Bear with me, I'm not a MatE, so I'm positing a material
that definitely exists, I'm just not sure quite which one.
One of the problems with any sort of orbital broom idea
that the impact of the sweeper is likely to scatter as
material as it collects. However, if your energy
material is something that, in orbit, will sublimate into
gas, you have some alternatives.
You launch a satellite with a large supply of gas, the
material in liquid form, and a small mixer/temperature
chamber. Once in orbit, this chamber foams the
freezes it into a solid, and extrudes the solid into
the miracle of printer technology) a giant, thick, sheet.
This foam acts as an energy absorbing layer which allows
any impacters to slow to a stop still inside the foam.
particulate that is sprayed from the foam sublimates
quickly into harmless gas. As the main foam sublimates,
the material remains adhered in the remaining surface.
Even better, dark debris should melt its way deeper into
the material over time from solar heating. Eventually
entire thing sublimates, returning debris to the
satellite/mixing chamber, which retains enough fuel to
orbit with all attached materials.
Specific properties that the material must have. Liquid
possibly gas, but I like liquid) at launch temperatures.
Below it's triple point in orbit. Somewhat-to-highly
adhesive in solid form. Ideally light or white colored in
foamed form in order to slow sublimation.
As far as the ideal material, I'm thinking plain foamed
water ice would work, as might dry ice (C02). If not, a
search of various organic compounds should turn up