SETI Fast-spinning, water-rich asteroid found


Larry Klaes (lklaes@bbn.com)
Fri, 23 Jul 1999 14:31:43 -0400


>Date: Thu, 22 Jul 1999 20:54:53 -0700 (PDT)
>From: JPLNews@jpl.nasa.gov
>Subject: Fast-spinning, water-rich asteroid found
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>FOR IMMEDIATE RELEASE July 22, 1999
>
>SUN NEVER SETS, FOR LONG, ON FAST-SPINNING, WATER-RICH ASTEROID
>
> Spinning faster than any object ever observed in the solar
>system, a lumpy, water-rich sphere known as 1998 KY26, about the
>diameter of a baseball diamond, is rotating so swiftly that its
>day ends almost soon as it begins, NASA scientists report.
>
> Asteroid 1998 KY26, where the Sun rises or sets every five
>minutes, was observed June 2-8, 1998, shortly after it was
>discovered and as it passed 800,000 kilometers (half a million
>miles) from Earth, or about twice the distance between Earth and
>the moon. Publishing their findings in tomorrow's issue of
>Science magazine, Dr. Steven J. Ostro of NASAís Jet Propulsion
>Laboratory, Pasadena, CA, and an international team of
>astronomers used a radar telescope in California and optical
>telescopes in the Czech Republic, Hawaii, Arizona and California
>to image the 30-meter (100-foot), water-rich ball as it twirled
>through space. It is the smallest solar system object ever
>studied in detail.
>
> "These observations are a breakthrough for asteroid science
>and a milestone in our exploration of the small bodies of the
>solar system," Ostro said. "Enormous numbers of objects this
>small are thought to exist very close to Earth, but this is the
>first time we've been able to study one in detail. Ironically,
>this asteroid is smaller than the radar instruments we used to
>observe it."
>
> The asteroid's rotation period was calculated at just 10.7
>minutes, compared to 24 hours for Earth and at least several
>hours for the approximately 1,000 asteroids measured to date. In
>addition to these findings, the minerals in 1998 KY26 probably
>contain about a million gallons of water, enough to fill two or
>three olympic-sized swimming pools, Ostro said.
>
> "This asteroid is quite literally an oasis for future space
>explorers," he said. "Its optical and radar properties suggest a
>composition like carbonaceous chondrite meteorites, which contain
>complex organic compounds that have been shown to have nutrient
>value. These could be used as soil to grow food for future human
>outposts. And among the 25,000 or so asteroids with very
>reliably known orbits, 1998 KY26 is in an orbit that makes it the
>most accessible to a spacecraft."
>
> The solar system is thought to contain about 10 million
>asteroids this small in orbits that cross Earth's, and about 1
>billion in the main asteroid belt between Mars and Jupiter.
>However, only a few dozen of these tiny asteroids have ever been
>found and, until now, hardly anything was known about the nature
>of these objects.
>
> Ostro and his colleagues used the 70-meter-diameter (230-
>foot) Goldstone, CA, antenna of NASA's Deep Space Network to
>transmit radar signals continuously to the asteroid and turned a
>34-meter-diameter (112-foot) antenna on it to collect echoes
>bouncing back from the object.
>
> 1998 KY26's color and radar reflectivity showed similarities
>to carbonaceous chondrites, primordial meteorites which formed
>during the origin of the solar system, and unlike any rocks
>formed on Earth. They contain complex organic compounds as well
>as 10 percent to 20 percent water. Some carbonaceous chondrites
>contain amino acids and nucleic acids, which are the building
>blocks of proteins and DNA, and hence, are of interest to
>scientists trying to unravel the origins of life.
>
> A second team of astronomers used optical telescopes to
>track 1998 KY26, which was discovered by the University of
>Arizona's Spacewatch telescope, the world's first instrument
>dedicated to searching for near-Earth asteroids. Dr. Petr Pravec
>of the Czech Republicís Academy of Sciences said collisions
>likely gave 1998 KY26 its rapid spin.
>
> But one way or another, Pravec said, this object's 10.7-
>minute "day" is the shortest of any known object in the solar
>system. "The motion of the sky would be 135 times faster than it
>is on Earth," he said. "Sunrises and sunsets take about two
>minutes on Earth, but on 1998 KY26, they would take less than one
>second. You'd see a sunrise or sunset every five minutes."
>
> Dr. Scott Hudson of Washington State University in Pullman
>found the asteroid's shape particularly surprising. Asteroids
>thousands of times larger have spherical shapes as a result of
>their large masses and strong gravitational fields, he said. 1998
>KY26 is very unusual, however, because gravity and mass play no
>significant role in its shape. Instead, the spheroid shape is the
>result of collisions with other asteroids.
>
> While much larger near-Earth asteroids could pose a long-
>term collision hazard, 1998 KY26's size makes it harmless if it
>were on a collision course. The asteroid would most likely
>explode in the upper atmosphere and its fragments would fall
>harmlessly to Earth. Moreover, 1998 KY26 is in an orbit whose
>shape and low inclination with respect to the ecliptic plane make
>it unusually easy to intercept.
>
> Tracking of 1998 KY26 by Ostro and his colleagues in the
>international scientific community was supported by NASA's Office
>of Space Science, Washington, DC, and by the Czech Republic's
>Academy of Sciences in Prague. JPL is a division of the
>California Institute of Technology, Pasadena, CA.
>
> #####
>7/22/99 DEA
>#99-060
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