Sneak peek on something going to hit your spaceflight news headlines coming next week...pic.twitter.com/8WomXStq5G
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...and it might have a milestone effect on human exploration of space, in many ways. Yet for most parts people involved absolutely don't like to talk about it (right now). More on this coming in the next days here.pic.twitter.com/GgNmBXS5HB
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At T-1 week, w/ a decade of development & 3 additional years of wait for its ride to space behind, 23 intense days to the Moon and back ahead, this may be as much a watershed moment of beyond Earth human exploration as the Crew Dragon launch just now...pic.twitter.com/on8X2MXfdO
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...but they are so shy that there has been literally close to no news of what any other places would proudly boast as one of their flagship spaceflight missions, one that might be only slightly easier than Mars Sample Return. Yes, the ultimate Chinese call to the Moon is here.pic.twitter.com/ZGTGHNcotp
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So, um, before going through details of this, I have to report on the bad news that per someone's insider contacts (see below) we probably won't get much news of Chang'e 5, at least during launch phase. Yup, Chang'e 5 has an official identity crisis.
https://twitter.com/Longmarch13/status/1326853162565730311/ …pic.twitter.com/J39QndMsOP
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(the dialogue was about how Ouyuan Ziyuan, the default unofficial Chinese lunar exploration spokes-scientist, is NOT planned to appear in any live coverages of Chang'e 5...but will be on a December 5th launch from Xichang, probably of the GECAM gravitational wave observatories)
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This doesn't retract from the fact that this mission has a lot that can go wrong, and yet being a fierce shot at the PRC's determination of beyond-Low-Earth-orbit robotic and human exploration at the same time. This rocket-rabbit logo (made by enthusiasts?) feels exactly that.
pic.twitter.com/8oMlhgf8XV
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Well they are rolling off a day earlier than reported! The Long March 5 rocket with Chang'e 5 is currently rolling out to its pad at Wenchang for launch on apparently November 23 evening UTC.pic.twitter.com/Wszi1L0E10
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Someone somehow got a video of the roll out this time: https://m.weibo.cn/detail/4572171316500284 …
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More flags and banners, with the spacecraft and rocket processing teams:pic.twitter.com/1PwQJPaXVT
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Conflicting insider sources with another reliable one saying there will be some coverage on launch day: https://m.weibo.cn/status/JuikP1PG7 …
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At the launch pad: https://twitter.com/Longmarch13/status/1328528387204292608 …
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(rant) Well I was trying to write up a step-by-step walk through of Chang'e 5 from launch to Earth touchdown. Turns out not only I don't have parameters of its science instruments, there's only ONE list of it in a 2017 paper in Chinese! If anyone have them, please let me know.
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(rant) There are also many holes in my understanding of the lunar sample transfer process. If someone have good diagrams (especially the sample storage of the ascent stage, plus how samples move from ascent stage to the Earth return capsule), please let me know too.
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OK so, since several days of additional waiting from me failed to turn up more recent info, here's my walk through of the mission that, unlike other sample return missions, will be all over in 23 Earth days. And it's HARD. Lots of things can go wrong in a blink.
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Firstly, the ride to the Moon. While scoring successes w/ last Dec.'s RTF, the next-gen crew S/C (w/o 2nd stage) in May and sent TW-1 to Mars in July, the Long March 5 is still an inexperienced rocket. With every of its launches flagships, the pressure must be intense every time.pic.twitter.com/sX4LDc80C5
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Look at the engines. The YF-77 "Chinese Vulcain" on the core stage scored 3 good flights since the July 2017 failure and lots of teething troubles in testing. The YF-75D on the upper stage (expander cycle & not the CZ-3B's gas generator YF-75) had just *2* good flights!
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(on the 1st launch in Nov. 2016 the YF-75D under-performed & required the YZ-2 U/S to correct it). The RP-1 YF-100 has had 5 more launches under LM-6/7, but still it's pretty young. Then there's GNC and other issues etc. The ~30 minutes through S/C sep. will be a long wait.
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After separation the whole spacecraft will be on a direct trajectory towards the Moon.
@coastal8049 made some calculations based on prior mission timelines and estimate the LOI will be around 4.5 days after launch, probably ~14:45 UTC on Nov. 28: http://satobs.org/seesat/Nov-2020/0156.html …pic.twitter.com/nPhw3bf9hh
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What goes afterward is a bit hazy as I have never saw any detailed description of the mission timeline after this, but the spacecraft should stay in an unknown lunar orbit awaiting the sun to rise at the landing site, then separates from the orbiter and land.pic.twitter.com/VsMd4ORf5f
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We still have no idea when it will land - I have seen Nov. 30 mentioned once but early Dec. is possible - but while the Chinese have 2 successful ones already, the 2 failed Moon landings still remind people that GNC is a harsh mistress.pic.twitter.com/KyOdQlpXpi
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With the lander probably a bit different from the ones used on Chang'e 3/4, even this part will still be a challenge to nail down. All these parts will apparently be observed by a descent camera like the last 2 landings, though the only official source is from a Chinese paper.pic.twitter.com/4STjkSxoEr
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Now the surface operations is rather spotty in terms of public info. It took me quite a long time to nail the scientific instrument suite that would help in the sampling: - Panoramic Camera (PCAM) - Lunar Mineralogical Spectrometer (LMS) - Lunar Regolith Penetrating Radar (LRPR)
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The only mention of the PCAM is the paper excerpt below - I'm not even sure where they are located, perhaps it's the rotating platform in the picture on the descent stage. I can't find their technical parameters either... (https://meetingorganizer.copernicus.org/EGU2016/EGU2016-3858.pdf …)pic.twitter.com/xZz5YUUurV
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The LMS is apparently a visual/near infrared spectrometer - according to https://meetingorganizer.copernicus.org/EGU2016/EGU2016-5644.pdf … this is similar to the VIS/NIR Imaging Spectrometer (VNIS) on the Chang'e 3 rover w/ some modifications. I can't find where it is (same as PCAM?) or its technical parameters.
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The LRPR works at 2 GHz frequency under the bottom of the descent stage and maps the regolith structure beneath it for ease of sampling/drilling analysis. Luckily we do have a detailed paper regarding its principles with photos: https://www.essoar.org/pdfjs/10.1002/essoar.10504784.1 …
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As for the most important part, sample retrieval, the landing site near Mons Rumker in Oceanus Procellarum is of new geological importance not seen in previous lunar samples.
@elakdawalla has it summarized here:https://www.patreon.com/posts/change-5-lunar-43869582 …Diesen Thread anzeigen -
And sorry for the interruption, but a certain insider has reported important timings of the mission! Launch time: 20:25 ~ 21:15 UTC on November 23 Landing time: Probably ~20:30 UTC on November 29 (base on MCC screen shots during final rehearsal) Source https://m.weibo.cn/u/5616492130 pic.twitter.com/f1SnOA8ZeD
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Also it appears that after McGregor Texas, Wenchang is also a major habitat of Rocket Cows (TM):pic.twitter.com/GYTWHDV0fr
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It seems that I won't have time to finish this overview until half a day later so I'll just leave you with views of the pad from last night and right now: https://twitter.com/Longmarch13/status/1330473033316802562?s=19 …
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