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posted by martyb on Thursday March 08 2018, @10:29PM   Printer-friendly
from the Kessler-syndrome dept.

An arXiv preprint suggests that evidence of intelligent (or trashy) life could be found by looking for space junk:

Its author, Héctor Socas-Navarro, spends most of his time at the Canary Islands Institute of Astrophysics in Spain studying the sun. But he was struck by a weird side effect of the ring of active and retired satellites circling Earth: it's a little bit opaque. And the more satellites we throw up there, the more opaque it gets. He realized that if we—or any technologically advanced aliens out there—build enough satellites, they'll eventually become dense enough to leave a faint shadow around the planet when it passes in front of a star.

And that's awfully convenient given that one of the best ways we have of spotting alien planets is by staring at their stars and waiting for tiny dips in brightness as planets pass in front of them. Essentially, Socas-Navarro's new paper proposes, if aliens have put enough satellites into orbit around their planet, we'll be able to spot the faintly opaque bubble before and after we spot the brightness dip of the planet itself.

The scale of the endeavor would be a real challenge for the aliens, however, since this idea relies on between 10 billion and one trillion satellites. "It's like building the pyramids," Avi Loeb, an astronomer at Harvard University, told New Scientist. "Each building block is easy, but putting it together is the hard engineering task."


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  • (Score: 4, Insightful) by Immerman on Friday March 09 2018, @02:54AM

    by Immerman (3985) on Friday March 09 2018, @02:54AM (#649823)

    Only on Earth, and only the beanstalk variety. Earth-based "beanstalk" space elevators are so far at the extreme edge of feasability that they look increasingly unlikely to ever be possible - Carbon nanotubes, which we have good reason to suspect are approaching the physical limits of tensile strength, have only barely the strength-to-weight ratio to make it possible, theoretically. And no engineer worthy of the name would even consider building such a structure with safety margins measured in single-digit percentages.

    On the moon though,and many other planet(oids) it's a whole different ballgame - existing bulk carbon fiber cable is more than strong enough to do the job with a decent safety margin. Even Mars wouldn't need much advancement in material science - If the population eer get

    And of course, there are many, many other concepts that fall under the umbrella of "space elevator" : fountains, tumbling cables/wheels, etc, etc, etc - many of which are quite feasible with existing technology, even here on Earth. They just mostly have such outlandish up-front costs or concepts that they're unlikely to get built until space-travel becomes far more routine, and additional incremental cost savings are desired beyond what fully-reusable rockets could deliver. But, assuming civilization doesn't collapse in the next few centuries, nor lose interest in space, that seems rather inevitable.

    It's rather like the difference between automobiles and rail - autos (rockets) are FAR more cost effective in low-traffic / low infrastructure use-cases, but rail is unquestionably vastly superior when it comes to efficiently moving large volumes of freight on a regular basis.

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