Communication | Pointing transmitter towards earth

Finding the Earth should be reasonably straightforward, given its proximity to the Sun, which would be bright from the vantage of Alpha Centauri. The on-board star tracker would also be useful, as would locking onto the Starshot laser system.

It may also be feasible to send commands and even reprogram the entire nanocraft via the Earth-based laser system. The angular diameter of a diffraction-limited beam, at a wavelength of 1 micron with a meter-class antenna, is on the order of 0.1 arcseconds. Pointing to this precision could be achieved by using the photon thrusters.

Research:

Nov 05, 2016 04:36 Breakthrough Initiatives Posted on: Breakthrough Initiatives

RE:
"Apr 13, 2016 09:08Rj HillanPosted on: Breakthrough Initiatives
I believe the best method would be using a separate and smaller information based laser system. since we already have the capability to use lasers as mediums for data, we could have a small satellite network set up and launched that use this laser data-transmitting technology to constantly maintain a connection with the nano spacecraft. if we could use the laser to maintain a near constant connection, the nano probe could use the laser as a guide to keep itself centered and on course. more would have to be thought about this if it was going to be used. but the concept of almost having a laser to always tell the probe where to point seems like it would remove the need for a few sensors, reducing cost and lightening the nano craft."

Answer:
Using the lasers near earth as a beacon is wonderful idea and we will include it in our planning.

- Avi Loeb, Breakthrough Starshot

Nov 05, 2016 04:36 Breakthrough Initiatives Posted on: Breakthrough Initiatives

RE:
"Apr 14, 2016 14:16Nemo in NihilumPosted on: Breakthrough Initiatives
Well, regarding the relays, please consider my post here:
https://breakthroughinitiatives.org/index.php?controller=Forum&action=viewforum&id=13&page=2

Regarding the LaserLightHouse ;) (guiding beam) described by Rj: An interesting Idea, to keep track of the Sol System (although the spectrum of our Sun would be usable as well) and maybe Earth. But don't forget the motion of the celestial bodies and the limited speed of light. The direction from which the laser is received, is not the straight direction to earth and most likely its vector does not point strait to our fly by area. Whereas I notice the necessity for me to read up on how to calculate he motion of solar systems on an intersolar scale.

Answer:
Using the laser beacon is a great idea. At that particular frequency the laser will be very bright versus everything else around. A problem with using sunlight is it covers a broad frequency band and difficult to distinguish from other near by sources.

- Avi Loeb, Breakthrough Starshot

Nov 05, 2016 04:37 Breakthrough Initiatives Posted on: Breakthrough Initiatives

RE:
"Aug 24, 2016 19:17Nicola Petts (nee Waite)Posted on: Breakthrough Initiatives
Hi 

Firstly let me say I'm not a scientist, I write science fiction in my spare time. I always think of science fiction writers as unofficial theoretical physicists (lol).

I would like to add a suggestion, not wanting to waste time as what I suggest may not be technically possible now but what if......
The initial craft was designed almost like a set of Russian Dolls, Craft 1 is launched with a laser from Earth to push it on its way. At a pre-determined distance it ejects a smaller craft 2 and using an on board laser pushes craft 2 on its way. Craft 1 remains fixed in space to act as a relay for information from craft 2. Similarly, craft 2 ejects craft 3 and pushes it on its way, remaining in position e.t.c until all craft are deployed and the target acquired."

Answer:
Thanks for the interesting ideas. In the rocket world this is called staging and works very well. Until someone is able to produce a low cost low mass energy source this approach will be difficult.

- Avi Loeb, Breakthrough Starshot

Nov 05, 2016 04:37 Breakthrough Initiatives Posted on: Breakthrough Initiatives

RE:
"Aug 29, 2016 22:31Joshua WestPosted on: Breakthrough Initiatives
If using the photon thruster is enough just be able to have enough time (which is dilated) to be able to counter-act the rotation of the camera which will change the orientation of the laser. Time to correct will be small if you are aiming at the star or another planetary body with only 4 thrusters to get back on target."

Answer:
Thanks for the interesting suggestion.

- Avi Loeb, Breakthrough Starshot

Nov 05, 2016 04:38 Breakthrough Initiatives Posted on: Breakthrough Initiatives

RE:
"Aug 31, 2016 16:27Elancha SecurityPosted on: Centauri Dreams
I'm not a physistist. But, why cant we launch like 10 or a couple 100 of these and have each one positioned in a line so that the main system relays the data to those closer to earth until it arrives. Wouldn't it make a signal faster if if was transferred for device to device instead of transferring once all the way to earth? This is a question that has been stuck in my mind for quite some time. I'd love a good answer."

Answer:
Having a series of relays would be slightly slower than a direct beaming. With relays the signal would first have to be received by the relay then retransmitted. Each of these steps takes some time. The single would be slowed down by a second or two as it goes through the relay as compared to a direct transmission.

- Avi Loeb, Breakthrough Starshot

Nov 05, 2016 04:38 Breakthrough Initiatives Posted on: Breakthrough Initiatives

RE:
"Sep 15, 2016 13:28Jacopo MaroliPosted on: Breakthrough Initiatives
on this scale a piezo motor would be more feasible https://en.wikipedia.org/wiki/Piezoelectric_motor
It consumes few energy, can be scaled as small as needed, can operate at high temperature and in presence of strong magnetic fields"

Answer:
Thanks for the interesting suggestion.

- Avi Loeb, Breakthrough Starshot

Nov 05, 2016 04:39 Breakthrough Initiatives Posted on: Breakthrough Initiatives

RE:
"Sep 23, 2016 20:19garypwilson@gmail.comPosted on: Centauri Dreams
Considering that we are considering this a logical and viable path of endeavor, would it not be amiss to consider monitoring our own local neighborhood for incoming nanocraft,surveying our neighborhood. Considering our recent discoveries of a multitude of exoplanets? It seems logical to assume that if this is the OSPF (Open Shortest Path First), we could assume that n other intelligence would do the same? Is it possible that we would find local nanocraft before our nanocraft got there?"

Answer:
This is a very interesting line of thought. It would be very difficult to detect a 1 gram very cold craft traveling at 20% the speed of light entering, the solar system from random directions. Regarding the detection of the beamer, see https://arxiv.org/pdf/1508.03043.pdf

- Avi Loeb, Breakthrough Starshot

Nov 05, 2016 04:39 Breakthrough Initiatives Posted on: Breakthrough Initiatives

RE:
"Sep 29, 2016 16:48jrwoods57@gmail.comPosted on: Centauri Dreams
If we take a low estimate of a 1W laser (on each nanocraft) with a 1cm waist, the divergence of the laser beam will make the area of the beam so large after 4LY that, as long as the beam is in the direction of the sun, we should be fine. The trick will be separating the signal from the output of the star. This should be aided by the fact that the laser signal will be monochromatic and polarized."

Answer
We agree this will be a very difficult problem but possible. We are also considering trying to create a large beam.

- Avi Loeb, Breakthrough Starshot

Dec 16, 2016 02:11 desk@mindey.com Posted on: Breakthrough Initiatives

So, I'd like to share this idea here, as it is probably closest to this topic.
https://www.halfbakery.com/idea/Extraterrestrial_20Nanolaser_20Transceivers

In short, the idea was that since we have nano-scale lasers available (see ref.), a hypothesis is that we would be able to accelerate them to relativistic speeds, orient and arrange them in a self-aligning sequence in space, forming a chain of transceivers, working like an optic-cable.

If each transceiver were to use its lateral side to collect data, we might not even need to send a gram-sized probe, because from a very long chain of lateral side views of nano-probes we could have enough information to reconstruct the target object.

The idea is akin to "active telescopy" or "particle telescopy", because just like in electron microscopy, we would be using the device-generated particle beam directed towards the targets to collect data about them.

Ref: https://www.utexas.edu/news/2012/07/26/smallest-semiconductor-laser-created-ut-scientists/

Jan 05, 2017 03:15 Breakthrough Initiatives Posted on: Breakthrough Initiatives

RE:
"Dec 16, 2016 02:11 desk@mindey.com Posted on: Breakthrough Initiatives"

Answer:
Thank you very much for your help. This problem is one of the top problems we face in sending a probe to our nearest star. It maybe that the proper answer is to set up a series of relays over the 4 light years. However, the issue of redundancy is problematic. If one of the relays fails, the entire string fails. It may be possible to define a scheme whereby if the first relay fails you look to the second vehicle and just skip over it. Questions remain however; How many failed relays in a row can the system withstand and still achieve the communications goals; how robust of a system will be required? This is one of the top three challenges we are trying to address with our work. We need all the help we can get and appreciate any brain cycles you can help with.

- Pete Klupar, Breakthrough Starshot

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