Artificial Asteroids
Published on Nov 15, 2007 at 8:39 pm.
2 Comments.
Filed under observing.
About a week ago, the Minor Planet Center announced the discovery of a near Earth asteroid. That asteroid, designated 2007 VN84 was found to have an orbit that would bring it very close to Earth. Naturally any asteroid passing near Earth bears watching. So, astronomers began to locate and plot the position of the new asteroid with the intention of determining its orbit carefully enough to predict where it will be in the future, and to assess the possibility of any potential impact with Earth. That sort of thing happens all the time. Asteroid near misses occur all the time. What makes this story particularly interesting, though, is that Russian astronomer Denis Denisenko noticed that the orbit for 2007 VN84 appeared to be identical to that of the European Space Agency’s Rosetta spacecraft, which was due to swing past Earth on November 12. Indeed, it turns out that that minor planet 2007 VN84 is, in fact, not a minor planet at all. The Rosetta spacecraft was launched in 2004 on its way to Comet 67P/Churyumov-Gerasimenko. Rosetta is scheduled to arrive at the comet in 2014. However, along the way, Rosetta uses a gravitational assist from Mars and three passes by Earth.
Now, it is interesting that this spacecraft was observed and mistaken for an asteroid. The first thing to note is that it was even seen at all. After all, Rosetta isn’t all that big. It measures about 3 meters by 2 meters. Now, granted, it is much more reflective than a typical space rock, probably reflecting as much light as a rock about ten times it size. But, still, that is impressive that it could be found.
However, this points out a flaw in the procedures for monitoring minor planets. Whenever a suspected asteroid is discovered the orbit of the suspected body is compared with known asteroid orbits. However, there appears to not be a routine and easy way to check against known man-made objects’ orbits. Of course, there really hasn’t been much of a need for that, either. Until the last few years we have not had the capability to detect things as small as man-made spacecraft flying around the Solar System. But, with more and more spacecraft being launched by more and more nations, there will eventually be a need for some international clearinghouse of information about the orbits of these craft.
Interestingly, Rosetta isn’t the first man-made body to be mistaken for an asteroid. In 2002 a body dubbed J002E2 was found that is believed to be debris from one of the Apollo moon missions (Apollo 12). Another body, dubbed 6Q0B44E was discovered in 2006 and soon found to likely be another man-made object left over from Apollo. And in 2000, an object was found and given the minor planet designation of 2000 SG344. But, 2000 SG344 was also thought to possibly be a leftover piece of a Saturn V moon rocket (now it seems that it may actually be an asteroid after all).
So, we have a list of objects that might not really be asteroids at all, hence the title of my post: artificial asteroids. However, I am a big science fiction fan, so the title reminds me of Arthur C. Clarke’s 1972 novel titled Rendezvous with Rama, in which astronomers discover an asteroid that changes its own orbit. They quickly realize that it is actually a spaceship that looks like an asteroid because it is essentially a hollowed out asteroid. Naturally a spacecraft is sent to investigate, and adventures ensue. It is actually a very good book. Clarke followed up on the original book in 1989 with Rama II, which I also liked. The next two books in the sequence did far less for me than the first two. However, I really enjoyed Rendezvous with Rama and Rama II.
-Astroprof
Ed Davies on November 16, 2007 at 6:07 am: 1
2007 VF189 has also caused some confusion with respect to Rosetta - being apparently a genuine asteroid on a path somewhat similar to Rosetta’s but trailing behind.
See:
http://tech.groups.yahoo.com/group/mpml/message/20008
and following messages, not all in the same thread.
A ler…-- Rastos de Luz on November 21, 2007 at 5:04 pm: 2
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