Phone Home

13 06 2016

Me, April 26, 2014:

Second, the big error in that mentality is that radio signals don’t go on forever.  A lot of people had just assumed that with each passing year, the “radio bubble” in a sphere around Earth expands precisely one light year per year, and therefore more and more star systems would be able to hear Earth broadcasts.  What they all forgot was the law of inverse squares for electromagnetic transmission and reception.  If you move twice your current distance from the light bulb, the light from it will be one-fourth as strong, three times from it, one-ninth as strong, and so on and so forth.  And it also applies to radio, which is just another form of electromagnetic TX/RX — SETI has figured that even the strongest regular Earth-bound transmissions will fade and and become indistinguishable from the background radio noise our galaxy makes at those frequencies from anywhere between one and two light years from Earth, which means “Wheel in the Sky” won’t even make it to Alpha Centauri in late August 2018.

(snip)

Incidentally, that’s going to be a problem for when we have the ability to do interstellar unmanned probes.  Sure, we may eventually develop the ability to send a big toilet bowl to Alpha Centauri, but how is it going to be able to phone home?

Turns out that really smart people have already thought about that and answered:

Upon reaching Alpha Centauri, there will be no possibility of slowing down. The nanocraft will have a few hours to take pictures and collect other measurements. Getting the data back to Earth over such vast distances will be another major challenge. You might think that a signal sent from Alpha Centauri would be hopelessly buried in the background noise of interstellar space, but it turns out that lasers can once again provide a solution. Thanks to much lower diffraction than radio waves, optical systems have much higher gain than radio systems of similar size. In fact, NASA recently performed a record-breaking laser communications demonstration at lunar distances as part of the LADEE mission. If the square-kilometer laser launch system can be made to double as a phased-array receiver, data rates of several kilobits per second could be achieved from Alpha Centauri with a 1-W laser transmitter on the spacecraft. It should even be possible to receive data at lower bit rates with the next generation of large optical telescopes set to come online in the 2020s.

I was getting worried there for a moment.  Worried that we would launch an interstellar probe before thinking of the phone home problem.


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10 responses

13 06 2016
Joshua Sinistar

Yeah, all this crap is just mental masturbation until we drop our loads of dead weight. Between the parasites, dindus and failed races, we in America are sliding backwards. NASA is just another welfare program at this point. Their commitment to “divershitty” is about as far from science as you can get in the Western World. We have to dump the trash and take out the garbage before this vaporware evaporates completely.

13 06 2016
AnAnon

A nuclear salt-water rocket could supposedly get to AC in about 120 years(3 to 4% of c top speed) for this type of flyby and the design was made in the 60s, but yes, little point in doing that if there is going to be no one here to pick up the phone.

13 06 2016
Hard Right

We could have gone to Alpha Centauri, but we had to fund Black-Run America.

13 06 2016
sondjata

” If the square-kilometer laser launch system can be made to double as a phased-array receiver, data rates of several kilobits per second could be achieved from Alpha Centauri with a 1-W laser transmitter on the spacecraft.”

I will re-iterate my Star Trek communications array suggestion from a few months back….

13 06 2016
countenance

I’d be doing a victory lap if I were you. Then again I mostly slept through Humility 101.

13 06 2016
13 06 2016
Lou de paolis

Whoa! And now your competing with my other favorite site “Beyond The Black” – a true Renaissance Man.

14 06 2016
countenance

Stick around for awhile and you’ll see that I have a lot of interests.

I don’t much care about art history or stamp collecting or model railroads, but other than that, most everything is fair game.

14 06 2016
Joshua Sinistar

The space program is garbage. Private firms by guys like Elon Musk are launching more shit than NASA. That space station is junk. It doesn’t even rotate to generate artificial gravity with centrifugal force. Astronauts cannot live long past six months without artificial gravity. Their bones start to break down like osteoporosis because the downward pull doesn’t force the body to rebuild bones. All of this is due to bad government. All those big money garbage contracts like that White Elephant F-35 that doesn’t work but obviously paid off some big donor and of course all the subsidies to welfare programs and social programs to help pay for Billionaire’s lawn care. I don’t know about you, but I’ve had enough. Its Trump or War. I’m not having my way of life destroyed by having the electrical grid collapse, no clean water and food shortages because these crooks sold out to greedy bastards that are filling every position with peons from places that never invented the wheel. I love Western Civilization and I’m gonna keep it, and if I have to keep it over their dead bodies, I’ll do that too.

24 08 2016
You Always Find Things Where You Least Expect Them | Countenance Blog

[…] we develop viable technology to send something there, and hopefully we will have solved the phone home problem before we send something that way, there’s talk of a “moonbounce” operation, in […]




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