[Igor Antunov]

Short version: Use 100GW megalaser array (mile across) to push a thousand 1 gram nuclear powered probes (processing power of an iphone with associated instruments) attached to reflective sails, for two minutes, accelerating them to 5% the speed of light, getting them to our nearest star system within 20 years. The probes would be cheap and expendable. Once the swarm arrives, these probes could then be contacted by a very large radio telescope array (we would know exact projected course/direction they take) and any photography and data readings they manage to take of other star systems/planets in that system would be downloaded over the course of 5 years.

Total power required to power the laser array would be the equivalent of 100 nuclear power (might need to leech the energy grid of an entire country such as France) plants per 2 minute 'push'. Total cost to set up the system ~$10 billion.

In an attempt to leapfrog the planets and vault into the interstellar age, a bevy of scientists and other luminaries from Silicon Valley and beyond, led by Yuri Milner, a Russian philanthropist and Internet entrepreneur, announced a plan on Tuesday to send a fleet of robot spacecraft no bigger than iPhones to Alpha Centauri, the nearest star system, 4.37 light-years away.

If it all worked out — a cosmically big “if” that would occur decades and perhaps $10 billion from now — a rocket would deliver a “mother ship” carrying a thousand or so small probes to space. Once in orbit, the probes would unfold thin sails and then, propelled by powerful laser beams from Earth, set off one by one like a flock of migrating butterflies across the universe.

Within two minutes, the probes would be more than 600,000 miles from home — as far as the lasers could maintain a tight beam — and moving at a fifth of the speed of light. But it would still take 20 years for them to get to Alpha Centauri. Those that survived would zip past the star system, making measurements and beaming pictures back to Earth.

Much of this plan is probably half a lifetime away. Mr. Milner and his colleagues estimate that it could take 20 years to get the mission off the ground and into the heavens, 20 years to get to Alpha Centauri and another four years for the word from outer space to come home. And there is still the matter of attracting billions of dollars to pay for it.

http://www.nytimes.com/2016/04/13/scien ... wking.html

Chief problems to overcome:

-The energy storage per burst; the charge to be utilized for the 2 minute blast must be stored ahead of time, in a mountain of batteries. No existing energy grid could withstand the amount of power drawn in such a short period of time. Batteries positioned at the site could.

-Communicating with the probes; the radio telescope array may have to be composed of hundreds of dishes spanning the territory of a small country.

[Potemkin]

This is encouraging; at least people are really starting to think outside the box now. For too long, we've been obsessed with rockets and manned spaceflight and setting foot on the surface of planets. What worked for the Moon is not really going to work for interstellar exploration.

[The Sabbaticus]

The youth in the West has been abandoning Facebook for some time now. It's only natural that Zuckerberg would try to find new vict... errr, 'customers'. Of course no one expected him to search for them in another solar system.

The English cosmologist and author Stephen Hawking is one of three members of the board of directors for the mission, along with Mr. Milner and Mark Zuckerberg, the Facebook founder.

[Rugoz]

Silly.

[Truth To Power]

Short version: Use 100GW megalaser array (mile across) to push a thousand 1 gram nuclear powered probes (processing power of an iphone with associated instruments) attached to reflective sails, for two minutes, accelerating them to 5% the speed of light, getting them to our nearest star system within 20 years. The probes would be cheap and expendable. Once the swarm arrives, these probes could then be contacted by a very large radio telescope array (we would know exact projected course/direction they take) and any photography and data readings they manage to take of other star systems/planets in that system would be downloaded over the course of 5 years.

When I see plans like this, which only come to fruition decades or centuries in the future, I often wonder about the economics of space science projects, given that technology will almost certainly become smaller, more powerful, etc. over project lead times, which are typically long to very long. ISTM that if we had taken the money spent on the space programs of the 1960s and invested it in stock index funds, today we would be able to afford a massively more capable program that would far outstrip what we have actually achieved. Similarly, if we had stopped spending money on terrestrial astronomy in the 1960s, and invested all that money, today we would be able to afford to put large observatories on the moon that would be able to see far better than even the orbiting ones.

At some point the pace of technological advancement will presumably slow, and then we will be able to plan long-term space exploration/settlement projects in a more stable technical environment using mature technologies. This should enable us to achieve far more at far lower cost.

[Harmattan]

When I see plans like this, which only come to fruition decades or centuries in the future, I often wonder about the economics of space science projects, given that technology will almost certainly become smaller, more powerful, etc. over project lead times, which are typically long to very long. ISTM that if we had taken the money spent on the space programs of the 1960s and invested it in stock index funds, today we would be able to afford a massively more capable program that would far outstrip what we have actually achieved. Similarly, if we had stopped spending money on terrestrial astronomy in the 1960s, and invested all that money, today we would be able to afford to put large observatories on the moon that would be able to see far better than even the orbiting ones.

I think there are two erroneous premises:

* A large part of the technology required to conquer space can only be developed by attempting to conquer space. And it takes decades because this is only after you failed, after you tried many things, after you collected data, that you truly understand what the problem is, what may work, what will not. Sure, modern advances in IT and a few others help, but it's not such a big deal.

* Even with much more money, I do not think the space conquest could have been significantly faster. Once again you must try, fail and/or collect data, retry. Even with hundreds of billions, designing and building a rocket still take years, and after the first one you will have more data and want a new generation, then another one, then another one, then another one.

[Igor Antunov]

We spend $200 billion over ten years designing a single fighter jet. I don't see what the issue is concerning spending that on something as civilization-changing as interstellar travel/exploration.

Solar sails are an enticing method. Even without lasers, barring the very slow acceleration courtesy of solar winds, we could conceivably reach 0.7c with such a technology. Mass engineering in space would allow us to build huge sails, and even space borne lasers to propel them so that we don't have to contend with the atmosphere which in this scenario is causing massive waste to the laser array through dissipation.

We NEED to move as much support infrastructure into space as possible. Everything would become cheaper, new avenues would open up.

[AFAIK]

accelerating them to 5% the speed of light

20% according to the article you quoted.

[foxdemon]

We spend $200 billion over ten years designing a single fighter jet. I don't see what the issue is concerning spending that on something as civilization-changing as interstellar travel/exploration.

Solar sails are an enticing method. Even without lasers, barring the very slow acceleration courtesy of solar winds, we could conceivably reach 0.7c with such a technology. Mass engineering in space would allow us to build huge sails, and even space borne lasers to propel them so that we don't have to contend with the atmosphere which in this scenario is causing massive waste to the laser array through dissipation.

We NEED to move as much support infrastructure into space as possible. Everything would become cheaper, new avenues would open up.

I agree. 10 billion is a small investment for the benefit. Graphine super capacitors might solve the storage problem. The benefit is by developing the technology, we can move from a hydrocarbon to full electrical energy economy. The space program just focuses research effort and the broader economy gets the spin off technology.

This idea of laser propelled nano probes is not new. It has been suggested that the cloud could be decelerated when approaching the Alpha Centauri system and obtain an orbit solution. One idea would be to accelerated proceeding particle clouds at appropriate velocities so to provide a braking medium for the probe swarm. Once the swarm has slowed down enough, the nano probes could use their sails for final deceleration and manoeuvre.

[Rugoz]

Similarly, if we had stopped spending money on terrestrial astronomy in the 1960s, and invested all that money, today we would be able to afford to put large observatories on the moon that would be able to see far better than even the orbiting ones.

Nonsense.

That money would not have made a dent. Terrestrial telescopes offer superior resolution since they can be built bigger and heavier. Space telescopes are built for wavelengths that are absorbed by the atmosphere (x-rays, gamma rays, infrared, ultraviolet). The moon offers no benefits expect perhaps for radiowaves.

We spend $200 billion over ten years designing a single fighter jet. I don't see what the issue is concerning spending that on something as civilization-changing as interstellar travel/exploration.

Interstellar probes are not the way to go. Telescopes will improve faster than the probes can get data. Imagine sending probes to a system 10 light years away (very close), it takes 60 years to get some data back.

By the way, we'll likely be the first generation in human history that will detect life beyond Earth. That's kind of exciting.

[Harmattan]

Terrestrial telescopes offer superior resolution since they can be built bigger and heavier.

No, there are two hard physical limitations:
a) The lens' resolution (550nm * distance / lens' diameter). Even a lens the size of the Earth would leave you with a 1km resolution for Alpha Centauri (closest system). What can we detect with that?
b) The probability that a photon will hit your lens.

An interferometer scattered over Earth's orbit would equate the aforementioned 1km resolution but you would stumble on the second problem. A space-based telescope orbiting the Sun to use its gravitational lensing would come up with the same resolution and fix the second problem, but it would be mostly static.

On the other end traveling probes could achieve excellent resolutions. 1cm may very well be possible. They are not only the best solution, they are the only one.

By the way, we'll likely be the first generation in human history that will detect life beyond Earth. That's kind of exciting.

No we won't. At best we may observe atmospheric components that are a good hint for photoynthesis.

Actually, without FTL, it seems impossible to directly observe extrasolar lifeforms before centuries or more, unless they signal themselves. Assuming of course that there is life to observe; Fermi's paradox sounds like a terrible omen.

[Rugoz]

b) The probability that a photon will hit your lens.

Long exposure times. But yeah, obviously for anything close to 1km resolution you need lots of mirrors (e.g. 1.5 million 3 meter mirrors). You would probably have to manufacture them off Earth. But if you solve the precision formation flying problem its actually doable and not a scifi dream like startshot.

On the other end traveling probes could achieve excellent resolutions. 1cm may very well be possible. They are not only the best solution, they are the only one.

Not 1g probes. The guy who finances the thing thinks it might be good enough to "make out continents". To my knowledge optics don't improve with Moore's law and if they do it would also apply to telescopes.

No we won't. At best we may observe atmospheric components that are a good hint for photoynthesis.

Science is all about probabilities.

[Harmattan]

Long exposure times.

But what if it takes a century to sample 90% of a one square meter surface? What if the light is so dim that you instead collect light diffracted or refracted from other stars?

Large-scale visible interferometry is limited because of this and will always be. It is not for high-resolution observations of low-intensity objects.

To my knowledge optics don't improve with Moore's law and if they do it would also apply to telescopes.

You can use three factors to improve the resolution: the sensor's resolution, multisampling, the optical system (and a telephoto objective could be achieved by having pairs of drones).

I do not know what the physical limitations are but we are not there yet and there have been fast improvements on all problems over the recent years, thanks to smartphones (energy storage, optical sensors, inertial sensors, antennas, processing, etc).

The guy who finances the thing thinks it might be good enough to "make out continents".

For now. But should we have such a system it could send better probes in the future without requiring changes.

[Truth To Power]

When I see plans like this, which only come to fruition decades or centuries in the future, I often wonder about the economics of space science projects, given that technology will almost certainly become smaller, more powerful, etc. over project lead times, which are typically long to very long. ISTM that if we had taken the money spent on the space programs of the 1960s and invested it in stock index funds, today we would be able to afford a massively more capable program that would far outstrip what we have actually achieved. Similarly, if we had stopped spending money on terrestrial astronomy in the 1960s, and invested all that money, today we would be able to afford to put large observatories on the moon that would be able to see far better than even the orbiting ones.

I think there are two erroneous premises:

* A large part of the technology required to conquer space can only be developed by attempting to conquer space. And it takes decades because this is only after you failed, after you tried many things, after you collected data, that you truly understand what the problem is, what may work, what will not. Sure, modern advances in IT and a few others help, but it's not such a big deal.

While it's true that space technology has to be developed through experience, it's equally true that non-space technological development quickly makes such space technology obsolete, especially when systems are designed for long lifetimes, like the Shuttle. For example, weight has been a critical limitation on space science, but miniaturization has really made huge strides, so that now they are talking about interstellar probes the size of a cell phone, and much lighter.

* Even with much more money, I do not think the space conquest could have been significantly faster. Once again you must try, fail and/or collect data, retry. Even with hundreds of billions, designing and building a rocket still take years, and after the first one you will have more data and want a new generation, then another one, then another one, then another one.

Not so. Every technology has a period of rapid change followed by a period of maturity, when you can use it confidently and it doesn't get much better with time. Consider civilian aviation. It got better rapidly until the 1960s, then leveled off. New planes are quieter and more efficient, but in terms of the passenger experience, speed, safety, etc. new planes are not much different from ones built 50 years ago. Processors hit a similar wall more than 10 years ago, when logic gates stopped getting smaller and speed essentially stopped increasing. We have developed workarounds like multiple cores, and software -- in some fields -- has improved, but silicon wafer data processing technology can be considered mature.

The big advance in space is now reusable launchers, which are now being built, and will make the economics of space exploration much more attractive (the Shuttle was nominally reusable, but for various reasons did not live up to the promise of cheaper access to orbit). If we had just invested all the billions spent on expendable rockets in the stock market, we would now have a massive fund to spend on the far cheaper reusables. I guess my point is mainly that while technological progress imposes a trade-off between speed and efficiency in every field, it is especially critical in space because of the weight and reusability issues.

Similarly, if we had stopped spending money on terrestrial astronomy in the 1960s, and invested all that money, today we would be able to afford to put large observatories on the moon that would be able to see far better than even the orbiting ones.

That money would not have made a dent.

Why not?

Terrestrial telescopes offer superior resolution since they can be built bigger and heavier.

Terrestrial scopes offer better resolution than Hubble? Give your head a shake. And the moon's gravity is only 1/6 earth's, so scopes can be built much bigger there because they will be lighter.

Space telescopes are built for wavelengths that are absorbed by the atmosphere (x-rays, gamma rays, infrared, ultraviolet). The moon offers no benefits expect perhaps for radiowaves.

The moon offers a source of bulk construction materials, no atmospheric interference, and a stable base to damp vibration. Astronomy is something a lunar settlement would be able to do a lot better than terrestrial observatories.

[Igor Antunov]

20% according to the article you quoted.

Ooops, that sounds about right, given the 20 year journey.

[MEAGAIN]

So what benefit is it to get there 20 years from now and die of old age before we get back?

IMO,we have done enough damage to this planet without screwing up the outer space.

Wonder what CERN will do or how long before the 9th planet Nebiru comes back around?

[Igor Antunov]

We literally can't screw up 'outer space'. We exist on such a minuscule/insignificant scale relative to the observable universe, that if we were to blow up 1,000 planets, or a 100 stars for shits and giggles the galaxy wouldn't even notice, and it is one of tens of billions.

Our solar system alone can support trillions of humans resource wise. That's one solar system out of 200 billion in this one galaxy alone. Andromeda next door has up to 600 Billion stars.

To bring things into perspective, we are microbes on a speck of dust in some bedroom closet, and you're worried that we will adversely affect the Earth from such a position.

[Truth To Power]

We literally can't screw up 'outer space'.

True, but it would be possible to screw ourselves in outer space, and to screw up planets that have indigenous life.

We exist on such a minuscule/insignificant scale relative to the observable universe, that if we were to blow up 1,000 planets, or a 100 stars for shits and giggles the galaxy wouldn't even notice, and it is one of tens of billions.

Consider the possibility that we will try some large-scale engineering in outer space, and something could go wrong, leading to catastrophe on earth. One example would be trying to move things around, and ending up hitting the earth.

Our solar system alone can support trillions of humans resource wise.

Quadrillions, if we dismantle the major planets. But technological advance will likely make people obsolete before we need that much room.

That's one solar system out of 200 billion in this one galaxy alone. Andromeda next door has up to 600 Billion stars.

Yes, an ecological niche offers energy and raw materials. Technology makes a lot more of both available in outer space.

[Rugoz]

Large-scale visible interferometry is limited because of this and will always be. It is not for high-resolution observations of low-intensity objects.

No, such telescopes are being proposed for direct imaging of exoplanets, I'm not pulling that out of my ass.

I do not know what the physical limitations are but we are not there yet and there have been fast improvements on all problems over the recent years

Telescopes have made great progress too, what's your point.

For now. But should we have such a system it could send better probes in the future without requiring changes.

Not for now. In a few decades when this thing is supposed to be ready (which it will never be, for other reasons than optics).

The big advance in space is now reusable launchers, which are now being built, and will make the economics of space exploration much more attractive (the Shuttle was nominally reusable, but for various reasons did not live up to the promise of cheaper access to orbit).

The whole idea of reusable rockets being automatically cheaper is nonsense. Reusability is certainly a long-term goal, but it will save very little in the beginning, if it saves anything at all. Great progress has been made in the space industry, but it is mostly related to better electronics (communication, observation, robotics etc.). SpaceX is cheaper because it has broken into a monopolist controlled market with little regard for its own profit. That alone won't change the long-term trend (don't believe all the hype).

Terrestrial scopes offer better resolution than Hubble? Give your head a shake.

In terms of angular resolution absolutely. Especially upcoming telescopes. It's not even a contest. The Hubble was from a time before adaptive optics which removes the effect of atmospheric distortions. The E-ELT will have a mirror diameter of 40m and an angular resolution of 0.001 arcsec.

The moon offers a source of bulk construction materials, no atmospheric interference, and a stable base to damp vibration. Astronomy is something a lunar settlement would be able to do a lot better than terrestrial observatories.

Space telescopes are put at Earth-Sun lagrange points for good reasons. Inform yourself.

[Harmattan]

No, such telescopes are being proposed for direct imaging of exoplanets, I'm not pulling that out of my ass.

But only coarse pictures, to study planet formation and composition, not to investigate possible civilizations.

Telescopes have made great progress too, what's your point.

As I said before, a perfect telescope as big as the Earth would not be enough. Those are hard physical limitations, not technological ones.

In a few decades when this thing is supposed to be ready (which it will never be, for other reasons than optics).

Maybe. It still is a good idea.