Author Topic: LIVE: Chinese CE-5-T1 (Chang'e 5 precursor) - CZ-3C/G2, Xichang - Oct. 23, 2014  (Read 237643 times)

Offline tolis

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This is probably going too far (literally)
but the last image, rotated cw by 90 deg, reminds
me of a Voyager 2 composite of miranda's limb
with Uranus and its rings in the background.



Offline Blackstar

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Top, the CE5 image. Middle, a shot from the pilot episode of Space 1999. Bottom, the middle image flipped horizontally.

Conclusion: the Chinese are filming this mission on a soundstage.
« Last Edit: 10/28/2014 03:14 pm by Blackstar »

Offline JimO

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Very rough SWAG based on angles [Earth is 2 degrees wide, moon image is eight times more], I'd say the image was taken about four lunar diameters away.

Offline JimO

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3474 km divided by tan 16 degrees [0.29] or ~12,000 km. Does that make any trajectory sense?

Offline satwatcher

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3474 km divided by tan 16 degrees [0.29] or ~12,000 km. Does that make any trajectory sense?
Yes, very. By propagating the Space Track orbital elements the closest approach was predicted at 19:03UT on the 27th at a distance of 11300 km above the surface .

Offline Phillip Clark

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If the closest approach to the Moon was just over three days after launch then a 7-8 days flight time suggests that the spacecraft is still on its way to a geocentric apogee after exiting the Moon's sphere of influence.   Right?
I've always been crazy but it's kept me from going insane - WJ.

Offline Nordren

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Zarya.info has landing in Inner Mongolia for Friday, October 31, at 21:55 UTC (05:55 Saturday morning Nov 1 Beijing time), apparently accurate to within a few minutes. No idea about the chances of any live coverage. Nothing in the CCTV schedule, of course.
« Last Edit: 10/29/2014 12:06 pm by Nordren »

Offline the_other_Doug

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If the closest approach to the Moon was just over three days after launch then a 7-8 days flight time suggests that the spacecraft is still on its way to a geocentric apogee after exiting the Moon's sphere of influence.   Right?

The flight time from launch to lunar flyby was just over four days (the number I have is 97 hours, which is four days and one hour).  Not three days.  So yes, as of your post it was still climbing away from the Moon and heading for the passage into the Earth's sphere of influence.

I would imagine it's crossed back into the Earth's sphere of influence by now, though.

-Doug  (With my shield, not yet upon it)
-Doug  (With my shield, not yet upon it)

Offline Phillip Clark

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Doug, an earlier posting here on the morning of October 28th said that the lunar fly-by had taken place "that night" which I assume is overnight October 27-28.   So that is about 3-3.5 days after launch at 18:00 GMT on October 24th.

If Zarya is right about a recovery on October 31st evening then that fits.   But the Chinese had talked about a flight lasting for ~8 days.   Of course, the Chinese might be giving us a lot of rounding.

It would be nice for the Chinese to give an official periselene date, time and distance, but I don't think that they have done yet.
I've always been crazy but it's kept me from going insane - WJ.

Offline Moe Grills

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  The trajectory makes no sense as far as sample-return missions go.
But for a man-rated spacecraft on a cislunar mission?
The Chinese space project planners obviously had that sort of thing in mind. WOOHOOOO!!!
Human beings are FINALLY going to return to the moon at the cusp of the next decade.

Offline Dalhousie

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It's testing the sample return capsule and relevant velocities, not the trajectory.  the human related stuff is  bonus I assume.
Apologies in advance for any lack of civility - it's unintended

Offline Phillip Clark

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Whilst playing with some Chang'E programme numbers, I noticed that the Chang'E 5 Precursor (as I call this mission) was launched on the seventh anniversary of the Chang'E 1 launch.
I've always been crazy but it's kept me from going insane - WJ.

Offline satwatcher

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Doug, an earlier posting here on the morning of October 28th said that the lunar fly-by had taken place "that night" which I assume is overnight October 27-28.   So that is about 3-3.5 days after launch at 18:00 GMT on October 24th.

Note that you are one day out; the launch was at 18:00UTC on October 23rd.

Based on the available orbital elements shortly after TLI show that it passed over the 4 day lunar antipode. This means the flyby would occur 4 days after launch, and this is supported by the propagated trajectory based on those orbital elements. Furthermore, the propagated trajectory is very similar to that shown on the mission control displays (see earlier in this thread).

The propagated trajectory is consistent with a free return with a reentry around 21:36UT on October 31st. Spaceflight 101 reported "A clock seen in video from mission control indicates that the Return Vehicle will arrive back at Earth on October 31 at 21:53 UTC for a mission duration of eight days and four hours" which is consistent with the prediction from the propagated trajectory.

Finally, comparing cloud patterns and location of the terminator from the gorgeous shot of the Moon and Earth suggests the image was taken between 19 and 20UT on October 27th; the propagated trajectory sets the closest approach at 19:03UT on that day.

Moderators note: Please, use the 'Attach' feature to publish the photos.
« Last Edit: 10/30/2014 11:16 am by Satori »

Offline Phillip Clark

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Thank you Satwatcher!   Old age and senility seem to be catching up with me.   Plugging October 23rd into my own software gives the same lunar GHA at launch as seen for Chang'E 3.

However, if we assume a parking orbit at 28.5-31 deg to the equator and a transit time of ~97 hours to periselene then we have a theoretical GHA of 55-75 deg, which is more than 10 deg less than the actual value.

Maybe some exact data concerning the periselene date/time and distance from the Chinese will answer some questions - if the data are made available sometime.
I've always been crazy but it's kept me from going insane - WJ.

Offline russianhalo117

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Have we confirmed the fate of the mother SC post capsule sep?

Offline satwatcher

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Zarya.info posted two NOTAMs for the reentry of Chang'e 5T1; the first NOTAM bounds the area where the skip reentry will occur, the other smaller one the final landing location. As he reported earlier, the latter coincides with the Shenzhou landing region.

The NOTAMs are valid from 22:19UTC to 22:49UTC on October 31st. This is about 45 minutes later than the 21:36UT reentry time predicted from the trajectory propagated from the pre-flyby JSpOC elements. Zarya.info kindly shared the NOTAMs with me and they show that at 22:19UT the propagated return trajectory is coplanar with the NOTAMs. This confirms that the mid-course corrections altered the trajectory, probably already on the outbound leg. This matches the timing of the Earth-Moon picture that Chang'e 5T1 took, as that appears to have been taken later than predicted by the propagated trajectory.

This plot shows the propagated trajectory aligning with the NOTAMs. Hopefully JSpOC will track and release TLEs of Chang'e 5T1 on its inbound leg.

« Last Edit: 10/30/2014 01:23 pm by Satori »

Offline satwatcher

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The large NOTAM area may actually mean that the Chang'e 5T1 bus will reenter the atmosphere...

Offline Nighthawk

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The large NOTAM area may actually mean that the Chang'e 5T1 bus will reenter the atmosphere...
probably not, offical reports indicate that the bus will miss home earth and continue on her new trajectory/orbit (type not clear yet).
Here is the source: http://zhuanti.spacechina.com/n763863/n763893/c768349/content.html
Quote
飞行试验器...由服务舱和返回器两部分组成,服务舱以嫦娥二号卫星平台为基础研制,具备留轨开展科研试验功能
Rough translation: The precursor...consists of the orbiter and the lander...the orbiter is based on CE2 probe and has the capability of remaining on orbit and conducting experiments.

The huge NOTAM zone, I presume, is due to the uncertain trajectory of the reentry, as well as the long range of two reentries. The parameters of the upper atmosphere are subject to some uncertainties, so the GNC on board may be improvising when heading for the land zone. 
« Last Edit: 10/30/2014 12:44 pm by Nighthawk »

Offline Galactic Penguin SST

Landing site in Inner Mongolia is now prepared to receive the capsule back to Earth in half a day's time. Weather forecasts shows that the landing area will be partly clear at landing time, with 30-40% cloud coverage, 6-8 m/s winds, temperature of -4 to -6 degrees Celsius and visibility of 20 km.

http://news.xinhuanet.com/2014-10/31/c_1113064853.htm

TV news report: http://news.cntv.cn/2014/10/31/VIDE1414741681548517.shtml
Astronomy & spaceflight geek penguin. In a relationship w/ Space Shuttle Discovery. Current Priority: Chasing the Chinese Spaceflight Wonder Egg & A Certain Chinese Mars Rover

Offline Galactic Penguin SST

BTW for those who were wondering about mid-course corrections: 2 were done on the 24th and the 25th while on the way to the Moon. The next 2 planned ones were canceled as they were not required. Another should have been done yesterday to put the spacecraft towards re-entry.

The entry corridor has a re-entry angle margin of 0.2 degrees, and while entering the atmosphere there will be 2 black-out periods, each more than 2 minutes long.

http://news.xinhuanet.com/tech/2014-10/30/c_1113051409.htm

http://politics.people.com.cn/n/2014/1031/c70731-25946150.html
Astronomy & spaceflight geek penguin. In a relationship w/ Space Shuttle Discovery. Current Priority: Chasing the Chinese Spaceflight Wonder Egg & A Certain Chinese Mars Rover

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