Author Topic: Queqiao (Chang‘e-4 coms relay sat) - CZ-4C - XSLC - May 20, 2018 (21:28 UTC)  (Read 32256 times)

Online Avengers

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APStar-6C is successfully launched, and Queqiao is the next launch from Xichang.

4 questions (I realize that some or all of them may not be answerable at this moment):

What tracking ship or ships will support this mission?

Will the launch be video/web-cast live?

What is the launch window time and length?

How many days will the window remain open?

yuawang-6 tracking ship

Online Steven Pietrobon

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Will the launch be video/web-cast live?

What is the launch window time and length?

How many days will the window remain open?

That information has not been publicly released. Its anyone's guess if China will have a live web cast. The recent string of successful launches may prompt a live web cast. The last web cast in July last year was a bit of an embarrassment for China, with CZ-5 failing before everyone's eyes.

You could use orbital dynamics and previous launches to work out a launch window. Depending on the performance of the launcher, the window could range from seconds to hours. Probably closer to seconds since a CZ-4C is being used.

Since lighting conditions on the Moon are probably not a restriction, there should be an opportunity every few days, twice a month.
« Last Edit: 05/04/2018 07:27 AM by Steven Pietrobon »
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Online Steven Pietrobon

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Here's a good image that shows the launch restriction. Imagine your launch site is at 28.5 degrees or less. Then twice every day, the launch site will pass within the Lunar orbit plane. After getting into LEO, you have to fire your engine at the point opposite the Moon from the centre of the Moon through the centre of the Earth. This point moves from 28.5 degrees South (as shown in the picture), through 0 to 28.5 degrees North, as the Moon orbits the Earth every 29.5 days (the synodic period).

For inclinations above 28.5 degrees, there is a line through the Earth where the Earth equatorial plane crosses the Lunar orbit plane. We need to do an inclination change along this line. The orbit plane we launch into also has to cross this line. For a minimum energy launch, we can launch into this plane once a day. However, the Moon has to be on the either end of the line, which means the opportunity only occurs twice a month. With some margin, we can extend the window per day and the days around these opportunities.

https://en.wikipedia.org/wiki/Orbit_of_the_Moon#/media/File:Lunar_Orbit_and_Orientation_with_respect_to_the_Ecliptic.tif
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Offline zubenelgenubi

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Will the launch be video/web-cast live?

That information has not been publicly released. Its anyone's guess if China will have a live web cast. The recent string of successful launches may prompt a live web cast. The last web cast in July last year was a bit of an embarrassment for China, with CZ-5 failing before everyone's eyes.
<snip>

Yes, I'm hoping recent launch successes and this payload being part of the Chang'e program will outweigh other concerns.  Chang'e-3 had live coverage.
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Online Phillip Clark

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The "live" launches tend to be lunar and man-related missions, plus the CZ-5 tests (which could be described as being "man-related", of course).

So on that basis I am hopeful for live coverage of the Queqiao launch.
I've always been crazy but it's kept me from going insane - WJ.

Online Galactic Penguin SST

APStar-6C is successfully launched, and Queqiao is the next launch from Xichang.

4 questions (I realize that some or all of them may not be answerable at this moment):

What tracking ship or ships will support this mission?

Will the launch be video/web-cast live?

What is the launch window time and length?

How many days will the window remain open?

yuawang-6 tracking ship

It actually just left its base on the Yangtze river earlier today.
Yuan Wang 7, which tracked the APStar-6C launch on May 3 over the central Pacific, will also move around for this launch.
Chinese spaceflight is a cosmic riddle wrapped in a galactic mystery inside an orbital enigma... - (not) Winston Churchill

Online Avengers

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APStar-6C is successfully launched, and Queqiao is the next launch from Xichang.

4 questions (I realize that some or all of them may not be answerable at this moment):

What tracking ship or ships will support this mission?

Will the launch be video/web-cast live?

What is the launch window time and length?

How many days will the window remain open?

yuawang-6 tracking ship

It actually just left its base on the Yangtze river earlier today.
Yuan Wang 7, which tracked the APStar-6C launch on May 3 over the central Pacific, will also move around for this launch.

Yes,Today’s news coverage。
https://weibo.com/3279752321/GfnxVkAOI?from=page_1005053279752321_profile&wvr=6&mod=weibotime&type=comment

Offline zandr

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What tracking ship or ships will support this mission?
http://russian.news.cn/2018-05/06/c_137159182.htm
Translation
Quote
The Chinese ship "Wanwan-6" began the mission of tracking of the satellite repeater", Zhuazao" lunar probe "Chang'e-4"
Nanjing, may 6 /Xinhua/ - the Ship monitoring of space flights "Wanwan-6" on Saturday left the port of Jiangsu province in Eastern China and went to the specified area of the Pacific ocean, to follow the flight of "Cacao" - data-relay spacecraft for the lunar probe "Chang'e-4".
Lunar probe "changye-4" will be launched at the end of this year, it will have to make the first landing in the history of mankind on the reverse side of the moon. Satellite-repeater ", Zhuazao" will be responsible for signal transfer between the Earth and the back side of the moon.
Tracking and control ", Zhuazao" from the sea will be implemented by the courts "Wanwan-6" and "Yuanyuan-7". The ship "Wanwan-7" just completed the mission to monitor the communications satellite APSTAR-6C and has traveled in a given area to perform the new job.

Offline satwatcher

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Under the assumption that CE-4 follows the same parking orbit as CE-2 and CE-5T1, and that a 4 day coast to lunar orbit is used, with translunar insertion about 19 minutes after launch, the launch time would have to be around 22:15UT if launched on May 21st.

Online Galactic Penguin SST

Under the assumption that CE-4 follows the same parking orbit as CE-2 and CE-5T1, and that a 4 day coast to lunar orbit is used, with translunar insertion about 19 minutes after launch, the launch time would have to be around 22:15UT if launched on May 21st.

Does that still holds for a launch towards the EM-L2 point, which this is heading to?
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Offline satwatcher

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Does that still holds for a launch towards the EM-L2 point, which this is heading to?
That is a good point, and it is not clear to me what the trajectory options are to reach EM-L2. Add this as an other assumption.

Online Galactic Penguin SST

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Offline Star One

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China preparing to launch Chang’e-4 relay satellite May 21

Quote
HELSINKI, Finland – China is set to launch a relay satellite to the second Earth-moon Lagrange point May 21, in a necessary precursor to the planned Chang’e-4 soft-landing on the lunar far side late in the year.

Chang’e-4 is the backup to the Chang’e-3 mission which put a lander and rover on Mare Imbrium in late 2013. Following that success, the lunar craft have been repurposed for a pioneering landing on the moon’s far side.

The lunar far side does not face the Earth as the moon’s orbital period matches its rotational period, thus requiring a relay satellite to facilitate communications.

Quote
Ian Crawford, professor of planetary science and astrobiology at Birkbeck, University of London, told SpaceNews the mission would be a “tremendous undertaking, as it would be the first time any spacecraft has successfully landed on the far side of the moon.”

The landing is currently expected to target the Von Kármán crater within the South Pole-Aitken Basin, though a decision on the final site has not been announced by Chinese scientists.

The South Pole-Aitken Basin is, Crawford notes, a high priority scientific objective for exploration, potentially offering unique insights into the formation of the moon and history of the solar system.

http://spacenews.com/china-preparing-to-launch-change-4-relay-satellite-may-21/

I like the lyrical name that it’s been given. But then again the Chinese always give their Lunar program components such lyrical names.
« Last Edit: 05/15/2018 07:19 PM by Star One »

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Offline zubenelgenubi

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What is the launch window time and length?
<snip>
You could use orbital dynamics and previous launches to work out a launch window. Depending on the performance of the launcher, the window could range from seconds to hours. Probably closer to seconds since a CZ-4C is being used.

Since lighting conditions on the Moon are probably not a restriction, there should be an opportunity every few days, twice a month.
And:
Here's a good image that shows the launch restriction. Imagine your launch site is at 28.5 degrees or less. Then twice every day, the launch site will pass within the Lunar orbit plane. After getting into LEO, you have to fire your engine at the point opposite the Moon from the centre of the Moon through the centre of the Earth. This point moves from 28.5 degrees South (as shown in the picture), through 0 to 28.5 degrees North, as the Moon orbits the Earth every 29.5 days (the synodic period).

For inclinations above 28.5 degrees, there is a line through the Earth where the Earth equatorial plane crosses the Lunar orbit plane. We need to do an inclination change along this line. The orbit plane we launch into also has to cross this line. For a minimum energy launch, we can launch into this plane once a day. However, the Moon has to be on the either end of the line, which means the opportunity only occurs twice a month. With some margin, we can extend the window per day and the days around these opportunities.

https://en.wikipedia.org/wiki/Orbit_of_the_Moon#/media/File:Lunar_Orbit_and_Orientation_with_respect_to_the_Ecliptic.tif
Thanks, Steven!

And a partial answer to my question from SpaceNews, dated May 14: China preparing to launch Chang’e-4 relay satellite May 21
Quote
...the three-day launch window opening on May 21 [CST/May 20 UTC, italics mine].
« Last Edit: 05/16/2018 03:39 PM by zubenelgenubi »
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Online Phillip Clark

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Not sure if it's significant but a very rough calculation suggests that the Moon is close to perigee at 20:00 on May 20th.   
« Last Edit: 05/16/2018 04:38 PM by Phillip Clark »
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Online Galactic Penguin SST

Still no NOTAMs yet but drop zone notices are starting to come out and confirms the launch time at just after 21:00 UTC on May 20.

The 1st stage drop zone is near Zunyi, Guizhou and the fairing drop zone is near Ninghua county in Fujian.

Chinese spaceflight is a cosmic riddle wrapped in a galactic mystery inside an orbital enigma... - (not) Winston Churchill

Offline Liss

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Are these NOTAMs relevant?

Quote
J4031/18 - ALTN RTE FOR A582/R595/Y579/Y27/Y533/Y531/Y59/ ARE ESTABLISHED DUE TO SPACEFLIGHT ACTIVITIES. 1.FLT PLANNED RTE IS REQ TO BE FILED AS FLW (1)A582:(BTN MAMIK AND NIMOX) ALTN RTE:NHC V91 MJC-ALBAX-NIMOX (2)R595:(BTN MJC AND TUNTO) ALTN RTE:MJC-ALBAX-NIMOX-TUNTO (3)Y579:(BTN AZAMA AND SAKON) ALTN RTE:AZAMA Y74 NHC V91 MJC-ALBAX-NIMOX (4)Y27:(BTN AMMEK AND SAKON) ALTN RTE:YURIX Y62 IKEMA-ALBAX-NIMOX (5)Y533:(BTN ALBAX AND AZAMA) ALTN RTE:ALBAX-IKEMA Y57 AZAMA (6)Y531:(BTN ALBAX AND YURIX) ALTN RTE:ALBAX-IKEMA Y62 YURIX (7)Y59:(BTN KAZIK AND AZAMA) ALTN RTE:AZAMA Y74 NHC V91 MJC B462 KAZIK 2.SEE NOTAM RJAAYNYX J4030/18. SFC - UNL, 2125/2140 2255/2310, 20 MAY 21:25 2018 UNTIL 20 MAY 23:10 2018. CREATED: 18 MAY 09:51 2018

J4030/18 - DUE TO SPACEFLIGHT ACTIVITIES,THE FLIGHT SAFETY OF THE AIRCRAFT IN FOLLOWING AREAS MAY BE AFFECTED ON MAY 20, 2018 DETAILS ARE AS FOLLOWS: ON MAY 20,2018 FROM 21:31-21:40 UTC AND 23:01-23:10 UTC AREA: 242432N1271117E 234250N1265819E 240231N1254146E 244420N1255418E,FOUR-POINT CONNECTION RANGE. VERTICAL ALTITUDE:SFC-UNL RMK/ATC WILL NOT CLEAR IFR FLT THRU THIS AREA FOR THE FLIGHT SAFETY. SFC - UNL, 2131/2140 2301/2310, 20 MAY 21:31 2018 UNTIL 20 MAY 23:10 2018. CREATED: 18 MAY 09:49 2018

Seems to be the case; and Stage 2 will overfly Taipei at some 05:30 local time. Heads up!

« Last Edit: 05/18/2018 12:05 PM by Liss »
This message reflects my personal opinion based on open sources of information.

Online Galactic Penguin SST

Various notices for falling rocket parts are up and one quotes a launch time of 21:28 UTC. All quotes the launch code as 07-87.

I'm not sure there will be any kind of coverage at launch - it has been dead silence since before the spacecraft reached Xichang!  ::)
Chinese spaceflight is a cosmic riddle wrapped in a galactic mystery inside an orbital enigma... - (not) Winston Churchill

Offline Star One

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Various notices for falling rocket parts are up and one quotes a launch time of 21:28 UTC. All quotes the launch code as 07-87.

I'm not sure there will be any kind of coverage at launch - it has been dead silence since before the spacecraft reached Xichang!  ::)

That’s really strange isn’t it as normally they publicise anything related to their Lunar program.

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