A year ago the tabloids were all agog about ‘Oumuamua, described by Wikipedia as: “the first interstellar object detected passing through the Solar System.” Even the Discoveroids were captivated, so we wrote The Discovery Institute and ʻOumuamua. As expected, they tied it into their “theory” of intelligent design.
When it turned out to be some kind of asteroid-like object that probably originated from another planetary system, and that it was moving too fast to be captured by the Sun, interest waned. But today we saw what we thought was more craziness in a UK tabloid. This is the headline in London’s Daily Mail: Mysterious interstellar asteroid ‘Oumuamua could be a giant solar sail ‘sent from another civilization to look for signs of life,’ claim astronomers. Here are some excerpts, with bold font added by us for emphasis, and occasional Curmudgeonly interjections that look [like this]:
A mysterious asteroid called Oumuamua, the first interstellar object ever seen in the solar system, could be a gigantic alien solar sail [Hee hee!] send [sic] to look for signs of life, a new study has claimed. Astronomers from the Harvard Smithsonian Center for Astrophysics (CfA) analyzed the strange cigar shape of the object, and an unexpected boost in speed and shift in trajectory as it passed through the inner solar system last year. They concluded that the strange asteroid ‘might be a lightsail of artificial origin.’
Whoa — real astronomers said that? We abandoned the tabloid, searched PhysOrg, and found this from two days ago: Could ‘Oumuamua be an extraterrestrial solar sail? PhysOrg says, with our bold font:
[T]here has also been some speculation that based on its shape, ‘Oumuamua might actually be an interstellar spacecraft (Breakthrough Listen even monitored it for signs of radio signals!). A new study by a pair of astronomers from the Harvard Smithsonian Center for Astrophysics (CfA) has taken it a step further, suggesting that ‘Oumuamua may actually be a light sail of extra-terrestrial origin.
Here’s a pre-publication copy of the paper by Shmuel Bialy and Abraham Loeb: Could Solar Radiation Pressure Explain ‘Oumuamua’s Peculiar Acceleration? (pdf file). You can read it on-line without a subscription. Okay, back to PhysOrg, which tells us:
While it did not show any signs of outgassing as it passed close to our sun (which would have indicated that it was a comet), a research team was able to obtain spectra that indicated that ‘Oumuamua was more icy than previously thought. Then, as it began to leave 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 increased 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. outgassing). The release of this material, which is consistent with how a comet behaves, would give ‘Oumuamua the steady push it needed to achieve this boost in velocity.
So why would the tabloids be interested? PhysOrg continues:
To this, Bialy and Loeb offer a counter-explanation. If ‘Oumuamua were in fact a comet, why then did it not experience outgassing when it was closest to our sun? In addition, they cite other research that showed that if outgassing 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 ‘Oumuamua could in fact be a light sail, a form of spacecraft that relies on radiation pressure to generate propulsion – similar to what Breakthrough Starshot is working on. Similar to what is planned for Starshot, this light sail may been sent from another civilization to study our solar system and look for signs of life.
Now we understand the tabloid’s interest. Let’s read on:
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 force that the sunlight exerts on its surface. For this force to explain measured excess acceleration, the object needs to be extremely thin, of order a fraction of a millimeter in thickness but tens of meters in size. This makes the object lightweight for its surface area and allows it to act as a light-sail. Its origin could be either natural (in the interstellar medium or proto-planetary disks) or artificial (as a probe sent for a reconnaissance mission into the inner region of the solar system).”
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 sail floating 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.
“This opportunity establishes a potential foundation for a new frontier of space archaeology, namely the study of relics from past civilizations in space,” Loeb wrote. “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 …
There’s a lot more in PhysOrg, but we’ll let you read it for yourself. We don’t know what to make of it, Whatever ‘Oumuamua is, we expect to see wild speculation from the tabloids, UFO blogs, and of course from creationists. It’s going to fun.
Copyright © 2018. The Sensuous Curmudgeon. All rights reserved.