[meteorite-list] Vulcan In The Twilight Zone (The Search for Vulcanoid Asteroids)

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 10:01:35 2004
Message-ID: <200206241648.JAA10232_at_zagami.jpl.nasa.gov>

http://news.bbc.co.uk/hi/english/sci/tech/newsid_2063000/2063200.stm

Vulcan in the twilight zone
By Dr. David Whitehouse
BBC News
June 24, 2002

Two US astronomers have been looking for a suspected belt of asteroids close
to the Sun by making observations from the back seat of an F-18 jet.

Dan Durda and Alan Stern, from the Southwest Research Institute (SwRI) in
Boulder, Colorado, are looking for the Vulcanoids, a ring of debris lying
between Mercury and our star.

First postulated over a century ago, the Vulcanoids are thought to range in
size from one to 25 kilometres. Finding them would change our understanding
of the innermost region of our Solar System.

If they do exist, it is possible they could still contain fragments of the
earliest materials that formed next to our star when it was newborn.

"Most comprehensive search"

Durda and Stern are flying at a height of 15 kilometres (49,000 feet) to get
the observing conditions that will best enable them to prove the belt's
existence.

Some theories suggest that a small number of kilometre-sized and larger
Vulcanoids could have survived in the inner Solar System, inside the orbit
of the planet Mercury, until now.

Named after the Roman god of fire, these asteroids would be exceedingly
difficult to observe from the ground because of the Sun's glare and the
distortion caused by the Earth's atmosphere.

"Our Vulcanoids search programme, conducted from an altitude of 49,000 feet
over the Mojave Desert, gave us a view of the twilight sky near the Sun that
is far darker and clearer than can be obtained from the ground," says Dr
Durda.

Shuttle camera

"This is the most comprehensive, constraining search yet conducted for these
objects," adds Dr Stern, director of the SwRI Space Studies Department.

Astronomers have conducted ground-based searches for the Vulcanoids before,
during total solar eclipses, and during the twilight period after sunset
just before the Vulcanoids themselves would set.

But to date, the asteroids have not been seen. Observations have only placed
upper limits on how many might exist.

The camera used in the latest search was originally conceived for the space
shuttle. It is trained on the region of space close to the Sun after the
star has dipped below the Earth's horizon. The camera grabs twilight images
at a rate of 60 frames a second.

The researchers are currently analysing their data. They hope to know if the
Vulcanoids exist in a month or two.
Received on Mon 24 Jun 2002 12:48:38 PM PDT