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Has a solar energy awning of an extraterrestrial civilization visited us last year? Or was the object name "Oumuamua even a fully functional spacecraft deliberately sent by extraterrestrials to Earth?" If such questions are asked in a scholarly journal, there are many who doubt the seriousness of the authors of the study and the publication medium.
But next to Shmuel Bialy, a junior researcher at Harvard University, also appears the name of Abraham Loeb in the corresponding publication. "Loeb is one of the most respected theoretical astrophysicists in the world," says Kevin Heng, director of the Center for Space and Habitability at the University of Bern. "He is Director of the Department of Astronomy at Harvard University and Director of the Institute of Theory and Computation." The study will be published nowhere next week, but in the prestigious journal "The Astrophysical Journal Letters".
An interstellar object
Although Loeb's reputation does not automatically mean that what the two researchers said in their release is true, says Heng. "But that means we should at least look carefully at what they propose."
In their publication, Loeb and Bialy deal with the extraordinary trajectory of Oumuamua (Hawaiian for "messenger of the distant past"). The object was discovered on October 19, 2017 by the Pan-Starrs-1 telescope in Hawaii. At first, it looked like a typical small asteroid moving at high speed. However, more careful observation has undoubtedly revealed that this celestial body does not originate from our solar system, like all the others previously observed, but from interstellar space, that is, to say stars.
& # 39; Oumuamua had more surprises in store. A team of astronomers in Hawaii discovered that the brightness of the object changes dramatically by a factor of 10 as it revolves around its own axis every 7.3 hours. This strong change in brightness means that 'Oumuamua is very elongated, so it has the shape of a cigar or maybe a pancake. Its length is estimated at least 400 meters and it crosses the solar system at a speed of about 300,000 kilometers per hour.
"Fully functional spatial probe"?
Recently, researchers around the Italian astronomer Marco Micheli in the journal Nature announced that Oumuamua had been accelerated in a way that could not be explained by the effects of solar gravitation. The acceleration was as if it was a comet that emits gas. But in Oumuamua, no evidence of gas emissions common to comets on the approach of the sun was found.
If it's not cometary activity, what could 'Oumuamua have accelerated? Loeb and Bialy show that acceleration could be explained if 'Oumuamua is an extremely fine object driven by the solar wind. Oumuamua should therefore be only about 0.3 to 0.9 millimeters thick.
So, what kind of object could this be? This question begins the most speculative part of the study. As Heng of the University of Bern says, Loeb also heads the advisory board of the Breakthrough Starshot Initiative, which aims to send a spacecraft to the nearest star. For the spacecraft should be equipped with an awning and powered by the solar wind. It is therefore not surprising that the authors suggest that "Oumuamua can be a giant canopy that stumbles as a space debris from a distant civilization through our solar system and is driven by the solar wind.
The authors also suggest an even more exotic scenario. Thus, "Oumuamua could be a" fully functional spaceship intentionally sent by an extraterrestrial civilization in the vicinity of the Earth, "says the publication.
Maybe a comet
Martin Jutzi of the Department of Space Research and Planetology of the University of Bern finds this study "very interesting". However, it would be very speculative, solely because of the observed non-gravitational acceleration of "Oumuamua" on an awning or even a guided probe to close. "In my opinion, as always, there are simpler and better explanations, and of course they are less sensational."
Jutzi did not specify whether a spacecraft similar to a solar sail could actually explain the sightings. "A possible problem is the orientation of the canopy extremely thin." Another problem is collisions with interstellar dust particles that would damage the sail. Although this problem is addressed in the document, it does not address potential mechanical damage caused by collisions.
As Marco Micheli writes in the aforementioned study in Nature, it is possible that the potential degbading of Oumuamua is undetectable because it was below the threshold of detection. "In my opinion, the observed non-gravitational acceleration can therefore be explained more simply by degbading," says Jutzi. "It means it's probably a comet-like object."
Nowadays, the search for artificial objects in other planetary systems is no longer science fiction.Kevin Heng, director of the Center for Space and Habitability of the University of Bern
But even this scenario is controversial, continues Jutzi. "You have to show in detail that it works." After all, theoretical models would suggest that interstellar comets occur with some frequency in our solar system. "It probably does not need an exotic explanation, as presented in the Bialy and Loeb article."
Unfortunately, it is already too late to investigate Oumuamua in more detail. The object is already too far from Earth to be studied with telescopes or visited with a spaceship. The researchers write that there is no other choice than to search for other objects of this type.
"It's one of the important messages of this publication," says Heng. "We live in a time when the search for artificial objects from other planetary systems is plausible and no longer science fiction." This search can not succeed. But it's important that you can now test ideas like Bialy and Loeb. "It's part of the scientific method."
(Editors Tamedia)
Created: 07.11.2018, 18:00 hours
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