Steven Den Beste Strawman

You are correct about the Earth-Moon L5 being the target and not the
mistaken Sun-Earth L5.
However, I calculated 8.89 days. But I'm kinda new to trying on
armchair rocket science:

Dist(Earth_Luna)=Dist(Earth_L5)=Dist(Luna_L5) = 384,400km*
(* I might be off by as much as the Earth's radius if I've looked that
up wrong)

384,400,000(m) / 500(m/s) = 768,800 seconds
= 12,813 minutes
= 213.5 hours
= 8.89 days

I'm writing a scifi/astronautics series, sticking firmly to known
science. In it, I answer the stopped momentum problem by using "catcher
ships," like fishing vessels of olde, which use leveraged braking tech,
as found in electric car brakes, to convert kinetic energy into
rotational/turbine potential stores. It cannot be 100% efficient, but
it brings it into the realm of the feasible.

- Joel 'Twisty' Nye
the OTHER science guy