A NASA JPL researcher has calculated that Oumuamua was probably a cloud of debris and not an interstellar space sail fragment. There was a Harvard research theory that Oumuamua was an interstellar space sail fragment. The new JPL analysis is simpler and explains other observations and is consistent with the way other dwarf comets break apart.
Oumuamua had a lot of anomalies in its orbit and path through the solar system. It had to be an interstellar object because it was moving a speed that is beyond the solar system escape velocity. This means it could not have had an orbit within our solar system.
Oumuamua had an acceleration which would not be a Keplerian orbit. This acceleration was 30 standard deviations beyond a regular measurement error for a large and heavy object.
Oumuamua could not be a large and heavy object because solar radiation would not be able to make such a large object move in that way. It could not have been outgassing because if outgassing caused the movement it would have been highly visible.
This means Oumuamua was not a regular large comet.
Oumuamua Was a Small Comet, It Broke Apart and then Became a Cloud of Debris
Here is the evidence and reason that Oumuamua started as a dwarf comet that was too small to survive getting close to the sun.
Although it is unknown how bright ‘Oumuamua was when approaching perihelion from interstellar space, it certainly was much fainter than required by Bortle’s survival limit. An estimate is provided by its failure to show up in the images taken with the Pan-STARRS telescope on June 17–22, 2017 (Micheli et al. 2018), when the object was at a heliocentric distance of 2.18 AU. Assuming the telescope’s limiting magnitude of ∼21, the absolute magnitude of ‘Oumuamua could not be brighter than ∼18, suggesting that the object fits the category of dwarf comets.
Oumuamua was missed on the way to perihelion because of its intrinsic faintness, more than 9 magnitude below the survival limit, it has since the very beginning been a perfect candidate for disintegration by virtue of its short perihelion distance. If so, the post-perihelion observations refer not to the object that had entered the inner Solar System, but to its debris.
In the absence of any sign of outgassing, the size of the solar acceleration implies a very high surface-area-to-mass ratio. This means it was a monstrous, extremely fluffy aggregate of loosely-bound dust grains.
10 tons of Space Dust Cloud
If we model it as a very irregularly shaped and devolatilized fluffy aggregate of loosely-bound dust grains, of extremely high porosity and ten million grams (10 tons) in mass (Sekanina & Kracht 2018), this model of ‘Oumuamua provides an opportunity to consistently explain its nongravitational acceleration as an effect of solar radiation pressure and to emphasize a chance that a number of its observed properties, including the lack of activity, tumbling, radiation pressure effect, and the inferred appearance, morphology, and elongated shape are of recent origin, not inherent to the object that was entering the inner Solar System in early 2017.
The rest of the parent dwarf comet’s debris was not observed after perihelion. The other pieces were too dark.
New work indicates that there are thousands of interstellar objects that have been captured in our solar system. If there are interstellar aliens with a technology that leaves a lot of junk, then it is possible that the gravity of our solar system has captured pieces of their civilization. This would be like coke bottles washing up on beaches or the plastic patch in the Pacific Ocean.
Currently, the most likely situation we are observing is that there are a lot of different sized rocks and dust and some of them behave in unusual ways.
Written by Brian Wang. Nextbigfuture.com