LIVE: TG-2 Tiangong-2 - CZ-2F/T2 - JSLC - September 15, 2016 (14:04 UTC)

[Star One]

I am mildly surprised that they don't go with two docking ports on their second station. I know this transition took a while with Salyut but then something like two docking ports had never been done before.

I would guess that the design changes required to have a second docking port - at the rear? - on Tiangong 2 are too great for a one-off mission.   The second docking port was introduced with the second generation Soviet Salyuts so it was not for a one-off station design: Salyuts 6, 7, the Mir core and the second generation Almaz stations.   So, a single docking port for Tiangong 2 makes perfect sense.

Is this station only to have a very limited life then, is there much at all design wise that is different from the first I wonder?

Unless the facilities were incorporated into Tiangong 1 but never intended for use, Tiangong 2 would need to have a propellant transfer system.   Also, it is clearly intended to host crews for longer than two weeks.   So, I would expect Tiangong 2 to be an "uprated Tiangong 1" rather than something radically new.

Would it be fair then to draw a parallel with the evolution of the Salyut stations where they reused the same design initially but with improvements?

[Satori]

Since the launch of TG-1 and the previous knowledge that China would build a modular space station on 2020, that the general idea (and projects) was the launch of TG-2 and TG-3. At that time we knew that TG-2 was the backup of TG-1 and that on TG-3 China would test the use of a cargo vehicle for refueling.

Then, the original TG-3 was dropped. We always thought that TG-3 would be something similar to Salyut-6/7 having two docking ports. Dropping TG-3 meant two things: one, there was no vehicle with two docking ports in development; two, extending the schedule for the launch of the 'new' TG-2 meant that they had the time to made significant structural changes on the 'original' TG-2 with the addition of an extra docking port and the addition of the necessary fuel lines for the refueling.

I find it strange to have a station similar to TG-1 in orbit and having a cargo/refueling vehicle on a nearby orbit for periodical resupply of the new station and packed with supplies for each crew. This will bring a associated risk on each mission that I find unnecessary when doing visits ŕ la Soyuz T-15.

[Phillip Clark]

I am mildly surprised that they don't go with two docking ports on their second station. I know this transition took a while with Salyut but then something like two docking ports had never been done before.

I would guess that the design changes required to have a second docking port - at the rear? - on Tiangong 2 are too great for a one-off mission.   The second docking port was introduced with the second generation Soviet Salyuts so it was not for a one-off station design: Salyuts 6, 7, the Mir core and the second generation Almaz stations.   So, a single docking port for Tiangong 2 makes perfect sense.

Is this station only to have a very limited life then, is there much at all design wise that is different from the first I wonder?

Unless the facilities were incorporated into Tiangong 1 but never intended for use, Tiangong 2 would need to have a propellant transfer system.   Also, it is clearly intended to host crews for longer than two weeks.   So, I would expect Tiangong 2 to be an "uprated Tiangong 1" rather than something radically new.

Would it be fair then to draw a parallel with the evolution of the Salyut stations where they reused the same design initially but with improvements?

Yes, although the Tiangong design will not be used as a space lab beyond Tiangong 2: after that the design will be used for the cargo freighters which will fly to the larger station(s).

[Star One]

I am mildly surprised that they don't go with two docking ports on their second station. I know this transition took a while with Salyut but then something like two docking ports had never been done before.

I would guess that the design changes required to have a second docking port - at the rear? - on Tiangong 2 are too great for a one-off mission.   The second docking port was introduced with the second generation Soviet Salyuts so it was not for a one-off station design: Salyuts 6, 7, the Mir core and the second generation Almaz stations.   So, a single docking port for Tiangong 2 makes perfect sense.

Is this station only to have a very limited life then, is there much at all design wise that is different from the first I wonder?

Unless the facilities were incorporated into Tiangong 1 but never intended for use, Tiangong 2 would need to have a propellant transfer system.   Also, it is clearly intended to host crews for longer than two weeks.   So, I would expect Tiangong 2 to be an "uprated Tiangong 1" rather than something radically new.

Would it be fair then to draw a parallel with the evolution of the Salyut stations where they reused the same design initially but with improvements?

Yes, although the Tiangong design will not be used as a space lab beyond Tiangong 2: after that the design will be used for the cargo freighters which will fly to the larger station(s).

I wonder if the large freighter craft will add any kind of cargo return capacity as they go along?

[baldusi]

I'm still wondering how much changes would be needed to test in-space fuel transfer. You don't actually need an airlock to the pressurized section. You just need the approach beacon/retros and the mechanical interface of the bocking mechanism. May be some automatic power and data connections. But if you attached a docking port on the back, without an actual airlock, but just enough for the fueling vehicle to actually get a mechanical connection. And then set your refueling probes on the unpressurized section,, you could route everything around the pressure vessel and then cover it up with MLI or the MOD protection layer. You would lose the crew actually being able to transfer cargo, but you could do your fuel demo with very little mods.

[Bob Shaw]

Some of the previously published cutaway views of Tiangong-1 showed a cylindrical space extending from the habitable volume; it looked just about the right size for a transfer tunnel, somewhat narrower than the Spacelab tunnel but wider than an Apollo tunnel. It came and went in different illustrations - I was never sure if it represented a real part of the design, though if it is indeed a transfer tunnel then it's the right shape and in the right place...

[Phillip Clark]

This photos - dating back around ten years - shows the two modules which comprise Tiangong.   There appears to be a connecting hatch between them.   This has always puzzled me.

[Eric Hedman]

New BBC article on China's plans for a new station.

http://www.bbc.co.uk/news/science-environment-24282060

[Satori]

From China Space facebook... 'Leakage test on Tiangong 2 space lab has been successfully completed.'

[Dalhousie]

This photos - dating back around ten years - shows the two modules which comprise Tiangong.   There appears to be a connecting hatch between them.   This has always puzzled me.

There were also models showing docking at each end of TG, though never both at the same time.

[Kryten]

There were also models showing docking at each end of TG, though never both at the same time.

I always assumed they were just plain wrong, rather than meaning anything significant. IIRC, the 'wrong end' model also had the pre-Shenzhou 7 OM on Shenzhou.

[Steven Pietrobon]

This photos - dating back around ten years - shows the two modules which comprise Tiangong.   There appears to be a connecting hatch between them.   This has always puzzled me.

There were also models showing docking at each end of TG, though never both at the same time.

I spoke with someone from the Chinese Manned Space Agency early this year and asked him that question. There is only one docking port according to him.

[beidou]

China's first astronaut Yang Liwei has revealed that China will launch the Tiangong-2 space lab in 2016 and will finish building a space station around 2022.

http://english.cri.cn/12394/2014/09/10/189s843637.htm

[Phillip Clark]

China's first astronaut Yang Liwei has revealed that China will launch the Tiangong-2 space lab in 2016 and will finish building a space station around 2022.

http://english.cri.cn/12394/2014/09/10/189s843637.htm

Since the core of the modular space station is supposed to be launched about 2017 I wonder whether there really is only one Shenzhou visit to Tiangong 2 planned.   At one point the Chinese were talking about three Shenzhou visits to each of Tiangong 1 and 2, with the very first being an unmanned mission: and this is what we saw with Shenzhou 8-10.

[Dalhousie]

China's first astronaut Yang Liwei has revealed that China will launch the Tiangong-2 space lab in 2016 and will finish building a space station around 2022.

http://english.cri.cn/12394/2014/09/10/189s843637.htm

I thought the core of the space station was going up in 2018.  That allows two years to overage TG-2. Which is about right.  They would need to fly a couple of crewed missions to gain experience, and probably a test flight of the Tianzhou cargo carrier.

[beidou]

Please update the thread title to "TG-2 Tiangong-2 - 2016", thanks!

[russianhalo117]

Please update the thread title to "TG-2 Tiangong-2 - 2016", thanks!

I införmed the mods via the Report to Moderator link.

[Satori]

Please update the thread title to "TG-2 Tiangong-2 - 2016", thanks!

I införmed the mods via the Report to Moderator link.

Already changed before the report.

[Satori]

From Xinhua: China to launch Tianzhou-1 cargo ship in 2016 to rendezvous with space lab.

"The Tianzhou-1, which literally means "heavenly vessel", will carry propellants, living necessities for astronauts, research facilities and repair equipment to China's second orbiting space lab Tiangong-2, said Zhou Jianping, chief engineer of China's manned space program."

I think this again opens the debate about TG-2 having two docking ports.

[Phillip Clark]

Unless the cargo vehicle has two docking ports, of course.

Then again I find it difficult to see a second docking port on either spacecraft - TG 2 would need some major modifications from the TG 1 design.