In the wake of the discovery of plastophages (plastic-eating bacteria) on the Colony, it was thought prudent to make an investigation into how exactly this contamination had happened.  At first, the idea was to prove that the contamination could not have come from the spaceship, by taking air, ground, and water samples from both the spaceship and the Colony, and testing them all for plastophages.  If the plastophages were found on the Colony but not the spaceship, this would (Helene asserted) prove that the source of contamination was already present on the Colony before the spaceship arrived.  After all, she pointed out, it was suspected that plastophages might have evolved more than once on Earth, in parallel, so there was nothing to say that it couldn't have happened on Mars as well.

Olivia found it highly unlikely that anywhere on Mars would have as optimal an environment for evolving plastophages as, say, the Great Pacific Garbage Patch on Earth, or even any large city's dump.  She shook her head, but said nothing.  Theodore and Lucas were selected to collect the samples, since it seemed prudent to have one Colonist and one crewmember (or, as the colonists put it, one Martian and one Earthling) so that everyone could have confidence in the results.  Theodore and Lucas both had a reputation among their peers for being thorough and reliable, and honest to a fault (often offending others by a too-honest expressing of their opinions).  No one would believe that they had been unwilling to tell them about an unwanted piece of new information, whichever way the tests went.

Next, when Theodore and Lucas took a mini-rover to collect the samples from the spaceship, it occurred to them that it would be an interesting set of controls, to take soil samples at several spots along the way.  This would help to verify that their sample collection procedure was not itself contaminated with plastophages.  The spaceship was a few kilometers away from the Colony, so they stopped at a few places, each at least one kilometer away from either site.

When even these control samples, when analyzed, gave evidence of microbial contamination, they grimaced, devised and carried out even more stringent protocols for sterilizing their sample collection equipment, and tried again.  When even this showed some microbes in the controls, they investigated more closely, and found something they were not expecting.

"Wait, what?" asked Olivia.  Also, Ophelia.  Well, to be honest, nearly everyone present when Theodore and Lucas disclosed the news.

"There is bacteria, on Mars, nearly everywhere we look," said Theodore.  "It's not plastophages, but it is most definitely bacteria."

"Technically," said Lucas, "they seem to be more like archaea, rather than bacteria.  Microbes, anyway."

"If they're even either one," said Theodore.  "They might be Martian in origin."

"Surely that would have been found before now, if it had been here all along," said Olivia.  "They had been doing tests of soil samples on Mars for the better part of a century before the Colony was set up."

"They have, if by that you mean 'once a decade or so for a century'," said Lucas.  "But never with very thorough testing methods, and only in a few spots.  By the time the Colony was established, the idea that Mars was dead was so fully established that I don't think at this site it even was tested for."

There was a long silence as those present wrestled with what Theodore and Lucas were telling them.

"Surely the more likely scenario is that they come from here, and have spread," said Helene.  Olivia, almost despite herself, had to nod in agreement.

"While it could well be, there doesn't seem to be any dropoff as you get further away from the Colony towards the ship," said Theodore.  "If it came from the ship or the Colony, we would have expected to see more of it closer to the source."

"If it was the ship we would," said Helene, "but if it was the Colony then it could have started many years ago.  I thought so."

Theodore and Lucas exchanged glances, inscrutable to the rest.  Emma grimaced, aware that Helene was interpreting everything they said to support her theory that the plastophages came from the Colony, not the ship.

"These aren't plastophages, though," said Lucas finally.  "They're something different; something we haven't seen before.  I don't know of any plastophage that could survive Outside for any length of time; they're adapted for moist environments and moderate temperatures, with lots of long carbon chains available to digest."

"What does this mean, then?" asked Oliver, trying to get the conversation back on track.

"I think that's what we're here to ask," said Lucas.  "We don't see plastophages anywhere Outside, but we do see some other kind of microbe that doesn't look like anything we've got any records of."

"What about on the ship?  Or around the Colony?" asked Olivia.

"There are plastophages in both," said Lucas.

"So it's been spread to the ship then," said Helene calmly, as if stating the obvious.

It was obvious to all present, that this was Helene reaching for any explanation that would avoid the obvious conclusion, that the plastophages had been brought to Mars by the ship, rather than the reverse.  What was not obvious to everyone, was that it was obvious to everyone else also.  Each person present, even Ophelia, could tell that the more likely explanation was that the plastophages, which were widespread on Earth, had been brought to Mars (which had never before seen them) by the ship.  If the conversation had dwelled on this topic, it would have been made clear to everyone, that no one found Helene's explanation likely.

Olivia, however, was more concerned with turning the conversation towards more practical questions than whether or not Helene's explanation made sense.  To her mind, it didn't matter now, and any time spent arguing about that was wasted time.  Emma, who knew this was what Olivia would do (instead of pointing out Helene's faulty logic publicly, in a case where everyone would agree), grimaced quietly.  But, being Emma, she also did not speak up, herself.

As Helene followed her proclamation by walking out of Building 3, where they were all gathered, it was hard for Emma to shake the feeling that there had been a decision made.  The only question was how long it would be before Helene announced it.