Two men on a wrecked spaceship in the asteroid belt come up with a unique way to call for help.

Shades of “Marooned Off Vesta” (as Asimov himself admits in The Bicentennial Man and Other Stories). I hate to say it, however, but “Marooned Off Vesta” is better—or, at least, one is more ready to forgive the earlier Asimov writing a simple puzzle story, which is all that this is.