Team designing laser propelled nanocraft. Reach Alpha Centauri in 20 year flight time

[gary]

In a June 6 2016 article in the Institute of Electrical and Electronics
Engineers (IEEE) Spectrum Magazine, Zac Manchester, a Postdoctoral Fellow
in the Agile Robotics Lab at Harvard University, outlines a project
to send nano-satellites, only weighing a few grams each, to Alpha Centauri
with a flight time of 20 years.

Originally Posted by Zac Manchester, IEEE Spectrum

In the 1960s, the physicist and space futurist Robert Forward proposed a radical method of sending a spacecraft to the stars. Roughly speaking, the idea was to attach the spacecraft to a large light sail, and then push it by illuminating the sail with an enormous laser. Forward suggested that a powerful laser could accelerate a spacecraft to a large fraction of the speed of light, allowing it to reach some of our nearest stellar neighbors within a few decades.

Until very recently, this idea remained solidly within the realm of science fiction. But today the outlook is beginning to change. In April, the physicist-turned-internet-billionaire Yuri Milner, together with Stephen Hawking and other notable scientists and engineers, announced that the Breakthrough Foundation would begin funding work on the concept of a laser-propelled starship, with the long-term goal of reaching the closest neighboring star system to our own, Alpha Centauri. Their initiative, dubbed Breakthrough Starshot, is a Silicon Valley take on Forward’s vision that imagines shrinking the spacecraft down to a mass of a few grams. A fleet of such “nanocraft”, each tethered to a light sail a few meters wide, could be economically launched into space and then accelerated toward Alpha Centauri with a terrestrial laser system. Illuminated by tens of gigawatts of laser light, the miniature spacecraft would reach 20 percent of the speed of light in about 4 minutes. After a 20-year cruise, they would zip through the Alpha Centauri system in a few hours and send data and images back to Earth from the brief encounter.

Article here -
http://spectrum.ieee.org/tech-talk/a...e-a-laser-beam

[glend (Glen)]

What are the laser arrays going to do to astronomy? Are these visible light lasers? What about the atmosphere? Birds?
Would space not be a better place for them? Orbital arrays, or ultimately put the laser array on the Moon, nuclear powered, they could be operated remotely.
As an astronomer the idea of laser arrays firing through the atmosphere concerns me. I know the effect a single low miliwatt laser can have in a night sky,.what happens when a piece of space junk passes through the light beams, and reflects back to earth - ruin your images, blinds you if your a visual astronomer. This concept needs a major environmental impact study.

[skysurfer]

When you read the article there are lots of challenges. Interstellar dust may (and probably will) destroy the nano spacecrafts.
And corrections afterwards are obvously impossible. Even with New Horizons that is difficult.

In case you’re wondering, some care will probably need to be taken not to hit airplanes or satellites with the laser beam, although the situation won’t be quite as dangerous as it might seem at first.

And 100GW on one square km equals to 100kW on one sq meter which is 100 times the Sun's radiation and can really pose a harm to aircraft or satellites. Looks something like the 'heat rays' in HG Wells 'War of the Worlds'.
So this is not really proven technology.

And why 1/5th of light speed in 4 minutes, why not (almost, e.g. 90%) full light speed in, say, 6 minutes ?

[bojan]

SF.
To Alpha-Centaurians, this will look something like the green Mote in the God's eye

[Shiraz (Ray)]

Originally Posted by skysurfer

And why 1/5th of light speed in 4 minutes, why not (almost, e.g. 90%) full light speed in, say, 6 minutes ?

I think because it gets a long way away real quick - you only have a very limited opportunity to give it any propulsion, before beam spread with distance reduces the laser power received by the sail.

[gary]

1 hour 17 minute video conference on the project here, including
speakers Yuri Milner, Stephen Hawking, Freeman Dyson and Pete
Worden, former director of the NASA's Ames Research Center -
http://livestream.com/accounts/18650072/events/5143435

[gary]

Back of the envelope comparison to Space Shuttle energy usage.

The Space Shuttle SRB's delivered 9.875GW for 123.7 seconds
and the SSME delivered 1.9875GW for a maximum of 761 seconds.
A total of around 2.73GJ of energy.

A 100GW laser for 240 seconds is equivalent to 24GJ.

[Steffen]

If they want to put that terrestrial laser anywhere in Australia they better join a local astronomy club, or the cops will come and confiscate it.

[multiweb (Marc)]

Originally Posted by Steffen

If they want to put that terrestrial laser anywhere in Australia they better join a local astronomy club, or the cops will come and confiscate it.

[janoskiss (Steve H)]

Hopefully the Planetary Society will test fly their first lightsail craft later this year or next year. Bill Nye (the CEO) sometimes talks about his dream of a laser on the Moon to propel such a vehicle. The PS seems like a pretty cool organisation and around 50k ordinary people have contributed to their first lightsail craft. It's like a massive global community project. For the foreseeable future they won't use lasers but only the Sun.

Check it out: https://www.youtube.com/watch?v=bI_FH_2Cqr8

[rustigsmed (Russell)]

Originally Posted by Steffen

If they want to put that terrestrial laser anywhere in Australia they better join a local astronomy club, or the cops will come and confiscate it.

[iasuka (Dmitry)]

Originally Posted by skysurfer

When you read the article there are lots of challenges. Interstellar dust may (and probably will) destroy the nano spacecrafts.

That probably can be overcome by sending a whole lot of those at the same time, or in batches. "Nanocrafts" will probably be relatively inexpensive so it should be economically viable to build a lot. Even if only a few make it to Alpha Centauri in one piece it's mission accomplished.

[AussieTrooper (Ben)]

What if it goes off target, and Alpha Centaurians think we are attacking them with lasers?

[mental4astro (Alexander)]

Ok, say we can get a nanocraft of a few grams out to Alpha Centauri in 20years - we are forgetting one thing, what sort of transmitter will these craft have to relay back any images that they take? With such a small craft, the battery technology involved to keep a charge for so many years, with enough power, and small enough to not be too much of a burden on the gross weight of the craft, that's a hell of a Motorola! And then we need to listen out for it... And it's not just a Sputnik-like beep, beep, beep. We are expecting intelligable data to be sent back. Plus the cameras and on board CPU will be effectively at absolute zero for the vast majority of this flight time and we then need to have these things autonomously wake themselves from their cryo-sleep. Just about all the interplanetary spacecraft we have now use nuclear power to provide working heat to these craft, and these a not power packs of a few grams.

Anyone thinking about this aspect?

Otherwise we are just throwing paper aeroplanes at Alpha Centauri...

Just playing Devil's advocate.

Try explaining to the coppers "Really! We are just launching nanobots! Honest. Yes, with that bloody big laser... "

[bojan]

Alex,
You are spot-on here.

One more detail: to obtain the images of reasonable resolution, the camera lens needs to be of a certain size.. unless those guys are hoping for some sort of integration technology that will use a movement of the sensor to compensate for it's small aperture.

To me all this seems to be just a publicity stunt...

[Eratosthenes (Peter)]

...at roughly 21.5% of the Speed of Light these little &%$#*@ can really move. About 18,000 times faster than the Voyager probes. Relativistic dilation effects generally come into play at speeds over 0.1c...

And lets not forget when this nano drone rocket reaches its nearest star destination of Alpha Centauri, it will take 4.3 years for the signal to reach earth telling us that it had arrived. I am assuming this nano %$#@ can send messages, images etc?? If not what is the point?

[ZeroID (Brent)]

Have to be careful here, the Alpha Centaurions might start throwing stuff back ..
'You started it, take THAT !!! "

[xelasnave]

Well we have to start somewhere just like the Wright Brothers.
An interplanetary war could be a good thing to unite our world and see full and efficient employment.
They will probably build something faster which will overtake the current craft...
Interesting that such a project is being considered.
Alex

[Eratosthenes (Peter)]

NASA designing nano-starship which travels at 20% the speed of light

Published time: 12 Dec, 2016 16:50

https://www.rt.com/usa/370057-nasa-star-chip-hawking/

interesting update which includes a 1 hour 15 minutes video presentation by Hawking, Milner et al (note: nano-sized spaceship is not a spaceship having the physical dimensions of a nanometer or a billionth of a meter. It is small, but postage stamp sized - one centimeter or two.)

[AussieTrooper (Ben)]

Originally Posted by ZeroID

Have to be careful here, the Alpha Centaurions might start throwing stuff back ..
'You started it, take THAT !!! "

You can just see some Alpha Centaran sentry sitting at a desk on night shift when his instruments pick this thing up, but it's gone in seconds and nobody else noticed it....and now it's back to snooze time...