"Чанъэ-4" (Chang'e-4), посадочный аппарат и луноход – CZ-3B – Сичан (XSLC) – 07.12.2018, 18:24 UTC

[tnt22]

Chang'e 4 - 100x15km Orbit

Scott Tilley

Опубликовано: 30 дек. 2018 г.

Propagating orbit to landing window at Von Karman.

https://www.youtube.com/watch?v=5m8cZkzvsLghttps://www.youtube.com/watch?v=5m8cZkzvsLg (0:30)

[tnt22]

https://gbtimes.com/how-the-change-4-spacecraft-will-land-on-the-far-side-of-the-moon

How the Chang'e-4 spacecraft will land on the far side of the Moon
by Andrew Jones | Dec 31, 2018 16:03 | MOON ● CHINA'S SPACE PROGRAM ● CHANG'E-4


CGI of Chang'e-4 lander and rover having set down on the lunar surface. Framegrab/CCTV+/CNSA

China's Chang'e-4 spacecraft is in lunar orbit and preparing to attempt the first-ever landing on the far side of the Moon in the first days of January. Here's how the landing will proceed.

The Chang'e-4 spacecraft lifted off fr om Xichang, southwest China, on December 7 universal time and enter lunar orbit on December 12, wh ere it tested communications with the Queqiao relay satellite and refined its orbit.

Chang'e-4 is currently in a 15 x 100 kilometre elliptical polar orbit ready for a landing at Von Kármán crater early in the New Year, according to the China National Space Administration (CNSA).

According to amateur spacecraft trackers, this orbit should take the spacecraft over the Von Kármán crater for a possible landing around January 2 or 3, which comes a few days after sunrise over the area to allow the mainly solar-powered lander and rover spacecraft to begin operations on the surface immediately.

Спойлер

China's first and so far only lunar landing was made by Chang'e-3 in December 2013. While similar, Chang'e-4's landing will feature new challenges and changes. While there was close-to-live coverage for the Chang'e-3 landing, this is very much uncertain for Chang'e-4.

https://www.youtube.com/watch?v=QzZkF1MAsb8
The Chang'e-3 landing full video in HD.

Beginning descent

It is expected that the spacecraft's orbit has been carefully adjusted so that the perilune—or closest approach to the Moon—at 15 km altitude will be reached on approach to the sel ected Chang'e-4 landing site.

At a predetermined point, Chang'e-4 will begin its landing manoeuvres and perform a burn using its variable thrust main engine to decelerate the spacecraft. It will use its laser range sensor developed by the Chinese Academy of Sciences to determine altitude and velocity for navigation.

Scott Tilley‏ @coastal8049 18:33 - 30 дек. 2018 г.

Subject to confirmation of #ChangE4's plane my best guess is a late January 2nd to early January 3rd landing at Von Karman. Epoch (MJD GMAT)=28482.58428964,SMA=1794.5,ECC=0.023683477,
INC=87.0,RAAN=248.0,AOP=315.0,TA=225.0

https://www.youtube.com/watch?v=5m8cZkzvsLg
Chang'e 4 - 100x15km Orbit
Propagating orbit to landing window at Von Karman.
youtube.com

During the 'quick adjustment phase' between 8 and 6 kilometres above the lunar surface, Chang'e-4 will rotate by 90 degrees using its smaller thrusters in preparation for a vertical landing, much earlier than the predecessor mission Chang'e-3, which reoriented at 3 km above the Moon.

Following this begins the approach phase, with the lander's descent camera beginning optical observations of the landing area for coarse hazard avoidance.

These processes are carried out autonomously, in part because of a more than 3-second delay in speed-of-light communications between Earth and Chang'e-4 via Queqiao.

Because the lunar terrain on the far side is much more rugged and variable, Chang'e-4 needs to precisely target areas which are relatively flat. To help with this requirement for greater accuracy, Chang'e-4's descent will be much more vertical than that of Chang'e-3.


An animation demonstrating the landing process for the Chang'e-4 mission. China Academy of Space Technology

At around 100 metres 3D laser scanning imaging will begin to provide elevation data, as illustrated in the animation above, as part of a hovering phase which will allow avoidance of obstacles on the surface which could threaten the landing.

At 30 metres, according to a paper presented by mission engineers from the Beijing Aerospace Command and Control Centre (BACC) at the International Astronautical Congress in Germany in October, begins the slow descent phase and engine shutdown.

The lander has a 1,200 kg dry mass and carries the 140 kg rover. At liftoff the spacecraft had a mass of close to four tonnes once loaded with propellant for the orbital corrections and powered descent.


The planned powered descent sequence for the Chang'e-4 lunar far side landing. BACC

Why is this the first landing attempt on the far side?

While six crewed Apollo missions and a range of rovers and sample return missions have touched down on the near side, landing on the far side of the Moon has not been done before due to the extra challenges involved.

The main challenge is that the far side never faces the Earth, due to the phenomenon of tidal locking. This means a satellite is required to be in place beyond the Moon to relay communications between terrestrial tracking stations and the spacecraft.

The Queqiao ('Magpie bridge'), launched in May, is operating in a halo orbit around the special gravitationally stable Earth-Moon Lagrange point 2, from which it can maintain line-of-sight with the Earth and lunar far side at all times.


An animation showing Chang'e-4 in lunar orbit and communicating with the Queqiao relay satellite at the second Earth-Moon Lagrange point. CAST

Apollo 17 astronaut and geologist Jack Schmitt had strongly pushed for a landing in Tsiolkovskiy crater on the far side using a repurposed weather satellite positioned at a libration point beyond the Moon to provide communications, but this was rejected by NASA because of concerns over risk and cost.

Site selection for such missions is complicated by constraints such as the far side having greater crater coverage and variability in surface altitude than the near side, with the threat of illumination occlusion from the lunar terrain.

This is because the far side looks very different to the near side, with greater visible crater coverage and few of the maria, or basaltic 'seas' created by lava flows that we can see with the naked eye as dark patches on the near side. Why this is so remains a mystery and the answers will help our understanding of the Moon's history and even the development of the solar system


Images of the near (left) and far side of the Moon. NASA

Where will Chang'e-4 land?

Chang'e-4 will land inside the South Pole-Aitken (SPA) basin, a huge and ancient impact structure which may contain exposed material from the lunar upper mantle and clues to the development and history of the Moon.

SPA is the Moon's oldest impact basin and stretches from the south pole up to Aitken crater. It is of huge scientific interest and is cited in the US Decadal Survey as holding answer to several high-priority science questions, and could boost understanding of all of the terrestrial planets in our solar system and the timing and character of the late heavy bombardment.

The sel ected landing site is in the southern section of the 186-kilometre-diameter Von Kármán crater, which offers relatively flat areas within the SPA basin with few slopes or apparent obstacles to a safe landing.

A number of subsequent impact craters in the surrounding region, such as Finsen, are expected to have delivered ejecta to the floor of Von Kármán, potentially providing a rich sample of the SPA basin and far side geologic history.


An image of the Von Kármán crater from a mosaic created by the Lunar Reconnaissance Orbiter Camera. NASA/GSFC/Arizona State University

To sel ect land sites and analyse them for topography, composition and assist with the landing itself, the Chang'e-4 project used openly available images and data from NASA's Lunar Reconnaissance Orbiter (LRO), including its wide and narrow angle cameras and Lunar Orbiter Laser Altimeter (LOLA), Japan's SELENE (Kaguya) Terrain Camera and Multiband Imager, and India's Chandrayaan-1 Moon Mineralogy Mapper data, as well as China's own earlier Chang'e missions.

Experts from countries around the world also contributed to papers on the candidate landing sites, further underlining the international nature of space exploration.

A paper published by Huang Jun et al in the American Geophysical Union's Journal of Geophysical Research: Planets outlines the area—the white box below—currently understood to be the sel ected landing area, with other papers also focusing on sections of Von Kármán as potential sites.


The white box indicates the Chang'e-4 landing area with the Von Kármán crater, according to a paper fr om Huang Jun et al, 2018. Huang et al, 2018.

Phil Stooke of the Centre for Planetary Science and Exploration at the University of Western Ontario, has also mapped out the other candidate sites noted in papers on the upcoming Chang'e-4 landing, such as Apollo crater, which was mentioned early on as a contender.


Chang'e-4 lunar fars ide impact basin targets identified by Wang and Liu (2016) (dark circles), landing areas fr om Jia et al. (2018a, b) (white rectangles) and other suggested sites. Phil Stooke

Von Kármán will offer the chance to analyse the variations of composition of the lunar surface and SPA melt sheet with the Visible and Near-Infrared Imaging Spectrometer (VNIS), while also returning unprecedented images with cameras on both the lander and rover.

The Lunar Penetrating Radar (LPR) and low‐frequency radio spectrometer (LFS) payloads will also return unique data fr om the landing region, while the Lunar Lander Neutrons and Dosimetry (LND) instrument and Advanced Small Analyser for Neutrals (ASAN) will provide insight into the space environment and interactions with the surface.


A view of Mare Imbrium taken by China's Chang'e-3 mission. Chinese Academy of Sciences

Also joining the mission is a mini biosphere including potato and arabidopsis seeds and silkworm cocoons for a first-ever test of photosynthesis and respiration in the low-gravity lunar environment.

China is looking to Follow Chang'e-4 with the Chang'e-5 sample return mission on the near side. If this is successful, Chang'e-6 could attempt a sample return fr om the far side or even the South Pole of the Moon.


The Chang'e-5 return capsule (right) and lander and ascend vehicle (background) undergoing tests. Framegrab/CCTV

[свернуть]

[tnt22]

YE Quanzhi‏ @Yeqzids 9 ч. назад

Elsewhere... in today's news program, China's Central Television confirms #ChangE4's landing date to be on Jan 3. Exact time unknown but @Skywatcher2018 thinks it might be around 0900 Beijing Time (0100 UT).

[Roman Vladimirovich F.]

Ребята, если у кого-то есть информация, где будет вестись трянсляция из ЦУПа посадки лунного модуля, поделитесь а?
Могу только предположить, что должно будет показано где-то там - http://tv.cctv.com/live/cctvrussian/

[tnt22]

Scott Tilley‏ @coastal8049 7 мин. назад

Amateur observations of the radio signal from #ChangE4 support a landing window at the Van Karman crater complex Jan 3, 00:30-01:00 UTC. CE4 has been busy in constant ground lock during observations made from EU from @DF2MZ https://twitter.com/AJ_FI/status/1080474805969797120 ...

Спойлер

[свернуть]

[tnt22]

FiLinX пишет:
где будет вестись трянсляция из ЦУПа посадки лунного модуля

Местные на прямую трансляцию не надеются...      

liuyi‏ @LiuyiYiliu 3 ч. назад

Chinese space fans predicted Chang'e 4 will landing on the far side of the moon at 8:45 【Beijing time】tomrrow, no live at this time. We must waiting official news coming, it is truely hard for everybody.


3 ч. назад

If Chang'e 4 is safe landed on the surface, the massive propogenda will active. We shall know the name of the rover, possible called Yu'tu 2. I guess rover seperate from the lander can live(not sure).


3 ч. назад

Chang'e 4 landing no live because this mission fullfilled with dangerous, especially in the landing. CNSA affrid they cannot make people reasonable if mission failed.

[Liss]

Посадку ждем в 08:45 пекинского = 03:45 московского.

[tnt22]

Scott Tilley‏ @coastal8049 2 мин. назад

Here's a summary of #ChangE4 Doppler data since insertion into lunar orbit. Note the change in amplitude corresponds to a fortnight. If they miss this landing attempt we need to wait ~14 days.

[tnt22]

Cosmic Penguin‏ @Cosmic_Penguin 2 мин. назад

Just saw newest rumors that #ChangE4 's landing time will be closer to 02:00 UTC.

[tnt22]

Scott Tilley‏ @coastal8049 4 мин. назад

This graphic is a quick sketch of how the orbit to orbit rotation of the moon will provide a new landing window. Not to scale or implying where it will land, just to convey the concept.

[tnt22]

Посадка!

YE Quanzhi‏ @Yeqzids 1 мин. назад

So around 0230 UT someone who might have access to credible sources just said #ChangE4 has been successfully landed. Further confirmation pending.

Ждём официальных сообщений...

[tnt22]

https://www.weibo.com/3279752321/HacMv1D07?ref=home&rid=3_0_8_2669647105988248546_0_1_0

 //+关注
林晓弈  
6分钟前 来自 航爱网牌Android 已编辑

嫦娥四号月球探测器于今天上午10点26分成功软着陆，成功了！航天爱好者网祝贺！！

Успешная посадка!! Посадочный модуль Chang'E-4 совершил прилунение в 10:26 по пекинскому времени

[tnt22]

liuyi‏ @LiuyiYiliu 2 мин. назад

confirmed landing is success,still have 8hours that rover roving at surface of the far side of the moon.

[tnt22]

Alan Boyle‏Подлинная учетная запись @b0yle 17 мин. назад

.@CGTNOfficial tweeted what looked like confirmation of #ChangE4 landing, but then deleted the tweet....

[tnt22]

Chris B - NSF‏ @NASASpaceflight 3 мин. назад

Hold on, are we calling it? Hate to class a ticker as a press release. Newscaster didn't say the words.

[tnt22]

[tnt22]

Да-а, пока с подтверждением какая-то фигня творится - твиты трут, ТВ оговаривается типа ждём посадки...     

Chris B - NSF‏ @NASASpaceflight 6 мин. назад

No, we're not calling it yet! We need one of the State-run Chinese news sites to officially announce it. It's all sounding hopeful, per well respected Chinese social media people, the deleted tweet and the apparently unapproved ticker above, but we really need a definitive call.

[tnt22]

Emily Lakdawalla‏ @elakdawalla 3 мин. назад

According to @barbylon, if Chang'e 4 has actually landed, @LRO_NASA's first opportunity to image it will be on 4 January.

[tnt22]

YE Quanzhi‏ @Yeqzids 1 мин. назад

Still unofficial: #ChangE4 solar panel deployed at 0350 UT.

[tnt22]

Есть подтверждение в 12-тичасовых новостях ТВ КНР

Andrew Jones‏ @AJ_FI 3 мин. назад

Chang'e-4 has landed successfully on the far side of the Moon!