Mars mission team prepares for its toughest challenge
As Beijing's residents bask among the spring blossoms, engineers and technicians in the capital's northwestern suburbs are busily preparing for a challenging maneuver involving a spacecraft hundreds of millions of kilometers from Earth.
The team members－spacecraft control professionals at the Beijing Aerospace Control Center－are making all-out efforts to ensure that Tianwen 1, China's first independent interplanetary mission, will soon safely land a rover on Mars to conduct scientific tests.
The rover was recently named Zhurong after an ancient god of fire.
"The next step will be the entry, descent and landing procedures, which will be the most challenging and risky parts of the entire mission," Cui Xiaofeng, chief controller of the mission at the center, told China Daily in an exclusive interview this month.
From February, the center's engineers and technicians have been working to a tight schedule to ensure that everything will be perfect before the landing is attempted, he said.
"Since the spacecraft started orbiting Mars and conducting extensive examinations of the preselected landing area in late February, it has generated a huge amount of data and images," Cui said.
"That's producing a heavy workload for my team members, who are responsible for making detailed arrangements for the investigative operations and conducting high-precision orbital control maneuvers. Furthermore, they are tasked with processing the data and giving the findings to scientists for analysis and research."
In addition, the controllers will continue working to improve the procedures for the entry, descent and landing maneuvers until the moment they actually occur.
"Even though the procedures were basically worked out months ago, our people need to keep simulating as many scenarios as possible and optimizing plans for the upcoming maneuvers," Cui said, adding that the team is racing to complete its tasks.
"Compared with landing on the moon, touching down on Mars is more demanding and complex as a result of the planet's unique atmospheric conditions and other uncertainties. That's why scientists call the process 'Seven Minutes of Terror'," the chief controller said. "The team is doing its best to make it a success."
The Tianwen 1 probe, named after an ancient Chinese poem, consists of two major sections－an orbiter and a landing capsule.
It was launched by a Long March 5 heavy-lift carrier rocket on July 23 from the Wenchang Space Launch Center in the southernmost island province of Hainan. As such, it kicked off China's planetary exploration program.
The mission's ultimate goal is to land a rover next month or in June in the southern region of Utopia Planitia－a vast plain within Utopia, the largest recognized impact basin in the solar system－to conduct scientific surveys.
If the robotic mission succeeds, Chinese scientists will get their first opportunity to closely observe Mars, which was first recorded in the country on oracle bone inscriptions in about 1300 BC.
In ancient China, the reddish celestial sphere was known as Yinghuo, or "flickering flame", a name derived from ancient astronomers' observations that it moved like a capricious light in the night sky.
Tianwen 1 is currently held in a parking orbit about 280 kilometers above Mars and it circles the planet every two days. The probe is now more than 280 million km from Earth.
The Beijing Aerospace Control Center is China's top body for controlling and tracking deep-space missions.
It was established in 1996 to serve the country's manned space programs and has taken part in all 11 crewed space flights and lunar expeditions.
The center's Mars mission control team was formed in early 2018 and most of the members are ages 30 to 40. Since the first day, the team members knew they would be facing a large number of difficulties and challenges because Tianwen 1 would be China's first attempt to send a spacecraft to the red planet.
The mission is highly sophisticated and has many differences from the country's previous space projects.
"We were supposed to have a short period of time to ready ourselves for the mission, which required a lot of planning, design and calculations," Jin Wenma, a senior deep-space control expert, said.
"The probe will have traveled more than 1,200 times the distance between Earth and the moon. We can't allow even a tiny error if we want to safely land the rover on the area chosen by the scientists.
"We needed to develop plans and technologies for major steps in the mission, including the Mars orbital insertion, the entry-descent-landing operation, long-distance tracking and communication, and the rover's movements on the Martian soil."
Thanks to the center's hard-working engineers and technicians, Tianwen 1 has smoothly completed all of its maneuvers ahead of the final landing. During the probe's seven-month voyage to Mars, the controllers assisted the spacecraft in carrying out four midcourse corrections and a deep-space orbital maneuver to ensure it was always precisely aimed at the planet.
They also performed comprehensive examinations of the probe's components to check they were working correctly.
Yu Tianyi, a senior control specialist, said the center's workers are expecting a successful touchdown, but after the landing they will also face many challenges.
For example, communicating with the semi-autonomous rover and manipulating its operations on the planet's surface will pose tremendous challenges.
"Driving a Martian rover will be very different to controlling a lunar buggy due to a number of factors: the much greater distance (between the two planets); the more complicated environment; and the effect of the Martian atmosphere," Yu said.
"Compared with our experience of operating lunar vehicles, we will have more difficulties in establishing and maintaining communications with the Martian rover. We will have a very short time every day when we will be able to contact it, so the number of signals and data we will be able to upload and download will be very limited. That will require us to make the best use of the precious transmission period every day and make sure our commands are succinct and precise."
Liu Shaoran, a deputy chief controller of Tianwen 1, said the team members have fulfilled their duties and commitments to the mission. Many have sacrificed much in the service of their country and its space endeavors, he said.
"For instance, Liu Xiaohui. a young woman in my team, postponed her wedding ceremony in her hometown three times in the past year so her work would not be affected," Liu Shaoran said.
"Before the third planned ceremony, everything was ready in her hometown and her family members and friends had been informed about the occasion, but she eventually called off her trip because she believed her work was more important than personal issues.
"No one persuaded or forced her to do that, it was simply her own decision."
Eventually, Liu Xiaohui and her husband used a video link to hold a "tele-wedding ceremony" attended by their relatives and friends in her hometown, he said.
Even though Liu Xiaohui is now expecting her first child, she continues to work as hard as ever, Liu Shaoran added.
Wang Cheng, another deputy chief controller, said Run Dong, a young man in his team, has spent almost all his time working at his post as a mission planner since he joined the center several years ago.
Dong's schedule leaves little time for family life. "However, he has rarely told anyone about his devotion and the sacrifices made in his private life," Wang said.
"I understand him. There are many people like him in this building who are doers rather than talkers. They are working hard for our nation."