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Forum:ESA - JAXA - China - International
Topic:Tiangong-1: Viewing, comments, questions
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issman1I'm pleased that Tiangong-1 was successfully launched into orbit, but what is the inclination?

If it's 42 degrees, like all previous Shenzhou missions, then it will not be visible from the UK.

PhilipJiuquan Satellite Launch Center is about 40° inclination...

Well done to the Chinese space program!

Jay ChladekI wish them continued success. Looking at an artist's rendering, it reminds me a little of the early Salyut/Almaz cores with its stepped cylinder configuration.

It can't be very big though as according to my references on the Long March, it can only lift payloads of about 12.3 tons into LEO, which is about half of what the Proton can do (23.15 tons, a little heavier capacity compared to what it had for Salyut 1). As such, the development of docking systems and a modular building block approach will be critical to a Chinese station program.

Robert Pearlman
quote:
Originally posted by Jay Chladek:
It can't be very big though as according to my references on the Long March, it can only lift payloads of about 12.3 tons into LEO...
According to state media, the Long March 2F T1 (the modified Long March 2F for lifting Tiangong-1) has a launch capability of 8.6 tons.

Tiangong-1 is 10.4 meters (34 feet) long, has a maximum diameter of 3.35 meters (11 feet) and had a liftoff mass of 8.5 tons.

Glint
quote:
Originally posted by issman1:
If it's 42 degrees, like all previous Shenzhou missions, then it will not be visible from the UK.
Even with its inclination of 42.7 degrees, it's still visible from the UK, although its passes will be low. From UK cities such as as London, at Latitude N 51.5, pass altitudes will be under +15 degrees. Using binoculars, even satellite passes under +10 degrees in altitude aren't difficult to observe -- especially ones as large as Tiangong-1.

The 28.5 degree inclination of HST doesn't prevent it from being seen from N 39.5 here despite the 11 degree difference. HST is frequently visible during its passes through our southern sky.

Granted, HST's greater height helps, but Tiangong-1 should be visible from some, though not all, of the UK when lighting conditions are favorable. However, with winter approaching, those opportunities will become fewer and farther between.

domA bizarre footnote to the launch is reported by the BBC.
China's state TV accompanied coverage of the historic launch of the country's first space laboratory with a patriotic US song, America the Beautiful.

The song is regarded by many as an unofficial national anthem for the US, and features the line: "America! America! God shed his grace on thee."

Some Chinese people say that CCTV must have made a mistake with the music. The broadcaster has not commented.

ProsperoI know it's a bit on the small side, but I'm surprised the Chinese government are referring to this as a "space lab" and not a "space station". It's a pressurised facility in orbit that's designed to be visited by crews and worked in. If there's some other definition of a space station, I don't know what it is. I'm assuming the sole distinction is size? In which case, how big does a "space lab" have to be before it's a "space station"?
Robert PearlmanTiangong-1 is the modern-day equivalent of the Agena target vehicle used during the Gemini program. Its primary purpose is teach China how to dock. That it can host experiments and brief crew visits reflects the legacy hardware on which it was based.
Jay ChladekThe main definition I can think of for why this module would be called a space lab as opposed to a station would be that it is a relatively small experimental vehicle. It has some capabilties, but can't necessarily be the primary habitat with its power being the exclusive provider to a crew onboard (with the Shenzou spacecraft in a hybernation state). The term Space Station tends to imply that the station can operate fully independent of another craft, or can act as the primary spacecraft when another vehicle is docked to it (with the other craft shut down).

Granted the name "Skylab" kind of blurred that difference somewhat between a lab and a station since it was more of a station than a laboratory. But, Skylab was also NASA's first pass at an orbiting station and they used it as a laboratory for practically every type of experiment in living and working in space from medical and life sciences, to astronomy studies, to even simple questions about if a space shower would work.

So since Tiangong-1 is essentially China's first pass at a station module, laboratory would work well here as well since it is a place where experiments are being conducted. Dock at least a couple specialized modules together, and then you have the beginnings of a space station I would think. And as Robert has said, right now it is closer to an Agena target vehicle than say an early Salyut.

GACspaceguyWould it be short sighted to say that in today's spaceflight culture an orbiting laboratory is used for intermittent habitation for a few years? A space station is for continuous habitation for long duration five plus years.
Jay ChladekI suppose that is one way to look at it. Of course, the Soviets called their first Salyuts space stations and those were relatively short term occupations. The continuous manning didn't really begin to happen until Salyut 6, 7 and Mir and even then, there were occassional gaps where no crew occupied the station. The ISS is I believe the first station that has stayed manned continuously from Expedition 1 onwards.

The ESA Spacelab and the Spacehab laboratory modules are a bit of a weird placement in the whole definition as they can't fly independently as they needed a shuttle to keep them powered. But when in operation, they essentially turned the shuttle into a short duration space laboratory of sorts. Even the ASTP docking module had some of those attributes as well as it contained some experiment packages that were conducted in orbit after the primary docking mission was concluded and the Soyuz returned home.

SkyMan1958
The mission, if successful, will make China the third nation to master the technology after the United States and Russia, paving the way for the nation to place a space station into orbit around 2020.
How about the European ATV? Aside from the autonomous aspect of it, wasn't that controlled by ESA/CNES?
issman1Technically that is true, although the ATV uses Russian hardware and can only dock with the Russian segment.
cspgDocking took place "at night"- because the Chinese do not want to provide clear pictures of both vehicles?
Robert PearlmanAccording to Chinese officials, the first docking was planned to occur during the night phase of Tiangong-1's orbit to avoid sun glint (the glare from the sun) which could interfere with the rendezvous sensors.

The next docking, which will occur after Shenzhou 8 detaches in 12 days time, will be during the day.

Jay ChladekSun glare can be a big problem for manned craft at least. Stafford mentioned it was tough to see his alignment targets in the COAS on ASTP when they did the first docking with a Soyuz. As such, I am not surprised the Chinese went for a night pass. Besides, it seems as though many of the shuttle ISS dockings tended to occur at night as well (although their approach paths probably negated the problems with sun glint since they were using an R bar approach, where they would come upwards under the station as opposed to coming in from the front or rear).

One thing I notice about the Chinese docking system is it utilizes an androgynous hardware configuration, like the type designed for ASTP and utilized on the US nodes and PMAs of the ISS. The Russians are still using a pin and cone arrangement on their Soyuz docking ports.

music_space
The docking mechanism, composed of up to 10,000 parts...
10,000 mechanical parts, really?

If the Apollo CSM probe-and-docking mechanism would have had that many, Michael Collins would really have had nightmares about it!

Jay Chladek
quote:
Originally posted by music_space:
10,000 mechanical parts, really?
China's system seems to be based on the APAS systems originally utilized on Apollo Soyuz and eventually refined for use on the ISS. The Apollo probe and drogue had its uses, but the thing had a few problems late in Apollo and during Skylab's missions, starting with Apollo 13. The APAS system was more complicated (maybe not quite 10,000 parts, but the final design had a lot more mechanisms to it), but even Tom Stafford even said he was more concerned with the Apollo probe and drogue possibly having another foul up on ASTP as opposed to the APAS system designed for the Soyuz side.

I hope 10,000 parts is an exaggeration as I have this line spoken by Mr. Scott from Star Trek 3 running through my head: "The more they overthink the plumbing, the easier it is to stop up the drain."

chetThe Week: The mystery behind China's aggressive push into space
Months after its scheduled re-entry into Earth's atmosphere — and a surprise cameo appearance in hit space flick Gravity — China's first space station boosted into a higher orbit. It still speeds around the planet, doing ... what, exactly?

No one outside of China's popular but opaque space program seems to know.

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