Stephen Hawking wants to send tiny space probes to the stars.   WTF? - Page 1
Forum section: electronics / general

author: JoeN
author_rank: Frequent Contributor
timestamp: April 13, 2016, 05:33:28 am
content: Assuming the transportation and automation works, how will these devices weighing a "few grams" possibly relay back their findings? Anyone? It has to be RF, right? But how? Or is this some sort of quantum entanglement idea? I thought that was debunked in any case.http://www.cnn.com/2016/04/12/us/breakthrough-starshot-space-probe-stephen-hawking-feat/index.html(CNN) Imagine hundreds of spacecraft the size of a butterfly, propelled by light beams at record-shattering speeds and journeying to distant stars 4.37 light years away -- far deeper into space than human-built probes have ever ventured.It's arguably the most ambitious space exploration project in history, and it may not be completed in our lifetimes.But if anyone can pull it off, it's these guys.Some of the world's most brilliant minds, including physicist Stephen Hawking and Facebook founder Mark Zuckerberg, are behind a $100 million program to send tiny "nanocraft" to explore Alpha Centauri, our nearest star system."Today, we commit to this next great leap into the cosmos," Hawking said alongside billionaire entrepreneur Yuri Milner at a press conference Tuesday in New York. "Because we are human, and our nature is to fly."Hawking, Milner and Zuckerberg make up the board of directors for the mission, which is called Breakthrough Starshot and seeks to apply Silicon Valley ingenuity to space travel. The project is led by Pete Worden, former director of NASA's Ames Research Center, and advised by a committee of top scientists and engineers.Their plan goes like this: They hope to build hundreds of little space probes, each weighing just a few grams and carrying cameras, photon thrusters, power supply, navigation and communication equipment. A rocket would ferry these nanocraft into space, where they would unfold tiny sails.Powerful laser beams from Earth would then push the sails, propelling the little nanocraft up to 100 million mph -- that's 20% of light speed, far faster than today's spacecraft can travel -- to Alpha Centauri, where they would collect images and other data and beam them back to Earth.Project leaders estimate that today's fastest spacecraft would take about 30,000 years to reach the Alpha Centauri star system, some 25 trillion miles away. But they believe these nanocraft could fly more than 1,000 times faster, which would allow them to reach Alpha Centauri in about 20 years.The project's leaders admit they face big engineering challenges, and that any launch is many years and billions of dollars away. But they say their plans are based on technology that already exists or is likely to become available soon.They also plan to ask the world's scientists for their help by posting public-domain research and soliciting ideas online.Some scientists are skeptical they can make this happen, given the current limits of technology and the difficulty of raising enough money to fund the project. The Russian-born Milner estimates it could cost as much as $10 billion.But he and his colleagues for now are optimistic."The human story is one of great leaps," Milner said in a statement. "Fifty-five years ago today, (Russian cosmonaut) Yuri Gagarin became the first human in space. Today, we are preparing for the next great leap -- to the stars."

author: TheAmmoniacal
author_rank: Unknown
timestamp: April 13, 2016, 05:36:59 am
content: Stephen Hawking went mental long ago.

author: MrSlack
author_rank: Frequent Contributor
timestamp: April 13, 2016, 05:48:17 am
content: This is the typical physicist who turns up with a design spec like an excited puppy and has to be let down gently because engineering is a slightly more holistic view of the problem."Battery will be flat by T+0:34. Try again."

author: TheAmmoniacal
author_rank: Unknown
timestamp: April 13, 2016, 06:21:24 am
content: These types of physicists ("futurists") where the same type of physicists that said we would have flying cars by now.

author: Lightages
author_rank: Unknown
timestamp: April 13, 2016, 06:31:07 am
content: This is a ridiculous proposition. Sorry Stephen Hawking, but you are out to lunch on this one. Something so light will be immediately blown of course by the galactic magnetic fields and random particle flux. Even if you send thousands of these, they will all go in random directions and the chances of getting something close to Alpha Centauri with this method is like pissing in the wind. So what if a random golf ball sized object actually gets there, how does it transmit anything back to Earth? What a stupid thing for Hawking to support.

author: ade
author_rank: Unknown
timestamp: April 13, 2016, 07:10:36 am
content: Quotep= mv.Whenvis 20% speed of light, there's going to be plenty ofp. Physics 101.Definitely an idea worth doing. Even if they fail to reach Alpha Centauri, the technological advances this project will enable will be well worth the effort.No thanks to you guys.

author: grumpydoc
author_rank: Super Contributor
timestamp: April 13, 2016, 08:42:34 am
content: Quote from: ade on April 13, 2016, 07:10:36 amYes but Ek= 1/2mv2, so at c/5 you need rather a lot of energy to get even a few grammes to accelerate up to that velocity - shining a ruddy laser at the thing is not going to cut it.

author: babysitter
author_rank: Frequent Contributor
timestamp: April 13, 2016, 09:03:30 am
content: Quote from: JoeN on April 13, 2016, 05:33:28 amThere is the mistake: They might be brilliant minds in their own field, not this.

author: MrSlack
author_rank: Frequent Contributor
timestamp: April 13, 2016, 09:05:47 am
content: Someone found out how to take money from Zuck. Life is good.

author: lwatts666
author_rank: Unknown
timestamp: April 13, 2016, 09:17:53 am
content: As the Physicist said to the dairy farmer. "Consider a spherical cow of uniform density"...

author: Mechatrommer
author_rank: Super Contributor
timestamp: April 13, 2016, 10:58:08 am
content: Quote from: JoeN on April 13, 2016, 05:33:28 amasking in forum full of bunch of hoobiests and bunch of "i dont have to go to school to be on top" seems like a good idea?QuoteQuote from: TheAmmoniacal on April 13, 2016, 06:21:24 amthe flying cars is not the problem. who's going to pay is. let alone traffic regulations, insurance policies, and making new roadways for it.

author: hayatepilot
author_rank: Frequent Contributor
timestamp: April 13, 2016, 11:32:51 am
content: With the estimated 10 Gigadollars it should be possible to realize those nano satellites.It' certainly more practical, than to build a single big spacecraft, thats for sure.Many of those could fail on the journey but one would still have some left to gather the data.And some of them could combine at the destination to form a large dish-like structure to transmit the data more effectively to the earth.And production is much cheaper when you can build them in the thousands than just one big probe.I hope they can gather enough funding to start the project. The gained knowledge developing this would be enormous!

author: ArdRhi
author_rank: Contributor
timestamp: April 13, 2016, 11:39:26 am
content: I think he did it so he gets to make the "starCHIP" pun.

author: Mechanical Menace
author_rank: Super Contributor
timestamp: April 13, 2016, 03:11:50 pm
content: Quote from: grumpydoc on April 13, 2016, 08:42:34 amYou've the initial velocity from the launch, you could add some gravity assist maneuvers, the "photon thrusters" may be able to add some, and the sun will shine on those sails as well as the ruddy laser. How much could they all add up over maybe a decade?Until we have more details on the actual proposed weight, the area of the sails, the power of the thrusters and more details about the laser I don't really think we can say if something near the goal of 20% of C is actually achievable or not.

author: MrSlack
author_rank: Frequent Contributor
timestamp: April 13, 2016, 03:17:12 pm
content: I'd rather they spent the cash on working out how to bend the rules.

author: tszaboo
author_rank: Super Contributor
timestamp: April 13, 2016, 03:19:33 pm
content: So the small unicorns will be propelled by the rainbow coming out of their back.There are so many technical issues I dont even know where to start. How do you focus a laser beam, so it is still has trust that far. What happens if it only hits one side, only for a fraction of a second. What happens when gravity starts affecting the laser beam. No way this works.

author: edavid
author_rank: Super Contributor
timestamp: April 13, 2016, 03:25:09 pm
content: Quote from: NANDBlog on April 13, 2016, 03:19:33 pmLarge lens.QuoteIt doesn't. The targets have to have attitude control.QuoteGravity of what? There's nothing massive between here and Alpha Centauri.

author: tszaboo
author_rank: Super Contributor
timestamp: April 13, 2016, 03:27:11 pm
content: Quote from: edavid on April 13, 2016, 03:25:09 pmYou quite obviously have no idea how light/laser or gravity works.

author: edavid
author_rank: Super Contributor
timestamp: April 13, 2016, 03:28:53 pm
content: Quote from: grumpydoc on April 13, 2016, 08:42:34 amTrue.QuoteDoes not follow. Don't you think Stephen Hawking is capable of calculating the laser power required?It's not like this is a new idea. There have been plenty of papers and studies working out the basic concepts, for example:https://en.wikipedia.org/wiki/Starwisp

author: krish2487
author_rank: Frequent Contributor
timestamp: April 13, 2016, 03:38:36 pm
content: QuoteNow that feature, I suspect, is going to take up a lot of the budget for the development...We do not have any actual intelligence, forget trying to develop artificial intelligence...

author: Mechanical Menace
author_rank: Super Contributor
timestamp: April 13, 2016, 03:38:58 pm
content: Quote from: NANDBlog on April 13, 2016, 03:19:33 pmApart from the sun what is massive enough in the neighbourhood to cause any gravitational lensing? And even that would just need compensating for the same as shooting with a constant side wind. You wouldn't be dealing with the "smearing" you get from large galaxies and/or clusters as the mass is distributed so uniformly. And I can't think of any reason why you'd send them close enough to the sun to even bring relativity into plotting the course.These speeds, the masses of the objects you'd go near on such a journey, you don't really have to worry about relativistic effects beyond some timekeeping issues.

author: grumpydoc
author_rank: Super Contributor
timestamp: April 13, 2016, 03:50:05 pm
content: Quote from: edavid on April 13, 2016, 03:28:53 pmHmm, from that article"Although the diffraction limit severely constrains the range of the transmitting antenna, the probe is designed to have an extremely high acceleration of 24 m/s2, so that it can reach a significant fraction of the speed of light within a very short distance, before passing out of range. The antenna uses a microwave lens 560 km in diameter, would transmit 56 GW of power, and would accelerate the probe to 10% of the speed of light."A 560km diameter antenna transmitting 56GW of microwave power (in orbit?) - sounds very doable, not, with current technology. Or even technology that might come along in the next half century.

author: Mechatrommer
author_rank: Super Contributor
timestamp: April 13, 2016, 03:54:39 pm
content: see? as said, there are many geniuses than hawking around here. hawking is nothing but a clueless about gravitation, cosmos energies and lasers. asking such questions is quite wise

author: MrSlack
author_rank: Frequent Contributor
timestamp: April 13, 2016, 04:08:01 pm
content: Quote from: Mechatrommer on April 13, 2016, 03:54:39 pmHe's absolutely totally clueless on a lot of things related to the field. He's a theoretical physicist. All the problems he wants solved are delegated to experimental physicists and engineers who have to work within the slightly not ideal constraints placed on them by technology and cash.It's like asking Knuth or Dijkstra to knock out a Java EE app...

author: wraper
author_rank: Unknown
timestamp: April 13, 2016, 04:08:08 pm
content: Quote from: TheAmmoniacal on April 13, 2016, 06:21:24 amWe have jet hoverboard though

author: wraper
author_rank: Unknown
timestamp: April 13, 2016, 04:18:54 pm
content: Quote from: NANDBlog on April 13, 2016, 03:19:33 pmComplete lack of understanding. You don't need continuous thrust. In the space, you just need to reach the speed, and then move without any additional energy.

author: tszaboo
author_rank: Super Contributor
timestamp: April 13, 2016, 04:39:48 pm
content: Quote from: Mechanical Menace on April 13, 2016, 03:38:58 pmWell, if you focus the beam, to say 10m at the target, then it takes "10m effect of gravity" to move the beam. The gravitational fields dont need to make the beam take a 90 degrees turn, they can modify its path by a 1/10000000 radian, and it will miss already. And there are massive gravitational fields here, and huge entropy. Imagine: There is a field which keeps the sun! circling around something. They dont know if there is an other one or two planet in the solar system (beyond pluto)!? So much about calculating with gravity.On the other hand it requires enormous amount of effort to keep a laser beam focused that far.Quote from: wraper on April 13, 2016, 04:18:54 pmNo, of course not. But when the craft is going 0.19C you still need to propel it. The last time I see something going 0.19C it was going very far very fast. I doubt they can shoot the Jupiter with a laser beam, yet alone deliver energy to something really small.

author: wraper
author_rank: Unknown
timestamp: April 13, 2016, 04:50:09 pm
content: Quote from: NANDBlog on April 13, 2016, 04:39:48 pmWhy should you need to still propel it? Also, this thing is not tiny. Tiny is the thing in the center, but it has some huge sails.QuoteWhy should'n they reach Jupiter, spot will be huge be tiny but completely reachable.

author: Mechanical Menace
author_rank: Super Contributor
timestamp: April 13, 2016, 05:12:39 pm
content: Escape velocity in regards to the solar system from the Earth/Moon system is 0.00014 of c, easily reachable long before the light sails come into play. The only thing in the solar system that could make aiming the laser a slight problem is the sun, when you're very very close to it. And that maths is well understood and bloody accurate. There's also no reason to get that close to the sun and if you were you wouldn't need the laser anyway as that thing puts quit a bit of energy. Even forgetting the solar winds the light pressure alone would have an appreciable effect on something so large and inconsequentially massive.Oh and you do realise the laser won't be steering the probes yes? You don't have to wait for the wind to be blowing in the exact right direction to sail somewhere...

author: CatalinaWOW
author_rank: Super Contributor
timestamp: April 13, 2016, 05:20:32 pm
content: While there don't seem to be any absolute barriers to this, there are lots of niggling little details. Like the communication back part. One method would be to do a gravity slingshot around the target star to return the probe to earth. Round trip in less than 50 years. But that is a long time in a tough environment. Assuming something like normal interstellar density there will be on the order of 8E18 molecular collisions during that round trip. At 0.2c even a single molecule isn't a laughing matter. There will be a lot of people working a long time to get the details down. Like how to get a laser of that power into space so that the backscatter from a beam of that power doesn't kill too many people.

author: edavid
author_rank: Super Contributor
timestamp: April 13, 2016, 05:29:26 pm
content: Quote from: Mechanical Menace on April 13, 2016, 05:12:39 pmAll the launch energy comes from the laser/light sail system, and it's efficient to accelerate the probe as much as possible while it's close to the launcher.QuoteTo keep the system practical, the launch beam has to be tightly focused, which means it does have to be pointed in the exact right direction.

author: Mechanical Menace
author_rank: Super Contributor
timestamp: April 13, 2016, 05:35:46 pm
content: Quote from: edavid on April 13, 2016, 05:29:26 pmSo they'll launch them, bring them to a full stop, then start accelerating them with the laser?QuoteTo hit the probes yeah, but not exactly spot on between the laser and the exact centre of Alpha Centauri. And the point is to get to the solar system, that's a big target.

author: edavid
author_rank: Super Contributor
timestamp: April 13, 2016, 05:38:28 pm
content: Quote from: CatalinaWOW on April 13, 2016, 05:20:32 pmI can't see a return mission being practical... I think they would use a communications laser system on the probes. The launch laser lens would also be the receivingtelescope.QuoteIt might be cheaper to have the launch laser outside the atmosphere, but if not, it could just be out in the desert (next to the PV array that powers it?).

author: XOIIO
author_rank: Super Contributor
timestamp: April 13, 2016, 05:49:54 pm
content: As far as the laser goes, I think it would be best to put one in orbit, or on the moon, keeping our atmosphere out of the way, the lazer could be lower power then, instead of being ludicrously powerful and needing a massive focusing array.Bugger, someone just beat me to it lol

author: edavid
author_rank: Super Contributor
timestamp: April 13, 2016, 05:52:50 pm
content: Quote from: Mechanical Menace on April 13, 2016, 05:35:46 pmLaunch them into orbit, deploy the sails, then launch them toward the target with the laser. Rocket launch can't give them any significant velocity toward the target.QuoteThat's where the probes will be. Any deviation from a straight line just wastes time.QuoteIt's a tiny, tiny target. No spacecraft has ever been navigated that accurately.

author: miguelvp
author_rank: Super Contributor
timestamp: April 13, 2016, 05:54:38 pm
content: 100 million dollars is chump change in the great scope of things.The crafts don't have to launch from earth on their own, but can be launched from orbit.Orbital microwave lasers are possible as well,maybe not 56GW but Japan is planning to do a 1GW orbiting solar power plant, so the tech to acheive 56GW doesn't seem unfeasible if you are directing the microwave laser towards space.The communication back via radio telescopes getting the combined data of the swarm and postprocess is not that out of reach, specially since it will take a long time to get there so our tech will be way better, the problem is that it will add 1/5 of the time that takes to reach the place, (so about 4 years more) but it will be streaming the information during the whole trip so it's ok.Since it's a collective, each probe doesn't have to send a lot of data and I would think they will use energy from the environment to be reflected back so they don't require the power to transmit that signal.But I guess I would have to find time to actually read the article instead of assuming that it will work, but I don't see it as too far fetched.Edit: I guess I did read the article after all since I did read the complete OP and it had it in its entirety.

author: Delta
author_rank: Super Contributor
timestamp: April 13, 2016, 05:55:29 pm
content: This smacks of nothing more than a publicity stunt. It's a shame the great Stevie H has put his name to it.

author: XynxNet
author_rank: Regular Contributor
timestamp: April 13, 2016, 07:13:00 pm
content: You can read it up here:http://arxiv.org/abs/1604.01356Take the link to the pdf.Original paper is always better than journalist's dumbed down version.On first reading the paper looks sound to me from a physicists perspective.

author: miguelvp
author_rank: Super Contributor
timestamp: April 13, 2016, 07:26:28 pm
content: Quote from: XynxNet on April 13, 2016, 07:13:00 pmImpressive numbers, pass Voyager I in less than 3 days, while it's been in flight since 1977! that's 39 years.QuoteSource, PDF on that link you provided. Direct link to PDF:https://arxiv.org/ftp/arxiv/papers/1604/1604.01356.pdf

author: Mechanical Menace
author_rank: Super Contributor
timestamp: April 13, 2016, 07:37:39 pm
content: Quote from: edavid on April 13, 2016, 05:52:50 pmWhat's the diameter of the Alpha Centauri system? Our solar system is about 4LY...

author: miguelvp
author_rank: Super Contributor
timestamp: April 13, 2016, 07:52:10 pm
content: Quote from: Mechanical Menace on April 13, 2016, 07:37:39 pmI think it's more like 4 light hours.(4.5 billion Km) / (300000 km/s) / (60 s/m) / ( 60 m/h) = 4.16 hoursBut it doesn't matter how big Alpha Centauri is, a target gets tinier based on distance not just size of the target.

author: grumpydoc
author_rank: Super Contributor
timestamp: April 13, 2016, 07:55:57 pm
content: Quote from: Mechanical Menace on April 13, 2016, 07:37:39 pmDepends on where you put the edgeMean orbit of Pluto is about 40au radius or 0.00063251381 light years , Alpha C is 4.25LY away so a solar system sized object at that distance has an angular diameter of about 60 arc seconds (if I have calculated it correctly).If you go out to the heliopause the "solar system" is a lot bigger, of course. Something like 180au diameter.

author: MadTux
author_rank: Frequent Contributor
timestamp: April 13, 2016, 08:11:56 pm
content: Even if the transmission problem could be solved, the probe would shoot trough Alpha Centauri solar system at 0.2c while taking pictures with an amazing camera that has the aperture size of a mobile phone (anything else doesn't fit or is too heavy). Good luck taking a nice picture of Jupiter with your Iphone.

author: miguelvp
author_rank: Super Contributor
timestamp: April 13, 2016, 08:15:47 pm
content: Quote from: MadTux on April 13, 2016, 08:11:56 pmI don't think each probe has a full camera, just light sensors so in essence just a pixel with different wavelength sensors.Plus light-field computation has come a long way, so it doesn't need to be in focus of anything.

author: apelly
author_rank: Unknown
timestamp: April 13, 2016, 08:18:36 pm
content: Russian billionaire > Some money > Steven Hawking > Much publicity > Much money > Russion billionaireLooks like the same old story to me.

author: edavid
author_rank: Super Contributor
timestamp: April 13, 2016, 08:19:21 pm
content: The distance between the A & B stars varies from 11-36 AU. It's not known if there are any planets.

author: jh15
author_rank: Frequent Contributor
timestamp: April 13, 2016, 08:47:29 pm
content: I think Carl Sagen said:: Do you really think it is a good idea to attract attention?In Earth past, one civilization dominates or takes over the discovered one. I guess Alpha's might put us on reservations or something...

author: Len
author_rank: Frequent Contributor
timestamp: April 13, 2016, 08:52:32 pm
content: Quote from: jh15 on April 13, 2016, 08:47:29 pmIt's too late to worry about that,they've already seen our TV shows.

author: continuo
author_rank: Frequent Contributor
timestamp: April 13, 2016, 09:42:06 pm
content: But what if one of the probes accidentally hits and wipes out the Alpha Centaurians capital city on their main planet? Travelling at 0.2c it carries a lot of punch, it could be considered a kinetic weapon, fired by the evil Earthlings. This could very well trigger an interstellar war!

author: MadTux
author_rank: Frequent Contributor
timestamp: April 13, 2016, 10:48:19 pm
content: Quote from: continuo on April 13, 2016, 09:42:06 pmIf they don't have an atmosphere. 1g @ 0.2c equals 9.18*10^13J, if I did calculations correctly.So a 10g spaceship would have 220kT TNT equivalent.With atmosphere, an impact would probably look similar to thishttps://en.wikipedia.org/wiki/Starfish_Prime(And the dudes there would wonder whether ailens did itWithout atmosphere, it's certainly much more unpleasant

author: miguelvp
author_rank: Super Contributor
timestamp: April 13, 2016, 11:55:09 pm
content: If they don't have an atmosphere then they surely deal with it on a daily bases or their planet will look like the moon.

author: JoeN
author_rank: Frequent Contributor
timestamp: April 14, 2016, 02:11:13 am
content: Quote from: XynxNet on April 13, 2016, 07:13:00 pmThanks. I could not find that. I will read it now.

author: radar_macgyver
author_rank: Frequent Contributor
timestamp: April 14, 2016, 03:48:48 am
content: How do they plan to slow the craft down when approaching Alpha Centauri?

author: apelly
author_rank: Unknown
timestamp: April 14, 2016, 03:58:55 am
content: Quote from: radar_macgyver on April 14, 2016, 03:48:48 amObvious: Big reach-around mirrors to shine the light on the other side.What really concerns me is what happens to future earth when this thing completes its lap of the universe?

author: CatalinaWOW
author_rank: Super Contributor
timestamp: April 14, 2016, 04:26:05 am
content: Reading the paper they make some rather glib assumptions. 1 Watt transmitter to achieve communication at one light year distance. Based on achieving one bit/photon encoding and using a receiving optic 10000 meters square. Which requires either maintaining or measuring the position of that 10000 meter mirror to a fraction of an optical wavelength. Except for ignoring noise in their analysis (implicit in assuming 1 bit per photon) they haven't violated physics, but have left some really tough engineering problems as exercises for the student. The same kind of grand assumptions riddle the paper. The one thing I wholeheartedly agree with is that the attempt will lead to some truly stunning technology development, even if they fall short of the goals by a couple of orders of magnitude.

author: Brumby
author_rank: Unknown
timestamp: April 14, 2016, 04:49:05 am
content: Quote from: CatalinaWOW on April 14, 2016, 04:26:05 am+1

author: JoeN
author_rank: Frequent Contributor
timestamp: April 14, 2016, 08:54:24 am
content: Quote from: radar_macgyver on April 14, 2016, 03:48:48 amThey don't. Just quickly grab as much data as possible on the way through. Whatever is missed can be made up by the next hundreds of craft that get sent. What is lost in quality is made up in quantity, I guess.

author: tszaboo
author_rank: Super Contributor
timestamp: April 14, 2016, 09:01:36 am
content: Quote from: JoeN on April 14, 2016, 08:54:24 amAnd it can do investigations for minutes? Because it is still very fast at 200mC.I think they are just thought provoking. I put it in the category of the space elevator.

author: MrSlack
author_rank: Frequent Contributor
timestamp: April 14, 2016, 10:35:28 pm
content: Quote from: CatalinaWOW on April 14, 2016, 04:26:05 amPerhaps they can stick a little cocktail flag on the photon so you know it's not just noise.

author: edavid
author_rank: Super Contributor
timestamp: April 15, 2016, 02:16:42 am
content: They have a "Challenges" page that talks about/handwaves over some of the issues raised here:http://breakthroughinitiatives.org/Challenges/3

author: Stray Electron
author_rank: Super Contributor
timestamp: April 20, 2016, 05:03:34 pm
content: Quote from: NANDBlog on April 13, 2016, 03:19:33 pmExactly. And what, pray tell, are they even supposed to do as the whiz by Alpha C at C/5??? Could you imagine the effect if one collided with a planet or perhaps even a spacecraft at that velocity? And wouldn't bombarding a planet with objects traveling at C/5 be considered an act of war?Has anyone attempted to calculate how long this journey would take? Even if they eventually reach C/5, the acceleration rate using solar sails would be miniscule so this trip would take a VERY long time. That means that the system reliability would have to be incredible. And at the same time, the small size would also mean that there would probably be no redundant systems on this tiny craft. Even the space shuttle has FIVE redundant systems for most functions and it's only intended to fly for a handful of days at a time. This journey would probably take centuries if not millennia! And the craft would have to supply their own power for their guidance, telemetry and other on board systems so has anyone even considered how to keep these powered for that length of time? AND what about heating and cooling? The space shuttle has huge radiators that they can open in order to get rid of excess heat and they use fuel cells (which require hydrogen and oxygen) for heating. They also rotate the entire shuttlefrequentlyin order to control solar heating from the sun. That also requires fuel or other power.You also have to wonder what the affect would be of pumping a huge powerful laser through the earth's atmosphere for CENTURIES!I think that the level of effort to do something like this would make the Moon Race look like child's play by comparison!

author: wraper
author_rank: Unknown
timestamp: April 20, 2016, 05:33:16 pm
content: Quote from: Stray Electron on April 20, 2016, 05:03:34 pmYou haven't read a tiny bit about it, didn't you? Because you are spewing a lot of BS completely unrelated to what was proposed. Few examples: travel time is about 20 years IIRC, not millenia. Laser beams are needed only for a short moment until reaching the full speed speed.

author: edavid
author_rank: Super Contributor
timestamp: April 20, 2016, 05:59:44 pm
content: Quote from: wraper on April 20, 2016, 05:33:16 pmThey are saying 10 minute launch time, but that doesn't seem very cost effective to me (lower power laser and longer launch time would be cheaper).