[meteorite-list] Mystery Object to Reenter Earth's Atmosphere (WT1190F)

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Tue, 3 Nov 2015 12:28:28 -0800 (PST)
Message-ID: <201511032028.tA3KSSb4024506_at_zagami.jpl.nasa.gov>


Mystery Object to Reenter Earth's Atmosphere
David Dickinson
Sky & Telescope
November 3, 2015
WT1190F will burn up over the Indian Ocean on November 13th, giving researchers
an unprecedented opportunity to follow its path - and figure out where
it came from.

An unknown object is headed for a fiery demise over the Indian Ocean on
November 13th - and observations so far show it might be a relic of the
early Space Age.

The object in question is WT1190F, first observed by the Catalina Sky
Survey in 2013. A couple years of observations have characterized its
curious orbit: its highly eccentric path around Earth takes the object
from its nearest point (perigee) of 21,221 kilometers (13,186 miles) out
to an apogee of 655,370 kilometers, 1.7 times the distance between Earth
and the Moon.

What Is WT1190F?

A diagram depicting the looping orbit of WT1190F. The blue circle is the
Moon's orbit.
Bill Gray / Project Pluto

Studies from the International Astronomical Union's Minor Planet Centre
and the European Space Agency's NEO Coordination Centre European Space
Research Institute (ESRIN) suggest that WT1190F is probably a piece of
discarded space junk from a Moon mission. Not only because of its orbit,
but also because WT1190 interacts with solar radiation pressure in a way
that suggests it has low density and might even be hollow - perhaps a
rocket booster, solar panel, or SLA Panels (Spacecraft Lunar module Adapter
panels used during the Apollo missions).

Calculations project WT1190F's reentry above the Indian Ocean, just south
of Sri Lanka, on November 13th at 6:19 UT, 11:49 a.m. local time.

This event provides astronomers the chance to model a reentry from a highly
eccentric orbit, so they can test similar scenarios involving incoming

"The object is quite small - at most a couple of meters in diameter -
and a significant fraction, if not all of it, can be expected to completely
burn up in the atmosphere," says Tim Flohrer in a recent ESA press release.

To this end, researchers from the SETI Institute and the High Enthalpy
Flow Diagnostics Group (HEFDIG) at the University of Stuttgart, Germany,
will conduct airborne observations of WT1190F's atmospheric reentry using
a specially equipped Gulfstream 450 jet supplied by the International
Astronomical Center in Abu Dhabi.

ESA researchers led similar airborne operations to observe the reentry
of Hayabusa, an asteroid sample return mission in 2010, as well as the
reentry of ESA's ISS ATV-1 supply spacecraft in 2008. See the video of
Hayabusa's reentry:

To date, researchers are unsure just what lunar mission WT1190F belongs
to. It will probably remain a mystery unless astronomers can link it to
earlier observations.

"We've managed to identify the object with one found in 2013," says Bill
Gray (Project Pluto), who has been working with the PanSTARRS team to
identify WT1190F and characterize its orbit. 'That got us a good enough
orbit that Marco Micheli was able to find images taken in December 2012
from PanSTARRS in Hawaii. So about all we can say at this point is, it
was launched sometime before December 2012."

But the more observations of WT1190F, the better. WT1190F won't pose a
good observational target for backyard observers - it's currently only
at magnitude +21 near apogee, though it'll approach magnitude +15 pre-reentry,
in range of large backyard scopes. Dedicated observers can generate topocentric
ephemerides using the Minor Planet Center's Distant Artificial Satellite
Observations (DASO) page.

Space Junk and Low-Flying Space Rocks

The Department of Defense's Space Surveillance Network (SSN) uses radar
and optical sensors to track more than 21,000 satellites and space debris
down to sizes of about 5 centimeters (2 inches) in low-Earth orbit. In
farther-out geosynchronous orbits, SSN can track objects down to sizes
of about 1 meter. But researchers can only recover objects in wider-ranging
orbits using imaging. Small, faint objects on wider orbits are extraordinarily
difficult to find, and their orbits, complicated by the gravitational
effects of the Moon, are difficult to characterize.

Other near-Earth asteroid discoveries have turned out to be space junk
as well: J002E3 was a Saturn V third-stage booster from the Apollo 12
mission, and 2010 QW1 turned out to be part of the Chinese Chang'e-2 lunar
mission. The reentry of WT1190F, however, marks the first time astronomers
have observed such an object returning to Earth.

Good luck to the team watching for WT1190F's reentry on November 13th!

Further resources:

Read Bill Gray's FAQ page at Project Pluto for an in-depth discussion
on WT1190F.

Received on Tue 03 Nov 2015 03:28:28 PM PST

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