Spacecraft controllers aim for the heights

Experts at a center in Beijing oversee operations of crews and missions, ensuring that nation's program continues to build upon recent successes. Zhao Lei reports.

Like many office workers, Hu Guolin and his colleagues deal with figures, charts and graphics on their computer screens.

However, the information in front of Hu's team comes from Earth's orbit or even planets hundreds of millions of kilometers away.

From the first day of its existence, people working at the Beijing Aerospace Control Center — like Hu, some of the smartest minds in China — have been tasked with applying their talent and expertise to realize the nation's ambitions in orbit, ranging from building a permanent space station to operating rovers on extraterrestrial bodies.

Established in 1996 to serve the nation's manned space program, the center has played an indispensable role in all crewed spaceflights. It is also the country's top body responsible for controlling and tracking deep-space missions.

During the past two years, mission controllers at the center, which is located inside the strictly guarded Beijing Aerospace City compound in a northwestern suburb of the capital, have often appeared on television monitoring spacecraft operations, calculating trajectories, uploading commands and conversing with astronauts.

The controllers, in aquamarine uniforms with the "China Space" logo on the back, were attentive, energetic and sharp-eyed on TV.

Behind that glamorous appearance, though, the work of these men and women is demanding, challenging and painstaking.

A nonstop flow of information related to trajectories and positions pours into the windowless control halls 24 hours a day from orbiting spacecraft and telemetry stations across the country, as well as tracking ships on the oceans.

The controllers monitor the data with rapt attention, make quick decisions on the measures to take in the event of alarms about in-orbit malfunctions or emergencies, and produce specific plans for the next step of each mission.

"Our controllers on the Tiangong space station program work 12-hour shifts that start at 8 am or 8 pm. Their job requires them to be utterly focused on information that changes in a matter of minutes or even seconds. Actually, they spend much longer than 12 hours here every day because they need to attend briefings before and after their shifts, and also often need to participate in workshops on mission details," Hu, head of the controllers in charge of long-term spacecraft operations, said during a recent media tour of the center.

The Tiangong space station was completed at the end of last year, after 12 launch missions.

As one of the largest space-based assets ever deployed in Earth's orbit, the station currently consists of: the Tianhe core module; the Wentian and Mengtian lab modules; the Shenzhou XV crew spacecraft; and the Tianzhou 5 cargo ship.

So far, four groups of astronauts have lived and worked inside the facility. The current crew — the three members of the Shenzhou XV mission — arrived in November. The astronauts are scheduled to live on the station until May, when the crew of Shenzhou XVI will take over.

Busy days

On a typical day shift in the space station operations team, the controllers start work by contacting and communicating with the astronauts inside Tiangong. A designated controller talks with the crew members about the arrangements for the day and notes their needs.

Meanwhile, those in charge of the tracking apparatus relay the daily tasks to tracking stations and ships, and ensure that they are able to do their jobs. The controllers also need to amend arrangements for tracking stations and ships and relay satellites whenever any of the assets are not functioning properly, Hu said.

"Some controllers are responsible for uploading commands. They prepare orders for the spacecraft based on what the mission planners want the vehicles to do, then send the signals to the spaceship in accordance with predetermined schedules," he said. "For instance, when the astronauts want to sleep, we will upload an order to the station's alarm system to shut down the voice alarms."

The chief controller said that there are many unpredictable factors when it comes to operating large orbiting infrastructure such as a space station in near-Earth space, which is already crammed with satellites and debris.

"It is not unusual that we have to move our space station higher or lower than its normal altitude to avoid incoming hazardous debris — and that is never easy," he said.

"Adjusting a spacecraft's position is not as simple as just typing some codes and sending them out, as some people may imagine. It requires systemic considerations: you must decide which tracking station or ship will upload the commands and monitor the spacecraft during the process; you need to pick another station or ship as backup; you also need to take a host of factors into account, including the orbital adjustment's impact on the space station's condition, like its power generation and the operation of internal equipment."

He added that the controllers must have clear, sharp minds and be quick and decisive to figure out solutions to potential risks.

"Not long ago, an alarm warned that the barometric pressure inside the Tiangong station was falling rapidly: if that were really happening, the situation would be highly dangerous for our mission crew. So, we immediately collected and analyzed all the readings and concluded that it was a false alarm caused by minor sensor errors," he said.

Ultimate goal

To further improve their efficiency and capabilities, the controllers continue to study and use cutting-edge technologies such as cloud computing and artificial intelligence, according to Hu.

"I am sure that AI technology has great potential in spacecraft control — for example, in the assignment of personnel duties and orbital positioning," he said.

He added that all the efforts have one ultimate goal, which is to guarantee the astronauts' safety and the long-term, smooth operation of the space station.

"Our task is to make the astronauts feel safe and comfortable, and let them know that they have our full support and that of the entire nation so they can do their jobs in a happy mood," he said. He noted that he and his colleagues often meet the astronauts in person, sometimes formally and sometimes informally.

"We all work inside the Beijing Aerospace City compound. Our office building and some of our residences are close to the Astronaut Center of China, so we often run into the astronauts," Hu said.

"Sometimes, when we go jogging before or after work, we find some astronauts running beside us. We also take part in preflight workshops and ground simulations with them. There are discussions and debates between us, and even though the astronauts may not remember our names, we know that they trust us and that we are all striving for the same goal."

'Loud and clear'

For Yuan Xudong, head of the center's communication engineers, his team's most important duty is to ensure that the astronauts are always "online". He and his engineers are in charge of establishing and maintaining communications between the center and spacecraft.

"The more reliable our communications system is, the smoother the link between our controllers and the astronauts is," he said.

"It is our responsibility to make the voices of the astronauts and controllers loud and clear, and that they can be heard by all posts throughout the ground control network."

In addition to the routine work, Yuan's team now has a new task. The members are required to provide a video link between the astronauts and tens of millions of school students in China for the Tiangong Class science lectures.

Launched in December 2021, the Tiangong Class is China's first extraterrestrial lecture series. It aims to popularize space science and inspire young people to pursue their science and space dreams. Every flight crew since the Shenzhou XIII mission has delivered one or two lectures during their stay in orbit.

"I took part in the preparations for China's first space-based science lecture, hosted by the Shenzhou X mission crew in June 2013. Compared with that time, we now have more knowledge and experience in ground-to-spacecraft communications and better land- and space-based infrastructure," he said.

Each time a Tiangong Class lecture takes place, schools across the country arrange for their students to watch. Sometimes, the students are allowed to repeat the experiments shown in the lecture.

After one recent lecture, Yuan was invited by his son's classmates — all primary school students — to share some interesting stories behind the lecture and some information about spacecraft communications.

"Childhood and youth are always filled with curiosity about the world and the universe. These lectures will plant the seed of science in the students, which will wait to blossom and bear fruit," he said.

"Every time I realize that through our work, more boys and girls can experience the wonder and magic of outer space, I am filled with a sense of honor and mission."