3 ms·

That is a good question. The Voyager spacecraft send out detectable signals with a ~20 Watt signal. This is larger than the ~3 W signal that a smartphone send

That is a good question. The Voyager spacecraft send out detectable signals with a ~20 Watt signal. This is larger than the ~3 W signal that a smartphone sends, but by less than an order of magnitude. Voyager is at ~130 AU. Alpha Centauri is at ~275,000 AU. With the 1/r^2 decrease in signal, that means the signal from earth will be smaller by a factor of ~3 x 10^6. Now, supposing we have ~1000 of these smartphone probes, this means that their combined signal will be weaker than the Voyager signal by a factor of ~3000. We might imagine that they are somewhat more optimized to send a stronger signal than an ordinary smartphone. Let's say they have a 30 W radio instead of 3 W. This means that they will have a weaker signal by a factor of ~300. This is a lot, but if they manage to build a detector that has a larger effective diameter than the Deep Space Network by a factor of ~15. Given the budget of the project, and the fact that they have 20 years of time to prepare after the launch, this could be feasible. Looking at the project's website, though, it looks like they are taking the approach of using a laser onboard the probe instead of using a traditional radio transmitter [1]. This would increase the efficiency of the transmission by several orders of magnitude. It might even be possible to detect the signal from a single probe with this approach. [1]: http://breakthroughinitiatives.org/index.php?controller=Forum&action=viewforum&id=14&page=1 http://breakthroughinitiatives.org/index.php?controller=Foru...

paulmd 11y ago
Another problem to consider is that the interstellar medium is noisier and interferes with the signal to a greater extent. Voyager is only just reaching that region, but this signal would have to travel through that for several lightyears. https://en.wikipedia.org/wiki/Interstellar_medium#Radiowave_propagation https://en.wikipedia.org/wiki/Interstellar_medium#Radiowave_... Not to mention there is also additional cosmic radiation outside the heliosphere. Something the size of a chip is going to be extremely vulnerable. Slower rad-hard electronics are going to be the order of the day, but even with thousands of these things, it's going to take a toll.
randyrand 11y ago
it seems ridiculous to use anything other than a laser IMO.
- antognini 11y ago
  Almost certainly. But using a laser requires much better aim than a radio transmitter.
ryao 11y ago
"The technique uses cryo-cooled nanotubes. The current performance is of order 2 bits per photon." How do you keep it cool with a 100GW laser pointed at it over 2 minutes?
e12e 11y ago
> Alpha Centauri is at ~275,000 AU. I wonder if it would be easier to string ~300 of these at ~1000 AU intervals, and use them for a relay? Or perhaps ~3000 at ~100 AU intervals. And I wonder if that would be construed as mining a common hyperspace lane by the galactic council... ;-)

paulmd 11y ago

Another problem to consider is that the interstellar medium is noisier and interferes with the signal to a greater extent. Voyager is only just reaching that region, but this signal would have to travel through that for several lightyears. https://en.wikipedia.org/wiki/Interstellar_medium#Radiowave_propagation https://en.wikipedia.org/wiki/Interstellar_medium#Radiowave_... Not to mention there is also additional cosmic radiation outside the heliosphere. Something the size of a chip is going to be extremely vulnerable. Slower rad-hard electronics are going to be the order of the day, but even with thousands of these things, it's going to take a toll.

randyrand 11y ago

it seems ridiculous to use anything other than a laser IMO.

antognini 11y ago
Almost certainly. But using a laser requires much better aim than a radio transmitter.

ryao 11y ago

"The technique uses cryo-cooled nanotubes. The current performance is of order 2 bits per photon." How do you keep it cool with a 100GW laser pointed at it over 2 minutes?

e12e 11y ago

> Alpha Centauri is at ~275,000 AU. I wonder if it would be easier to string ~300 of these at ~1000 AU intervals, and use them for a relay? Or perhaps ~3000 at ~100 AU intervals. And I wonder if that would be construed as mining a common hyperspace lane by the galactic council... ;-)