Cruise | Interstellar dust

Based on estimates of the density of dust in the local interstellar medium, over the course of a journey to Alpha Centauri each square centimeter of the frontal cross-sectional area of the StarChip and lightsail would encounter about 1,000 impacts from dust particles of size 0.1 micron and larger. However, there is only a 10% probability of a collision with a 1 micron particle, and a negligible probability of impact with much larger particles.

A 0.1 micron dust particle moving at 20% of the speed of light would penetrate and melt the StarChip to a depth of order 0.4mm. To estimate scale effects, calculations were made assuming a 10cm X 0.1mm thickness. Traveling with the nanocraft’s edge facing parallel to the velocity vector would reduce the cross section to 0.1cm2, for a 10 cm StarChip with a 0.1mm thickness. A protective coating of beryllium copper could be added to the leading edge of the StarChip, as a sacrificial layer for additional protection from dust impacts and erosion. If needed, the StarChip geometry could be elongated (‘needle’ geometry), to further minimize the cross-section.

To mitigate the impact of dust further the sail could potentially be folded into a streamlined configuration during the cruising phase to Alpha Centauri. This would minimize the frontal area of the sail. The nanocraft’s electronics could also be designed so as to be less vulnerable to localized damage from dust.

The momentum kick from 0.1 micron dust particles is small, and its effect on the nanocraft’s trajectory might be compensated for by photon thrusters.

Comments (25)

  1. Breakthrough Initiatives:

    RE:
    "Aug 30, 2016 13:22Nathan BemisPosted on: Breakthrough Initiatives
    As included in the Atmosphere Challenge section, I suggest to change the shape of the chip to a thin tube/needle "bullet example" to minimize space debris and dust collision risk. Or have the components aligned and the chip formed into a long thin stick. We are going to see another advance in chip technology too. Intel is releasing chips that claim are 10x more durable, much more faster, and do not use transistors. The structure holding the cells read and transfers the information instead.
    You could have the sail operate like an umbrella, opened to receive the lasers then have it collapse/fold to lead and protect the nanocraft in addition to protection already included on the chip itself. 
    With the sail streamlined, dust impact protection would only need to be applied to the leading nose of the craft. Allowing the sail to be redeployed when needed since it should have not taken damage. Sail redeployment could be useful if there's a return plan, used to transmit data, and other purposes. 
    An idea for craft return: Perform an eventual "U-turn with thrusters perhaps?" and slowed with the laser array for recovery. If the chip is programmable enough, you can map a space grid to guide it to, from, and around objects and points of reference. If we figure out how to make it return and how to slow it, it can come to a stop and received at designated coordinates.
    **Has there been a review of an approach to have a laser source on the craft itself? This way it will provide MUCH longer term laser propulsion, near zero atmosphere interference, and could be reliably accurate on the sail. The heat onto the sail won't be as intense and there won't be as much g-force demand on the sail once in space since the onboard laser/s provide the rest. Then once at desired speed, the laser/s can point ahead of the crafts path to divert dust and particles.
    Could the LHC be an example to achieve relativistic speeds in space? Perhaps the laser light itself can be exploited inside of a mirrored device, in the same manner magnets propel particles in the LHC."

    Answer:
    Thanks for the response. The ideas on dust avoidance are excellent and will certainly be used in the analysis. For a recent study of the impact of dust, see https://arxiv.org/pdf/1608.05284.pdf

    We are open for ideas to slow the craft once in system. We have not found a viable alternative. Carrying a laser and the power source would make the craft to heavy using technologies avaialabe today. If someone invests a low mass power source it might make these alternative approaches possible.

    - Avi Loeb, Breakthrough Starshot

  2. Nathan Bemis:

    Thank you for your time and responding to all of us Professor Loeb,

    I hope the on board laser idea can be considered further. I believe there's lasers already in the design that will be used for transmitting data. What if these same lasers can be made to provide a secondary boost for the craft to reach its top potential speed and able to clear dust and particles further ahead in the crafts path?
    It's said laser propulsion is scalable to size and weight of the craft, this may be one exception to explore that may provide a safe voyage and have multiple purposes.
    Maybe the sail itself can use what ever energy it gathers along the way can help with providing power. I don't know how much heat is applied to the craft in cruise phase or how it can gather energy from star light and passing dust particles. Maybe Elon's battery company can figure something out. Another idea is a bacteria battery https://www.youtube.com/watch?v=lj23qMhpVcg It surely would be lightweight, but I don't know if it can be applied for use in a space environment. Perhaps another type of battery that can achieve the same thing.
    Could something like Vantablack https://en.wikipedia.org/wiki/Vantablack be useful for absorbing light for battery energy during cruise phase? Just a shot in the dark here.
    I feel a bit out of my league trying to propose ideas for this project. Like a 4th grader having a conversation with a teacher. The ideas may be vague or even flawed from the start to you and people on the project. It's a try anyways. It's humbling to see a couple ideas were on the right track to be solutions to challenges. I have read the pdf, not that I understood any of the equation examples or how in detail the explanations work. Good to see the research is being worked on and tested.
    Thanks again.

  3. Breakthrough Initiatives:

    RE:
    "Nov 05, 2016 16:57 Nathan Bemis Posted on: Breakthrough Initiatives

    Thank you for your time and responding to all of us Professor Loeb,

    I hope the on board laser idea can be considered further. I believe there's lasers already in the design that will be used for transmitting data. What if these same lasers can be made to provide a secondary boost for the craft to reach its top potential speed and able to clear dust and particles further ahead in the crafts path?
    It's said laser propulsion is scalable to size and weight of the craft, this may be one exception to explore that may provide a safe voyage and have multiple purposes.
    Maybe the sail itself can use what ever energy it gathers along the way can help with providing power. I don't know how much heat is applied to the craft in cruise phase or how it can gather energy from star light and passing dust particles. Maybe Elon's battery company can figure something out. Another idea is a bacteria battery https://www.youtube.com/watch?v=lj23qMhpVcg It surely would be lightweight, but I don't know if it can be applied for use in a space environment. Perhaps another type of battery that can achieve the same thing.
    I feel a bit out of my league trying to propose ideas for this project. Like a 4th grader having a conversation with a teacher. The ideas may be vague or basically elementary in design, but there it is. It's humbling to see a couple ideas were on the right track to be solutions to challenges. I have read the pdf, not that I understood any of the equation examples or how in detail the explanations work. Good to see the research is being worked on and tested.
    Thanks again."

    Answer:
    Thank you very much for your positive thoughts and ideas. This is a very difficult problem and we need all the help we can get.

    - Avi Loeb, Breakthrough Starshot

  4. Joseph Cyril:

    The vacuum created around the main chip ship or star shot would allow interstellar dust to be moved out of the way by launching othet star shots built with a different design and moving ahead of the main working star shot will create a trong vacuum clearing a bubble and a vacuum from interstellar dust, the other stat shot ahead or a few in formation may need a different composite material or shape if possible in trisngliaion fotmation ahead the main starshot. Basic synopsis laymens terms below.
    Proposal Summary
    Edit
    The "Chip Ship", which will allow a small craft the size of a paper clip to travel at the 1/4 speed of light faces failure before even being launched. I will go right to the solution. I believe if we launch similiar "Chip Ships" ahead of the one designed to record or investigate other planetary objects we can create a draft such as a draft as when race car drivers are racing and a car is in front of another car, it allows an opening because it is pushing air here on earth creating a non-resitant place therefore gaining acceleration for the vehicle. In space this would still work since instellar dust would be affected by the gravity of the moving objects ahead of the main "Chip Ship". The item would have to be of similiar design in order to be able to keep speed but made of a tougher material. I would also suggest a series of these ahead of the main ship along with slowing down the main ship slightly so that it would prevent it crashing into other "Chip ships" ahead of itself as they would be receiving interstellar dust which would cause it to slow down. More simulations need to be done this is one idea out of a few, the others do not seem to be viable at this time. Lastly, a magnetic charge pulse being released from the star shots ahead on the same trajectory may work.

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  5. Breakthrough Initiatives:

    RE:
    "Dec 07, 2016 01:59 Joseph Cyril Posted on: Breakthrough Initiatives"

    Answer:
    Thanks for your help. The idea of drafting is a good one. We need to develop a decent model of the InterStellar Medium in order to be able to predict the effect of sending a ship to clear a path for the Star Chip. Depending on the velocity, direction and density assumed various paths might be suggested. At this point, models need to be built with the appropriate assumptions to verify that it is possible to clear a path.

    - Pete Klupar, Breakthrough Starshot

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