back to article Prof Hawking to mail postage-stamp space craft to Alpha Centauri using frickin' lasers

Famed physicist Stephen Hawking and Russian billionaire Yuri Milner are putting their weight behind a research project to send a tiny spacecraft to another star system. The Breakthrough Starshot campaign aims to create a craft about the size of a postage stamp and propel it with blasts of energy from an array of laser beams. …

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Laser powered spaceflight has been mooted, and even demonstrated experimentally, but the idea that they can aim the laser accurately enough through the atmosphere to propel something the size of a postage stamp is surely piling on more complexity than they needed to?

It would of course also be quite useful as a ground based weapon...

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star wars

It's actually the opposite: we can do that exactly because of laser weapons (http://spie.org/newsroom/technical-articles/4853-did-adaptive-optics-end-the-cold-war).

It looks like the star wars project might do some good in the end.

To be fair, most of the research is actually coming from astronomical observatories, given that the military technology is still secret.

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They're aiming for a metre-wide sail and it's suggested the lasers will use adaptive optics. They admit they can't afford the lasers (about $1-trillion), that the array would be a handy ground based weapon, and that we have no material that can be used to build the sail. They even acknowledge there is no way for the probe to communicate back. The $100-million is to research these problems.

They don't mention that getting the probe to hit Alpha Centauri will be really tricky; small errors add up over a parsec. Nor do they talk about cosmic rays which will evaginate the unshielded silicon -- they're going to have to fire a lot of probes in the hope one gets there.

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Re: star wars

To be fair, most of the research is actually coming from astronomical observatories, given that the military technology is still crap, retardely expensive, easy to defeat and likely to stay so.

FTFY

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evaginate

Thank you for tomorrows word of the day :-)

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evaginate the unshielded silicon

Sounds like something that would happen if Glen Quagmire starred is a Ross Meyer film.

*giggity*

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> It would of course also be quite useful as a ground based weapon...

A frickin' gigawatt laser would be nice to have when the Alpha Centaurians come looking for whoever shotgunned them with 1000 ludicrous-speed bullets.

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I'm also sitting here wondering how a postage stamp sized spacecraft can, alongside all the other sensors and mission equipment house an RF transmitter capable of getting useful information back to planet earth.

So, the wires connecting to the Solar sail will be an antenna, but the transmit signal has got to be strong enough to be heard above all the other noise out there at that distance with the path loss.

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Happy

Tricky!

They might impact on the local planning office in Alpha Centauri. Still, they might also find information on any demolition plans

More seriously, simply dust along the way could seriously damage a craft flying at that speed, even if cosmic rays miss it. Still a fascinating project. We need people doing weird science, and hey, it's got frickin' lasers involved. All we need is sharks

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Happy

Re: Tricky!

SPACE sharks. . . .

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Anonymous Coward

They've been able to hit mirrors on the moon as part of the Lunar Ranging Experiment since the 60s, so there's no reason why not with today's technology.

Although quite how they'll steer it to allow for mid-flight course correction I have no idea.

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"I'm also sitting here wondering how a postage stamp sized spacecraft can, alongside all the other sensors and mission equipment house an RF transmitter capable of getting useful information back to planet earth."

I don't think they'll get far enough to worry about that. At 20% of the speed of light even a small amount of tenous gas or dust will turn the craft into high temperature plasma.

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Anonymous Coward

Re: evaginate the unshielded silicon

oh yeah!

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"They've been able to hit mirrors on the moon as part of the Lunar Ranging Experiment since the 60s, so there's no reason why not with today's technology."

LLR targets are about ~0.5m wide. But by the time the beam reaches one, it's ~6km wide. And the amount of energy reflected is not enough to be seen by the naked eye. It's hitting it and hitting it with enough energy that's the problem.

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Not if you fire them at 3 month intervals and use the string of craft as a relay back to earth

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You could just have the probes sent say a month apart so each one could relay the data to the ones behind it with enough redundancy that one or two lost probes in the chain can still make a link. What could possibly go wrong!

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"It would of course also be quite useful as a ground based weapon..."

Russian billionaire?

Does he have a private island by any chance?

With a dormant volcano on it?

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Re: Tricky!

> SPACE sharks. . . .

Surely it's the "logical" next iteration of Sharknado.

Or the Muppets ("Shaaaarks Iiiiin Spaaaaace")

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"At 20% of the speed of light even a small amount of tenous gas or dust will turn the craft into high temperature plasma."

The Local Interstellar Cloud contains both Sol and Alpha Centauri and is about 0.3 particles/cc. Iff the energy from all those hits was fully absorbed, it would result in a few millijoules per second of heating. (I've assumed the atoms were stationary -- i.e. ignored their thermal energy.)

But heating is not going to be a problem because those particles are protons with tens of MeV: they will punch through the wafer-thin probe, taking most of their energy with them. The sail is expendable, once accelerated. But the electronics needs to survive a billion cosmic rays per second for decades. Expect to find more of your electronics on the outside that the inside. As I said, evaginated.

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Mushroom

"heard above all the other noise out there at that distance with the path loss."

Noise dwarfs path loss. It's got to be heard over a pair of omnidirectional transmitters broadcasting 1027W spread over every frequency band from RF to X-rays.

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Trollface

Re: SPACE sharks. . . .

With frickin' LAZERZ!

Looks like they're already here! (after a fashion...)

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Anonymous Coward

3 months x 0.2c = a distance of 0.05 light years between them, or 470 billion kilometers.

For comparison, Voyager 1 is currently just over 20 billion kilometers away. We can just about receive a message from it, since:

1. It has a radioactive power source, currently generating about 250 watts

2. It has directional antenna

3. We capture it using a network of huge antennas around the earth.

http://voyager.jpl.nasa.gov/mission/didyouknow.html

"The sensitivity of our deep-space tracking antennas located around the world is truly amazing. The antennas must capture Voyager information from a signal so weak that the power striking the antenna is only 10 exponent -16 watts (1 part in 10 quadrillion). A modern-day electronic digital watch operates at a power level 20 billion times greater than this feeble level."

Now try to make a postage stamp which works as well as this - both as transmitter and receiver. Oh, and make it work over a distance 25 times larger, so the signal is 625 times weaker.

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More information for those interested

http://www.scientificamerican.com/article/100-million-plan-will-send-probes-to-the-nearest-star/

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Re: More information for those interested

100GW - that's a lot of power! You're not going to get that for 100million.

The cost of the lasers may drop but you are going to have to build 30 Hinkley C's at 18 billion a piece and rising.

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Lasers on earth?

Surely they should be mounted on the moon, around the edge and in the centre of a huge circular crater.

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Joke

Re: Lasers on earth?

Thats no moon :D

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Alien

Re: Lasers on earth?

I have just the moon you need

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Re: Lasers on earth?

"Surely they should be mounted on the moon, around the edge and in the centre of a huge circular crater."

This makes sense to me. However. given the vast expense of such an exercise, there's clearly no budget for such niceties as safety rails

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No return

Even if this is possible, how is this tiny spacecraft going to be able to phone home when it gets there? The only way to retrieve the data gathered by this thing would be to slingshot it back to Earth using some massive object. It seems to me there's more chance of a butterfly causing a hurricane than that happening.

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Re: No return

That's one of the "future problems" they hope someone will solve.

Personally, I reckon you're looking at a wide area telescope to receive (SETI in spaaaace), and then hope that you can synchronise the fleet to take advantage of constructive interference

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Re: No return

In Robert Forward's original 1980s-vintage "StarWisp" proposal (which was for a maser-driven sail), the probe would include actuators in the sail. When the probe was due to pass through the target system, the driving lasers would flood that system with laser light. The sail would return data by using the actuators to modulate the reflected light.

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Anonymous Coward

Re: No return

Easy, they just reverse the polarity of the lasers and suck it back to Earth. Haven't you ever seen a single Star Trek episode?

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Re: No return

My understanding of Starwisp is that, being driven by masers, they would sent a slug of maser (radio) energy to meet it at the target star. That would be used to power up the circuitry to make observations, and also to power the return signal.

Starwisp is not a single postage stamp-sized chip, it's a mesh of wires with electronic nodes at the intersections. So it has a wide area for making optical observations, and for shaping the return beam.

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Re: No return

They could save a bundle of money by sending an actual postage stamp instead of developing and sending a postage stamp sized spacecraft. Then the Alpha Centaurians could just post some photos back to us.

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Re: No return

The photos would arrive bent

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Coat

Re: No return

How to get it back? Just tell the philatelist community it's an actual, extremely rare, stamp.

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Boffin

"how is this tiny spacecraft going to be able to phone home when it gets there? "

Well usually the idea has been to modulate the driving beam.

Like a passively powered RFID tag.

On a very large scale.

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Re: No return

they just need to include a note:

"Greetings,

"Peace and Prosperity to you and all your fellow Centaurian beings. I am Mr Amatee Mbogo, Finance Minister for a small nation-state on planet Sol 3 (which we call Earth) and am in possession of 274 bazillion Centaurian dollars. Please send a small finder's fee of 500 Centaurian dollars to the following space-time coordinates and a generous share of the fortune will be sent straight away."

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Isn't it pointless

To have cameras and sensors without a frackin huge transmitter onboard?

Or are we supposed to slosh through the boating pond and retrieve our toy spaceship when it gets where it's supposed to go?

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Re: Isn't it pointless

By the time it gets there, we'll have developed FTL travel and will be waiting for it, with flags waving and a band playing.

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Re: Isn't it pointless

If we use that reasoning, we'll never invest in the technology which might eventually lead to FTL travel.

Also, we don't even have anything close to a theoretical model for how we could achieve that. So I'd say nope - we'll get there faster the this way.

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Re: Isn't it pointless

"By the time it gets there, we'll have developed FTL travel and will be waiting for it, with flags waving and a band playing."

More likely, by the time it reaches its destination, we'll be extinct. :/

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Anonymous Coward

Re: Isn't it pointless

By the time it gets there, we'll have developed FTL travel and will be waiting for it, with flags waving and a band playing.

I hear my boss presenting his latest plan.

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Re: Isn't it pointless

It will have a usb stick. They hope the aliens will plug it in their pc when it gets there.

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Pint

Re: Isn't it pointless -- USB stick

Nice one. We'll send 100 USB sticks. Assuming aliens have the same intelligence as college students, 48% will plug them in.

...However, given unknowns about alien anatomy, we only hope that plugging them in does not make them pregnant.

Have a virtual pint.

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Mot(i)e - sized probes?

I thought Larry Niven and Jerry Pournelle had the patent on this one?

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Re: Mot(i)e - sized probes?

Nah, Motie sailprobes are Apollo-sized.

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Alien

It's a historic day for Alpha Centuri!!

I have to say that Astronaut Ronthax and I are proud to be the first Centurians in orbit. We make this voyage with the hope of one day meeting other intelligent beings and peacefully sharing the wonderous galaxy we all live...wait a second...We're getting some incredibly bright beam of light here!....It's blinding!!....Centuri control, I think we're under attack!!.....What's that coming...some projectile...It's about the size of a postage stam...QUICK!! EVASIVE MANEU (CRUNCH!!!).....Centuri control!! No hull integrity and thrusters out!!....Avenge us! Avenge us!!....(silence)

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Alien

Re: It's a historic day for Alpha Centuri!!

This event will be covered up by Smoking Alien.

You only imagined you heard this on CB (Centauri Band) amateur radio and mission control personnel regrettably all died because the salad being served in the canteen that day was infected with Centauri tapeworm.

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In a galaxy shark shark away...

hat for money here...

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