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. …
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...
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.
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.
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.
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
"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.
"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.
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.
"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.
"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
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.
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.
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.
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."
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.
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)
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.
So the Techno Pollination* of the Universe begins. Why not send various bits of DNA and other organic molecules/chemistry along for the ride as well?
Also, quite what the telephone sanitizers and/or hair dressers who, very improbably, receive these gifts in a galaxy far far away are meant to do with it all is anybody's guess.
* Pollution (optional)
Well, AIs and/or Life spreading out throughout the universe is inevitable. A mathematical structure being selected that is tuned "just so" that glowing balls of burning hydrogen rapidly emerge and put out first, lego bricks and then an energy stream that can be harvested by self-assembling structures doing suspiciously fast parallel search so that large information-processing structures emerge in the galactic blink of an eye?
It's like seeing a probabilistic program running that puts all the right values in the all the right places of the Excel sheet eventually.
He's thinking, "This is utter madness. It'll never work. Stupid stupid stupid..."
His voice speaks, "I FULLY SUPPORT THIS PROJECT. YURI MILNER IS A GENIUS."
He's thinking and blinking, "NO NO NO NO NO NO..."
His voice speaks, "YURI MILNER IS A GENIUS. YURI MILNER IS A GENIUS. YURI MILNER IS A GENIUS."
Let's imagine it one of these gets anywhere near the Alpha Centauri system (which would be an impressive feat in itself, even if you send thousands of them).
Then it flies through the system at 20% of the speed of light. Unless it's incredibly lucky, any planets in the system will be nothing more than a single pixel on its (presumed) smartphone sensor.
If it were really, incredibly lucky and gets within (say) the earth-moon distance of a planet, it will have maybe 10 seconds to measure anything before it's gone again.
Then how is that data going to be sent back to Earth? A swarm wireless mesh network perhaps?? Even if you sent one probe every hour, they would be 200 million miles apart. Without directional antennas. And without meaningful power sources.
You will have to keep that lazer on-target for more than a few minutes...
Amazingly, on the project website they write:
The rising power and falling cost of lasers, consistent with Moore’s law, lead to significant advances in light beaming technology.
I didn't realize that "Moore's law" (more like Moore's rule of thumb of economics - valid till we hit the physics brickwall) applied to high-power lasers... evidence of that is sparse.
"You will have to keep that lazer on-target for more than a few minutes..."
It says two minutes here:
http://www.space.com/32551-breakthrough-starshot-interstellar-spacecraft-infographic.html
And "a few minutes" here:
http://www.theatlantic.com/science/archive/2016/04/yuri-milner-zuckerberg-starshot-interstellar-centauri/477669/
... but, yeah, the info-beam-back-to-Earth bit is missing.
Plus, I've just finished reading The Dark Forest and we should not in any way indicate where the probe came from - evasive maneuvers are mandatory. Oh, wait...
Looks like a neat idea however. Couldn't we use it to fire stuff at targets within the Solar System? As long as we kept the speed down quite a bit, made do with quick flybys and actually sorted out the call home bit?
>like "Forge of God"
Nah*, think Asimov and the simple, stripped-down, kind of big ideas he had for Foundation. You might or might not have agreed with Psychohistory's premises, but they make you think.
It's long, quite clever, lacks much action and is in parts utterly brilliant - like the reason for the title. Plus, it's Chinese but rags on Mao-era Communism in the first book, Three Body Problem, so that's a definite plus. Both books are also fairly self-contained.
* I wasn't a big fan of Forge and especially not Anvil. While not as scientific as Asimov, Liu is mostly more hard SF than Bear in the actual science, except for the occasional handwavium. And, yes, am aware Bear has some science degree or another.
it does not matter how big the laser is because as the earth turns, being able to even find the thing much less stay on it, is going to be impossible. THERE ARE TOO MANY VARIABLES FOR MOVEMENT.
The equator rotates at 1000 miles per hour, less going north south, near zero at the poles. So an astro from the space station is going to put the stampship say out on a stick and down on earth they are going to spot it and zap it from time to time, right? WRONG.
funny thing is this - they will get the money for the project and do some periodic zapping and tell the world that everything is going according to plans and calcs and they themselves will really never know if that is correct. Yeah, after earth changes orbit, season, revolution etc they are going to home in on a button light years away no problem. CAN I GET A REFUND?
@anniemouse I think you'll find the poles still rotate, they just stay in a fixed position relative to the rotation of the rest of the planet.
At the end of the day this whole thing is a technology driver. It's not supposed to work, it's supposed to make people think about the obstacles to making it work. So they'll come up with new technologies while scratching their heads, which will feed back into civilian use. Expect novel ways of creating substances like graphene, new and cheaper superconductors etc. In much the same way the space race of the 1960's gave us non-stick frying pans and velcro.
Quite plausible. Then we are in for some real sheet. Laser pushing an object with that sort of accuracy? Sounds like a prelude to zapping incoming asteroids, or hitting enemy alien invaders lightyears away before they get to us, or assassinating a country leader giving an outdoor public speech with a zap trick shot bouncing one off the moon, or how about the reverse- a tractor beam?
Because, you know, it makes the optics easier, and putting them in the right solar orbit would mean you could use absolutely massive solar arrays to power them. Come on Bigelow, we need some inflatable orbital solar panel factories, and Elon, we need your launcher to get them up there...
Mind Controlled; because, well, Steven Hawking.
Just don't let the Illuminati get control of them, because you'll need a precision engineered tinfoil hat to avoid getting your mind fried.
If Milner wants to fund an interesting research project - I would be happy for him to get me a Rival 41 and I will verify the effects of rum punch on humans while they sit an anchor in palm fringed anchorages in the Caribbean.
This would need to be a long term research project and of course we would need to check the effects of all sorts of alcohol all over the place. On the upside, the return would be somewhat quicker than a 20 year mission to Alpha Centauri - I estimate 8 to 10 years would allow a thorough investigation.
That was my first thought too - more of the energy available on the target rather than heating up the atmosphere and easier to target?
Then I thought, who fancies having a deathray like that up in space?
My other unrelated thought started out as - "When do they jettison their sails?", because when they get nearer the target, the solar wind from that star will otherwise slow them down & push them away?
It then moved on to "Sounds a bit like we are talking about throwing a message in a bottle over the side of a ship and expecting the bottle to end up on a particular beach the other side of the world".
Is that even going to be possible to predict all the eddies and flows of energy that will act on such a small payload over that distance to the target star system?
If "the ship" (our world) is in the wrong place when we chuck the bottle over the side (push the postage stamp craft with a laser), there may be no way to get it to land in the right "current" that will take it to the target destination anyway?
“Gravity pins us to the ground but I just flew to America. I lost my voice but I can still speak thanks to my voice synthesiser. How do we transcend these limits? With our minds and our machines.
“The limit that confronts us now is the great void between us and the stars. But now we can transcend it, with light beams, light sails, and the lightest spacecraft ever built we can launch a mission to Alpha Centauri within a generation. Today we commit to this next great leap into the cosmos, because we are human and our nature is to fly.”
Уважаемые все,
Ваши комментарии являются самыми полезными. Спасибо. Вы спасли мне по крайней мере, 25 миллионов из 100 миллионов, я запланировал для исследования. Теперь мы можем позволить себе больший отпечаток. Есть пиво!
Мое пальто один с красной звездой на рукаве
Юрий
PS. AC for fear of withering comments and multiple downvotes
The Register 
Biting the hand that feeds IT
Copyright. All rights reserved © 1998–2024
