2 0 3 6
Asteroid's Near-Miss
May Be a Home Run For Scientists
A p o p h i s
Is one of more than
600 known potentially hazardous
asteroids and one of several that scientists hope to study more closely.
In Apophis' case
additional measurements are necessary
because the 2029 flyby
could be followed by frequent close approaches thereafter, or even a collision.
Ann Arbor MI (SPX) Aug 17, 2005
A University of Michigan-led research team has discovered
that for the first time in history, scientists will be able to
observe how the Earth's gravity will disrupt a massive asteroid's spin.
Scientists predict a near-miss when Asteroid 99942 Apophis passes Earth in 2029.
An asteroid flies this close to the planet only once every 1,300 years. The chance to
study it will help scientists deal with the object should it threaten collision with Earth.
Only about three Earth diameters will separate Apophis and Earth when
the 400-meter asteroid hurtles by Earth's gravity, which will twist the
object into a complex wobbling rotation.
Such an occurrence has never been witnessed but could yield important clues to
the interior of the sphere, according to a paper entitled, "Abrupt alteration
of the spin state of asteroid 99942 Apophis (2004 MN4) during its 2029 Earth flyby," accepted for publication in the journal Icarus.
The team of scientists is led by U-M's Daniel Scheeres,
associate professor of aerospace engineering, and includes U-M's Peter Washabaugh,
associate professor of aerospace engineering.
Apophis is one of more than 600 known potentially hazardous asteroids and one of
several that scientists hope to study more closely. In Apophis' case,
additional measurements are necessary because the 2029 flyby could be
followed by frequent close approaches thereafter, or even a collision.
Scheeres said not only is it the closest asteroid flyby ever predicted
in advance, but it could provide a birds-eye view of the asteroid's "belly."
"In some sense it's like a space science mission 'for free' in that something
scientifically interesting will happen, it will be observable from Earth,
and it can be predicted far in advance," Scheeres said.
If NASA places measuring equipment on the asteroid's surface, scientists could
for the first time study an asteroid's interior, similar to how geologists study
earthquakes to gain understanding of the Earth's core, Scheeres said.
Because the torque caused by the Earth's gravitational pull will cause surface
and interior disruption to Apophis, scientists have a unique opportunity to
observe its otherwise inaccessible mechanical properties, Scheeres said.
Throwing the asteroid off balance could also affect its orbit and how close
it comes to Earth in future years.
"Monitoring of this event telescopically and with devices placed on the asteroid's
surface could reveal the nature of its interior, and provide us insight into how
to deal with it should it ever threaten collision," Scheeres said.
The asteroid will be visible in the night sky of Europe, Africa and Western Asia.
The asteroid was discovered late last year and initially scientists gave
it a 1-in-300 chance of hitting the Earth on April 13, 2029. Subsequent analysis
of new and archived pre-discovery images showed that Apophis won't collide with Earth
that day, but that later in 2035, 2036, and 2037 there remains a 1-in-6,250 chance that
the asteroid could hit Earth, Scheeres said. Conversely, that's a 99.98 percent chance
that the asteroid will miss Earth.
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