Reaching for the stars, finally - will the young ones among us get pics of Alpha C.?

[Alex K]

If their propaganda numbers are really based on an acceleration of 14000 g, I have a problem with this. What kind of sail is supposed to be stable enough? Fortunately, if you cut the g force by a factor 10, you only have to accelerate 3 times as long to reach the same final velocity

[zebo-the-fat]

The problem I see is getting enough power for a tiny probe to send information back, they are talking about something small, so no big power supplies, antenna arrays, solar panels or transmitters. No point geiing there if we get no information back.

[Alex K]

The problem I see is getting enough power for a tiny probe to send information back, they are talking about something small, so no big power supplies, antenna arrays, solar panels or transmitters. No point geiing there if we get no information back.

That's another issue - but I have no good idea what kind of power is needed for such a transmission with a big space antenna on the receiving end.

[Kosh]

The problem I see is getting enough power for a tiny probe to send information back, they are talking about something small, so no big power supplies, antenna arrays, solar panels or transmitters. No point geiing there if we get no information back.

That's another issue - but I have no good idea what kind of power is needed for such a transmission with a big space antenna on the receiving end.

Exactly Zebo.
 
Look at the New Horizons space probe for comparison.  The dish antenna on the probe is about 7ft in diameter, and a power output of 12 watts.  The probe can only transfer about 2,000 (2kbps) bits per second to earth so it's going to take until 2017 to receive all the data/images gathered as it went by Pluto.  When the probe communicated with Earth during it's Jupiter flyby the data transfer rate was 38kbps.  That is a helluva transfer rate drop in such a modest (relatively speaking) distance. 

The only way I could see this working is if 1000's of the little critters made the journey in one piece, and were able to communicate with each other like a hive.  At that point maybe they could arrange themselves into some sort of large antenna array.

[vorlon13]

The article noted the launching lasers require similar power to launching a space shuttle.

This is an appreciable percentage of the total installed electrical generating capacity of the United States.  Either the lasers are spread around the country, near poser plants (unlikely since it complicates an already complicated laser system) or we build a massive set of electrical power transmission lines to the launching lasers. Pricey.

I also assume the acceleration would be done at night so we don't have to blackout the nation during that phase.

That 2 minutes is going to be a considerable challenge too, ramping up big generating plants and back down in that period is tricky, and there will be big costs involved in making that even possible let alone reliable.  

As noted above, the data rate back to earth is going to be low.  Very low.  However, compensating for that will be the extremely brief data collection period at possible planets in the target star system.  At 20% light speed, getting even a single unblurred and properly exposed photograph of, oh let's say something very similar to our moon, is going to yield a picture with only 1 or 2 pixels that will be some shade of gray.  Transmitting those 2 pixels back (probably 2 10 bit bytes, and some engineering overhead) might only take a few more years (not counting the time it takes to get to earth from there).

Here's a 300X enlargement of the expected first picture returned from Proxima Centauri.  Enjoy!

[AFTT47]

Although I have the utmost respect for the brilliant Steven Hawking, I can't help but wonder if his later years (and the pure hell it must have been to live all those years with his physical limitations) have dulled his intellect. The first thing that made me wonder was his paper about it not being wise to advertise our presense to possible aliens. Just about any layman could point out that we can't hide. Even with our current technology, it would be possible to build a space telescope with a shield blocking the glare of the parent star to get a spectroscopic image of our planet's atmosphere from many light years away. For an alien race capable of coming here and threatening us, it would be trivial. The spectroscopic data would indicate not only the certainty of life but of technological activity producing hydrocarbons.

Steven Hawking has accomplished great things in his life - things I could only dream of accomplishing. The same can be said of another great man: the late Arthur C Clark. But in their later years, both men got a little "out there." Clarke insisted photographs of Mars showed extensive forestation. He had willingness to believe in ghosts.

Occam's Razor points to both of these great men losing it at the latter point of their lives. Mental degradation is a sad fact of old age.

I might be totally wrong and I accept that possibility but I want to put it out there that Hawking maybe shouldn't be taken at face value these days.

[Alex K]

I could be wrong but I don't think Hawking has much to do with the technological or conceptual side of this project. My impression is that they needed a popular figurehead to promote the project and asked him, and he thought it was cool and agreed to do it. You don't need Hawking to do anything in this project, there are plenty of people with a much better understanding of materials science and laser systems than him.

[I_am_not_mafia]

Although it would be amazing to get a probe to another star system I just don't understand how this could work. The probe won't be able to make any course corrections because it has no means of propelling itself or any fuel on board. And once it's in that solar system all the planets will be mere specks of light and there won't be any large telescopes to see them up close. So it's not like we're going to see lots of close ups of alien worlds.

It would make more sense if we knew exactly what planets are in that system and could calculate their position once the probes reach them so they could do a fly-by.

[Alex K]

Given the results of my little calculation above, it seems to me that a first use of such a system would be to get more useful payloads in the kg-Range to the outer solar system in minutes or do quick deliveries to a Mars station etc.

[Alex K]

The article noted the launching lasers require similar power to launching a space shuttle.

This is an appreciable percentage of the total installed electrical generating capacity of the United States.  Either the lasers are spread around the country, near poser plants (unlikely since it complicates an already complicated laser system) or we build a massive set of electrical power transmission lines to the launching lasers. Pricey.

It would be very suboptimal if they had to draw several Gigs directly from powerplants for a few minutes and nothing before and after. This cries out for some form of short term energy storage like a giant capacitor array which can be charged for a day with a few megawatts (something a truck sized diesel plant can do nowadays) and then release the power into the lasers in 2 minutes.

This beauty here delivers 35 Megawatts. Let it run for an hour and you have the necessary 2 GW*min. The High Magnetic Field Labs in Dresden are using an almost 1 Megawatt-minute capacitor bank already (50 MJ). This should be scalable by a factor 2000 for finite money if it's an international effort. So I'm not too worried about the power supplies for a Gigawatt-scale laser drive.



The capacitor bank