- WASHINGTON (Reuters) - Even
small asteroids that never hit Earth could have deadly consequences, because
they might be mistaken for nuclear blasts by nations that lack the equipment
to tell the difference, scientists said on Thursday.
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- One such asteroid event occurred June 6, when U.S. early
warning satellites detected a flash over the Mediterranean that indicated
an energy release comparable to the atomic bomb dropped on Hiroshima, U.S.
Brig. Gen. Simon Worden told a congressional hearing.
-
- The flash occurred when an asteroid perhaps 10 yards
in diameter slammed into Earth's atmosphere, producing a shock wave that
would have rattled any vessels in the area and might have caused minor
damage, Worden said.
-
- Little notice was taken of the event at the time, but
Worden suggested that if it had occurred a few hours earlier and taken
place over India and Pakistan, the outcome might have been horrifying.
-
- "To our knowledge, neither of those nations have
the sophisticated sensors that can determine the difference between a natural
NEO (Near Earth Object, such as an asteroid) and a nuclear detonation,"
Worden said.
-
- "The resulting panic in the nuclear-armed and hair-triggered
opposing forces could have been the spark that ignited a nuclear horror
we have avoided for over half a century," he told a committee investigating
the risk posed by asteroids and other objects that might collide with Earth.
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- SHOCK WAVES AND TSUNAMIS
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- Astronomers have long been concerned about damage from
asteroids, meteors and comets, and since 1998 NASA has worked to identify
90 percent of all large near-Earth objects -- those with a diameter of
.6 miles or more -- by 2008.
-
- NASA's head of space science, Ed Weiler, told the committee
that scientists have identified 619 of the suspected big, dangerous asteroids,
which is about half the number astronomers believe are out there.
-
- This kind of large asteroid hits Earth a few times every
million years, and when it does, causes regional calamity. By contrast,
a so-called doomsday asteroid 3 miles across -- like the one believed to
have wiped out the dinosaurs -- hits once every 10 million years or so.
-
- The one that caused the flash over the Mediterranean
in June was probably about the size of a car, and was harmless to Earth.
Such asteroids hit the atmosphere twice a month.
-
- However, asteroids ranging from about 100 feet to hundreds
of yards can cause serious damage, including spawning a powerful shock
wave or a tsunami if it lands in an ocean, causing widespread catastrophe
if the tsunami occurs near a populated shore.
-
- These smaller bodies are not part of NASA's survey, and
Worden suggested there might be an Air Force role in tracking these smaller
objects, and also the potential for sharing early warning of incoming celestial
objects with other countries that lack the technology.
-
- Worden said the United States is unique in the world
in being able to determine whether an incoming object is an asteroid or
a bomb in less than a minute.
-
- The United States spends about $4 million a year to track
asteroids and comets, but very little on strategies to get them out of
Earth's way, scientists said last month.
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