The first laboratory module will provide additional navigation avionics, propulsion and [[Yaw, pitch and roll#Aircraft attitudes|orientation]] control as backup functions for the [[Tianhe Core Module]] (TCM). Both LCMs provide a pressurized environment for researchers to conduct science experiments in freefall or zero gravity which could not be conducted on Earth for more than a few minutes. Experiments can also be placed on the outside of the modules, for exposure to the [[space environment]], [[cosmic rays]], vacuum, and [[solar wind]]s.
The axial port of the LCMs will be fitted with rendezvous equipment and will first dock to the axial port of the CCM. A mechanical arm dubbed, as Indexing robotic arm, looking a sort of [[Lyappa arm]] used on the Mir space station will then move the module to a radial port of the CCM.<ref>{{cite news |url=https://www.nasaspaceflight.com/2021/04/china-station-construction-begins/ |title=China readies launch of Tianhe module, start of ambitious two-year station construction effort |first1=William |last1=Graham |first2=Chris |last2=Gebhardt |date=April 28, 2021 |publisherwebsite=NASASpaceflight.com |quote=This means the two future science modules, Wentian (“Quest for the heavens”) and Mengtian (“Dreaming of the heavens”), cannot dock directly to their planned radial port locations. [...] To account for this, each module will carry a Russian Lyappa robotic arm — like the ones used on Mir for the same purpose — to move the module from the forward port to its respective permanent ___location on a radial port of Tianhe's docking hub.}}</ref> It is different from Lyappa as it works on a different mechanism. Lyappa arm is needed to control the pitch of the spacecraft and redocking in a different plane. But the indexing robot arm where docking is needed in the same plane. In addition to this arm used for docking relocation, the Chinarm on ''Tianhe'' module can also be used as a backup.<ref>{{Cite book |last=Hong Yang |url=https://www.amazon.in/Manned-Spacecraft-Technologies-Space-Science/dp/9811548978 |title=Manned Spacecraft Technologies |publisher=Springer |year=2020 |isbn=978-9811548970 |___location=China |pages=355 |language=en |doi=27-08-2020}}</ref><ref>{{cite news |url=https://www.nasaspaceflight.com/2021/04/china-station-construction-begins/ |title=China readies launch of Tianhe module, start of ambitious two-year station construction effort |first1=William |last1=Graham |first2=Chris |last2=Gebhardt |date=April 28, 2021 |publisherwebsite=NASASpaceflight.com}}</ref>
[[Electrical power]] is provided by two steerable [[solar power]] arrays, which use [[photovoltaic]] cells to convert sunlight into electricity. Energy is stored to power the station when it passes into the Earth's shadow. Resupply ships will replenish fuel for LCM 1 for station-keeping, to counter the effects of atmospheric drag.
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==Launch==
Both modules are due for launch in 2022 on [[Long March 5B]] launch vehicles from [[Wenchang Satellite Launch Center]]. ''Wentian'' is scheduled to launch in 24 July 2022,<ref name="PressConference">{{Cite web |title=SCIO briefing about China's progress on space station construction {{!}} |website=english.scio.gov.cn |url=http://english.scio.gov.cn/pressroom/node_8030952.htm |access-date=2022-04-18 |website=english.scio.gov.cn}}</ref> while ''Mengtian'' is scheduled to launch in October.<ref name="TSS-schedule"/> They will be inserted into a [[low Earth orbit]] with an average altitude of {{convert|393|km|mi|abbr=on}} at an [[orbital inclination]] of 42 degrees, centered in the Earth's [[thermosphere]].<ref name="nsf-20210301">{{cite web |last=Barbosa |first=Rui C. |date=1 March 2021 |url=https://www.nasaspaceflight.com/2021/03/china-preparing-to-build-tiangong-station-in-2021-complete-by-2022/ |title=China preparing to build Tiangong station in 2021, complete by 2022 |workwebsite=[[NASASpaceFlight.com]] |date=1 March 2021 |accessdate=15 March 2021}}</ref><ref name=LCM>{{cite web |last=David |first=Leonard |url=https://www.space.com/11048-china-space-station-plans-details.html |title=China Details Ambitious Space Station Goals |work=[[Space.com]] |date=7 March 2011 |access-date=23 February 2012}}</ref>
