[ExI] Brake lights

[Rafal Smigrodzki]

I keep thinking about how to decelerate a starship at the destination star
system enough to allow orbital insertion. Obviously, the amount of energy
needed to decelerate a payload will be almost identical to the energy
needed for acceleration but deceleration is likely to be much harder than
acceleration to achieve technically.

Let's assume we want to move the smallest payload sufficient to start a
colonization process at a destination star. This would be probably a few
grams of self-replicating machinery (nanotech or highly modified
biotechnology) capable of photosynthesis in an abiotic planetary
environment, and capable of then bootstrapping radio antennas and the
computational substrate to receive the colonist minds beamed from the
origin star system.

The most promising technology to accelerate this kind of payload is laser
powered light-sail. One interesting implementation of this idea are small
lasers powered by solar arrays that would coordinate to produce massive
terawatt beams. These would not have a single origin but rather originate
from a swarm distributed over the whole solar system. In this way the
extreme acceleration of the payload could be sustained over a long stretch
as the payload traverses the laser swarm and receives continuous boost from
the swarm elements that are closest to it at the time. This would be much
better than a single giant laser that could accelerate payload only for a
shorter period of time.

Now let's use this distributed swarm to accelerate millions of wafer-ships,
each with a built-in solar array, communications and a small laser, similar
to the elements of the swarm itself. The waferships would be set to arrive
at their destination over a stretch of time. The first-arriving waferships
would blip through very fast but during that short time they would use
their lasers to slow down the subsequent waferships. Each subsequent wave
of ships would be slower, which means they could spend more time beaming
lasers to slow down the next wave, until eventually you would have a swarm
of stellar-powered small lasers similar to the swarm at the origin system.
The payload would be launched with the last wave of waferships, and given
the presence of a the distributed laser swarm at destination, such payload
could receive the deceleration needed to cancel out its interstellar speed.

Of course, the amount of mass needed for the scheme as a whole would be
many orders of magnitude larger than the mass of the payload but given the
tiny size of the needed payload the overall mass expenditure would most
likely not be prohibitive. And of course you could re-use the laser swarms
to send payloads in all directions and to send multiple payloads to each
system to assure success at every star, no exceptions.

Interstellar travel will be easy.

-- 
Rafal Smigrodzki, MD-PhD
Schuyler Biotech PLLC
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