[meteorite-list] J002E3: An Update

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 10:06:58 2004
Message-ID: <200210100017.RAA27360_at_zagami.jpl.nasa.gov>

http://neo.jpl.nasa.gov

J002E3: An Update
Steve Chesley and Paul Chodas
NASA's Near-Earth Object Program Office
October 9, 2002

We have new results since our September 19 report on the
distant Earth satellite J002E3. Evidence continues to accumulate that
J002E3 is the lost S-IVB third stage from the Saturn V rocket used to
launch the Apollo 12 lunar landing mission in November 1969.

J002E3 passed into the daytime morning sky around Sept. 24, and a week
later amateur astronomers Richard Fredrick and Vance Morgan at Powell
Observatory in Kansas recovered the object after it had crossed into
the evening sky. However, their measurements did not match the
predicted position unless we added a gentle push from solar radiation
pressure to our acceleration model. As more observations were reported
over the next few days, it became clear, not only that radiation
pressure was detectable in the motion of the body, confirming that
J002E3 is a man-made object, but also that the size of this
acceleration matches very well with what we would expect for an S-IVB.

With the quality of our orbital solution improving, we decided to look
to see if this relatively bright object had been detected by other
telescopes before its discovery in the first week of
September. Indeed, using the SkyMorph online search system, we
found a single trail from the fast-moving object on an image taken by
the NEAT-Palomar NEO survey on June 16, 2002. After we notified
him of the detection, Reiner Stoss of DANEOPS
[http://earn.dlr.de/daneops/] immediately measured the precise
position for us.

The new precovery data extended the arc of observations from 35 days
to 114 days, dramatically improving our ability to determine the past
and future paths of this object and to measure the acceleration of
solar radiation pressure. At our last report we had only 15 days of
observations and there was greater uncertainty about what the future
held for J002E3. We were not sure how long it would remain in the
Earth's vicinity, although it appeared likely to escape next June. We
could not even rule out the possibility of a collision with the Earth
or Moon over the the next year. It is now certain that J002E3 will
depart the Earth-Moon system in June 2003 and that there is no
possibility of an impact for several decades. In the years ahead
J002E3 may be recaptured, but the first opportunity for this will not
be until the mid-2040s.

Looking into the past, we are still unable to connect the motion of
J002E3 with the last know position of the Apollo 12 S-IVB. One reason
is that the solar radiation pressure is not constant in time, but
rather changes with its position around the sun; to precisely account
for this effect we need to know the pole of rotation. Furthermore, if
J002E3 is the Apollo 12 S-IVB then that stage spent more than a year
in a highly chaotic orbit around the Earth. So far these two factors
have combined to prevent us from predicting the position of J002E3
with sufficient precision to definitively link these two
objects. Nonetheless, we are hopeful that with continued observations,
and with the possibility of additional precovery observations, this
link can be conclusively established before J002E3 slips back into
solar orbit next summer.
Received on Wed 09 Oct 2002 08:17:41 PM PDT