Hmm. How strange. This is going to sound far fetched, but do you remember how forerunner ships could split apart in case of flood infection? Perhaps this 'ship' was a fragment of a ship of similar design, even if it was not forerunner. What surprises me is that spark doesn't outright say 'yeah, they're dead', which would suggest that, as well as O2 emissions and a distress signal, that there were life signs.