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Starship Voyages

Tyneside, UK
2017 Sep 22
Friday, Day 265

Maintained by:

Yuan Wang Events:

Shenzhou 10 undocked from Tiangong 1 June 24 at 23:05 UTC and headed for re-entry/landing the following day. The Yuan Wang tracking ships were on hand to play a part if a problem had arisen that prevented it setting down in China.

Retro-fire to Landing

Landing was set for June 26 at 00:07 UTC. All the major pre-landing events occurred in the dying minutes of June 25 UTC. Shenzhou 10 landed in the same area of Mongolia as its predecessors. The main NOTAM for it was worded similarly to the ones for previous missions:
N4318E11403-N4209E11405-N4021E10259 BACK TO START. VERTICAL LIMITS: GND-UNL. GND - 
UNL, 25 JUN 23:40 2013 UNTIL 26 JUN 00:21 2013. CREATED: 25 JUN 03:27 2013
Further NOTAMs listed a number of air route closures over the area to protect recovery aircraft movements in the several hours following the landing.

The map shows the main events from retro-fire to landing. All times are ±1 minute as determined from post-landing news items and analysing contemporary video.

Re-entry events

The three Tianlian 1 satellites at 17° east, 77° east and 177° east could see the whole of the Tiangong 1 orbit for all of the time. When their coverage zones appeared on the map in mission control, the visibility limit shown was the limb of the Earth, indicating the satellites' visibility from ground level. Because of this, the map appeared to indicate a coverage gap over the eastern Pacific. For something in orbit, the Tianlians can see further by virtue of the satellite's altitude above the Earth's surface. Tianlian 1B and 1C did actually cover the apparent 'gap' when measured against Shenzhou's orbital altitude.

At re-entry, Tianlian 1A at 77° east was able to 'see' every event starting with separation of the Orbital Module.

One thing the map illustrates is how carefully the overseas tracking stations sites were chosen to fit in with Shenzhou missions. Every major Shenzhou 10 re-entry event was in sight of one of them. It suggests that China's space station plans are very firmly tied to the 42° inclination Shenzhou/Tiangong orbit.

Yuan Wang

When Shenzhou 9 was in orbit, China had four active ships in the Yuan Wang fleet. Since then, Yuan Wang 4 has been retired as a result of damage leaving only Yuan Wang 3, Yuan Wang 5 and Yuan Wang 6.

This time, there was no ship off Namibia to monitor OM separation. It was there for earlier missions probably because the event occurs at Swakopmund's horizon. Yuan Wang 4's loss, and subsequent absence of an Atlantic ship, indicates China's confidence in the Tianlian constellation.

Emergency Scenario

The ships played no part in the actual return to Earth. However, if re-entry had been delayed because of a technical issue and a landing in China became problematic, there was the always the possibility of a splashdown in the Pacific Ocean - something that crews have practiced. There was reportedly a rescue vessel stationed in the Pacific near Yuan Wang 6.

About two hours after the intended landing, had it still been in space, Shenzhou 10's orbit would have carried it overhead each of the ships in turn as it passed southwards across the Pacific. retro-fire over western China could have been used to initiate a ballistic, rather than a lifting, re-entry to splash it down near Yuan Wang 6.

Re-entry events

The scenario is speculative, and the times are very approximate, but it fits with the emphasis that China has placed on a possible maritime recovery, and the way in which the ships are positioned.

Page Date: 2013 July 22

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