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Eleven Minutes

Fiction · 3 min read

The booth at the university's open day promised that anyone could drive a Mars rover.

Leila had wandered over on a whim. She was sixteen, had come with her cousin, and expected to be bored. The graduate student running the stand, a tall man named Tomasz, handed her a laptop with a grid of colored squares and a single large button marked SEND. "This is the Mars simulator," he said. "There's a rock ahead of you. Tell the rover to turn left. Just don't expect anything to happen right away."

She typed LEFT 30 and pressed SEND.

Nothing happened. The little rover on the screen sat there with its wheels still, and a clock in the corner ticked upward, fast: 01:00, 02:00, 03:00.

"What's it doing?" she asked.

"Waiting for the message to get there," Tomasz said. "I've sped the clock up sixty times, or you'd be standing here a long while. Mars is far enough away that a command takes real time to cross the gap. Radio travels at the speed of light, about three hundred thousand kilometers every second. That sounds fast. But Mars is somewhere between fifty-five million kilometers from Earth, when we're closest, and four hundred million when we're on opposite sides of the Sun. Do the division."

She did, on her phone. Fifty-five million divided by three hundred thousand was a little over a hundred and eighty seconds. Three minutes. Four hundred million divided by three hundred thousand was about thirteen hundred and thirty seconds. She frowned and divided again.

"Twenty-two minutes," she said. "One-way."

"One-way. That's the worst case. Today's setting is eleven minutes. So the command takes eleven minutes to get there. Then the rover does it. Then the picture of it doing it takes eleven minutes to come back. If you want to see whether your command worked, that's twenty-two minutes of waiting. The delay is the whole problem."

Leila stared at the frozen rover. "So you can't drive it. Really."

"You can't use a joystick. Nobody can." Tomasz pulled up a chair. "So you plan. You look at the last picture, work out what the ground looks like, and write a whole day of commands at once. The rover carries them out on its own, an autonomous machine using its own sensors to avoid hazards, and sends you a report. The mission team meets, looks at what came back, and plans the next day."

The clock reached 22:00 and the rover turned. A tiny rock appeared at the edge of the picture. It was a new one, not the one she had meant to avoid.

"That wasn't there before," she said.

"It was always there. You couldn't see it from where you were. That's why you plan with room to spare, and why the rover is allowed to say no. If it senses a hazard it stops and waits."

She thought about it for a while. In her head she had always pictured space as a place where you pushed a button and a thing happened. Now she saw something she liked better: a conversation where each sentence took twenty minutes, so every sentence had to be careful.

"Could I try planning a whole day?" she asked.

Tomasz grinned. "That's the actual job."

She pulled the laptop closer and started with a question he said later most beginners skip: what if the first thing I do is wrong?

Words in this story: simulator, autonomous, hazard, delay, one-way