PULLMAN, Wash. — Scott Hudson, Washington State University radar astronomer, with his Jet Propulsion Lab colleague Steven Ostro and an international team of astronomers have characterized the smallest solar system object observed to date. Asteroid 1998 KY26 spins faster than any object ever observed in the solar system, completing one full revolution in only 10.7 minutes, compared to Earth’s 24-hour day.
Its minerals probably contain about a million gallons of water, enough to fill several Olympic-sized swimming pools. The object is a potential oasis for travelers who one day might venture into deep space.
The researcher’s findings were published in the July 23 issue of Science magazine. The lumpy sphere, about the diameter of a baseball diamond, was observed June 2-8, 1998, as it passed 500,000 miles from Earth, about twice the distance between Earth and the moon.
Hudson and colleagues used a radar telescope in California and optical telescopes in the Czech Republic, Hawaii, Arizona and California to image the asteroid. The 230-foot-diameter Goldstone, Calif., antenna of NASA’s Deep Space Network was used to transmit radar signals continuously to the asteroid, while a separate 112-foot-diameter antenna collected echoes bouncing back from the object. Hudson then could compute the asteroid’s size, shape and other physical characteristics.
The observations present a milestone in exploring small bodies of the solar system, which probably contains about 10 million asteroids this small in orbits that cross Earth’s. There are about one billion objects in the main asteroid belt between Mars and Jupiter. However, only a few dozen of these tiny asteroids have been found, and little was known about their nature until now.
1998 KY26’s size makes it harmless if it were on a collision course with our planet, since it most likely would explode into fragments in the upper atmosphere and fall harmlessly to Earth. Moreover, 1998 KY26 is in an orbit particularly easy to intercept, if necessary.
Hudson and his team are the only ones so far to detail Earth-crossing asteroids. Hudson is a leading authority on interpreting radar data in terms of physical properties and behavior of asteroids. He has characterized the Earth-crossing asteroids Castalia, Geographos and Toutatis, among others. The International Astronomical Union named asteroid “5723 Hudson” after him to honor the pioneer who calculates shapes and rotations of asteroids by radar.
The team is working on another major breakthrough in asteroid science. An announcement is expected soon.


Reporters and editors note: See images and more details about 1998KY26 at .