CHAPTER 17

The conference at 2100 hours was not held. At 1930 hours, O'Brien called Sisko and Dax to the laboratory. His safety system simulators were on small stands, their indicators all glowing green. O'Brien explained that a green indicator meant safe, that is, activated. A red indicator meant that the safety system had been deactivated.

"Watch this," O'Brien said simply. "It takes a while, be patient." He placed a tricorder over one of the simulators and, about forty seconds later, its light switched from green to red.

"That's the gravitational sensor," Dax said.

"Right. And this," O'Brien hefted the tricorder in his hand, "is a geologist's tricorder. Not all geologists' tricorders have graviton emitters, but this one does, and it's a good bet that Observer had one just like it. Deactivation of the gravitational system, it turns out, is fairly easy to do. It takes about forty or fifty seconds for the sensor to respond to a change in gravitational gradient. So you'll notice that the gravitational gradient system is deactivated. And you should notice something else."

It wasn't obvious to Sisko or Dax what the something else was.

O'Brien didn't keep them waiting. "The light is still red. I've got the tricorder here. I'm not administering any gravitons. But the gravity-based safety system is still deactivated."

As if on cue, the light changed from red to green.

"And now, the gravity-based safety system is active once again," O'Brien said. "It has to do with the sensor. Once the sensor is satisfied that the correct gravitational gradients are present, it deactivates the safety. If there's another change in gravity, it takes another forty seconds or so before that change registers. The gravitational gradient sensor is very reliable, but it is also very slow."

"Did Observer have a geologist's tricorder in its Bay?" Sisko asked.

"We don't know," O'Brien said. "It's not part of the official equipment in the Bay and I couldn't see one in the re-creation of Observer's probe preparation Bay. Some parts of my scans didn't have very good resolution, so it could be there, blown to pieces, I don't know. But I do know that Observer had several models of tricorders on board. I also know that, if they had a tricorder with a graviton emitter, programming it to issue graviton pulses is fairly straightforward. Strictly speaking, you could do the same thing with other pieces of equipment, but a geologist's tricorder would be the most obvious choice." O'Brien stepped up to the next sensor. "Now, watch this."

O'Brien pulled a wand-shaped instrument from the wall and placed it near the simulator.

The light changed from green to red.

"How did you do that?!" Dax exclaimed.

"Which system is that?!" Sisko demanded to know.

"This is the environmental system," O'Brien said. He hefted the wand, and as soon as moved it away from the simulator, its light promptly changed from red to green. "And this is a wand-type active scanning emitter bank. It can generate wave-particle reps having various desirable characteristics. In particular, it can emit a signal that mimics the composition, temperature and pressure of the lower atmosphere of a gas giant."

"Did they have something like that wand aboard Observer?" Sisko was nearly breathless.

"They did. Prepare yourself for a shock, sir. They had, in fact, this very type of an emitter bank in the Probe Preparation Bay. An emitter bank like this is standard on a model 1706 scanner."

Sisko could feel his heart rate speed up.

O'Brien continued. "An emitter bank is useful for several types of close active scans, but that functionality was unnecessary for Observer. Officially unnecessary, anyway. The crew of Observer didn't need an emitter bank to do probe scans. But whether Observer needed an emitter bank or not, it had one."

"Could Observer's emitter bank have been set up to do what you just showed us?"

"Absolutely. I was able to program this wand in about an hour and a half. It took quite a bit of trial and error, but still doable. The wand can't do gravitons, in case you're wondering, so you'd still need something else like the tricorder to spoof the gravitational sensor. But this wand is fully capable of spoofing the environmental sensor, no question about it."

"It can't be a coincidence that Observer just happened to have in its Bay an instrument that could defeat one of the safety systems," Sisko intoned.

"It's hard to see it as a mere coincidence," O'Brien agreed.

Dax summed things up. "So of all of the safety systems, the only one left is the life detection system. All of the other safeties could be neutralized. And a detonation command could have been given. Only the life system stands in the way."

"That's right," O'Brien said.

"Chief," Sisko said, "they must have been able to defeat the life detection system as well."

O'Brien shrugged. "If they did, they're geniuses; dead geniuses. I can't find a way to do it. None of the literature shows a way to do it. I'm a multi-cellular life form, and when I'm using this wand, I've got to be standing less than a meter away. That sensor is going to detect my life signs no matter what I do. If I were a thousand kilometers away, it might be different; or if I were standing outside the Bay itself with all its sensor shielding, it might be different; but at this proximity, there's no way my life signs can't be detected. And as long as my life signs are detected, a 'no life' signal can't be issued. You can't block the sensor and you can't spoof it. Localized shielding doesn't work. Camouflage doesn't work. Masking doesn't work. Overloading doesn't work. Using this wand doesn't work. Interfering doesn't work. Signal matching doesn't work. Jamming doesn't work. I tell you, sir, this life sensor is a tough son of a bitch. There's no way to beat it!"

Sisko huffed. "Keep at it."

O'Brien had no idea what things he could try that he hadn't tried already, but he answered, "I will."

"We seem to be so close," Sisko said.

"Are we?" Dax asked. "Suppose Miles finds a way to beat that supposedly unbeatable sensor. All that means is that we've found a way that the explosion could have happened, but we haven't necessarily shown that this is how it actually did happen. But even if it did happen that way, doesn't it follow inescapably that the probe team must have plotted to detonate one of the probes on board the ship? There must have been a conspiracy involving the people in the Probe Preparation Bay and the people in Probe Control, because some steps had to be performed in the Bay and other steps had to be performed in Probe Control. And if the members of the probe team did conspire, they must have had some reason or goal for that conspiracy. Are we close to finding any evidence supporting any such a reason or goal?"

Sisko rubbed his eyes. "You're right. We keep coming back to the 'Why?' question." He looked at Dax, then at O'Brien. "Maybe we're not all that close to explaining this incident. But we are close to showing that an event widely thought to be flatly 'impossible' is within the realm of the 'quite possible,' and that is an achievement in itself."