Credit: shutter stock.com
I’ve been wondering over the past couple of days whether it would be worth my time to blog about the latest flurry of “alien spacecraft” stories, prompted by speculation in an astrophysics preprint posted on arxiv.org. I’ve decided it’s worthwhile to provide some further perspective on the claim that the interstellar object known as ‘Oumuamua might be an alien spacecraft.
(The consensus among space scientists seems to be “no,” by the way.)
On November 6, Harvard University astronomy postdoctoral student Shmuel Bialy and Harvard astronomy department chairman Abraham (Avi) Loeb posted a preprint they authored on arxiv.org, “Could solar radiation pressure explain ‘Oumuamua’s peculiar acceleration?” The paper has been accepted for publication in Astrophysical Journal Letters.
Keep in mind that ‘Oumuamua is the first and only interstellar object observed in our solar system. There is no basis for comparison between it and anything else.
In this paper the authors speculate that “if [solar] radiation pressure is the accelerating force, then ‘Oumuamua represents a new class of thin interstellar material, either produced naturally, through a yet unknown process in the ISM [interstellar medium] or in protoplanetary disks, or of an artificial origin. Considering an artificial origin, one possibility is that ‘Oumuamua is a lightsail, floating in interstellar space as a debris from an advanced technological equipment.” Here Loeb cites his own writing, published in Scientific American and elsewhere, as the source of this speculation. “The lightsail technology might be abundantly used for transportation of cargo between planets (Guillochon & Loeb 2015) or between stars (Lingam & Loeb 2017)…dynamical ejection from a planetary System could result in space debris of equipment that is not operational any more(Loeb 2018).” (You can see that Loeb has been working on this fringe-y idea for a while.) “A more exotic scenario is that ‘Oumuamua may be a fully operational probe sent intentionally to Earth vicinity by an alien civilization.”
Bialy and Loeb conclude: “A survey for lightsails as technosignatures in the Solar System is warranted, irrespective of whether ‘Oumuamua is one of them.” I’d say we need to leave it up to billionaire SETI enthusiasts, like Milner, to take up this challenge.
As soon as the preprint was posted, headlines followed – for example, “Cigar-shaped interstellar object may have been an alien probe, Harvard paper claims.”
By November 7, journalists were reporting that other scientists were dismissing the Bialy-Loeb claim – for example, “Sorry, this strange space rock was not sent by aliens to save us” (Washington Post); “Predictably, online media go nuts over ‘Oumuamua and Harvard scientists” (Ars Technica); “‘Oumuamua, oh my! Was interstellar object actually an alien solar sail? Not so fast” (GeekWire). Yet today, November 8, I’m still seeing new stories popping up online, propagating the ‘Oumuamua “alien spacecraft” claim.
Avi Loeb is chairman of Harvard University’s astronomy department. Such a position gives him instant authority. (My dissertation was a study of the role that journalists play in the social construction of scientific authority. You can read an introduction to the subject here.) Most of the stories I’ve read about this preprint don’t mention Loeb’s interest in the search for extraterrestrial intelligence (SETI).
According to his web site, Loeb chairs an advisory committee for the Breakthrough Starshot Initiative, serves as “science theory director” (whatever that means) for all Initiatives of the Breakthrough Prize Foundation. He also chairs the Board on Physics and Astronomy of the National Academies (more authority).
The Breakthrough Initiatives, funded by billionaire Yuri Milner, are “are a program of scientific and technological exploration, probing the big questions of life in the Universe: Are we alone? Are there habitable worlds in our galactic neighborhood? Can we make the great leap to the stars? And can we think and act together – as one world in the cosmos?”
Breakthrough Starshot “is a $100 million research and engineering program aiming to demonstrate proof of concept for a new technology, enabling ultra-light unmanned space flight at 20% of the speed of light; and to lay the foundations for a flyby mission to Alpha Centauri within a generation.” Another Breakthrough initiative is Breakthrough Listen, allegedly “the largest ever scientific research program aimed at finding evidence of civilizations beyond Earth.”
Loeb wrote a blog post for Scientific American, published (coincidentally?) September 27, on the subject of “how to search for dead cosmic civilizations.” With Harvard professor Manasvi Lingam, Loeb coauthored a paper posted on arxiv.org September 24, “Dependence of biological activity on the surface water fraction of planets,” which addresses “implications for the prevalence of microbial and technological species in the Universe.”
You may recall that upon ‘Oumuamua’s discovery in October 2017 – the first interstellar object detected in our solar system – there was some speculation that it could be an object constructed by extraterrestrial intelligent beings. Responding to speculation that if the object was, indeed, an alien craft, it could be leaking radio signals, the Breakthrough Listen project made an attempt to detect signals from the object. The results? Nothing.
Scientific American reported on December 11, 2017, that Loeb “helped persuade [Breakthrough’s] Milner to pursue the observations. This article noted that Loeb is “pessimistic about prospects for uncovering aliens…. Then again, Loeb [said], ‘perhaps the aliens have a mothership that travels fast and releases baby spacecraft that freely fall into planetary system on a reconnaissance mission. In such a case, we might be able to intercept a communication signal between the different spacecraft’.”
(Can you hear me slapping myself upside the head?)
In April, astrobiologist and SETI enthusiast Adam Frank wrote for npr.org about a conversation he had with Loeb “about what we should be thinking about when we consider exo-civilizations.” Frank concluded that “Loeb is essentially optimistic about the search” for so-called technosignatures – signs of technology produced by extraterrestrial intelligent life. That is, SETI. See my recent blog post about a recent workshop on technosignatures sponsored by NASA at the direction of Rep. Lamar Smith (R-TX), outgoing chairman of the House Science, Technology, and Space Committee, with authorizing jurisdiction over NASA. Rep. Smith is a fan of SETI and held several SETI “love-fest” hearings” in recent years. I expect that incoming Democratic chair Rep. Eddie Bernice Smith (D-TX) will take a more balanced approach to assessing NASA’s space science priorities.
As “news” fodder, SETI is easy material. It’s all speculation, and scientists and the reporters who write about claims such as Loeb’s can’t be wrong. I’m not at all sure whether this sort of speculation helps non-experts understand the scientific search for evidence of extraterrestrial life. There’s so much interesting, and scientifically grounded, research going on in the field of astrobiology. I wish it drew more attention. (Full disclosure: I am a part-time consultant to NASA’s astrobiology program. No one asked me to write this post.)