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On October 19th, 2017, the Panoramic Survey Telescope and Rapid Response System-1 (Pan-STARRS-1) in Hawaii announced the first-ever detection of an interstellar asteroid, named 1I / 2017 U1 (AKA 'Oumuamua).
In the following months, multiple follow-up observations were conducted that allowed astronomers to get a better idea of its size and shape, while also revealing that it had the characteristics of both a comet and an asteroid.
Interestingly enough, there has been some speculation that it is based on its shape, it may actually be an interstellar spacecraft (Breakthrough Listen even monitored it for signals of radio signals!).
A new study by a pair of astronomers from the Harvard Smithsonian Center for Astrophysics (CfA) has taken a step further, suggesting that 'Oumuamua may actually be a light sail of extra-terrestrial origin.
(Starshot breakthrough)
The study – "Could Solar Radiation Pressure Explain 'Oumuamua' s Peculiar Acceleration?", Which was released by Shmuel Bialy and Prof. Abraham Loeb. Bialy is a postdoctoral researcher at the CfA Institute for Theory and Computation (ITC), Prof. Loeb is the director of the ITC, the Frank B. Baird Jr. Professor of Science at Harvard University, and the head of the Breakthrough Starshot Advisory Committee.
To recap, 'Oumuamua was first spotted by the Pan-STARRS-1 survey 40 days after it made its closest pbad to the Sun (on September 9th, 2017).
At this point, it was about 0.25 AU from the Sun, and already on its way out of the Solar System. In that time, astronomers remarked that it appeared to have a high density (indicative of a rocky and metallic composition) and that it was spinning rapidly.
Whereas it has been reported that it has been reported that it has been reported that it has been reported that it has been reported that it has been reported that it has been reported that Oumuamua was more than previously thought.
Then, the Solar System, the Hubble Space Telescope snapped some final images of 'Oumuamua that revealed some unexpected behavior.
After examining the images, another international research team discovered that 'Oumuamua had grown in velocity, rather than slowing down as expected. The most likely explanation, they claimed, was that 'Oumuamua was venting material from its surface due to solar heating (AKA outgbading).
The release of this material, which is consistent with how to behave, would give 'Oumuamua the steady push it needed to achieve this boost in velocity.
To this, Bialy and Loeb offer a counter-explanation. If 'Oumuamua were in fact a comet, why then did it not experience outgbading when it was closest to our Sun?
In addition, they cite other research that showed that they were responsible for the acceleration, it would have also caused a rapid evolution in 'Oumuamua's spin (which was not observed).
Basically, Bialy and Loeb consider the possibility that it could be a light sail, a form of spacecraft that is linked to radiation propulsion – similar to what Breakthrough Starshot is working on. Solar system and look for signs of life. As Prof. Loeb explained to Universe Today via email:
"We explain the excess acceleration of Oumuamua away from the Sun as the result of the Sunlight exerts on its surface. millimeter in thickness but tens of meters in size. This is the case for the surface of the surface or the surface of the surface. has a probe sent for a recognition mission to the inner region of the Solar System). "
Based on this, Bialy and Loeb went on calculating the likely shape, thickness, and mbad-to-area ratio that such an artificial object would have. They also thought that this object would be able to survive in space and that it would be able to withstand the tensile stresses caused by rotation and tidal forces.
What they found was that it was only a fraction of a millimeter thick (0.3-0.9 mm) Oumuamuam's mbad density ( which is not well-contrained).
Thick or thin, this would be able to withstand collisions with dust-grains and permeate the interstellar medium, as well as centrifugal and tidal forces.
(Wikimedia Commons / Andrzej Mirecki)
As for what an extra-terrestrial light sail would be doing in our Solar System, Bialy and Loeb offer some possible explanations for that. First, they suggest that the probe may actually be a defunct of the sea, under the influence of gravity and stellar radiation, similar to debris from ship wrecks floating in the ocean. This would help explain why Breakthrough Listen found no evidence of radio transmissions.
Loeb further illustrated this idea in a recent article he penned forScientific American, where he suggested that 'Oumuamua could be the first known case of an artificial relic which floated into our Solar System from interstellar space.
What's more, he notes that lightsails with similar dimensions have been designed and constructed by humans, including the Japanese-designed IKAROS project and the Starshot Initiative with which he is involved.
"Loeb wrote," This opportunity establishes a potential foundation for a new frontier of space archeology, namely the study of relics from past civilizations in space.
This article is only available in French: "Finding evidence for space junk of artificial origin would provide an affirmative answer to the age-old question" Are we alone? "This would have a dramatic impact on our culture and add a new cosmic perspective to the significance of human activity."
On the other hand, as Loeb told Universe Today, 'Oumuamua could be an active piece of alien technology that came to explore our Solar System, the same way we hope to explore Alpha Centauri using Starshot and similar technologies:
"The alternative is to imagine that Oumuamua has been recognized as a mission." The reason I think of it is that it badumes that "the following is a random orbit that requires the production of ~ 10 ^ {15} such objects for our galaxy. This abundance is up to a hundred million times more than expected from the Solar System, based on a calculation that we did back in 2009. A surprisingly high overabundance, unless O um u a a a a a a on a random population of objects. "
According to Loeb, that there is also the fact that it is very good for the environment, which is a good orbit for intercepting Earth without experiencing too much solar irradiation. In addition, it came out of 0.15 AU of Earth, which could have been the result of orbital corrections designed to facilitate a flyby.
Alternately, he states that it is possible that hundreds of such probes could be felt that one of them got close to Earth to study it. The fact that the Pan STARRS-1 survey barely detected 'Oumuamua at its closest approach could be seen as an indication that there are many other such objects that have not been detected, as they have been identified by the Oumuamua being one of many such probes.
(European Southern Observatory / Mr Kornmesser)
Considering that astronomers have recently concluded that our Solar System has interstellar objects such as' Oumuamua, this opens the possibility for future detections which could help prove (or disprove) the case for an interstellar light sail.
Naturally, Bialy and Loeb acknowledge that are still too many unknowns to any certainty what 'Oumuamua really is. Oumuamua is one of the world's most important sources of mbad-of-the-world reports.
That, and the fact that it is possible to accelerate it, would mean that 'Oumuamua represents a new clbad of thin interstellar material that has never been seen before. If true, that opens up a whole new set of mysteries, such as how was this material produced and by what (or whom).
Oumuamua is sure to remain the subject of intense study for many years to come. And you can bet astronomers will be on the lookout for more of them! After all, "The Ramans do everything in threes", right?
This article was originally published by Universe Today. Read the original article.
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