Building Earth's First Starships
Announcing “Breakthrough Starshot”: Building Earth’s First Starships, SpaceRef
“Plans for Earth’s first starships are being announced today in New York City. At a midday press conference, Yuri Milner’s Breakthrough Prize Foundation is unveiling its latest project: “Breakthrough Starshot”. If Milner’s team can pull this off, people alive today could see starships depart from our planet and reach another star system within their lifetime. And everyone will be invited to help make that happen. The plan is simple: create an immensely powerful, system of ground-based lasers and use them to propel tiny starships up to 20% of the speed of light. The starships’ first target would be the Alpha Centauri star system 4.3 light years away. These starships would arrive just 20 years after leaving Earth.”
Breakthrough Starshot Project Announced by Yuri Milner and Physicist Stephen Hawking
“Breakthrough Starshot is a $100 million research and engineering program aiming to demonstrate proof of concept for light-propelled nanocrafts. These could fly at 20 percent of light speed and capture images of possible planets and other scientific data in our nearest star system, Alpha Centauri, just over 20 years after their launch. The program will be led by Pete Worden, the former director of NASA AMES Research Center, and advised by a committee of world-class scientists and engineers. The board will consist of Stephen Hawking, Yuri Milner, and Mark Zuckerberg.”
Keith’s note: I asked NASA for a comment on the Breakthrough Starshot announcement. They replied: “In 2015, the NIAC program selected University of California, Santa Barbara Professor Philip Lubin’s study on directed energy propulsion for exploring other worlds. NASA is pleased to hear that Professor Lubin has received external funding to continue the work started in his NIAC study. When the study’s final report has been cleared for 508 compliance, it will be posted online here. The NASA Innovative Advanced Concepts (NIAC) program focuses research on futuristic but technically credible concepts that could one day “change the possible” in aerospace.” I have asked for a copy of this report – I do not need a 508 compliant version. This is a hot topic right now. Talk about a cosmic spinoff.
Keith’s update: According to NASA: “Professor Lubin actually does a really good job of keeping everyone updated on his own page. His report can be found here.”
Not a bad idea, although getting data back from them might be a challenge. It makes sense – you want your interstellar probe to be as small as possible to do the tasks it needs to do, because that reduces the amount of energy necessary to get it to its destination.
Not a bad idea at all. To be fair, it also isn’t an original one (it’s been floating around in science fiction stories for decades) but there’s nothing wrong with that. Also borrowing from the ideas which have been floating around, communications could use the launch laser. By tacking, the spacecraft could modulate the laser light reflected back towards Earth, and basically tap out Morse code to an observatory. Another issue (also not an original one) are the political and military aspests: How happy would another country be, about building a 100 GW output laser array designed to target spacecraft? I think that more-or-less defines a violation of every treaty or agreement regarding anti-satellite weapons.
I thought about that too. Would it be destructive if it pointed at a satellite? Or if one went though it’s beam? Maybe not if it will point at a nano craft without damaging it, but I guess I don’t know the design. Will they have to monitor beam path and turn it off when/if something passes through?
Cool stuff
See: http://www.popsci.com/solar…. The power density in the beam here would be much higher. One advantage of pre-launching the tiny satellites and accelerating them in just a few minutes is that one can plan a launch window with no weather, no satellites in the path of the beam.
I wonder if they could “daisy chain” the data. Launching hundreds of the tiny satellites, with staggered release over a few years, each would only need to be able to contact the one behind it, instead of all the way back to Earth.
Possibly, but the tiny size of the spacecraft would seem to make any directional transmission of data difficult, to say the least.
it’s a very “nice” (as in super interesting and hard) problem, with lots and lots of challenges…! Just for reference: with a 1 gm probe, at 20% of c, the kinetic energy works out to be about 1,800,000,000,000 Joules, if I did that number right. Time to accelerate determines the g-loads on the sail and payload combination, and the laser output power required. If the acceleration must occur in 5 minutes or so, then that is quite hard. Also, concerning communications: with an area of about 100 meters, and assuming perfect reflection at 4-plus light years will yield the scale of the detection challenge for a reflection-based communications approach. The available time for the data collection and transmission will be another challenge: a probe of this type would take only hours to go through the Alpha Centauri system. And on the far side, reflected light might be lost in the glare of the star. Etc.
Nuclear rocket is the way to go.
At least with a nuclear spacecraft you have a readily available (high) power source to use to power a transmitter to (hopefully) get the data back to earth.
I remember reading an article in Discover magazine(20 years ago, wow)about this very subject. Basically the scientist/engineer came to the conclusion that the only way to get to the nearest star systems was via a “nano” sized probe.
It was a fun article, back then it seemed so utterly unrealistic..
Reminds me of how we saw self-driving cars back in the day, imagining some sort of wire or sensor embedded in roads for cars to ‘read’. Of course nobody predicted GPS systems (now, what three and counting?), plus radar affordable enough for production vehicles, plus other sensors and cameras that use the existing environment for piloting. Now Tesla on autopilot pretty much drives itself, at least on the freeway, although the car is still tentative. But the tech is coming.
Okay, I found the Discover magazine article(Oct, 95) discussing several different ways to send spacecraft to the nearest stars:
http://tinyurl.com/6c2dsp
“After meeting for several days with experts from all walks of space travel, Belbruno concluded that there is a practical way of overcoming Einstein’s special relativity theory and, with a reasonable amount of energy, getting a spaceship to the stars. What would solve the problem, says Belbruno, would be to make a spacecraft about the size of the head of a pin. A nanotechnology spacecraft.”
Another important question is: how to slow down at the destination. This idea has been around but what is the point of screaming through the destination system going that fast??? (As John Mankins points out). Could we possibly sense something useful?
A really fine (and very recent) science fiction novel on this general topic is “Arkwright”, which I highly recommend…
The light-sail is basically a boosted solar sail, so light pressure from the destination stars (and A-Centauri A/B is >200% Sol output in total) will be the main decelerator. Mostly, though, it will be zip through the system and take photos of pre-determined high-probability planet locations, a bit like how the early Pioneers and Mariners didn’t enter orbit around their target objects.
I wonder if there would be any way to use the laser to assist in actually slowing the probes, much like sailboats are able to use the wind against itself by adjusting the sails to slow the vessels.
Or for that matter, as the probes get closer their destination, they might even attempt to use the Centauri solar winds to assist in slowing down (not significantly, but enough to turn a potential flyby of a few hours into one that may a couple of days or even weeks.
Solar sails can “tack” but not “against the wind” like a sailboat can, the sails operate on very different principles. They can raise or lower their orbits, but not fly towards the Sun.
Also, it’s a common misconception that solar sails use the solar wind, they do not. They use photon pressure from sunlight.
That makes sense. Still that brings the second thought that as these probes get closer and closer to the Centauri system, the opposing photon pressure from multiple sources (A, B & Prx Cent) may cancel out the long-distance laser push, and then even start to very, very, very, slowly provide a deceleration. Nothing great, but perhaps just enough to allow for a system-wide loiter time that’s longer than a feared couple of hours.
They might even be able to slow down enough to be captured into solar orbit, but that would probably involve some very long swings around the star as it slows down.
Good strategy to gamble with. Considering the plan is to launch hundreds, even thousands of these nano-probes… and even assuming an 80+% attrition in getting there (not just interstellar dangers, the Centauri system has its own Ort cloud(s) and Kuiper belt(s)), I wouldn’t put it past the Mission Controllers to attempt having at least half of the remaining fleet make the attempt.
After a 20-yr voyage, what’s another 5 years? Even more so, with very long swings come multiple opportunities for the same individual probes to view our neighbor’s system. I would also suggest for a swarm that’s arriving, they’d take varying paths to do their swing-about maneuvers.
But now new complication may arise with the fact that with these orbital swings means the probes aren’t flying in a straight line, so the lasers from ~4.3 LY away would have some very fine directional tuning to follow. Of course, by then, the probes could just take their main power from their host suns and not need Mother Earth to push them anymore, but still to maintain a TM lock on Home. We’d need only to listen, watch and learn.
Yeah, I don’t think lasers based in our solar system are going to have any effect at that distance, they’d have to use the light from whichever Centauri star they are aimed at.
One would assume – hope – that while designing and building this swarm of “Earthian Space Locusts”, that there would be equal effort in scrutinizing the three stars for absolute confirmation of planets, and type them for future visits. I’d love to hear of an Earthlike planet that is in fact EARTH-like, to focus our probes’ attention.*
A & B Centauri are a binary pair, and while there is some indication of planets there, the candidates are hellishly close. Personally, even though it’s a red dwarf, I’m rooting for little Proxima; it’s a closer and it has just as much a chance (maybe better) than its binary neighbors.
*- This brings an interesting question:
How much kinetic energy would a nano-probe produce, if it weighed ~2-5 lbs (coke-can instrument package PLUS don’t forget the entire sail), impacting a planetary surface, going 0.2 Light-speed? It would be bitterly ironic to discover Centauri-sauruses seconds before rendering them extinct! (Hmmm…. maybe we should take another look at that crater in S. Mexico)
Well, if the planet has life it will also have an atmosphere which would decelerate the nano-probe pretty effectively.
I wouldn’t doubt an atmosphere would slow the probe, but barring effective deceleration by the host sun, the probe would come in at 0.2 LS (20%) = 37,256 mps or 134 Million mph (rounded down). If the host sun was able to slow down (w/o laser assist) to let’s say very optimistically: 0.01 LS (just 1%), that makes it 1,862 mps (or a measly 6.7M mph).
Even if the probe disintegrates before hitting the ground, the shock wave would leave a telling farewell message. Remember that space rock that blew apart over that populated Russian area? No damage by the physical mass, but the overpressure alone left a nasty widespread mark when it reached the ground.
OTOH, given the probe sizes and the vastness of space, the odds of an intersection with a planet would be probably a million times higher than if another asteroid smacked us again. Plus I’d bet our astrophysicists (and software engineers) would be advanced enough by then to ensure no probe would get THAT close to a planet!
I think even 0.2 c would only result in a bright flash on the ground, (with reference to https://what-if.xkcd.com/20/ I think the micro-probe would pretty much pass through the atmosphere like it was nothing) but nothing on the scale of a civilization ending impact, the micro-probe just isn’t massive enough for that.
Referring to https://what-if.xkcd.com/20/ I think at 0.2 c the micro-probe would pretty much pass through the atmosphere like it was nothing
Found the page I was looking for earlier on Solar Sail “tacking”
http://wiki.solarsails.info…
I seriously can’t see this idea going past the discussion phase and a few glitzy conferences. Photon thrust efficiency is very low at first (v/c) so hitting the nanosat with a short pulse of light once a day will not increase the velocity very quickly. Any probe sent would be tiny and not able to transmit back to Earth. So the best that could be obtained would to be send a dinner invitation to distant aliens.
Remember that the lasers will be acting as a booster on top of the extant solar light pressure. That said, yes, the best idea would be to send the probe carrier to EML-1 to reduce the Earth escape energy requirement.
Recalling the words of Carl Sagan: “billions and billions…!”
They are going to need those “fast charging batteries”! Hopefully Musk will by the time of launching these will have shrunk the power source technology the size of another chip…
AND have it be capable of soaking up some of that laser to maintain some internal heating for the probe to survive the long interstellar trip between suns…
AND also be able to last at the 20-30 years to get there (plus margin to permit actual science)
Actually, that would be another use for those sails, besides catching lasers is to also collect some solar rays – an not just from our end, but eventually they could find themselves grabbing some extra power from the Centauri suns!
Finally, some folks with a grand vision, commitment and money to back it up….!!! More power to them.
I would think that probes this tiny would probably not have the ability to do much in the way of remote sensing like looking for planets or gathering data about a star they are whizzing past. I would think more mass would be needed for that. And as mentioned any data coming back would likely be drowned out by radiation since any receiving antenna would have to be pointed directly at the star.
But if the probes were at least capable of gas sensing this might be a good way to investigate the heliopause and interstellar space.
Modifying the present nanoprobe concept for humans might take some doing. AIUI, the boost phase is 60,000 g for 2 minutes…
I’ll be the contrarian one here, playing Debbie Downer, in the middle of all this positive energy and enthusiasm. Sure, efforts like this “StarShot” make for great gatherings, sort of like book of the month clubs, or comic-cons, where we all get to meet people who love what we love and talk about it and analyze it endlessly.
Not that I wouldn’t enjoy that myself. I’d have a blast!
I’ll hope they realize that to keep up interest they have to show some near term real work, at a steady pace, with real stuff in space, with who knows what pushing along. Otherwise this type of initiative quickly devolves into mensa-like gatherings with pretty pictures and Teddy-chats and lots of deep-talk, over beer.
I’m reminded of all the message-in-a-bottle sci-fi out there (Lure, Existence, Rollback, etc.) which has held my attention well enough to enjoy, but which always flames out at the end. These are always the lame story endings consisting of just philosophizing and summarizing the previous 400 pages of what-if. After all, it’s when Bowman (2001) or Arrowway (Contact) get to go on the trip themselves that we have a really good story.
If we could build a 1GW laser in Earth orbit or on the moon, it would serve a number of purposes. It could deorbit spacejunk and cleanup Earth’s orbital debris field. It could change the trajectory of asteroids (or even comets) that threaten Earth. AND it could propel probes to the far reaches of the solar system or other star systems. And for a method of slowing down at the destination using a solar sail, just read “The Mote in God’s eye” by Pournelle/Niven. In that story, the “primary solar sail” separates and reflects the focused light back on to a secondary sail that decelerates the payload. Of course the primary sail (with no payload now) will begin accelerating away rapidly.
If you imagine a one gram spacecraft flying by the Earth at 36,000 miles per SECOND, what useful things would you learn about Earth during that encounter? What kind of science payload could you fit into the fraction of a gram of spacecraft mass not taken up by essential systems? Perhaps the money would be better spent to place a very large telescope in Earth orbit, which will probably collect more useful information about any planets in that star system.
Using the radiation pressure from Alpha Centauri to slow the spacecraft or capture it into orbit seems unlikely, given that the radiation pressure is only significant very close to the parent star. You will not be able to start braking while crossing the system’s Oort cloud, and the density of starlight even close up to the star is probably much less than the energy density of the laser that propelled it on that journey in the first place.
Speaking of the laser, since Alpha Centauri is not visible from the USA, the laser will need to be located in the southern hemisphere. Perhaps Australia has a close enough relationship with the US Government to be allowed to host the laser system. I’m guessing that ITAR will kill the project before it gets started since US researchers will be prohibited from discussing their ideas with foreign counterparts.
So the laser light that spills over past the probe would arrive at Alpha Centauri well ahead of the probe. The Mote in God’s Eye has been mentioned. Recall that a laser beam from the Mote planet (operating for much longer than a few minutes, true) was easily noticed by humans. Stephen Hawking, take note.
Some of the technologies he needs would have wipe spread use more locally before they were used for this scheme. For example, he needs high beam quality CW lasers some 100x cheaper (per unit of power) than what we have now (down to $0.10/watt). Placed in orbit (or, at least, beam directing mirrors placed in orbit w. ground lasers), these would enable laser-powered aircraft with unlimited range and no CO2 emission.
I would be a little worried about a gigawatt laser beam pointed downward and sweeping across the country tracking a plane. However the basic principle of multiple lasers transmitting in phase has extraordinary range and power and many applications.
You could choose a wavelength that is absorbed by water vapor, so it could power a plane at cruising altitude but not lower in the troposphere. Climb to cruise altitude using batteries.
BTW, the power of the largest commercial jet engine is ~70 MW.
Eccentric billionaire, crazy project, hazy justification… Anyone else thinking of Howard Hughes and the Glomar Explorer ‘mining for manganese’ cover story? What’s really going on here. Did Milner’s ET project make contact and this giant laser is the communication terminal or homing beacon?