China's Space Program News Thread

[crobato]

Re: china manned space - news and views

Well I believe the European space freighter capsule can be outfitted with life support so with the the Latest Ariane rockets, would they be able to put this capsule into lunar orbit with the necessary equipment for a moon landing??

You're going to have to do a lot of mathematical calculations first.

Boosters for the Shuttle are more powerful than the Saturn V used on Apollo, and all they do is take the Shuttle to low Earth orbits. And the Shuttle still has to use its own engines as well.

To travel farther, you need less mass for the same amount of energy.

 

[Engineer]

Re: china manned space - news and views

With two Ariane rockets, one carrying a forth stage for the transfer orbit, another carrying the ATV and lander, it might be possible to first dock them in orbit, then send the entire assembly to the moon and back.

Here comes a list of issues:

1. Modifying the ATV to lift people into space is most definately a no go idea. At 20 tons, it is way too heavy to be accelerated by an escape tower should an accident occurs. Beside, ATV isn't even designed to carry people to space to begin with. It's a freighter, not a capsule.
   
2. Since the ATV can't lift people into space, you will need a capsule such as the Soyuz or Shenzhou to dock with the assembly, and let the astronauts transfer over. The thing is though, that the lander would take up the only docking port of the ATV.
   
   One solution is to add an additional module between the ATV and the lander, which will allow the capsule to dock in an off axis fashion. Another solution is to sacrifice living space/propelling section and build the said module directly into the ATV. In either case, having a spacecraft docked off axis would significantly alter the inertia of the spacecraft, which means the capsule needs to be detached before the entire assembly leaves for the moon.
   
   A third solution is to open up a docking port at the bottom of the lander, so that everything can be put together along the center axis. However, the lander won't be able to leave for the moon unless the capsule is detached. In short, cost have been going up quickly now that you will need three rockets, and you will still have to leave behind the capsule. Not good.
   
3. I won't say how, but assuming you get the above issues solved, you still have the problems from the ATV itself. ATV is designed for low earth orbit, thus it doesn't carry the necessary shielding to protect the electronics from the Van Allen belts, let alone people. You can't just beef up the ATV by adding more shieldings either, because that will significantly increase the mass. You will then have to do even more work to revise the design to reduce the mass, and the final result won't be an ATV anymore.

In short, yes, you might be able to send the ATV to the moon and back. It's just that you aren't going to be able to do anything with it. :roll:

Going to the moon will require proper infrastructures, and I think China is moving along the right track.

 

[tphuang]

Re: china manned space - news and views

Well, according to this

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新华社合肥１０月２８日电（记者 熊润频、蔡敏）在２８日举行的２００８中国（合肥）北斗卫星导航科技与产业发展论坛上，国家卫星导航工程中心副主任冉承其透露，２００９年前后，北斗卫星导航定位系统将再发射１２颗卫星上天，力争２０１０年为我国及周边地区提供基本服务。

北斗系统是中国自行研制的卫星导航定位系统，具有导航、定位和授时的功能。自２０００年以来，北斗卫星导航定位系统已经先后拥有了５颗卫星，并于２００３年建立北斗导航实验系统，为中国及周边地区的交通运输、渔业、勘探、森林防火等领域提供有源服务。

“整个北斗卫星导航定位系统的空间段由３０多颗卫星组成。明年前后再发射１２颗卫星，将使北斗卫星导航定位系统具备区域无源服务能力，也就是不需要用户发送定位请求信号，就能完成导航定位等功能。在此基础上，逐步发展全球服务能力。”冉承其说。

据悉，我国正式开始研制独立自主的卫星导航系统始于１９９４年。此前，世界上只有美国、俄罗斯和欧洲自主研制生产卫星导航系统。

They are going to try to get 12 satellites up for the beidou navigation system before and after 2009. Hoping to have China and surrounding areas all covered by 2010. Eventually, they would like to have over 30 satellites. There are already 5 and it sounds like they are going to launch 12 (rather than launch 7 to get to 12 operating in total). They started developing this system in 1994.

 

[bladerunner]

Re: china manned space - news and views

Jean Yves Le Galle the CEO of Ariane Space Agency stated in a recent interview with Business Week that Chinese made satellites have a life expectancy of about 5yrs yet the recently launched Chinese made Venezuelan satellite is expected to have an operating life of 15yrs, according to all the after launch publicity.
While the US embargo on dual use technology has undoubtedly affected the quality of China's satellites.Given such a large divergence in perception on Chinas satellite quality,what's the formum members objective opinion on the matter?

 

[antiterror13]

Re: china manned space - news and views

Jean Yves Le Galle the CEO of Ariane Space Agency stated in a recent interview with Business Week that Chinese made satellites have a life expectancy of about 5yrs yet the recently launched Chinese made Venezuelan satellite is expected to have an operating life of 15yrs, according to all the after launch publicity.
While the US embargo on dual use technology has undoubtedly affected the quality of China's satellites.Given such a large divergence in perception on Chinas satellite quality,what's the formum members objective opinion on the matter?

I believe Chinese satellite tech is still lag behind, but China is catching up extremely fast now. Regarding life expectancy of chinese satellites, 15 years is extremely good. And if it was only 5 years, still goo too, as long as it does the job and remember the technology in 5 years will be quantum leap, imagine your computer 5 years ago comparing to your computer now

so, as long as economically competitive, it doesn't matter whether the life expectancy is 5 years or 15 years. In fact shorter life expectancy in some ways better because you wil get the latest tech sooner than others

 

[AssassinsMace]

Re: china manned space - news and views

I read that one over on another forum. As someone pointed out there the article says Chinese satellites average 5 years while Western satellites last as long as 18 years. There's a difference between average lifespan against longest.

 

[Schumacher]

Re: china manned space - news and views

Jean Yves Le Galle the CEO of Ariane Space Agency stated in a recent interview with Business Week that Chinese made satellites have a life expectancy of about 5yrs yet the recently launched Chinese made Venezuelan satellite is expected to have an operating life of 15yrs, according to all the after launch publicity.
While the US embargo on dual use technology has undoubtedly affected the quality of China's satellites.Given such a large divergence in perception on Chinas satellite quality,what's the formum members objective opinion on the matter?

China is quite new in the international commercial communication sat business. The first one was just 2 years ago for Nigeria & now this recent one with Venezuela, they're definitely designed to go 15 yrs so maybe the 5 yrs figure is from the past. You can't expect the CEO to speak too highly of a up & coming low cost competitor in both launch & sat, can you ?
But like I said, China is new so it remains to be seen if their sats will go the designed 15 yrs, but that's the same with others' sats as well, some will not go the distance.
As the other poster said, price competitiveness/consideration is important. Depends how much one is willing to pay for better quality, perceived or otherwise.

 

[bladerunner]

Re: china manned space - news and views

I believe Chinese satellite tech is still lag behind, but China is catching up extremely fast now. Regarding life expectancy of chinese satellites, 15 years is extremely good. And if it was only 5 years, still goo too, as long as it does the job and remember the technology in 5 years will be quantum leap, imagine your computer 5 years ago comparing to your computer now

so, as long as economically competitive, it doesn't matter whether the life expectancy is 5 years or 15 years. In fact shorter life expectancy in some ways better because you wil get the latest tech sooner than others

That is a point but.If one is looking to have a replacement satellite ready to go within an avg timeframe of 5yrs, how much newer technology can be applied if one factors in the design and build time. Chinese satellites would have to be considerably cheaper than India's even, once you factor in the cost of the launch?

 

[bladerunner]

Re: china manned space - news and views

oh and there's more space junk added to an increasing amount of redundant satellites and other launch debris

 

[Engineer]

Re: china manned space - news and views

I read that one over on another forum. As someone pointed out there the article says Chinese satellites average 5 years while Western satellites last as long as 18 years. There's a difference between average lifespan against longest.

Correct! The exact statement is as follow:

A typical Chinese bird will last only about five years in orbit, compared with as long as 18 years for western built one.

The statement is extremely misleading and is nothing more than the typical "their company sucks and our's is better" style marketing line.

There are many factors that affect a satellite's lifespan in orbit, one of which is size. Generally, the bigger the satellite, the longer life span it has. A bigger satellite can carry more fuel for station keeping, more batteries to enable the satellite to survive eclipses, larger solar arrays for recharging the batteries, and more shieldings to protect the electronics from radiation. However, the bigger the satellite is, the higher the mass, and a more powerful launch vehicle is required. The payload of the current CZ series is limited, hence limiting the size and lifespan of the satellite that are launched. Once CZ-5 comes online, this wouldn't be an issue anymore.

Another obvious factor is the mission requirement. Just because you can make a satellite last 18 years in space, doesn't mean you should. Many missions don't even require their satellite to last that long. Nice for Mr. CEO to include all those missions and compare to the longest living Western satellite.

If the launcher failed to reach the proper orbit, the 18 years lifespan satellite is as good as junk. If it is a GSO communication satellite we are talking about, then extra money will have to be spent to purchase an out-date second hand satellite, decrease what little lifespan it has to maneuver it to a new orbit. You might just as well buy two cheap communication satellites to begin with. Although each won't last as long, you will get a second chance immediately if the first one blew up. If the first one works, then you can launch the second one as a replacement a few years afterward.