2016 Oct 21
Friday, Day 295
Shenzhou 9 Return to Earth - June 29
Working from orbital information and history, it had already been possible to create an outline of the landing schedule on June 29. Then, June 27, China issued a Notice to Airman (NOTAM) detailing the area reserved for the landing, and confirming the earlier calculations.
NOTE 1 - the locations of tracking ships and retro-fire/re-entry events are approximate but the maps serve to illustrate the way re-entry and recovery happened.
NOTE 2 - times on this page have been updated since original publication to reflect actual events. Some of the times differ by about one minute from those forecast, One issue with real times is that the clock showing in a helicopter-based video of touchdown was running one and a half minutes slow! Timing based on it has been corrected.
Before retro-fire, Shenzhou 9 let go of its Orbital Module which will remain in orbit. It will re-enter naturally after a few weeks as a result of its orbit decaying through air drag.
OM Separation was about 01:16 UTC, followed by retro-fire at about 01:17.
All events were monitored from one of the "Yuanghuan" tracking ships anchored off the coast of Namibia. A permanent land-based tracking station set up by China near Swakopmund within Namibia is positioned on the ground track to monitor the ongoing engine firing.
Descent Module Re-entry
DM Separation occurred at about 01:37 UTC at an altitude of 140 kilometres as Shenzhou left the Indian Ocean and headed across Pakistan towards China. Another "Yuanghuan" tracking ship was in place to monitor the event. Entry into the atmosphere of both the DM and the ServiceModule/Instrument Unit started a few seconds later. The latter was destroyed by frictional heating. The DM was protected by its heat shield but entered a four minute radio blackout period which lasted until it got down to 40 kilometres.
Landing was on the Old Long Prairie area of Inner Mongolia at 02:02:50 UTC (±2s) in the same area used by previous Shenzhou missions. Shenzhou slowed down due to the drag as it fell through the atmosphere and descent for the final 10 kilometres was by parachute. Touchdown was partly cushioned by solid-fuel rocket motors set into the base of the DM, igniting at 1.2 metres above the ground ensure the landing speed was 1-2 m/s. They were exposed when the base part of the heat shield was jettisoned shortly after the main parachute deployed.
From the broadcast video the landing looked rather hard and it was on an upward slope. The DM flipped head over heels in the uphill direction and settled with the nose pointing downhill. The crew got out of the DM about 75 minutes after touchdown and seemed in good spirits.
The actual touchdown point was about 30 kilometres to the north-east of the Aim Point indicated on the map below. It was near 42°.2 north, 111°.2 east.
Communications between recovery forces and the Beijing Aerospace Command and Control Centre used links established via the two Tianlan-1 relay satellites in geosynchronous orbit.
TV views of the descent confused the issue of the precise touchdown time. Originally, it did not fit with times calculated from orbital information, it seemed to be a couple of minutes early. Later in the day, in a press conference, Yuan Jie - vice president of China Aerospace Science and Technology Corporation, gave 10:03 Beijing Time (02:03 UTC), exactly in line with the calculated value. A close look at online video available from the CNTV web site reveals that the in-frame clock on the helicopter-borne camera that captured the landing was running about 93s slow! Actual touchdown was 10:02:50 Beijing Time rather than 10:01:17 as indicated by the video.
Two Notices to Airmen (NOTAMs) were issued initially. One for the smaller area on the map was followed about three minutes later by one for for the larger area - outlined in yellow. The times were the same so the larger, later, one takes precedence.
The NOTAM reserves the area from 01:36 - 02:17 UTC, nicely encompassing the estimated landing at 02:03 UTC:
A0798/12 - A TEMPORARY RESTRICTED AREA ESTABLISHED BOUNDED BY N430400E1024100- N431800E1140300- N420900E1140500- N402100E1025900 BACK TO START. VERTICAL LIMITS: SFC-UNL. ALL ACFT ARE PROHIBITED TO FLY INTO THE AREA. SFC - UNL, 29 JUN 01:36 2012 UNTIL 29 JUN 02:17 2012 ESTIMATED. CREATED: 27 JUN 06:10 2012
A late change in the landing zone weather could make it unsuitable for use. In the event, a second landing point is available, about 1000 kilometres back along the re-entry track, near the Jiuquan launch site from where the crew departed June 16.
The backup landing zone serves a second purpose. If there is a problem with the Descent Module's landing control system then the cabin can be made to rotate during the re-entry to nullify the lifting effect of its offset centre of gravity. In that case, the crew will endure a higher level of 'g' forces as the Descent Module will follow a ballistic trajectory, causing it to land at there.
On June 29, as was done with Shenzhou 8, a further NOTAM closing some air routes that cross the landing zones was issued. They are shown as red lines on the map and give the impression that the actual touch-down point is a busy area for commercial aircraft:
A0809/12 - THE FLW SEGMENTS OF ATS RTE CLSD:
1.V16:MAMDA-DENGKOU VOR 'DKO'
2.B208:NIXAL-HOHHOT VOR 'HET'
3.W32:INTIK-HOHHOT VOR 'HET'
4.G343:TUMURTAI VOR 'TMR'-NIXAL
5.B458:TUMURTAI VOR 'TMR'-EREN VOR 'ERE'
6.A575:EREN VOR 'ERE'-MANSA
7.G218:POLHO-TUMURTAI VOR 'TMR'
8.B330:MORIT-YABRAI VOR 'YBL'.
29 JUN 01:36 2012 UNTIL 29 JUN 02:17 2012. CREATED: 28 JUN 02:34 2012
The map below brings together all the events covered on this page.
NOTE: The maps on this page and the data used to create them are copyright to www.zarya.info. They may not be copied or reproduced in any form without prior agreement from this web site.
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