Here I was all set to write about the discovery of carbon dioxide on HD 189733b when Alpha Centauri made its way back into the news. Twentieth Century Fox will be transmitting the re-make of the science fiction classic The Day The Earth Stood Still to Alpha Centauri on Friday the 12th, timing the event to coincide with the film’s opening here on Earth. The transmission is being handled by Florida-based Deep Space Communications Network, a private organization that offers transmission services to the public (not to be confused with the Deep Space Network that manages communications with our planetary probes).
Why does Deep Space Communications Network offer transmission services to the stars? From its FAQ:
For a number of reasons, one is because we have the equipment, and the know how so we can, and also because we thought it would be an interesting public service that is not currently available.
We’re doing it because we can…
This dubious news comes on the heels of the in many ways excellent National Geographic special Journey to the Edge of the Universe. I’m always fascinated with the way the media handle nearby stars and the planets that may orbit them, especially as our inventory of confirmed planets continues to grow, and the show’s graphics were superb, its narration gripping. But how puzzling to run into a fundamental misunderstanding about our nearest stellar neighbors.
The putative travelers have moved out through the Solar System, passing (an ingenious touch) the various probes and artifacts we humans have scattered from Mercury out to the Kuiper Belt. As we move to the nearest stars, we pass what is obviously the red dwarf Proxima Centauri and make for the binaries Centauri A and B. Describing them, the narrator says, “Not one but three stars, spinning around each other locked in a celestial standoff, each star’s gravity attracting the other, their blazing orbital speed keeping them apart.”
And then this: “Get between them and we’d be vaporized.”
Not a chance. We don’t yet know whether there are planets around Centauri A or B. But we do know that there are stable orbits around these stars, and that both of them could have planets in the habitable zone, where liquid water can flow on the surface. Their mean separation is 23 AU. There is, in other words, plenty of room between Centauri A and B for a spacecraft to move without danger of being vaporized. I feel like I’m nitpicking given the intense effort that went into this production, but it seems important to clear up misconceptions that are widely distributed.
As with the show’s treatment of Gliese 581 c. The National Geographic special shows the planet as a living world of continents and oceans, and indeed, the discovery announcement made it appear that 581 c was squarely in the habitable zone of this tiny red dwarf. But almost every subsequent study has shown this to be deeply unlikely — conditions on Gliese 581 c are probably much more like Venus than Earth. Moreover, although the show depicted the planet as rotating, so that the day/night terminator continued to shift, it’s much more likely that this planet is tidally locked to its primary, one side always facing the star.
We ran through the entire GL 581 c story here over the past few years — you can use the search function to pull these stories up. An initial euphoria (all too incautiously embraced in my opening story on the discovery) quickly gave way to skepticism. Indeed, if there is a habitable planet in the GL 581 system, it may (just possibly) be GL 581 d.
As far as Twentieth Century Fox goes, my thoughts on METI are no secret. But look, there are advocates who make a strong case for METI, just as there are reputable and serious scientists who question whether brightening our signature in the electromagnetic spectrum is a good idea. I can listen and learn from both, but what I find deeply troubling is the notion that we can take a serious issue — one that deserves thoughtful study in many disciplines — and casually throw it out the window by yet another fait accompli.
Is it too late to lock down the mania for METI? Probably, as we’re beaming everything from movies and ads for the Doritos to watch them by seemingly at will. And a case can be made that our TV and radio signals are already reaching nearby stars, and that an advanced civilization could pick them up, as well as detecting biomarkers in our atmosphere. That’s plausible, but a sudden and deliberate brightening of our signal for whatever purpose strikes me as unwise given how little we know about the conditions that surround us. I doubt seriously that such transmissions endanger us, but the point is, we don’t know, and in the absence of that knowledge, caution and further study seem a more prudent course.