Ashley inhaled sharply.
Then I told her what Rawling had explained to me. Back in 1994, a comet named Shoemaker-Levy 9 appeared from out of the darkness beyond the solar system, like some sort of prehistoric shark cruising up from the unexplored depths of the ocean. Jupiter's massive gravity pulled Shoemaker-Levy 9 closer and closer, and the comet crumpled. Splitting into 20 pieces, it slammed into Jupiter's upper atmosphere. Each explosion released the energy of a gigantic nuclear bomb, and it took over a year for the black clouds of the explosion to disappear from the telescopes aimed at Jupiter from Earth.
Now another comet was headed our way, like a lone black rocket of death. From what we were told by the Earth scientists, they expected this one, too, to break up as it passed Jupiter. The pieces, however, would miss Jupiter completely this timeâand intercept Mars a few months later.
Unlike Jupiter, Mars has no atmosphere thousands of miles high to absorb the chunks of comet. Compared to Jupiter, Mars is the size of a marble. If only a few of those pieces hit anywhere on the planet, the impact would destroy the dome. If all those pieces hit, it could shatter the planet completely, sending a shock wave into the inner solar system. And with chunks of Mars flying in all directions, there was a big, big possibility that the Earth would be hit several months later by debris.
Rawling said it was my job to stop the comet before it stopped us.
“Today's a workday,” Rawling said. “Try to make it as short as possible. We want you in the virtual Hammerhead for at least a couple of hours.”
I was back in the lab again. Earlier than usual. Considering how important it was for me to fly a Hammerhead in space, Mom and Dad and Rawling had agreed that my schoolwork could be put aside for now.
“Work?” I said. “I was hoping to see the actual Hammerhead. You know, for inspiration.”
“Work,” Rawling said firmly. “We want you to try something on the dome telescope. Blowing sand out of some rotational gears. I'm hoping that's the problem. We need the telescope operational to allow us to track the pieces of comet as it gets closer. Right now we're going blindly on the advice of Earth scientists who have to watch it from 50 million miles farther away. We can't afford to make any errors as we track the pieces of comet. Last time we did that kind of maintenance we had to send techies up in space suits. Not only did it take them hours, it was dangerous work up there. You, on the other hand ⦔
“Rawling, I thought the purpose of all this was to be able to explore the universe. You know, go boldly with a robot where no man has gone before.”
“That too,” he said. “Just not now. If you want to feel good about this kind of work, think of what the robot body cost the space program. That makes your boring maintenance work worth millions of dollars per hour.”
Rawling helped me out of my wheelchair and onto the narrow medical bed. Then he began to strap me in place. What used to be exciting was now routine.
“For all those millions per hour, you want me to climb the ladder outside the dome?” I asked Rawling.
“Right. Techies have already set up the robot with a backpack and compressed air tank. All you have to do is blow sand out of the exposed gears. Shouldn't take much more than five minutes. Then you can get back to the Hammerhead virtual-reality program. The sooner you've got the training in, the sooner we can get you into space.”
That was a good incentive. A very good incentive.
I nodded. “Checklist.”
“Checklist,” Rawling replied.
“First,” I said, “no robot contact with any electrical sources.”
“Check.”
After all, my spinal nerves were attached to the plug. Any electrical current going into or through the robot could do serious damage to the robotâand to my own brain.
Rawling snugged down the straps across my stomach and chest to keep me from moving and disengaging the plug.
“Second,” I said, continuing the list, “I disengage instantly at the first warning of any damage to the robot's computer drive.” All I needed to do to disengage was mentally shout the word
Stop!
“Check.” Rawling placed a blindfold over my eyes and strapped my head in position. While I controlled the robot body, it was important for me not to be distracted.
“The robot is at the dome entrance?” I asked.
“Outside the dome entrance. The techies moved it there already to save you the time of clearing the double entrance. And when you're finished, leave it out there too. The techies will move it back in. That should save you 10 minutes in each direction and give you an extra 20 minutes on the Hammerhead program.”
“Robot battery at full power?”
“Yes.”
“Unplugged from all sources of electrical power?”
I already knew the answer. So did Rawling. If the robot was outside the dome, it was definitely unplugged. But Rawling was very strict about going through the entire checklist.
“Unplugged,” he answered.
“I guess we're ready, then,” I said. “If I have any other questions, I'll radio them in to you from the top of the dome.”
“Checklist complete,” Rawling said. He placed ear protectors on me as the last step. I was soundproofed and ready to go. I waited.
By now the sensation was familiar. In the darkness and silence of entering the robot computer, it felt like I was falling off a high, invisible cliff into a deep, invisible hole.
I kept falling and falling and falling. â¦
When my imaginary fall ended, I was on the surface of the planet Mars.
Although my body was still strapped on a narrow bed in the dome laboratory, all the sensations reaching my brain through the robot told me I was on the planet's surface.
I love controlling this robot body. While my own body is in a wheelchair, this robot gives me the sensation of more freedom than any other human has experienced.
Except today wasn't Mars exploration but maintenance work.
I still didn't mind.
It beat sitting in a wheelchair.
I brought both the robot's titanium hands up in front of a video lens and flexed the fingers, wiggling them to make sure everything worked properly.
I switched to the rear video lens. As promised, the compressed air backpack was in place.
I rolled forward to circle the dome.
Ashley has told me that the sky on Earth is blue and the sun is yellow but too bright to look at for more than an instant. She told me clouds are white or, if they hold rain, gray. She said when the sun rises or sets, it stays the same color, but the clouds might turn pink or red or orange or a mixture of all those colors.
On Mars, when the sun rises, it is blue against a butterscotch-colored sky.
A few hours had passed since sunrise, and now the sky was red because sunlight scattered through dust particles at a different angle. At sunrise, it had been about minus 100 degrees Fahrenheit. Now it was 50 degrees above zero. Mars has such radical daily temperature differences because the atmosphere is too thin to hold heat. As soon as the sun set at the end of the day, the planet's heat would bleed back into the cold of outer space.
The 40-mile-an-hour wind and the sand it threw at my titanium shell didn't bother me. With such little atmosphere, even strong winds don't have the force they would on Earth. And the robot body, about the size of a man, was built so tough that it would be standing long after human bodies fell.
I reached the ladder to the dome. Without hesitation, I grabbed one rung with the titanium fingers of my right hand and pulled, holding the entire weight of the robot with one arm. I reached for the next rung with my left hand. One hand after another, I climbed quickly, robot wheels bouncing against the ladder. My arms had such strength that I didn't need to support myself with legs.
It took less than a minute to get to the top of the dome. I dragged myself onto the platform surrounding the telescope lens.
From there I had an incredible view. I saw the dome's greenhouse about a half mile away, where scientists were trying to raise plants that would grow on the planet's surface. As I scanned the horizon, the red mountains, and the brownish red sand of the valley plains, movement on the other side of the greenhouse caught my attention.
Movement?
It was far too small to be a platform buggy on an expedition. Unless it was a techie or a scientist in a space suit, there should be nothing moving out there except sand shifted by the wind.
I clicked my forward video lens to get a close-up and nearly jumped out of my robot's titanium shell.
It was another robot. Making circles in the sand.
Impossible.
“Rawling.” My voice sounded mechanical since it traveled through a sound-activated communication device attached to the robot body.
“Tyce. You're at the telescope. Need more instructions?” Rawling asked.
I swiveled the robot video lens. The part of the telescope that extended from the dome observatory was like a short tube, twice as wide as the robot's outstretched arms. It rotated on a track railing. Spraying compressed air into the rotational gears would be a simple task.
“No,” I said. “Yes.”
“No? Yes? Make sense, Tyce.”
“No, I do not need instructions on how to clean the gears. Yes, I need advice.”
“On what?”
“I am going to switch one of my lenses to the video screen in the lab. You tell me what you see.”
“Sure.”
I made the switch. I zoomed in even closer and waited for Rawling. What he would see was a robot body like mine but different.
Rawling's whistle of surprise broke the silence around me. “If I didn't know better, I'd say it was a robot.” His voice, though still calm, was louder in the communication device.
“Me too. And one sleeker than mine.”
The robot body I controlled looked bare bones compared to this new one, whose legs, arms, and fingers were sheathed with shiny silver, like metallic skin.
“Tyce,” Rawling said into the speakers, “it looks to me like a second-generation robot.”
“My guess too,” I said. I paused. I didn't want to ask Rawling this question. But I had to do it. “Have you been keeping a secret from me?”
“No,” he said a second later. “And as dome director, I should know about this. Which means someone somewhere has been keeping it secret from both of us.”
“That's not good, is it?”
Rawling knew what I meant. The former director of the dome, Blaine Steven, had kept too many secrets. I couldn't forget that the last secret he kept nearly killed Rawling and me and my dad during our expedition across the planet.
“No,” he said, “that's not good at all.”
“Should I try to catch that robot?” I asked.
“Finish your telescope maintenance and get back down as soon as you can.”
“Butâ”
“I'll explain why when you return.”
“Tyce, I've pulled up on the computer screen the last 48 hours of activity at the dome entrance.”
We had finished three hours of training on the Hammerhead virtual-reality program, and I now sat in Rawling's office. “So who moved that other robot out there?” I asked. It would definitely show on the activity record. There was no other way in or out of the dome.
“Look for yourself.” Rawling turned the computer screen my direction.
Digital images of the dome entrance flashed in front of me. It was like entering an igloo with two sealed doors. The outer door remained sealed when the inner door opened. Once the people or cargo moved into the entrance area, the inner door closed and sealed before the outer door opened so oxygen wouldn't leak out and the dome's pressure wouldn't change. It was a 10-minute process and so important that the entrance was under computerized surveillance all the time.
I kept watching the computer screen. In the lower right-hand corner, digital numbers flicked, recording the time. Rawling was fast-forwarding the images so quickly that in less than five minutes, I saw all 48 hours.
“The only robot going outside is mine,” I said.
“Exactly. Which is very disturbing. What does that tell you?”
I thought it through before I answered. “The robot has been outside longer than 48 hours. Which means if it has been used at all, it should need recharging. But the only source of charging is inside the dome. So either it hasn't been used much, or it doesn't need recharging.”
Rawling nodded. “What really scares me is that I reviewed the dome entrance surveillance discs as far back as they go. One month. That robot did not enter or leave the dome in the entire time. So it's been out beyond the greenhouse, hidden from anyone in the dome for at least a month. And I'd be surprised if today was the only time that robot was active.”
“Surprised?” I asked.
“You saw what the other robot was doing. Practice activities. Lifting. Circling. Digging. Practice is just that. Practice. Repeated activities. So what are the chances that the only time someone activated it was while you were on top of the dome?”
“Slim. It would have to be a big coincidence.”
“No one but you and I and two techies knew you were going up there for maintenance work today. The top of the dome is probably the only place that would give anyone the chance to see the robot. So whoever practices it would have felt safe to use it. I'd say it's much more likely that the robot has been used often and daily.” Rawling rubbed his chin. “And that tells us ⦔
I thought again. “First of all, someone else in the dome is running a robot. And second, either the robot has an incredible battery power that doesn't need charging very often, or it has a way of replenishing its power outside the dome.”
“Yes and yes,” he said. “But it's something even bigger that bothers me the most.”