Sep 29, 2016 16:29 jrwoods57@gmail.com Posted on: Centauri Dreams

Has the concept of a redundant sail been considered? If the initial light sail can withstand the intense initial laser acceleration, maybe it could be maintained long enough to confirm survival, velocity and direction of travel then discarded with a new sail folding out upon arrival to transmit back to Earth. Also. could the shape of the nanocraft (discussed above, I believe) be such that impacts would be at a high glancing angle.

Sep 29, 2016 22:48 Nathan Bemis Posted on: Breakthrough Initiatives

If you streamline the whole craft for cruise phase, with the chip itself at the tail end, you'll only need impact protection at the leading nose of the craft unit. This will achieve minimal protective coating weight added to the craft and allow for preservation of the sail for other later purposes. Now that the area for this impact protection is minimized, You should be able to consider even thicker and stronger materials for the job.

Nov 05, 2016 03:07 Breakthrough Initiatives Posted on: Breakthrough Initiatives

RE:
"Sep 29, 2016 16:29jrwoods57@gmail.comPosted on: Centauri Dreams
Has the concept of a redundant sail been considered? If the initial light sail can withstand the intense initial laser acceleration, maybe it could be maintained long enough to confirm survival, velocity and direction of travel then discarded with a new sail folding out upon arrival to transmit back to Earth. Also. could the shape of the nanocraft (discussed above, I believe) be such that impacts would be at a high glancing angle."

Answer:
These are all good ideas that need to be balanced against the mass requirements. It is not clear that one can achieve the mass goals with two sails.

- Avi Loeb, Breakthrough Starshot

Nov 05, 2016 03:08 Breakthrough Initiatives Posted on: Breakthrough Initiatives

RE:
"Sep 29, 2016 22:48Nathan BemisPosted on: Breakthrough Initiatives
If you streamline the whole craft for cruise phase, with the chip itself at the tail end, you'll only need impact protection at the leading nose of the craft unit. This will achieve minimal protective coating weight added to the craft and allow for preservation of the sail for other later purposes. Now that the area for this impact protection is minimized, You should be able to consider even thicker and stronger materials for the job."

Answer:
We consider this an excellent approach. We are also trying to optimize the protective material such that is may serve many purposes. Maybe there is a way to harvest energy for the erosion of this materials. You can read some related discussion at the recent paper, https://arxiv.org/pdf/1608.05284.pdf

- Avi Loeb, Breakthrough Starshot

Nov 27, 2016 21:23 Nikita Kiselov Posted on: Breakthrough Initiatives

Would it be possible to have an extremely strong magnet at the front of the craft?

It would repel the positively charged protons and attract the negatively charged electrons. This avoids the impacts of the much heavier former particles, and additionally attracts the latter only. If these electrons impacted in a special area, it would create a current, and another current could be induced in coils by the passing by protons.

The magnet would strongly affect the starchips electronics, and thus it is unclear how to install it while minimally affecting the area at its back. Additionally I am unsure whether it is possible to manufacture a magnet strong enough to alter the trajectory of particles at relativistic speeds.

However, if these two challenges were solved, there should be less shielding requirements and an additional source of electricity, at possibly quite low mass costs.

I must admit that I lack the knowledge to calculate the needed strength of the magnet and the feasibility of the whole idea, so it may very well turn out useless.


This would be another idea in the direction already proposed earlier by Micheal Million:
May 26, 2016 13:42 michael.million@sky.com posted:
"If we applied a powerful positive charge to the rim or leading edge of an edge on sail it would discourage the more massive positive ions from hitting the sail, but attract the less massive electrons. Very high voltages can be created on sharp edges and therefore create high deflection forces."

Jan 05, 2017 02:18 Breakthrough Initiatives Posted on: Breakthrough Initiatives

RE:
"Nov 27, 2016 21:23 Nikita Kiselov Posted on: Breakthrough Initiatives"

Answer:
Thank you for your help in this matter. The scheme for avoiding impacts along the path is very dependent on what one considers the makeup of the InterStellar Medium (ISM) is. If it is mostly dust and very few ions or subatomic particles, then charge control will be of little use. However, if the ISM is dominated by gas, protons and electrons then charge control and magnetic control maybe very useful. It seems we need to first make assumptions about the ISM then we can design an approach to conquer the hazard. It will be difficult to control the charge in deep space, however there is interesting work being performed at Stanford using LED along these lines. The following paper discusses the space experiment: https://arxiv.org/abs/1202.0585

- Pete Klupar, Breakthrough Starshot

Sep 30, 2019 00:34 cewcathar@hotmail.com Posted on: Centauri Dreams

Hi,
On
Nov 27, 2016 21:23
Nikita Kiselov
wrote:
>Would it be possible to have an extremely strong magnet at the front of the craft?

>It would repel the positively charged protons and attract the negatively charged electrons. This avoids the impacts of the much heavier former particles, and additionally attracts the latter only. If these electrons impacted in a special area, it would create a current, and another current could be induced in coils by the passing by protons.

>The magnet would strongly affect the starchips electronics, and thus it is unclear how to install it while minimally affecting the area at its back. Additionally I am unsure whether it is possible to manufacture a magnet strong enough to alter the trajectory of particles at relativistic speeds.

>However, if these two challenges were solved . . ."

I assume you all have seen the discussion of shielding a toroidally-shaped craft using superconducting wires strung around the circumference of the ship: http://superdarn.thayer.dartmouth.edu/downloads/JSR09.pdf
The author suggests that the magnetic field inside the ship can go to zero by threading a few of the wires around the reverse direction.
This does not shield the sail however.
(I do myself also like Nikita wonder about a magsail-type coil at a craft front; or alternately a trio of 3-solenoid-shaped magnetic shields around the ship nose -- three will just fit if set just past the nose -- with a very reflective nose -- my idea is titanium plus nanondiamond nose coating so that some particles/radiation bounce some [I still do like copper barium; it is not a bad coating idea from what you say] -- I am not sure if either of these 2 ideas will work). Would neutrons change at all at 1/5 lightspeed collisions or whether they would still be just neutrons streaming? I imagine neutral atoms would ionize some and thus interact with magnetic shielding.
Best,

--C. E. Whitehead

Dec 20, 2019 18:47 Breakthrough Initiatives Posted on: Breakthrough Initiatives

This is an interesting approach. The difficulty we see in using it for our StarShot application is in generating, powering and maintaining a strong enough magnetic field in the gram-class nanocraft. Nonetheless, it would be useful for us to do some calculations as to what level of power and system might be needed.

S. Pete Worden
Executive Director, Breakthrough Starshot

Nov 15, 2020 01:10 John Weiss Posted on: Breakthrough Initiatives

put holes in the sail, or make the entire sail permeable, so dust just flies through it.

retract the sail when not in-use. (don't the earth lasers stop pushing it after some distance?)

Nov 15, 2020 01:14 John Weiss Posted on: Breakthrough Initiatives

"It is not clear that one can achieve the mass goals with two sails."
- Avi Loeb, Breakthrough Starshot

But if the first sail is discarded early in the flight, then you will achieve your mass goals for the duration of the flight.