Opening her eyes, she glanced out the JPM window.
And groaned.
Of course. She really was Doctor Obvious. Ham communications needed line-of-sight to make contact! And there was nothing below the ISS except water, as far as she could see.
The ISS was over the Pacific, and except for Australia, there were very few places that could respond.
She swam over to the laptop and pulled up the station’s orbital parameters. They were on a descending node, crossing the Pacific Ocean, and beginning to start the long climb up over South America. It would be a while before they would be in a good line-of-sight for communicating.
She floated backward. She’d try again, but she wasn’t about to wait. She needed to try something else.
So what next? Kimberly thought briefly about using the links that transmitted experimental data from the JPM to the ground station at Marshall Space Flight Center. All the ISS experimental data were relayed to the Payload Operations Center in Huntsville. If the links were still up and running she wouldn’t be able to transmit voice or anything else, but she could modify the data, just like she had tried to modify Farid’s crazy transmission of the threat to deorbit the ISS.
She pushed over to one of the experiment platforms, the same one she’d been using earlier when the station was boarded. The crystal growth experiment used a handheld sub-terahertz, 98 GHz traveling wave tube to accelerate the molecular reactions for crystalline growth. A camera was set up to periodically take pictures through the microscope of how the crystals reacted to the millimeter waves, and those pictures were transmitted down to Alabama for analysis.
Kimberly traced her fingers along the camera interface, and her hopes of disengaging the camera from the optics quickly plummeted. It was hardwired to the device. She knew she could eventually take it apart, change its focal length, and then reassemble it to take a photo of a “Help! I’m alive!” drawing.
But …
She realized that before the picture was transmitted she’d have access to the data, meaning that she might be able to embed a message in the picture.
What did they call it? Steganography: embedding information covertly in a picture. But she didn’t want her message to be secret and unseen; she wanted people to see it and understand it. She needed to embed an alphanumeric message spelling out that she was still alive and safe—for the time being—and if NASA could think up anything that she could do to stop the terrorists, to contact her.
Kimberly glanced around the JPM. JAXA, the Japanese Aerospace Exploration Agency, had a Ka-band link that could carry voice, but it had to be enabled from the ground. Besides, it was only line-of-sight, and would work only when over a Japanese ground station.
But she also knew that the JAXA Kodama satellites might be able to relay the Ka-band link—and, better yet, if the handshake was right, NASA’s Tracking and Data Relay Satellites might be able to allow her direct voice communications with NASA. That’s what she’d put in her message. That, as well as getting the JAXA to activate their two video cameras in the JPM so they could keep track of what she was doing, and use them as a backup by writing messages to them if something happened to the voice link.
She knew it was a long shot, and she may not know if they even were able to receive her embedded message, but she had to keep moving and give it a try. Then she could go on to the next item on her priority list.
Kimberly had already prevented the terrorists from deorbiting the ISS, at least temporarily.
That left rendering them helpless … or killing them.
JAPANESE MODULE (JPM)
After digitizing the photo of crystalline growth Kimberly inserted a very simple but straightforward message into the data stream, including details of what had happened on board after communications with the ground had been cut, and specific directions of how to establish voice comm with her.
She wrote out the message by hand several times before she was satisfied with the size and length. She’d have preferred to print it out, but the printers were only in the U.S. lab and the Russian service module. And before she took a picture of the message with the confocal microscope, she tried to balance getting the information down to JSC with not having the photo thrown out by any software review that filtered out corrupted data.
She wasn’t sure if the experimenters would actually look at the photo or instead rely on automated computational analysis. She hoped they weren’t lazy and would do the former rather than the latter, but she feared that this new generation of scientists depended more on technology than intuition, and she didn’t want to take the chance. Their software might skip over her message and instead mark the data stream as tainted.
She included directions on how to communicate back to her, by voice-enabling the JAXA Ka-band, so she’d know pretty quickly if her steganography idea worked or not. She’d rather be much more straightforward communicating with JSC, but if Farid or Bakhet discovered that she was exploiting the experimental data links, they’d cut them off in a heartbeat, just as they’d done with the other comm links.
So instead of sitting around and waiting for either JSC to respond to her implanted message or the ham radio to be in line-of-sight, Kimberly told herself that now she needed to track those two crazies down and find out exactly where in the ISS they were located. If she was ever going to render them helpless and prevent them from trying to deorbit the station, she’d first have to find out where they were.
She glided back to the laptop, pulled up a schematic of the station’s electrical functions, and traced a finger over the lines connecting the station’s modules. Each module contained a slew of equipment, ranging from food warmers to sophisticated astronomical devices. When in use, each piece of equipment drew current and produced a drop in voltage, which could be detected, quantified, and located.
By using Ohm’s and Kirchhoff’s laws as well as knowing the station’s circuit layout, Kimberly could easily deduce what equipment was in use and where it was situated. She’d be able to detect all the myriad equipment in the ISS and exploit them as sensors.
Which gave her another idea. She could send out a simple Morse code message to the mission control center by pulsing currents in the JPM! MCC would be monitoring the currents in the JPM as well as the rest of the station, and she could modulate the current to tell them where to look in the payload image data stream!
She wrote a short routine that monitored various traditional and nontraditional sensors, then quickly isolated the LED screens, carbon dioxide monitors, temperature gauges, the zero-gee toilet, oxygen monitors, and a scad of other equipment.
There. She enabled the routine, then started pulsing the currents in the JPM by switching the lights on and off, hoping that someone at MCC would notice the modulation.
After cycling through her Morse code message she turned to watch the rest of the station’s electrical activity as it appeared on the schematic on her laptop’s display. She felt her heart rate speeding up as she found that the two terrorists had retreated away from the JPM and separated from each other. One of them appeared to be holed up in the U.S. lab, while the other was down at the Russian end of the station, moving back and forth between the control panel in the SM module and the FGB.
What on earth were they doing? Studying the drain on the station’s electrical circuitry, Kimberly deduced that they’d powered up most of the laptops in the modules. Probably trying to get around the administrative lock she’d put on accessing the thruster propellant lines. She assumed that although the two of them were crazy enough to want to deorbit the ISS, killing themselves and taking out who knows how many people, they were both sane enough—and probably competent enough—to hack into the ISS systems and retake control of their functions. Including the propellant valves, thrusters, and whatever other controls they needed to carry out their suicidal fantasies.