Ban Xia sat on the steps at the entrance of the apartment building, holding a thin, yellowed bamboo pole. One end rested in her hand while the other touched the ground beside her foot. She hummed a tune contentedly, squinting one eye to check if the pole was straight enough.

Next, she tied a one-meter-long white plastic strip to the end of the bamboo pole. While working on this task, she glanced up at the thin bamboo pole planted in the grass across from her. As a gentle breeze passed by, the colored strips tied to that pole fluttered in the wind. The girl stared at it for a moment before lowering her head to focus on her work again.

After securing the strip, she carried the pole upstairs and set it up in the attic.

She had already erected five or six such poles. With a small notebook and pencil in hand, she checked them four times daily, recording entries like:

“December 10

8:32 AM, Southeast wind, Level 2

12:02 PM, Northeast wind, Level 3

4:33 PM, Northern wind, Level 3

10:01 PM, Western wind, Level 3″

She checked them once in the morning, once at noon, once in the afternoon, and once at night – four times each day. This was Ban Xia’s new job, which she did during breaks from debugging the PSK data transmission link. She had become something of a weather observer.

Wind speed was difficult to measure and could only be estimated. BG4MXH said there was a rhyme for estimating wind levels, like a nursery rhyme: Level zero, smoke rises straight to heaven; Level one, smoke drifts with the wind’s direction; Level two, gentle breeze on your face; Level three, leaves dance and red flags wave; Level four, branches sway and papers take flight—just like Oppenheimer, throw a handful of papers into the air, and if they get blown away, that’s five hundred thousand tons of yield… ah no, that’s Level 4 wind!

“BG, what’s the point of collecting these statistics?”

“I’m not sure either, it’s just what they requested,” Bai Yang replied. “Uncle Zhao and the others have been quite mysterious these past few days, perhaps they have some grand plan? Young Miss, has the camera on your end returned to normal? OVER.”

“The new one couldn’t focus properly, so I replaced it again.”

Yesterday, Ban Xia had accidentally dropped and broken the camera while adjusting it, forcing her to use a new one.

“Any issues with the program running? OVER.”

“There are still bugs, but at least everything’s installed now.” The girl let out a long sigh. “It’s so hard, why does it have to be so difficult to meet you all?”

She had truly experienced the difficulty of debugging PSK, which was far more challenging than AFSK. At her most difficult moments, Ban Xia found herself lost in an endless mountain of code, unsure of who she was, where she was, or what she was supposed to do. During those times, she just wanted to smash the motherboard and monitor, and then burn everything to ashes.

But after calming down, she had no choice but to face the confusing code again, methodically debugging with help from the experts on the other side. Each session was an exhausting long march.

As the world’s most brilliant programmer, she spent ninety-nine percent of her time debugging.

“Technical problems are the hardest to solve. They’re like math exam papers – if you don’t know how to solve it, you won’t figure it out no matter how hard you rack your brain or try your absolute best. If someone handed me a college entrance exam math paper right now and said the world could be saved if I got a perfect score, I’d still be helpless,” Bai Yang sighed. “Things that can be accomplished with effort aren’t truly difficult. The truly difficult things are impossible to even begin, OVER.”

“BG, when will the rocket launch?”

“Should be the 18th of this month, from the Guiana Space Center in French Guiana, OVER.”

“Where’s that?”

“In South America, Young Miss. Do you know where South America is?” Bai Yang said, “It’s on the other side of the Earth. The satellite is being fitted now, being airlifted to the Guiana Space Center for final assembly, OVER.”

The girl remained silent in the darkness for a while, presumably trying to comprehend just how far the other side of the Earth was.

She shook her head, unable to imagine it. She could only picture a world the size of Nanjing city; anything larger was beyond her comprehension.

“What kind of satellite is it?”

“It’s a super camera. It will fly over your head taking pictures, locate the position of the Big Eyes, then transmit the data to our side so we can formulate response strategies,” Bai Yang answered. “It’s like a scout. Before any military operation begins, scouts must be sent to gather intelligence about the enemy, OVER.”

“Really?” The girl was startled, then became excited. “Can it take pictures of me?”

Bai Yang faltered.

“Well… probably not. You’re too small for it to see, OVER.”

Even though the satellite’s synthetic aperture radar imaging could achieve resolution within one meter, capturing a human girl from a vertical angle would still be too difficult. Besides, its mission wasn’t to photograph Ban Xia – the Big Eyes plus its legs were seven or eight meters tall, making it impossible to hide from the synthetic aperture radar’s view.

“Oh.” Ban Xia was a bit disappointed.

“That thing takes poor-quality images, and they’re only in black and white,” Bai Yang consoled her. “You wouldn’t want it taking your picture, Young Miss. It’s not as good as the camera you have, OVER.”

“When will it pass by?”

“Using my time coordinate system, it will return to Earth orbit in twenty years. Using your time coordinate system, it will return in eight days,” Bai Yang answered. “That is, if nothing goes wrong along the way, OVER.”

The command center had developed a kind of path dependency, launching everything into space. In Zhao Bowen and the others’ view, space was the best way to send time mail – far from Earth, in the vast cosmos, with no interference. There were just a few minor drawbacks—like the long preparation period, high transport costs, potential launch failures, potential recovery failures, and possible damage from spending twenty years in space—well… when you put it that way, maybe space wasn’t such a great idea after all.

But it was cool!

Was there anything more important than being cool?

“So in my time coordinate system, it’s already in space, right?” Ban Xia looked up at the pitch-black ceiling.

It was amazing when you thought about it. Time was such a wonderful thing – the satellite that hadn’t even launched yet on one end had already been traveling through space for twenty years from her perspective.

“Not necessarily. There might be nothing at all, Young Miss,” Bai Yang said. “The launch might fail in eight days, in which case you won’t receive anything on your end after eight days. Remember the First Law of Time Mail? You can only potentially receive things that have already become facts on our end. If it hasn’t become a fact on our side yet, it won’t become a fact on your side either, OVER.”

“What if we want it to become fact?” Ban Xia asked. “Like if you set the satellite’s return time for tomorrow, and I receive the satellite’s signal tomorrow and transmit it to you, but you haven’t launched the satellite yet…”

“Based on my personal experience sending time capsules, the result would be a failure. That fact can’t form – the universe won’t allow it. You simply won’t receive the satellite’s signal,” Bai Yang pondered for a moment. “Then we’d learn the satellite return failed, temporarily cancel the launch plan, and reschedule the launch for later, which would result in you not receiving any satellite signal tomorrow, OVER.”

“Is there anything I need to do?” Ban Xia asked.

“Yes,” Bai Yang said. “The satellite can’t connect directly with the radio station. You’ll need to help receive the satellite signals, OVER.”

“How do I help?”

“Hit it!” Bai Yang said. “Hit the satellite!”