Rockets of Today

TIĀNGŌNG SPACE STATION (天宫号空间站) — China, 2021

China has long been banished from the ISS (due to a past history of stealing aerospace technology), but they aren’t taking the ban meekly. They’re building their own modular station. It was a long term goal in their space plans as long ago as the early nineties, so it was not something they were going to just let slide. They practiced with small orbital laboratories called Tiāngōng (天宫) 1 and 2, which acted as testbeds for the needed technology. The first of those went up in 2011 and the second in 2016, and they deorbited in 2018 and 2019. (#3 was cancelled.) They were inhabited by eight taikonauts (including China’s first women in space) for almost 48 days. In 2017 they launched a cargo craft called Tiānzhōu (天舟), and practiced docking it with Tiangong 2 and transferring fuel. Tianzhou 2 will be used to resupply the new space station. The Tianzhou is a variant of the original Tiangong design. A Tianzhou full of food and equipment launched on a Long March 7 shortly after the first module of their brand new station reached orbit, docking with it before the people went up.

The new station started with a core module called Tiānhé (天和, “Joining of Heaven”), which went up on a Long March 5B in 2021. It is 17 meters long and masses about 22 tons. It has a service and propulsion section at the back end, a multiway docking port at the front, reaction control thrusters all around, small solar panels, gyros, a robot arm, and all the necessities inside to support a crew of three. It has docking setups for passenger and cargo craft on the front and bottom ports of the forward junction, and the top port was used temporarily as an EVA airlock. Cargo carriers can also dock at the back end. The ports are compatible with current international standards based on the Russian APAS-95 system, the arm is based on the Russian Lyappa design used on Mir, and like the Canadarm it can mount itself at multiple places on the station. The entire module is part of a design lineage based on the old Russian Salyut series, which makes it a modernized cousin of the Zvezda module at the heart of the ISS’s Russian end.

The side ports are for attaching two laboratory modules: Wèntiān (问天, “Quest for Heaven”) to port and Mèngtiān (梦天, “Dream of Heaven”) to starboard, also known as Experiment Module I and II. These are around 14 meters long and 4.2 in diameter, and are equipped with larger solar panels, and their own reaction control thrusters. Each has an unpressurized section at the outer end sticking out another 4 meters or so, with Mengtian’s being larger, and accessible with their own airlocks, including a proper EVA lock on Wentian. The outside of the station has dozens of attachment points for any device or experiment that wants exposure to space. (The large diameter of the Long March 5 fairing let them bolt on all kinds of external stuff that would ordinarily have to wait for a spacewalk.) For indoor lab work, they already had a list of 100 experiments queued up before the first crew arrived. Wentian has three extra sleeping berths for use during crew changeover. It also has an additional five meter robot arm, and one place that arm can be used is as an extension of the ten meter main arm.

The interiors will follow the established style, with sectional equipment racks that give a square interior cross section. In fact, the racks will be compatible with those used on the ISS. By concentrating on essentials (that is, by minimizing crew luxuries), they’ve managed to fit in nearly as many experiment racks as the much larger ISS. This should help facilitate cooperation on experiments with any other country that’s interested in collaboration. (In rejecting such cooperation with China, the USA is essentially standing alone.)

When fully loaded the station should mass around 100 tons. Its normal crew compliment is three people. The habitable space in Tianhe will be about 50 cubic meters, with each laboratory module adding about 30 more. The station as a whole is called Tiangong for short, like the little test stations were except with no number after it. Gōng () means palace.

One way this station is more advanced than the ISS is that Tianhe has ion engines at its back end for orbital maintenance. This will greatly reduce propellant consumption, at the cost of reducing available electric power when they’re in use.

how it might be used

The Russians have expressed interest in visiting this station. They and the Chinese are cooperating in space on lunar activities, so why not here as well? There are two issues to overcome for this to happen: first, they would have to finally update the Soyuz with modern docking rings, and second, they will need to launch from someplace well south of their usual launch sites at Baikonur and Vostochny, because the Chinese station is orbiting at a lower latitude. This would probably mean launching from the ESA spaceport in French Guiana, which has launched plenty of uncrewed Soyuzes but no people. This also requires the ESA to be politically accepting of supporting such cooperation, which at the moment is absolutely ruled out by the outrage at Putin’s invasion of Ukraine. Failing all that, they’d have to beg a ride on a Chinese rocket.

Finally, I should mention the Xúntiān (巡天, “Heaven Cruiser”) space telescope. This will not be attached to the station but will orbit nearby, able to dock with the station for maintenance. It will be nearly comparable in size and performance to the Hubble scope, with a two meter mirror, but with a much wider field of view. This might go up a couple of years after the station is completed. (Why haven’t we built other such telescopes over the years? We should. At least we are putting up our own wide-field scope soon. It’s made from a recycled spy satellite and is about Hubble’s size. In fact, there’s some talk that they might put up two. We should have a dozen. After all, we’re working pretty hard at ruining the view for ground-based scopes nowadays.)

If you’re curious about why some Chinese spacecraft use the word shén and others use the word tiān, when both translate as “heaven”, well I can’t clarify things too much, except to say that apparently the latter word is more identified with Taoism, and may carry more of a connotation of “deity” whereas the former carries a connotation of “spirit” or “magic”, though both refer in a more literalist way to the sky. I may be off base there... probably only a native speaker of the language could clarify this. The political intent of using these very traditional words is just to sound poetic and inspirational so as to increase public support — that much I can say. The policy of using traditional poetic names in the space program, analogously to how America used Greco-Roman names during the space race, was started by Deng Xiaoping, replacing the previous rule of using terms evocative of the Communist revolution, and has been followed ever since.

Will the station be commercialized? Will they do like NASA has done, and permit millionaires to visit, or cosmetic companies to use astronauts in ads, for a price? (The going labor rate for purely commercial use of orbiting astronauts is seventeen thousand dollars an hour.) Yes — they are definitely open to commercialization. And if other countries don’t put up something new, they’re looking forward to having the premium offering as the ISS gets less and less crepit, and eventually has to retire.

The most extravagant commercial use of the ISS will come when actor Tom Cruise and director Doug Liman go up to shoot a movie there — a visit for which NASA will charge $10 million or more on top of what SpaceX charges for the ride up. The Russians, after hearing about this, sent up an actress and director of their own in 2021, getting there first, shortly after the new Nauka module was installed. They did a nationwide casting call stunt to select Yulia Peresild for the role, making a TV show of the selection and training process. Klim Shipenko, who had previously directed a rather fictionalized version of how the dead Salyut 7 station was restored to service by cosmonauts, went up as her director and film crew. I’m guessing it’ll be quite a while before anything like that happens on the Chinese station.