News Stephen Hawking's Alpha Centauri

[jedidia]

A Very Deadly Array

Wasn't that a "Very dangerous array"?

Ignoring the pressure - wouldn't the power requirement in the laser(s) beam fry the sail anyway?

That's what you have dispersion for... The aim is to always hit the full area of the sail, which is going to be quite an interesting problem in and of itself, I guess.

 

[Thunder Chicken]

Ignoring the pressure - wouldn't the power requirement in the laser(s) beam fry the sail anyway? As well as the payload being on the laser(s) side of the sail after all . . .
Sorry my maths not good enough to calculate

If the sail is super shiny (low absorbtivity, high reflectivity), then the laser bounces off the sail, desired for thrust. It would have to be sooper really shiny, as even an absorbtivity of 0.01 would be 1% of 17.6 TW is 176 GW. The other side is exposed to the cold of space, but the temperature of the sail would be approaching NaN before it could re-radiate that much absorbed power.

 

[steph]

Well, it doesn't really have to be the final version from the first try. Maybe they could experiment with solar system missions first. Mass-production of such nano-probes would also help. I mean, we could pretty much do flybys of every solar system body, multiple times. A few months to Jupiter, Saturn or even Pluto doesn't sound bad at all, especially when you can have multiple probes doing the passes. Also , don't forget about the much - hyped "planet nine" that's supposed to lurk out there.

 

[MaverickSawyer]

Wasn't that a "Very dangerous array"?

You are correct. :facepalm:

 

[Thunder Chicken]

Well, it doesn't really have to be the final version from the first try.

Log from first test mission:

"Test went well until the planet destroying death ray laser propulsion system was switched on, unexpectedly disassembling the probe into its constituent subatomic particles. These particles did achieve a high velocity, but overall the design lacks robustness."

 

[MaverickSawyer]

I'm still trying (and failing) to wrap my head around a photon pressure of 5.3 psi... :blink:

 

[Thunder Chicken]

I'm still trying (and failing) to wrap my head around a photon pressure of 5.3 psi... :blink:

They basically want the highest energy wavelengths they can get while still being perfectly reflected off of the sail material. Then it is a matter of pumping out enough photons per second to get the energy to work out.

They should name the first prototype Alderaan.

 

[MaverickSawyer]

I'm wondering if they need to scale back the power levels by two orders of magnitude. It's still going to be going scary fast in real short order, but it's far less likely to vaporize the craft! :lol:

 

[Keatah]

What sort of power will these little chipships need to emit to get information back to earth? How low of a signal can we detect?

 

[birdmanmike]

Not Star Wars -any aliens will think it's an incoming Motie ship possibly loaded with watchmakers and laser it from other end.
At least it'll slow it down . . .

 

[RGClark]

A private group backed by Hawking will spend its hammers and gold to send chip-sized spacecraft in a tiny, laser-driven version of Project Longshot.

BBC: Hawking backs interstellar travel project

I've been thinking of ways we can get such nanocraft to link up through self-assembly and form larger structures that can do more detailed observations and experiments. This could work even for visits to far off destinations still in the Solar System such as Kuiper belt objects like Pluto or the Oort cloud.

The main problem is getting the many objects flying independently and getting further apart the further out they go to gradually be drawn to each other and link up. Once they link up, I don't it would be to difficult to then get them to do self-assembly.

But it's that drawing together step that is the sticking point.

Bob Clark