with small veins of metal running through it.
2014 RC is a fast spinner. Brightness measurements made with the Lowell Observatory’s 42-inch Hall Telescope by A. Thirouin, B. Skiff, and N. Moskovitz suggest that the asteroid is rotating once every 15.8 seconds. This makes 2014 RC the record holder for fastest spinning asteroid, beating out the previous record holder 2010 JL88 by over 9 seconds.
2014 RC was a little larger than expected. The asteroid flew close enough that it was detectable using the Goldstone radar system. Lance Benner and Marina Brozovic (JPL) reported that the echoes off the asteroid were weaker than expected due to the rapid rotation speed. The rotation broadened the frequency of the radar pulse by nearly 500Hz. Based on this frequency broadening, Benner and Brozovic calculate that 2014 RC’s diameter was 22m (72 feet) assuming a rotation rate of 15.8 seconds. This is a little bit larger than initial estimate of 15m (49 feet) for the asteroid’s diameter. The asteroid was close enough to Earth that the Goldstone radar was theoretically capable of resolving features on 2014 RC’s surface. However, due to the extremely fast rotation, no surface features were seen.
2014 RC was not related to the Managua explosion. Eyewitness reports place an explosion that formed a 12m (40 foot) wide crater just outside of the Managua, Nicaragua airport at around 11pm local time. This explosion occurred more than 13 hours before the closest
approach of 2014 RC, when the asteroid was still well beyond the Moon’s orbit. While the Nicaraguan government claims that an asteroid impact was responsible for the explosion, that explanation is in doubt. There were no reports of a large fireball (which certainly would have preceded the explosion) or any meteorites, although the impact should have been small enough for many fragments to survive the initial explosion.
After its close encounter with Earth, 2014 RC retreated back into the depths of space. The gravitational pull of Earth shortened its orbit by nearly 51 days. The new orbit places 2014 RC on the list of JPL’s Near-Earth Object Human Spaceflight Accessible (NHATS) objects, which are a set of criteria to identify NEOs that could be candidates for manned missions. While it’s fun to dream of a far-future manned mission to 2014 RC, the asteroid’s rapid rotation probably rules out any chance of that happening. Barring a future collision with Earth, Sunday’s flyby will probably be the best look we get at this asteroid for a long while.
Featured image credit: NASA/JPL-Caltech