Genetics question?

You have recovered a phage very similar to T4 that infects bacteria found in soil samples returned from the surface of one of Jupiter’s moon. Treating these extra-terrestrial phage with proflavin causes mutations very similar to those studied by Crick, Brenner et al (i.e. single base pair deletions or insertions). But, curiously, no combination of insertion and deletion mutants within the rII-like gene can restore function. How might the code be different between life on earth and on Jupiter’s moons? You can ume that the rII gene has roughly the same structure and function on the two planets.