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{{short description|China crewed lunar surface lander}}
{{Use American English|date=July 2023}}
{{Use dmy dates|date=July 2023}}
{{Infobox spacecraft class
| name             = Lanyue<br />{{Lang|zh|揽月}}
| image            = Chinese crewed lunar lander mockup 01 - NMC.jpg
| image_caption    = Model of planned ''Lanyue'' lunar lander (attached to its propulsion stage) in 2023
| image_alt        =
| manufacturer     = {{flagicon|CHN}} [[China Academy of Space Technology|CAST]]
| designer         =
| country          = {{CHN}}
| operator         = [[China Manned Space Agency|CMSA]]
| applications     = Crewed lunar landing as part of [[Chinese Lunar Exploration Program]]
| spacecraft_type  = Crewed
| design_life      =
| launch_mass      = about {{convert|26000|kg|lb|abbr=on}} (with propulsion stage)<ref name=AJ17072023>{{cite news | author=Andrew Jones | title=China sets out preliminary crewed lunar landing plan | url=https://spacenews.com/china-sets-out-preliminary-crewed-lunar-landing-plan/ | work=spacenews.com | date=17 July 2023 | access-date=24 July 2023}}</ref>
| dry_mass         =
| payload_capacity =
| crew_capacity    = 2<ref name=AJ17072023 />
| length           =
| diameter         =
| volume           =
| power            = Solar
| batteries        =
| equipment        = crewed lunar rover<ref name=AJ27022023>{{cite news | author=Andrew Jones | title=China unveils lunar lander to put astronauts on the moon | url=https://spacenews.com/china-unveils-lunar-lander-to-put-astronauts-on-the-moon/ | work=spacenews.com | date=27 February 2023 | access-date=24 July 2023}}</ref>
| orbits           = [[Low Earth orbit]], [[lunar transfer orbit]], [[lunar orbit]], [[lunar surface]]
| status           = Under development
| built            =
| orders           =
| launched         =
| operational      =
| retired          =
| failed           =
| lost             =
| first            =
| last             =
| lastretired      =
| derivedfrom      =
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| insignia         =
}}
The '''Lanyue''' ({{zh|s='''揽月'''|p=lǎn yuè|l=embracing the moon}}) lander, formerly known as the '''China crewed lunar surface lander''' ({{Lang|zh|中国载人月面着陆器}}) or simply as the '''lunar surface lander''' ({{Lang|zh|月面着陆器}}), is a spacecraft under development by the [[China Academy of Space Technology]]. The purpose of the lander is to carry two astronauts to the lunar surface and to return them to lunar orbit after a set period of time.<ref name=AJ27022023 /> The lander's initial lunar-landing attempt is envisioned to occur by 2030.<ref name=AJ17072023 />
== Nomenclature ==
The official names for both the crewed lunar lander and the next-generation crewed spacecraft, the [[Mengzhou (spacecraft)|Mengzhou]] ({{Lang|zh|梦舟}}), were revealed by the [[China Manned Space Agency]] (CMSA) on 24 February 2024.<ref name=segeryu224 /><ref name=cndaily2024 /> One possible English translation for ''Lanyue'' is ''Embracing the Moon'' while the English translation for ''Mengzhou'' can be ''Vessel of Dreams'' or ''Dream Vessel''.<ref name=cndaily2024 />
==Overview==
Since at least August 2021, Western news media has reported that China's main spacecraft contractor was working on a human-rated landing system for lunar missions.<ref name=AJ09082021>{{cite news | author=Andrew Jones | title=China is working on a lander for human moon missions | url=https://spacenews.com/china-is-working-on-a-lander-for-human-moon-missions/ | work=spacenews.com | date=9 August 2021 | access-date=12 September 2023}}</ref> On 12 July 2023, at the 9th China (International) Commercial Aerospace Forum in [[Wuhan]], Hubei province, Zhang Hailian, a deputy chief designer with the CMSA, publicly introduced a preliminary plan to land two astronauts on the Moon by the year 2030. Under this plan, the astronauts will conduct scientific work upon landing on the Moon, including the collection of lunar rock and regolith samples. After a short stay on the lunar surface, they will carry the collected samples back into lunar orbit in their spacecraft and subsequently, to Earth.<ref name=AJ17072023 />
The preliminary plan describes a 'landing segment' that consists of a new lunar-lander attached to a propulsion stage which together are to be launched autonomously into a [[trans-lunar injection]] (TLI) orbit by the under-development [[Long March 10]] rocket. The lander-propulsion stage arrangement is somewhat analogous to the lander-orbiter architecture of the 2020 [[Chang'e 5]] and the 2024 [[Chang'e 6]] robotic lunar sample-return missions; however, unlike the orbiters for the robotic missions, the propulsion stage for the crewed lander will descend from lunar orbit together with the lander rather than remaining in lunar orbit.<ref name=AJ17072023 /> (The propulsion stage will undergo a controlled impact landing on the Moon after it separates from the crewed lander during the final stages of the descent, while the lander itself will attempt a powered soft landing).
On 24 April 2024, Lin Xiqiang, deputy director of [[China Manned Space Agency]] (CMSA), stated that the initial development of various products for China's lunar missions, including the Lanyue lander, is complete; according to Lin, mechanical and thermal articles for the lander and other mission segments have been constructed and the requisite rocket engines are undergoing hot fire tests. Lin further elaborated that prototype production and tests are in full swing and that the crewed lunar exploration launch site is currently under construction near the existing coastal [[Wenchang Space Launch Site|Wenchang spaceport]] in Hainan province.<ref name="AJ-24-04-2024">{{Cite web |last=Jones |first=Andrew |title=China on track for crewed moon landing by 2030, space official says |url=https://spacenews.com/china-on-track-for-crewed-moon-landing-by-2030-space-official-says/ | date=24 April 2024 | access-date=24 April 2024 |website=SpaceNews |language=en-US}}</ref> On 29 October 2024, CMSA announced that a separation test for the two modules of the landing system (presumably the lander and its propulsion stage) had been carried out.<ref>{{cite news |author=huaxia |title=China fully advances manned lunar landing program |url=https://english.news.cn/20241029/f3b00a0da3f842319b90e5606825d1b6/c.html |work=xinhua.net |access-date=29 October 2024 |date=29 October 2024}}</ref>
==Lander attributes==
A model of the under-development lunar lander was unveiled at an exhibition to mark three decades of China's human spaceflight program on 24 February 2023 at the [[National Museum of China]] in Beijing.<ref name=AJ27022023 />
The physical model of the under-development lander, when considered together with the presentation by Zhang Hailian on 12 July 2023, suggests the future spacecraft will have the following components: four 7500-newton main engines, numerous attitude-control thrusters for precise maneuvering, a stowed lunar rover capable of carrying two astronauts, docking mechanisms (for docking with the [[Mengzhou (spacecraft)|Mengzhou]] spacecraft), a crew hatch (for [[Extravehicular activity|EVA]]s), a ladder attached to one of the landing legs, two solar arrays, various antennaes and sensors.<ref name=AJ17072023 /><ref name=AJ27022023 />
The estimated mass of the fully-fuelled landing segment (lunar-lander plus propulsion-stage) is {{convert|26000|kg|lb|abbr=on}}.<ref name="xinhua20072023" />
===Lunar rover===
Models of the crewed lander includes a four-wheeled rover stowed on the lander's external wall. CMSA previously issued an open call to private, public, and educational institutions to submit development plans for the future lunar rover; according to CMSA, fourteen groups submitted proposals in response to the open solicitation and eleven of the fourteen proposals advanced to the expert-review stage. On 24 October 2023, CMSA announced that two of the remaining eleven submitted proposals have advanced to the detailed design phase while another six groups will receive continued support to enable them to continue research into innovative aspects of their proposals.<ref>{{cite news |title=载人月球车研制方案征集初选结果公告 |url=https://www.cmse.gov.cn/gfgg/202310/t20231024_54490.html |date=2023-10-24}}</ref> On 29 October 2024, CMSA awarded contracts to two teams (one team from the China Academy of Space Technology and a second team from the Shanghai Academy of Spaceflight Technology) to develop prototypes of the lunar rover, and production work was underway; a public call for proposed rover names is anticipated.<ref name=AJ10292024>{{cite news | author=Andrew Jones | title=China selects 2 proposals for crewed moon rover | url=https://spacenews.com/china-selects-2-proposals-for-crewed-moon-rover/ | work=spacenews.com | date=29 October 2024 | access-date=30 October 2024}}</ref>
Survey of journal literature reveals that the planned lunar rover may incorporate "differential-braking" and "off-ground detection" technologies to enhance its anti-slip and steering-stability characteristics during high-speed traverse. Engineering prototypes have been built for design verification purposes.<ref>{{cite journal |title=Design and Optimization of Stable Control Strategy for Manned Lunar Rover |author-last1=CAO |author-first1=Jianfei |author-last2=LIANG |author-first2=Changchun |author-last3=WANG |author-first3=Rui |author-last4=WANG |author-first4=Yaobing |author-last5=WANG |author-first5=Zhifu |author-last6=WANG |author-first6=Jun |display-authors=2 |year=2023 |journal=Journal of Astronautics |volume=44 |issue=9 |pages=1379–1391 |doi=10.3873/j.issn.1000-1328.2023.09.011 }}</ref>
The rover's planned mass is about 200 kilograms, and it will be able to carry two astronauts; it has a planned traverse-range of about 10 kilometres.<ref name=AJ17072023 /><ref name="xinhua20072023" />
==Lander mission architecture==
Under CMSA's crewed lunar landing plan, the landing segment initially will be injected into an Earth-Moon transfer orbit via the Long March 10 carrier rocket, and subsequently acquire lunar orbit under its own power. It then will await a [[lunar orbit rendezvous]] with and docking by the separately launched [[Mengzhou (spacecraft)|Mengzhou]] spacecraft (formerly known as the ''next-generation crewed spacecraft'', the analog to the Apollo program's [[Apollo command and service module]]) whereupon two astronauts will transfer to the lander, undock from Mengzhou, and maneuver the landing segment for a lunar-landing attempt.<ref name=AJ17072023 />
The landing segment's powered descent phase will employ a "staged-descent" concept. Under this concept, the combined lander and propulsion stage will begin descending from lunar orbit with the latter providing the necessary deceleration; when the stack is close to the surface, the lander will separate from the propulsion stage and proceed to complete the powered descent and a soft-landing under the lander's own power (the discarded propulsion stage meanwhile will impact the lunar surface a safe distance away from the lander). At the conclusion of the surface portion of the mission, the full lunar lander will act as the ascent vehicle for the astronauts to return to lunar orbit.<ref name=AJ27022023 /> According to a report by the [[Xinhua News Agency]], the lander also will be capable of autonomous flight operations.<ref name="xinhua20072023">{{Cite web |url=http://www.news.cn/politics/2023-07/20/c_1129760361.htm |title=中国载人登月初步方案公布，登月装备研制进展如何？ |date=20 July 2023|publisher=新华网|language=zh-hans |accessdate=18 October 2023}}</ref>
As of 2022, the landing system is envisioned to enable a six-hour stay on the lunar surface by two astronauts.<ref name=AJ22082022>{{cite news | author=Andrew Jones | title=China claims progress on rockets for crewed lunar landings and moon base | url=https://spacenews.com/china-claims-progress-on-rockets-for-crewed-lunar-landings-and-moon-base/ | work=spacenews.com | date=22 August 2022 | access-date=12 October 2023}}</ref> It is unclear from the source if the quoted 'six-hour stay on the moon' references the lander's total time on the lunar surface or the astronauts' surface-[[Extravehicular activity|EVA]] duration; if the latter, then the proposed surface mission duration would be comparable to those carried out by the United States' [[Apollo 11]] and [[Apollo 12]] missions. During the previously-cited 2023 aerospace forum in Wuhan, Zhang Hailian also stated that a lunar surface-EVA spacesuit with an endurance period of no less than eight hours is currently under development.<ref name=AJ17072023 />
===Lunar EVA spacesuit===
On 28 September 2024, CMSA unveiled a spacesuit designed to allow astronauts to conduct extravehicular-activities in the lunar low-gravity environment. The EVA suit has been designed to be lightweight compared to China's current [[Feitian space suit|Feitian]] orbital-class EVA spacesuit. The new spacesuit will protrect astronauts from the radiation, thermal variations, and dust that they will encounter in the lunar surface environment. The suit also allows an astronaut to perform movements such as squatting and bending in order to facilitate the performance of work in complex lunar topography. A public competition to name the new spacesuit is currently underway.<ref name=AJ28092024>{{cite news | author=Andrew Jones | title=China unveils lunar spacesuit for crewed moon mission | url=https://spacenews.com/china-unveils-lunar-spacesuit-for-crewed-moon-mission/ | work=spacenews.com | date=29 September 2024 | access-date=30 September 2024}}</ref>
[[File:Chinese crewed lunar lander mockup 02 - NMC.jpg|thumb|upright=1.3|Another view of a model of the Chinese crewed lunar lander in 2023]]
==Potential landing sites==
Members of the [[Chinese Academy of Sciences]] have begun site selection research ("suggestions") for the anticipated crewed lunar exploration program. Thirty prime landing sites have been identified (narrowed down from a preliminary list of 106 and an interim list of 50); the thirty sites are located in both the lunar north and south polar regions as well as in the lunar near and far sides. Numerous criteria, intended to maximize mission scientific value while taking into account crew safety and engineering feasibility, were considered by the team. Examples of the 30 prime sites include the following: [[Ina (crater)|Ina crater/depression]], [[Reiner Gamma]], and [[Bode (crater)|Rimae Bode]] on the lunar near side, [[Apollo (crater)|Apollo basin]], [[Aitken (crater)|Aitken crater]], and [[Mare Moscoviense]] on the lunar far side, [[Shackleton (crater)|Shackleton crater]] in the lunar south polar region, and [[Hermite (crater)|Hermite crater]] in the lunar north polar region.<ref>{{cite journal |title=Scienntific Objectives and Suggestions on Landing Site Selection of Manned Lunar Exploration Engineering |author-last1=NIU |author-first1=Ran |author-last2=ZHANG |author-first2=Guang |author-last3=MU |author-first3=Lingli |author-last4=LIN |author-first4=Yangting |author-last5=LIU |author-first5=Jianzhong |author-last6=BO |author-first6=Zheng |author-last7=DAI |author-first7=Wei |author-last8=ZHANG |author-first8=Peng |display-authors=2 |year=2023 |journal=Journal of Astronautics |volume=44 |issue=9 |pages=1280–1290 |doi=10.3873/j.issn.1000-1328.2023.09.002 }}</ref>
==Earth-Moon trajectory design==
Preliminary trajectory designs based on specific landing sites and landing periods have also been carried out by a team from the [[Nanjing University of Aeronautics and Astronautics]] and from the China Astronaut Research and Training Center. In particular, the team analyzed possible Earth-Moon transfer trajectories based on seven potential landing sites, including Rimae Bode, a series of lunar [[rille]]s west of the [[Bode (crater)|Bode crater]], and Mare Moscoviense, covering the period from 2027 until 2037.<ref name="DYQZ-2023.9">{{cite journal |title=Assessment and Analysis of Transfer Trajectory and Landing Regions for Manned Lunar Exploration |author-last1=DING |author-first1=Baihui |author-last2=YANG |author-first2=Bin |author-last3=QIN |author-first3=Zheng |author-last4=LI |author-first4=Shuang |display-authors=2 |year=2023 |journal=Journal of Astronautics |volume=44 |issue=9 |pages=1471–1482 |doi=10.3873/j.issn.1000-1328.2023.09.019 }}</ref> The analysis employed a dynamic weighting method that quantified mission efficiency factors and engineering constraints, combined with the application of a pseudostate trajectory model to optimize the computational efficiency of trajectory design and landing site/time selection.<ref name="DYQZ-2023.9" />
The pseudostate model was first proposed by J.S. Wilson<ref>{{cite conference |title=A pseudostate theory for the approximation of three-body trajectories |last=Wilson |first=J.S. |year=1969 |conference=Astrodynamics Conference |book-title=AIAA Paper 1970-1061 |location=Santa Barbara, CA, USA}}</ref> in 1969 to study Earth-Moon spacecraft transfer trajectories. In the context of an Earth-Moon-spacecraft three-body system, the pseudostate method usually is more computationally efficient than the traditional [[Patched conic approximation|patched-conic]] method of trajectory design.<ref name="ZYD-2022.1">{{cite journal |title=Overview of Earth-Moon Transfer Trajectory Modeling and Design |author-last1=ZHANG |author-first1=Jiye |author-last2=YU |author-first2=Huichang |author-last3=DAI |author-first3=Honghua |display-authors=2 |year=2022 |journal=Computer Modeling in Engineering and Sciences |volume=135 |issue=1 |pages=5–43 |doi=10.32604/cmes.2022.022585 |s2cid=252627993 |doi-access=free }}</ref>
The patched-conic method essentially seeks to "patch" together two (Keplerian) two-body ellipses (the conics) at a point of intersection defined by the Moon's gravitational [[Sphere of influence (astrodynamics)|sphere of influence]], while taking into account the various physical constraints. This method can result in large errors that may be controlled by a possibly unstable and time-consuming iterative computational process.<ref name="ZYD-2022.1" /> The pseudostate model modifies the conic-patching method by defining a ''pseudostate transformation sphere'' (PTS), a region in which the spacecraft trajectory is calculated as an approximate solution to the [[Three-body problem#Restricted three-body problem|restricted three-body problem]]. The method starts by calculating an initial simple two-body Earth-spacecraft ellipse and using it to propagate the spacecraft's position to a point within the Moon's PTS (the spacecraft's ''pseudostate''), next the approximate restricted three-body solution is applied and the pseudostate is backward propagated to a point on the surface of the Laplace sphere, which defines the beginning of the Moon's gravitational sphere of influence, and finally a two-body Moon-spacecraft conic is calculated and the spacecraft location is forward propagated from the surface of the Laplace sphere to an arbitrary perilune point.<ref name="ZYD-2022.1" /> The Laplace sphere and the gravitational sphere of influence concepts used in the two models, when applied to Earth-Moon system with an approximately circular orbit, is given by
<math display=block>R_\text{Laplace} \; = \; D \; \left( \frac{m}{M} \right)^{2/5},</math>
where <math>R_\text{Laplace}</math> is the radius of Laplace sphere, <math>D</math> is the average Earth-Moon distance, <math>m</math> is the mass of the Moon and <math>M</math> is the Earth's mass. Strictly speaking, the Laplace sphere is not a sphere but a changing hypersurface defined at each point of the path of a gravitational mass. The criterion for calculating the Moon's Laplace sphere is to analyze the Moon's gravity as the primary force acting in the region under consideration while the Earth's gravity is treated as a perturbing force.<ref name="MNRAS-2020">{{cite journal |title=On the local and global properties of gravitational spheres of influence |author-last1=SOUAMI |author-first1=D. |author-last2=CRESSON |author-first2=J. |author-last3=BIERNACKI |author-first3=C. |author-last4=PIERRET |author-first4=F. |display-authors=2 |year=2020 |journal=Monthly Notices of the Royal Astronomical Society |volume=496 |issue= 4|pages=4287–4297 |doi=10.1093/mnras/staa1520 |doi-access=free |arxiv=2005.13059 }}</ref><ref>{{cite journal |title=Gravitational Spheres of the Major Planets, Moon and Sun |author-last=CHEBOTAREV |author-first=G.A. |year=1964 |journal=Soviet Astronomy |volume=7 |issue=5 |pages=618–622 |bibcode=1964SvA.....7..618C |url=https://articles.adsabs.harvard.edu/pdf/1964SvA.....7..618C }}</ref> The Laplace sphere differs from the [[Hill sphere]] because the calculation of the latter sphere requires the presence of stable orbits while the former does not.<ref name="MNRAS-2020" />
== See also ==
* [[Apollo Lunar Module]]
* [[LK (spacecraft)]]
* [[Altair (spacecraft)|Altair]]
* [[Starship HLS]]
* [[Blue Moon (spacecraft)|Blue Moon]]
* [[List of crewed lunar lander designs]]
* [[Lunar lander]]
* [[Comparison of crewed space vehicles]]
== References ==
{{Reflist|refs=
<ref name="segeryu224">{{Cite tweet
|author= Seger Yu
|user=SegerYu
|number=1761207275920978365
|title=CMS 说新一代载人飞船叫"梦舟（Mengzhou, MZ）"；月面着陆器叫"揽月（Lanyue, LY）"。}}
</ref>
<ref name="cndaily2024">{{cite news
| author1=Zhao Lei
| title=Chinese lunar lander and new crew spaceship names revealed
| url=https://www.chinadaily.com.cn/a/202402/24/WS65d9506aa31082fc043b8df2.html
| accessdate=February 24, 2024
| publisher=[[China Daily]]
| date=February 24, 2024 }}</ref>
}}
{{Clear}}
{{Crewed spacecraft}}
{{Crewed lunar spacecraft}}
{{CNSA space program}}
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