For 22 years the International Space Station (ISS) was the one station in orbit (apart from a interval from 1986 to 2001 when the Russian Mir station was in operation). A multinational collaborative challenge involving 5 taking part area businesses (United States, Russia, Japan, Canada, and the European House Company), the orbiting station dominated area, however now it has competitors.
The Tiangong area station is being constructed in low Earth orbit between 340 and 450 km (210 and 280 mi) above the floor. Its first module, the Tianhe (“Concord of the Heavens”) core capsule, was launched on 29 April 2021 and two extra modules are set to be launched subsequent 12 months.
So, how will the brand new station evaluate to the ISS?
Let’s begin with the fundamentals. How excessive within the sky is every area station? The ISS roams at an altitude of round 400 km (258 mi), whereas Tinagong will orbit between 340 and 450 km (210 and 280 mi) above the floor. So principally, the 2 stations don’t differ a lot on this standards.
When totally loaded, the Tiangong House Station could have a mass of round 100 metric tons (220,500 lb), roughly one-fifth the mass of the ISS. Coincidentally that is across the dimension of the decommissioned Russian Mir area station.
Each the ISS and Tiangong use solar energy to maintain themselves. The ISS’s electrical system uses photovoltaics, the place photo voltaic cells immediately convert daylight to electrical energy. Massive numbers of cells are assembled in arrays to provide excessive energy ranges, however this course of typically builds up extra warmth that may injury spacecraft gear.
To cope with this, the ISS makes use of radiators – shaded from daylight and aligned towards the chilly void of deep area – to dissipate warmth away from the spacecraft.
In the meantime, Tiangong uses two steerable solar power arrays situated on every module. These make use of use gallium arsenide photovoltaic cells to transform daylight into electrical energy. The station additionally shops vitality for the interval when the orbiting station is not uncovered to the solar.
At first, these two strategies may sound very related, however they do have necessary variations. The primary one is that Tiangong makes use of photo voltaic arrays whereas the ISS makes use of “wings.” These photo voltaic array wings –typically abbreviated SAW – include two retractable “blankets” of photo voltaic cells and are the biggest ever deployed in area.
Every wing weighs greater than 2,400 kilos, can attain 35 metres (115 ft) in size, and 12 metres (39 ft) in width when prolonged. Altogether, the 4 units of arrays can generate 84 to 120 kilowatts of electrical energy – sufficient to offer energy to greater than 40 properties.
Nevertheless, because the station is just not all the time in direct daylight, it additionally depends on lithium-ion batteries to see it by means of darkish durations. These account for 35 minutes of a 90-minute orbit. The batteries are recharged when daylight is current. Up till 2017, the ISS relied on nickel-hydrogen batteries. These have been changed from 2017 to 2021 with more practical lithium-ion ones.
The Chinese language area station is ready to be a third-generation modular space station, similar to the ISS. Third-generation area stations are modular stations, assembled in orbit from items launched individually.
The Chinese language area station is at the moment set to have three modules (the Tianhe core module, the Wentian Laboratory Cabin Module, and the Mengtian Laboratory Cabin Module) whereas the ISS has a whopping 16 modules, with two extra scheduled to be added. The ISS is made up of 5 Russian modules ( Zarya, Pirs, Zvezda, Poisk, and Rassvet), eight U.S. modules ( BEAM, Leonardo, Concord, Quest, Tranquility, Unity, Cupola, and Future), two Japanese modules (the JEM-ELM-PS and JEM-PM) and one European module (Columbus).
The Tiangong area station is constructed across the Tianhe core module. This part is the principle one and gives life assist and residing quarters for 3 crew members, in addition to steering, navigation, and orientation management for the station. That is additionally the place the station’s energy, propulsion, and life assist techniques are saved. It boasts three sections: residing quarters, a service part, and a docking hub.
The ISS then again is split into two sections. There’s the Russian Orbital Segment (ROS) that’s operated by Russia, and the United States Orbital Segment (USOS) that’s run by america, along with plenty of different nations. Every has its personal residing quarters in addition to science laboratories.
Robotic Arms and Airlocks
The ISS boasts very helpful and environment friendly robotic arms and airlocks that aren’t current within the Chinese language area station.
“Robotic arms are mounted outdoors the area station. The robotic arms have been used to assist construct the area station. These arms can also transfer astronauts round once they go on spacewalks outdoors. Different arms function science experiments,” writes NASA in a statement.
“Astronauts can go on spacewalks by means of airlocks that open to the skin. Docking ports enable different spacecraft to hook up with the area station. New crews and guests arrive by means of the ports. Astronauts fly to the area station on the Russian Soyuz. Robotic spacecraft use the docking ports to ship provides.”
Tiangong is fitted with the Chinese language Docking Mechanism, primarily based on the Russian Androgynous Peripheral Connect System (APAS-89/APAS-95) system. That is utilized by Shenzhou spacecraft and in addition in earlier Tiangong prototypes.
There have been claims that Tiangong’s docking system is a clone of the APAS system, which ought to make it suitable with the ISS’s docking system. Nevertheless, others argue that the 2 techniques will not be totally suitable.
The ISS’s mission is to check spacecraft techniques that shall be required for long-duration missions to the Moon and Mars and Taingong’s is kind of related. The China Manned Space Agency (CMSA), who operates the area station, has listed the brand new area station’s objective as:
“Additional growth of spacecraft rendezvous know-how; Breakthrough in key applied sciences resembling everlasting human operations in orbit, long-term autonomous spaceflight of the area station, regenerative life assist know-how, and autonomous cargo and gasoline provide know-how; Take a look at of next-generation orbit transportation autos; Scientific and sensible purposes at large-scale in orbit; Improvement of know-how that may assist future deep area exploration.”
The ISS has supported as many as 13 crew members onboard whereas the Taingong is at the moment geared up to deal with three.
OK, it is not truthful to match the experiments of the 2 stations, contemplating the ISS has been round for over twenty years, but it surely needs to be famous that Tiangong has an ambitious experimental schedule planned. The brand new area station shall be geared up to carry greater than 20 experimental racks with enclosed, pressurized environments, and greater than 1,000 experiments have been tentatively accredited by CMSA.
These embody experiments in area life sciences and biotechnology, microgravity fluid physics and combustion, material science in area, and fundamental physics in microgravity, all areas that the ISS’s experiments additionally discover.
In the long run, the 2 area stations share extra similarities than variations. They’re each area stations in spite of everything. What shall be fascinating to see is that if the Chinese language area station slowly grows to be as large and as productive because the ISS. Its makers undoubtedly have the ambition to make it so. Time will inform whether or not they attain this lofty purpose.