November 05, 2018


About a year ago, what was thought to be a new comet was seen moving into the inner solar system at unusually high speed, subsequent observations indicated that  C 2017/U1 PANSTARRS was traveling at well past solar system escape velocity, indicating it was an extra solar object. As it approached the sun it did not outgas like a comet indicating that it's either rocky or metallic. The object turned out to be red and elongated (actually about 10 times as long as it is wide). The object was given the name Ê»Oumuamua, which is Hawaiian for "Advanced Scout".

The thing came close enough to the sun to get a decent slingshot effect from its pass and then streaked at a blistering pace out of the solar system. 

As it moved away from the sun, it performed what is described as a "non-gravitational acceleration".


This was most peculiar and many scientists have naturally been trying to explain this phenomenon. Among them are  Shumel Bialy and Abraham Loeb of the Harvard Astrophysics department. They have published a short paper that attempts to explain the observed acceleration as being due to solar pressure, since everything else has been pretty much ruled out. There are a lot of equations explaining their hypothesis, which they admit is somewhat hampered by the limited data gleaned during the objects high speed pass. 

At the end of the paper on solar pressure as an explanation for ʻOumuamua's behavior, there is this single paragraph...
Alternatively, a more exotic scenario is that ‘Oumuamua may be a fully operational probe sent intentionally to Earth vicinity by an alien civilization. Based on the PAN-STARRS1 survey characteristics, and assuming natural origins following random trajectories, Do et al. (201 derived that the interstellar number density of ‘Oumuamua-like objects should be extremely high, ∼ 2×1015 pc−3, equivalent to ∼ 1015 ejected planetisimals per star, and a factor of 100 to 108 larger than predicted by theoretical models (Moro-Martin et al. 2009). This discrepancy is readily solved if ‘Oumuamua does not follow a random trajectory but is rather a targeted probe. Interestingly, ‘Oumuamua’s entry velocity is found to be extremely close to the velocity of the Local Standard of Rest, in a kinematic region that is occupied by less than 1 to 500 stars.
Emphasis mine.

That is indeed a more exotic scenario.

Even without that scenario, this visitor from beyond certainly warrants scientific attention. It was initially thought that due to its incredible speed it could not be studied anymore, however,  there have been some study of the problem and the Interstellar Studies Initiative has identified some ways to do it. Additionally JPL is proposing a mission using a SpaceX BFR rocket and combined solar and Jovian gravity assist. The window for this is limited but still doable. If launched in 2025 the probe would rendezvous with Ê»Oumuamua in 2039*. 

So this very interesting interstellar visitor may not be completely out of the news just yet. 

* Assuming, of course the object didn't perform any more anomalous accelerations!

Posted by: The Brickmuppet at 10:40 PM | Comments (3) | Add Comment
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1 Sorry, "Rendezvous with 'Oumuamua" just sounds silly.

Posted by: Pixy Misa at Tue Nov 6 01:40:30 2018 (PiXy!)

2 So... it's Rama then, is it?

Posted by: Wonderduck at Tue Nov 6 01:43:46 2018 (9gv+L)

3 That would mean we get two more shots at it.

Posted by: Mauser at Thu Nov 8 22:21:44 2018 (Ix1l6)

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