Comments (28)

  1. Robert Clark:

    Don't know where to put this but I think it should also be investigated using self-assembly in space to get large spacecraft.

    The problem is small craft have a good area to volume ratio, and with volume as a proxy for mass, a good area to mass ratio. This is important for getting a high acceleration due to light pressure.

    However, one way to maintain the high area to volume(mass) ratio for a large craft would to keep the large craft very thin, just as thin as the small craft. The large mass is obtained by area dimension large.

    Bob Clark

  2. Breakthrough Initiatives:

    RE:
    "Apr 06, 2017 17:13 michael.million@sky.com Posted on: Centauri Dreams"

    Answer:

    Something like this may be possible. We are looking into many options for building and protecting the electronics.

    – Zac Manchester, Breakthrough Initiatives

  3. Breakthrough Initiatives:

    RE:
    Jun 06, 2017 02:56 Robert Clark Posted on: Breakthrough Initiatives

    Answer:
    You’re totally right about needing to keep the area to mass ratio very high. However, there are some other considerations when thinking about making the craft very large and thin. For example, material strength and structural stiffness.

    – Zac Manchester, Breakthrough Initiatives

  4. Pete Koziar Koziar:

    I think it's important that you choose a processor that's already space qualified, hopefully one that's already been successful. There's a time to go bleeding edge, and a time to go with what has been proven. This is a time to go with what's been proven.

    I agree with other comments that the more modern consumer processors have very small features that make them more prone to failure because of cosmic radiation.

    Considering the amount of funding that you have, and the tight constraints, you might want to consider a rad hard ASIC and implement something like a triply redundant processor core within it. There are additional aspects to improve reliability - ECC RAM, flash and processor registers, for example, plus a watchdog timer.

    The cold of interstellar space will be a real issue. It's really hard to get electronics to work below -40 degrees, so if electronics are expected to run, they generally need heaters.

  5. Pete Koziar Koziar:

    I did find this link to a paper on ARM ultra-reliable processors: https://ieeexplore.ieee.org/abstract/document/7575387?section=abstract

    The ARM Cortex R5 reliable processors are currently available for automotive applications. Here's a list of TI offerings:
    https://www.ti.com/microcontrollers-mcus-processors/microcontrollers/arm-based-microcontrollers/products.html#p887=Arm-Cortex-R4F;Arm-Cortex-R5F

    I don't, however, know if any of these are rad hard and space qualified, or, at least, able to be space qualified.

    I'm a minimalist at heart, and I try to do most of my designs with no operating system, where possible.

    The hardest part of this project, as I see it, will be navigation. There's no way to point the spacecraft accurately enough at launch to reach the target star, given all the unknowns about the interstellar medium (especially gravity gradients). The software will need to recognize the target and be able to control the spacecraft in order to reach the star itself.

    Then the challenge really begins, to pick out a planet in the habitable zone, and navigate close enough to get images. I haven't worked out how much thrust will be available from light pressure on the sail itself as it approaches the star, but hopefully, it will provide adequate maneuverability.

    Then the craft will have to have enough flash or RAM to store video images.

    Then it will have to orient itself on Earth with enough precision for a tight beam laser to be received here.

    It's not impossible, but also not easy by any stretch of the imagination.

  6. Atis Freimanis:

    I am assuming that it has been considered and likely rejected due to not being a long-standing field proven technology, but I am wondering why quantum entanglement is not more visible in the discussions as a means to potentially eliminate the 4 year delay in receiving information and possibly offer real time communications and navigational control?

    https://en.wikipedia.org/wiki/Quantum_entanglement

    Also, on the light(er) side, there will be practical issues to consider in cases where one of the lasers in the light beamer array fails (burns out) possibly resulting in less energy on one section of the light sail, which might send the craft off course. With sufficient recalculation by the scientists, course corrections can be made and the failing laser can be swapped out. A project of this size will need to plan for the manpower requirements needed to accomplish this task, so the question then becomes - How many astrophysicists does it take to change out a laser?

  7. Breakthrough Initiatives :

    Thanks for the questions!

    The main reason why standard quantum entanglement is not being considered for communications is that it is fundamentally not possible to transmit information using entanglement (there are a bunch of popular articles on this). It is possible to use entanglement to create a secure quantum key simultaneously at two locations that can be used to decode a message sent via a normal transmission route (see quantum key distribution) but this doesn't help the communication time lag.

    The phasing of the beamer will certainly have to be managed by a pretty powerful computer (rather than a large number of astrophysicists!) and include laser failures and active phase measurements.

    Prof. Phil Mauskopf, ASU
    Starshot Communications Lead

  8. Atis Freimanis:

    Thank you for the clarification about quantum entanglement.
    If it is not applicable for communications, you might want to consider a few particles as payload anyway.
    If CERN received significant funding to get particles to travel fast, there might be some other research team who would be willing to provide funds to see what happens to quantum entanglement when particles travel far.

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