Hi Jean,

This is about as conclusive as such a 'no' can be. The
orbital analyses done independently by JPL and me already
showed that it's not been in our neighborhood since 1929.

We now have a _lot_ more data, even leaving out the radar
astrometry (which hasn't been published yet anyway). Just
with what we've got, it's clear that the object came within
.011 AU of Venus in February 2006, not the sort of close
flyby one would expect. It really is solidly tracked back
to that 1929 encounter (and probably could be tracked back
further; I didn't bother.)

I didn't mention this in my previous post, but I did
run some orbits with solar radiation pressure included.
Even with large effects (i.e., assuming a light, large
object such as a booster), the results didn't change
by very much. Certainly not enough to put this near the
earth since 1929, let alone near the earth at the time
of the launch.

The "coincidences" mentioned by Michael Khan are not
as coincidental as they might seem. He mentions that:

-- The semi-major axis (a) is about one AU, hence a
period of one year;
-- The perihelion distance (q) is a bit under .7 AU;
-- The aphelion distance (Q) is a bit over 1.3 AU.

But these are linked quantities: q + Q = 2a. So if a=1 and
q<.7, then Q will be greater than 1.3 AU, every time. (What
would _really_ be amazing would be an object with a=1 AU,
q<.7 AU, and Q<1.3 AU... mathematically impossible, in fact.)

I looked through an 'mpcorb.dat' list of asteroid orbital
elements and looked for those roughly fitting these specifications
(I used .95 < a < 1.05 and e > .3). That got me 90 such objects.
Considering there is nothing particularly sacred about a being
near 1, you could find thousands of objects that "look like"
artificial objects after planetary encounters. (Many of them
more so than this one.)

To make this an artificial object, you'd have to assume...
well, a lot of coincidences. After the planetary encounter
(in this case, with Venus), it would have to do a maneuver
some time after that encounter. (Otherwise, we'd have been
able to backtrack it to Venus.) Also, the encounter plus
the maneuver would have to leave the object headed very close
to us, which would not be particularly likely.

Someday, such a thing might happen. I don't expect to
see it happen in my lifetime, nor my daughter's.

In fairness, I should mention that I have personal experience
in being confident that an object was artificial, then having to
reverse myself. In November 2007, the Rosetta spacecraft made
an entirely expected flyby. However, MPC and the asteroid
community didn't know about it, so it got imaged and was thought
to be an asteroid for a while. Then, a few days later,
something came along in what looked, on the face of it, to be
in a suspiciously similar orbit. I leapt to the assumption that
it must be a booster or Rosetta-associated junk. Then I had to
reverse that opinion a few hours later. See

http://tech.groups.yahoo.com/group/mpml/message/20008

and a slew of follow-up posts for details.

-- Bill