News Stephen Hawking's Alpha Centauri

[sorindafabico]

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

 

[GLS]

Getting something there is probably within the reaches of current technology, but I think getting data back might not be "as possible" yet.

 

[Col_Klonk]

Starting to sound like https://en.wikipedia.org/wiki/Panspermia

 

[orb]

They surely also need to get Sid Meier on board.

 

[MaverickSawyer]

Hmm... with the accelerations they're stating, they don't need to go to orbit. Just load the craft aboard a sounding rocket or other similar highly suborbital launcher, punt it up high enough for the sail to deploy, then fire your laser array and begin the boost.

 

[Enjo]

Hmm... with the accelerations they're stating, they don't need to go to orbit. Just load the craft aboard a sounding rocket or other similar highly suborbital launcher, punt it up high enough for the sail to deploy, then fire your laser array and begin the boost.

The drag could still be higher than the thrust, or could make for a very unstable system.

 

[Notebook]

100 million research and engineering program will seek proof of concept for using light beam to propel gram-scale ‘nanocraft’ to 20 percent of light speed. A possible fly-by mission could reach Alpha Centauri within about 20 years of its launch.

Mark Zuckerberg is joining the board.

http://breakthroughinitiatives.org/News/4

 

[Hlynkacg]

Crazy Eddie?

 

[MaverickSawyer]

The drag could still be higher than the thrust, or could make for a very unstable system.

The specs I saw being bandied about said 30 minutes to .2C. :blink: Now, 30 days, I would believe, maybe even 30 hours...

EDIT: Okay, looks like they're targeting 60,000 Gs of acceleration. Mother of God.

 

[Enjo]

EDIT: Okay, looks like they're targeting 60,000 Gs of acceleration. Mother of God.

It's a clever idea to send just the probes so fast to get the info back ASAP, isn't it?
Next stop - orbital lasers, powered by gigantic solar panels.

 

[GLS]

It's a clever idea to send just the probes so fast to get the info back ASAP, isn't it?

How will that info get back to Earth? :huh:

 

[Enjo]

Light seems to be the only option.

 

[GLS]

Light seems to be the only option.

I don't see how a chip will produce enough light to be seen from 4 light-years distance (or whatever it is).
IMO it would be easier to load the chip with bacteria, sent it as planned, hope it crashes in a planet that can sustain life, wait until the bacteria develops into a civilization, let them do the exploration there and then send the data back to Earth. :lol:

 

[Notebook]

I would use hexadecimal, or arrange the StarChips into a very large semaphore...

N.

 

[MaverickSawyer]

I gave it some thought... Perhaps if you have enough of them strung out in a line, you could somehow get all of them to store an earthbound databurst and a timing signal, and then make them into a giant phased array antenna?

 

[Thunder Chicken]

The specs I saw being bandied about said 30 minutes to .2C. :blink: Now, 30 days, I would believe, maybe even 30 hours...

EDIT: Okay, looks like they're targeting 60,000 Gs of acceleration. Mother of God.

Guidance electronics in artillery shells are rated to something like 15,000 g's. 60,000 g's is probably doable with some care.

 

[MaverickSawyer]

Yeah, but the solar sail material... 16m^2 and under a tenth of a kilo? How is it going to withstand that?

 

[Thunder Chicken]

Yeah, but the solar sail material... 16m^2 and under a tenth of a kilo? How is it going to withstand that?

Acceleration isn't force. Large acceleration and low mass can yield acceptable forces.

If the entire craft is on the order of a kilogram, the force to accelerate this mass at 60000 g would be:

Force = 60000 * 9.81 m/s2 * 1 kg = 588.6 kN (132,320 lbf)

Area = 16 m^2 (172.2 ft^2)

So the average pressure would be

Pressure = Force/Area = 36.8 kPa or 768 lb/ft^2 or 5.3 psi.

About 1/3rd of an atmosphere applied differential pressure on the sail material.

---------- Post added at 11:49 PM ---------- Previous post was at 11:20 PM ----------

The power calculation is interesting. At this acceleration, this 1 kg spacecraft would be accelerated to 0.2 c in 102 seconds and would travel 3.062 million kilometers.

Average Power = Force*Distance/Time = (588.6 kN)*(3.062 million kilometers)/102s =17.6 TW, with a total energy delivery of 1806 TJ.

For perspective, the National Ignition Facility lasers have an instantaneous power of 500 TW, but 1.8 MJ, for only fractions of a second.

A laser that could sustain tens of TW for minutes would be a beast. Do not look at laser with remaining space-borne telescope!

 

[MaverickSawyer]

Acceleration isn't force. Large acceleration and low mass can yield acceptable forces.

If the entire craft is on the order of a kilogram, the force to accelerate this mass at 60000 g would be:

Force = 60000 * 9.81 m/s2 * 1 kg = 588.6 kN (132,320 lbf)

Area = 16 m^2 (172.2 ft^2)

So the average pressure would be

Pressure = Force/Area = 36.8 kPa or 768 lb/ft^2 or 5.3 psi.

About 1/3rd of an atmosphere applied differential pressure on the sail material.

---------- Post added at 11:49 PM ---------- Previous post was at 11:20 PM ----------

The power calculation is interesting. At this acceleration, this 1 kg spacecraft would be accelerated to 0.2 c in 102 seconds and would travel 3.062 million kilometers.

Average Power = Force*Distance/Time = (588.6 kN)*(3.062 million kilometers)/102s =17.6 TW, with a total energy delivery of 1806 TJ.

For perspective, the National Ignition Facility lasers have an instantaneous power of 500 TW, but 1.8 MJ, for only fractions of a second.

A laser that could sustain tens of TW for minutes would be a beast. Do not look at laser with remaining space-borne telescope!

It's not going to be a single, all-powerful laser, but a very distributed array... A Very Deadly Array, to take a term from both a webcomic and a sci-fi novel series it inspired.

Part of the way I can see them paying for these arrays would be to use an isolated laser emitter with a mirror on orbit to police space junk.

 

[birdmanmike]

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