A ball of crumpled aluminum foil would work well, especially since the spacecraft's tanks are covered with aluminized thermal blanketing that looks somewhat like aluminum foil.
(A ball of crumpled aluminum foil; would work well; ) (aluminized thermal blanketing; looks; somewhat like aluminum foil)
A ball of crumpled aluminum foil aluminized thermal blanketing
would work well looks
somewhat like aluminum foil