[meteorite-list] Asteroid Hunter's Once In A Blue Moon Find (J002E3)

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 10:08:24 2004
Message-ID: <200209111653.JAA04270_at_zagami.jpl.nasa.gov>

http://www.guardian.co.uk/spacedocumentary/story/0,2763,789827,00.html

Asteroid hunter's once in a blue moon find

Lunar knowledge may be eclipsed by latest discovery
Tim Radford
The Guardian (United Kingdom)
September 11, 2002

Throughout history stargazers, skywatchers, astrologers and priests have
consoled themselves with just one moon. That is, until September 3, when Bill
Yeung, a Canadian amateur asteroid hunter with a string of asteroids and
comets to his name, discovered Earth's second moon.

"This is bizarre - the universe really is stranger than we can imagine," said
Duncan Steel, an astronomer and asteroid expert at the University of Salford,
last night. "I don't know of anyone having suggested an asteroid in orbit around
the Earth before."

The object so far is known only as J002E3. It is designated as an asteroid.
However, to astronomers asteroids are minor planets or lumps of rock. The
difference is that this minor planet or lump of rock is in orbit not around the sun,
but around the Earth. It circles the Earth every 49.5 days along an elliptical path
which sometimes has it 840,000 km (520,000 miles) from Earth, sometimes a
trifling 300,000 km, and tilted at 21 degrees from the plane of the Earth's own
orbit around the sun.

The distance of the more familiar moon - the one wooed by lovers and poets
and visited by astronauts - is about 380,000 km on average and it circles the
Earth every 27.32 days.

J002E3's size is uncertain: if it is a lump of space rock, then judging by the light
reflected from it is a mere 50 metres across. No astronaut will ever land on it.
But its composition is also uncertain: there is a chance that J002E3 is an old
rocket body, strayed improbably far from home. If so, and if it is painted white
to make it a good reflector, then it might be a only 10 or 20 metres in length.
But then if it is manmade, it hardly counts as a moon. The planet is ringed with
thousands of orbiting man made satellites.

If it is a moon it is, however, certainly a new moon. Any object bright enough to
have been picked up by an amateur telescope would be too bright to have
escaped discovery for long. Nasa researchers have already guessed that at some
point in its freewheeling adventures in orbit, it was "captured" by the Earth's
gravitational field. This is how Jupiter must have acquired at least some of its
treasury of moons.

One scientist has gone further: Paul Chodas of the Jet Propulsion Laboratory in
Pasadena thinks that it was "likely captured from heliocentric orbit during the
April/May time period" when it strayed to a spot where the Earth's and the sun's
gravitational tug cancel each other.

If J002E3 is declared a moon, then its next name is likely to be no more exciting:
it will be designated S/2002E1. The S stands for satellite, the E1 for the first
satellite of Earth discovered in 2002.

Dr Steel does not rule out the lost rocket theory. In 1991 two objects in orbit
around the sun were classified as asteroids but turned out to be manmade
satellites.

"We have seen returning spacecraft before, but this one is different. It has
recently arrived in orbit around our planet. Astronomers have made mistakes
with returned rocket bodies before," he said.

"If this really is a new moon - an asteroid captured into orbit around the Earth -
then it heralds a great new era of space exploitation. It will be the easiest
celestial object to get to, and so a wonderful source of raw materials. When we
start building space colonies, this could be where we get the metals and oxygen."
Received on Wed 11 Sep 2002 12:53:27 PM PDT