
Light-induced propulsion of graphene-on-grid sails in microgravity - bookofjoe
https://www.sciencedirect.com/science/article/abs/pii/S0094576520301582?via%3Dihub
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trhway
>Light sailing is the only existing in-space propulsion technology that could
allow us to visit other star systems in a human lifespan.

as this article shows the light sailing requires unobtanium to make the real
light sail. Whereis nuclear explosion propulsion - project Orion - can me made
with existing materials. Of course bringing into orbit the required several
millions tons of cargo to build the ship from, majority of it being the tens
of thousands of nukes, seems to be an endeavor behind our current
capabilities.

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jawns
This research pertains only to the question of how we propel an object in a
way that enables interstellar travel with a duration of fewer than ~100 years.

There's a whole other question, which must be answered separately, about how
to keep that object from being destroyed during its travels.

The effectively 2D graphene material might be the right material from a
propulsion perspective, but it may be totally unsuitable in terms of making
sure the object gets to another star system in one piece.

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BobbyJo
The most interesting piece of the link isn't the sail application, it's the
theoretical implication. More thrust was experienced than expected from photon
pressure alone. A lot more.

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mrfusion
How why? New physics?

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BobbyJo
All good questions.

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sudoaza
> The measured thrust is one order of magnitude larger than the theoretical
> calculations for radiation pressure alone.

Nice!

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sandworm101
>> 2D sails pave the way for reaching other star systems in a human lifespan.

Pave the way? Explain to me how the laser is going to work? There are some
fundimental size/optics restrictions here that keep the sail very much a
seconday concern in terms of interstellar travel.

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lowdest
What are the size/optics restrictions?

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sandworm101
You have to focus the outgoing light, the laser energy, just as a telescope
does inbound light. To hit a small target (say a 1x1km light sail with a 4x4km
beam) at interstellar ranges would require laser emitting equipment many
kilometers in size repeated across multiple locations.

How large of a telescope is needed to focus the image of a 4km feature on
Pluto? Then multiply that by a few orders of magnitude. Then plug in a laser
powerful enough to vaporize a small town. Those are the real problems, not the
mass of the sail.

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Elof
Love seeing when science fiction starts to turn into reality!

