Oumuamua – Maybe it is Alien Tech, After All

 Oumuamua – Maybe it is Alien Tech, After All

Observations of Oumuamua

A number of scientific papers have been published about the unusual object known as Oumuamua, over the past few years.

Oumuamua caught people’s attention for a number of reasons:

·       First, its trajectory and velocity indicated that it must have originated from outside of our solar system, the first object detected for which that was almost certainly true.

·       Next, its shape was very unusual, elongated by about a 5:1 factor, at least.  In other words it was at least 5 times longer than it was wide or deep.  Like Joe DiMaggio, it appears to be a splendid splinter.  This is highly unusual for objects in space.

·       Finally, there was the departure of its motion from a purely gravitational track, indicating that its course has been influenced by a force of some other kind.  The effect is small but seems to be confirmed to a high level of confidence.

There had been some speculation that Oumuamua could be an object powered by non-natural means (e.g. a light sail), though a natural explanation was generally preferred.  As the saying goes, “Extraordinary claims require extraordinary evidence”.  The consensus view tended towards a sort of comet explanation, whereby the impulse was generated by the off-gassing of volatiles, as the object was heated by our sun (as the comet that the Rosetta space probe visited shows below). 

There were some problems with this theory, though – one was that the usual signs of such cometary activity (especially the detection of carbon-based molecules) were absent from telescope observations and the other was the idea that the outgassing would produce rapid changes in the body’s rotational motion, which haven’t been  observed.

It was then speculated that the object might have an unusual composition, which would account for the lack of the expected coma and the degree of acceleration.  Energy considerations implied that it must be off-gassing something other than water ice (the object’s surface area isn’t big enough for the amount of ice that would need to be sublimated by the sun’s heat), and/or be made of some very non-dense material (if  radiation pressure is to account for the acceleration it can’t have much mass).

Is Oumuamua Composed of H2 Ice?

One candidate that has been proposed is hydrogen ice (Evidence that 1I/2017 U1 (‘Oumuamua) was Composed of Molecular Hydrogen Ice), which could provide the necessary energy for the acceleration observed.  In addition, off-gassing of hydrogen would be difficult to observe, which would account for the lack of an observed coma or emissions in general from Oumuamua.  Calculations also show that he long-term passage through the solar system would have affected Oumuamua’s size and shape, so that by the time we observed it would have shrunk in size and had been made more eccentric, thus accounting for its unusual shape.

This fits Oumuamua rather well, but there is the question of just where and how a primarily hydrogen ice object would form.   The most likely candidates noted in the paper are Giant Molecular Clouds (GMC), the precursors to star formation. It was calculated that fairly large bodies of the Oumuamua type (e.g. 300 meters in radius at the time of formation) could be created by aggregation of small grains in relatively short time scales (about 10 K years), that might then be ejected from the cloud by gravitational perturbations.  Eventually, one could wander into our own solar system to be observed.  The paper estimates that time scale would be about 100 million years for Oumuamua, given the distance to the nearest likely GMC.

How Long Could H2 Ice Oumuamua Last?

However, a new paper (Destruction of Molecular Hydrogen Ice and Implications for 1I/2017 U1 (‘Oumuamua)) has been published that casts some doubt on this idea, and  therefore reopens the door to the non-natural explanation (alien tech, if you will).

The reasons given to doubt the H2/GMC theory (Hydrogen Ice from Giant Molecular Cloud) are mostly related to how long such a body would last, and therefore how likely it is that such a body could travel for the time required to traverse distances involved in getting from the nearest GMC to Earth.  H2 ice is rather easily destroyed (low binding energy) and it is calculated that an H2 ice body would not last for long in the interstellar medium or in the solar system.  The mechanisms involved are:

• Heating within the interstellar medium, via starlight and the cosmic background radiation.
• Photo-desorption via UV light.
• Destruction by cosmic rays.
• Destruction by collision with interstellar matter.
• Destruction by solar radiation within the solar system.

Some of these effects are calculated to be very significant over the time scales involved and others are not so large.  The result of the calculations are given in the paper (you can check them out for yourself), namely that a 300 meter object would last about 10 million years in the interstellar medium, which doesn’t give enough time for Oumuamua to travel from the nearest GMC to Earth.

In addition, the paper gives reasons to doubt that such a body could even make it out of the GMC, as it would likely be destroyed by collisional heating within the cloud before it could escape.

So, if the paper’s reasoning is correct, Oumuamua is back to being an interstellar object whose properties and behaviour still don’t have a good natural model that explains these features.  So, perhaps a non-natural explanation is still a reasonable prospect.

 

Sources:

Non-gravitational acceleration in the trajectory of 1I/2017 U1 (‘Oumuamua), Marco Micheli, et al, Nature 27 June 2018

Evidence that 1I/2017 U1 (‘Oumuamua) was Composed of Molecular Hydrogen Ice, Darryl Seligman1 and Gregory Laughlin2, Astrophysical Journal Letters, June 2020

Destruction of Molecular Hydrogen Ice and Implications for 1I/2017 U1 (‘Oumuamua), Thiem Hoang1,2 and Abraham Loeb3, Astrophysical Journal Letters, August 2020

 

 

Now that you have read about a real interstellar interloper (natural or not), you should consider reading some Science Fiction.  How about a short story, also about interstellar interlopers.  It also features one possible scenario to explain why we haven’t met ET yet (as far as we know, anyway).  Only 99 cents on Amazon.

The Zoo Hypothesis or The News of the World: A Science Fiction Story

Summary

In the field known as Astrobiology, there is a research program called SETI, The Search for Extraterrestrial Intelligence.  At the heart of SETI, there is a mystery known as The Great Silence, or The Fermi Paradox, named after the famous physicist Enrico Fermi.  Essentially, he asked “If they exist, where are they?”.

Some quite cogent arguments maintain that if there was extraterrestrial intelligence, they should have visited the Earth by now. This story, a bit tongue in cheek, gives a fictional account of one explanation for The Great Silence, known as The Zoo Hypothesis.  Are we a protected species, in a Cosmic Zoo?  If so, how did this come about?  Read on, for one possible solution to The Fermi Paradox.

The short story is about 6300 words, or about half an hour at typical reading speeds.

Amazon U.S.: https://www.amazon.com/dp/B076RR1PGD

Amazon U.K.: https://www.amazon.co.uk/dp/B076RR1PGD

Amazon Canada: https://www.amazon.ca/dp/B076RR1PGD

 

Alternatively, consider another short invasion story, this one set in the Arctic.  Also 99 cents.

The Magnetic Anomaly

Summary

An attractive woman in a blue suit handed a dossier to an older man in a blue uniform.

“Give me a quick recap”, he said.

“A geophysical crew went into the Canadian north. There were some regrettable accidents among a few ex-military who had become geophysical contractors after their service in the forces. A young man and young woman went temporarily mad from the stress of seeing that. They imagined things, terrible things. But both are known to have vivid imaginations; we have childhood records to verify that. It was all very sad. That’s the official story.”

He raised an eyebrow. “And unofficially?”

“Unofficially,” she responded, “I think we just woke something up that had been asleep for a very long time.”

U.S.: http://www.amazon.com/gp/product/B0176H22B4
U.K. http://www.amazon.co.uk/gp/product/B0176H22B4
Can: http://www.amazon.ca/gp/product/B0176H22B4
Australia: http://www.amazon.com.au/gp/product/B0176H22B4
Germany: http://www.amazon.de/gp/product/B0176H22B4
Japan: http://www.amazon.co.jp/gp/product/B0176H22B4