[zeestephen]

1.85 billion miles round trip in 2 years.

That works out to 105,000 mph.

What happens when a space craft hits a tiny space pebble at 105,000 mph?

Depending on the speed and direction of the pebble, I am thinking the kinetic energy would blast a hole right through the space craft.

[alexander_busek]

What happens when a space craft hits a tiny space pebble at 105,000 mph?

Pretty much the same thing that happens when a tiny space pebble strikes the spacecraft at 35,000 mph.

Hint: That scene in "The Empire Strikes Back," when the Millennium Falcon attempts to escape the Empire by deliberately manoeuvering into an asteroid field, grossly exaggerates (by a factor of roughly 100 trillion) what a stable* asteroid field looks like.

Regards,

*"Stable" = won't decay / self-destruct / re-coalesce within 10,000 years (a miniscule time-frame on the cosmic scale).

[Destroyer Sailor]

You would need a deflector shield like the Enterprise .