[meteorite-list] Hermes Found 66 Years Later - Long-Lost Object Is A Bright Binary

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 10:28:33 2004
Message-ID: <200310212228.PAA20246_at_zagami.jpl.nasa.gov>

http://www.lowell.edu/press_room/releases/recent_releases/Hermes_rls.html

For Immediate Release

October 21, 2003

Contact: Edward Bowell, Director
LONEOS (928) 774-3358 ext. 219 or
Brian Skiff, Observer
LONEOS ext. 224

NEAR-EARTH ASTEROID HERMES RE-SPOTTED, 66 YEARS LATER
UPON CLOSE OBSERVATION LONG-LOST OBJECT IS BRIGHT BINARY

Flagstaff, AZ--The re-discovery of Hermes started early on October 15th by
Brian Skiff of the Lowell Observatory Near-Earth-Object Search (LONEOS). Not
seen since 1937, asteroid 1937 UB (Hermes) continues to astonish and excite
astronomers worldwide. Further observations revealed late yesterday that
Hermes is actually two objects--called a binary--circling around one another
while about to pass by Earth again.

"This re-sighting of Hermes is the Holy Grail of near-Earth asteroid
discovery," said Edward Bowell, LONEOS Director. "Its orbit has been better
calculated and observers have confirmed its re-appearance and also shown its
binary nature... well, an asteroid's return just does not become more
profound than this."

The binary object was some 19 million miles out at the time of re-discovery
last Wednesday, nearly 66 years after it was first seen. Hermes, which poses
no threat to Earth, will make its closest approach on November 4th. By then
it will be 4 million miles away and bright enough for amateurs to see using
backyard telescopes.

The same day Skiff captured the first images of Hermes, Discovery
Communications, Inc. and Lowell Observatory announced a partnership to build
the new Discovery Channel Telescope near Flagstaff, Arizona.
(http://www.lowell.edu/press_room/releases/recent_releases/dct_rls.html) One
research objective for this new $30-million, 4.3-meter telescope will be to
significantly accelerate the search for near-Earth objects, including those
smaller than Hermes.

First images of the kilometer-size asteroid were captured by a CCD camera
during early morning observation through the LONEOS 24-inch Schmidt
telescope. More than six decades ago, Hermes was discovered by Karl Reinmuth
at Heidelberg, Germany on October 25, 1937. Fast forward to a few days ago
when Andrea Boattini of Instituto di Astrofisica Spaziale, Rome, Italy, and
Timothy Spahr of the Minor Planet Center in Cambridge, Massachusetts
analyzed the new positions of Hermes and determined what it was: the
long-lost asteroid.

"Since we find new near-Earth asteroids fairly regularly (I found, for
instance, two near-Earth asteroids the same night), my only reaction upon
finding it was that it was unusually bright," Skiff told BBC News Online on
Friday.

Up before dawn, Spahr quickly posted Skiff's discovery on the web, alerting
astronomers to follow the asteroid. James Young, at the Jet Propulsion
Laboratory's Table Mountain Observatory in California, was the first to
respond, just five hours later. Spahr then located observations made on
October 5 by the Near-Earth Asteroid Tracking program
(http://neat.jpl.nasa.gov), LONEOS observations from September 28, and
unpublished observations made by the MIT Lincoln Laboratory Near Earth
Asteroid Research program (http://www.ll.mit.edu/LINEAR), extending the
observational arc back to August 26
(http://cfa-www.harvard.edu/mpec/K03/K03T74.html).

At this point, the identification with Hermes was clear from the similarity
of the orbits from the 1937 and 2003 sightings, but it was not a simple
matter to compute an orbit that linked all the observations together. Steven
Chesley and Paul Chodas of the Jet Propulsion Laboratory found that Hermes'
trajectory is very chaotic due to frequent close encounters with the Earth
and Venus. Following its flyby of the Earth in 1937 at a distance of 460,000
miles (just 1.8 times the Moon's distance), Hermes made an unobserved close
approach to the Earth in 1942 of just 1.6 lunar distance. Using JPL's Sentry
impact monitoring software, Chesley and Chodas were able to find twelve
distinct dynamical pathways that produced an encounter in 1937. Picking out
the true orbit was then an easy matter , and led to the further prediction
that Hermes will not approach the Earth more closely than 8 lunar distances
within the next century (http://neo.jpl.nasa.gov/news/news140.html).

On October 16, Andrew Rivkin and Richard Binzel of MIT observed a spectrum
of Hermes using the NASA Infrared Telescope Facility in Hawaii, and were
able to ascertain that the asteroid is of a type known as S class. Because
the surfaces of S-class asteroids reflect, on average, 24% of the sunlight
falling on them, Rivkin and Binzel were able to deduce that Hermes is 0.9 km
(about 1,000 yards) in diameter.

Over the next few days, the world's most powerful radar, the 1,000-foot
dish, at Arecibo, Puerto Rico, projected radar beams on to the asteroid and
captured the faint returning echoes. Jean-Luc Margot, of the University of
California, Los Angeles, and his team saw that the asteroid is strongly
bifurcated. Two separate components, of roughly equal size and almost in
contact, are revolving about their common center of mass in up to 21 hours.
It appears that the components have tidally evolved into a situation where
their spin period is equal to their orbital period and therefore present the
same face to one another all the time, just like the Earth-Moon system.
There are now about 10 radar-observed binary near-Earth asteroids, about 1
in 6 of NEAs larger than 200 m in diameter. "We certainly did not expect to
find a binary with roughly equal-sized components," said Margot. "All the
binary NEAs that we have imaged so far show a secondary that is only a
fraction of the size of the primary."

Amateur and professional astronomers are collaborating to observe the way
Hermes changes in brightness as its components rotate. Eventually, they
should be able to determine the components' orbital plane, an accurate
period of revolution, and, perhaps, the shapes of the individual bodies. See
http://www.asu.cas.cz/~asteroid/binneas.htm for a list of binary NEAs.

The only near-Earth object not also identified by number, Hermes shares a
name in Greek mythology with the son of Zeus, messenger of the gods, god of
science, commerce, eloquence, and arts of life. "The name `Hermes' also
means hastener, and representations of him are symbolic of the messenger or
the speed and majesty in flight," according to Schmadel's Dictionary of
Minor Planet Names.

Lowell Observatory was founded in 1894 by Percival Lowell with a mission to
pursue the study of astronomy, especially the study of our Solar System and
its evolution; to conduct pure research in astronomical phenomena; and to
maintain quality public education and outreach programs to bring results of
astronomical research to the general public. Visit http://www.lowell.edu;
and Friends of Lowell at http://www.lowell.edu/friends/.

LONEOS is one of five programs funded by NASA to search for asteroids and
comets that may approach our planet closely. Their current goal is to
discover 90% of near-Earth asteroids larger than 1 km in diameter by 2008.
There are thought to be about 1,200 such asteroids.

For more information on the discovery and images of Hermes, visit the LONEOS
website at http://asteroid.lowell.edu/asteroid/loneos/loneos.html.

#END#
Received on Tue 21 Oct 2003 06:28:58 PM PDT