Written by C. Christian Monson
How would you like to vacation in a Palace in the Sky? That’s exactly what Tiangong means, the name of the space station China is currently constructing in low Earth orbit. However, with about 110 cubic meters, or around 4,000 cubic feet, of planned habitable space, just 4% the volume of an Olympic swimming pool, Tiangong isn’t exactly designed to be a holiday home. Instead, the space provides living quarters for three Chinese astronauts, or Taikonauts, and room to conduct scientific research.
The Tiangong Space Station is actually the culmination of a project spanning back three decades that has included two other functioning space stations. Started in 1992 under the title Project 921, when finished, the Tiangong Space Station will represent the completion of the third and final step of the Chinese Manned Space Program, one of the most successful projects in history dedicated to the exploration of space.
THREE SMALL STEPS FOR MAN
Step one of the CMS was to send a human being into space. Although China had been researching spaceflight since 1968 and launched its first satellite in 1970, by 1992 they still hadn’t completed a manned mission. That September the CMS started work on the Long March 2F, their first rocket designed to launch human beings into orbit.
By 1999, the CMS had finished developing the Shenzhou 1 as well, a spacecraft whose name in Mandarin translates to “the Divine Vessel on the Heavenly River,” referring to the Milky Way. It would eventually carry Taikonauts into space, but the first model was uncrewed and therefore not equipped with life support. It also didn’t have the unfolding solar panels that would provide power for later Shenzhou models.
Coming in at a full 7,600 kilograms, which is roughly 17,000 pounds or nearly the weight of a Tyrannosaurus rex, the Shenzhou 1 test mission launched from Inner Mongolia on 19 November 1999, after which is successfully orbited the earth 14 times in 21 hours before re-entering the atmosphere. The test proved the functionality of the spacecraft’s attitude control and heat shield, as well as its separation from the Long March 2F. Though it hasn’t been confirmed, rumors also claim that the Shenzhou 1 carried 100 kilograms of seeds into space to record the effects they experienced in the extreme environment.
Shenzhous 2-4 followed that first flight, all of them successful and providing data for Shenzhou 5, China’s first manned spaceflight. It launched on 15 October 2003 with Taikonaut Yang Liwei onboard, making China the third country to send a person into space. Yang spent over 21 hours in orbit before landing safely back in Inner Mongolia.
Step two was to launch a space laboratory that would allow CMS to develop docking technology for spacecraft and provide a platform for testing short-term habitation in space. CMS wasted no time with this step, and the Shenzhou 6 launched in October 2005 carrying Taikonauts Fei Junlong and Nie Haisheng on a multi-person, multi-day flight that spent four days completing 76 orbits. Then in 2011, CMS launched Tiangong 1, a kind of prototype space station. Shenzhou 8 followed and, though uncrewed, successfully completed a rendezvous and docking. Shenzhou 9 then carried three Taikonauts who successfully manually rendezvoused and docked with Tiangong 1, after which Shenzhou 10 did the same, allowing its three scientists to spend 12 days living in space during which they conducted experiments and gave video lectures for Chinese students.
Weighing 8,000 kilograms, or 18,000 pounds, the Tiangong wasn’t all that much bigger than the Shenzhou spacecraft itself, and at just over 10 meters long, or around 35 feet, the space station was far from a roomy stay. In fact, it only had 15 cubic meters, or just over 500 cubic feet, of pressurized habitable volume, hardly any bigger than my office. During its two years of life, Tiangong 1 was only occupied for about three weeks, but it did give Chinese scientists considerable insight into space habitation.
In 2016, CMS followed Tiangong 1 with Tiangong 2 launched aboard the Long March 7 rocket, which was capable of heavier payloads than the previous Long March 2F. Tiangong 2 was the same size as its predecessor, but CMS decided to push the limits of its capabilities a little further.
First, Shenzhou 11 took two astronauts to the space station where they spent 30 days, up till then China’s record for time in space. Additionally, in 2017, the Tianzhou 1 cargo spacecraft, whose name means “heavenly vessel,” successfully docked with Tiangong 2 and completed refueling maneuvers, proving that China could successfully resupply a long-term space station.
This represented the end of the second step and ushered in the third and final step, currently in progress.
PALACE IN THE SKY
The Tiangong space station is already under construction with three Chinese Taikonauts commanded by Zhai Zhigang living on it as I record this, which they have been doing since October 2021. The first module was launched in April 2021 on a Long March 5B rocket, nicknamed “Pang-Wu,” or “Fat-Five, the most powerful Chinese rocket in operation and third most powerful in the world after Falcon Heavy and Delta IV Heavy.
Called Tianhe, or “Harmony of the Heavens,” this first module represents the core of the Tiangong space station and alone is longer than Tiangong 1 and 2 at 16.6 meters in length, or around 55 feet. It weighs a full 22,600 kilograms, nearly 50,000 pounds, which is why it had to be launched aboard the Pang-Wu.
Compared to Tiangong 1 and 2, the Tianhe module has a little more room for the Taikonauts to stretch their legs, but not much: 50 cubic meters of living space, or about 1,800 cubic feet, still less than a quarter the size of an average Manhattan apartment. Although they do get access to all three dimensions, this is a tight squeeze for three roommates.
This is especially true since the Taikonauts must also work in the station. In addition to three sleeping berths, a kitchen and a toilet, the Tianhe module has computers, a scientific research station, and communications equipment and WiFi, as well as a robotic arm called the “Chinarm.” It’s all primarily powered by photovoltaic solar power arrays, though Tianzhou spacecraft do have to refuel the station’s chemical propulsion systems and ion thrusters, important features considering Tiangong has twice had to dodge SpaceX Starlink satellites.
Tianhe isn’t the only module planned for the Tiangong space station, though. In fact, Tiangong is what’s referred to as a “third generation modular space station,” similar to Russia’s Mir and the International Space Station, which means it will be constructed piece by piece with individually launched modules, thereby reducing costs, improving reliability and allowing for more specialized equipment.
By the end of 2022, CMS plans to add two more modules to the space station: the Wentian and Mengtian laboratory modules. These will give scientists more room to conduct life-science experiments in microgravity that wouldn’t work well on Earth and study cosmic rays and the solar wind. Both of these LCMs are essentially the same size, and, at about 18 meters or 60 feet long, actually slightly larger than the Core Tianhe module itself.
Although there are no concrete plans yet, CMS may eventually expand Tiangong to six modules.
THE HIGH LIFE
China initially conceived of the Tiangong space station because they were excluded from the International Space Station, but due to the repeated success of the program, a number of other countries and agencies, including the European Space Agency, France, Sweden, Russia and Germany, have come knocking to see if their scientists or experiments could spend time on the station in the future. That might be because, on top of all the scientific resources, life aboard Tiangong actually seems pretty comfortable—if you can get past the cramped space and suction toilet, a $23-million “Universal Waste Disposal System” that treats and recycles the Taikonauts’… deposits.
For example, there’s a WiFi network, and each Taikonaut has their own headphone set and microphone that works by conducting sound through bone. This facilitates the many lectures and experiments the Taikonauts perform live for Chinese school children to inspire their interest in science.
There’s also a shower, and one of the three sleeping berths even has a small window, though I don’t know how they decide who gets it. Taikonauts also have access to gym equipment and a neuromuscular electrical stimulator, both of which are essential for minimizing muscular atrophy due to the low gravity.
The menu is impressive as well with 120 different kinds of food available on the station, including shredded pork, kung pao chicken, pickled cabbage, and drinks like tea and juice. Most of the food is solid and made in small pieces to help with eating and digestion problems caused by the low gravity. However, the Tiangong coolers do carry some fruits and vegetables in addition to condiments like Szechuan sauce, an important thing to include since spaceflight can cause head congestion and a decrease in the sense of taste and smell. Most impressively, the Taikonauts can always have their food hot thanks to an onboard microwave oven, the first ever in space.
So while it might not be a “palace” in the traditional sense, Tiangong is certainly living up to its name when it comes to space habitability, not to mention setting spaceflight and space construction milestones. CMS hopes it will serve their Taikonauts for at least 10 years, possibly even 15, during which time the rotating three-person crew will advance space science, inspire and teach a generation of Chinese students, and eat plenty of kung pao chicken with the world’s greatest view.
“About CMS.” CMS. http://en.cmse.gov.cn/aboutcms/
“Astronauts conduct second Chinese space station spacewalk.” Space News. https://spacenews.com/astronauts-conduct-second-chinese-space-station-spacewalk/
“China Manned Space Program.” Wikipedia. https://en.wikipedia.org/wiki/China_Manned_Space_Program
“China preparing to build Tiangong station in 2021, complete by 2022.” NASApaceFlight.com. https://www.nasaspaceflight.com/2021/03/china-preparing-to-build-tiangong-station-in-2021-complete-by-2022/
“Handbook—China Space Station and its Resources for International Cooperation.” United Nations Office for Outer Space Affairs. CMS. https://www.unoosa.org/documents/doc/psa/hsti/CSS_1stAO/CSS_1stAO_Handbook_2018.pdf
“It turns out that the toilet in the Tiangong space station looks like this. How convenient is it for astronauts?” iMedia. https://min.news/en/tech/a2e85ef3e7d267a1f1eb665c77b1c563.html
“Long March 2F.” Wikipedia. https://en.wikipedia.org/wiki/Long_March_2F
“Long March 5.” Wikipedia. https://en.wikipedia.org/wiki/Long_March_5
“Shenzhou (spacecraft).” Wikipedia. https://en.wikipedia.org/wiki/Shenzhou_(spacecraft)
“Shenzhou 1.” Wikipedia. https://en.wikipedia.org/wiki/Shenzhou_1
“Space travel can affect astronauts’ sense of taste and smell.” Physics Today. https://physicstoday.scitation.org/do/10.1063/PT.5.025900/full/
“Tiangong-1” Wikipedia. https://en.wikipedia.org/wiki/Tiangong-1
“Tiangong-2.” Wikipedia. https://en.wikipedia.org/wiki/Tiangong-2
“Tiangong-3.” Wikipedia. https://en.wikipedia.org/wiki/Tiangong-3
“Tiangong program.” Wikipedia. https://en.wikipedia.org/wiki/Tiangong_program
“Tiangong space station.” Wikipedia. https://en.wikipedia.org/wiki/Tiangong_space_station
“Tianhe core module.” Wikipedia. https://en.wikipedia.org/wiki/Tianhe_core_module
“Tianzhou 1.” Wikipedia. https://en.wikipedia.org/wiki/Tianzhou_1