China's Space Program News Thread

[escobar]

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[AssassinsMace]

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Yes when the US and Great Britain go unchallenged, do they let adversaries write the rules that they have to play by? No. I remember about a decade ago some US writer wrote a book romanticizing the US soldier as warrior who loves adversity. They thrive on it. Well you can't face adversity when you're whining about what the other side can do and are demanding the enemy to stop it.

 

[siegecrossbow]

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This is dumb sense objects in space can only lose heat via radiation, so they stand out against the background like a sore thumb if you use thermals. No matter how low the RCS is they can still be easily tracked.

 

[Inst]

This is dumb sense objects in space can only lose heat via radiation, so they stand out against the background like a sore thumb if you use thermals. No matter how low the RCS is they can still be easily tracked.

IR is suppressible as well, although against cosmic background radiation you need extreme levels of suppression. And in day time, you're likely absorbing solar heat, so it's very hard to deal with limiting your IR signature.

 

[Richard Santos]

This is dumb sense objects in space can only lose heat via radiation, so they stand out against the background like a sore thumb if you use thermals. No matter how low the RCS is they can still be easily tracked.

you could make sure the object in space radiates heat strongly in directions away from the IR sensor, while presenting only a cool, or even an actively cooled, surface to the IR sensor.

 

[huemens]

View attachment 75230
【220吨级补燃循环氢氧发动机完成首台工程样机生产】据北京航天动力研究所消息:近日，重型运载火箭220吨级补燃循环氢氧发动机完成首台工程样机生产，标志着该发动机关深阶段研制工作圆满完成。220吨级补燃循环氢氧发动机是我国重型运载火箭的芯二级发动机，性能指标达到国际先进水平，能更好地满足我国未来运载火箭和重大航天任务的动力需求，是航天强国的重要标志之一。
在关深阶段研制过程中，研制团队边论证、边设计、边生产、边验证，实现了四大技术跨越，即“一年完成论证设计、两年完成关键组件生产、三年实现预燃室等组件试验、四年完成预燃室-氢/氧涡轮泵联动分系统试验”，初步突破了补燃循环起动关机过程控制、大流量高压预燃室、先进制造技术等9大关键技术。发动机推力、真空比冲、推重比等技术指标达到国际先进水平，形成多项核心自主知识产权，实现了对设计技术、试验方法等的全方位创新，并首次实现了氢氧发动机全数字化研制，为发动机后续工程研制奠定了坚实的基础。目前，发动机各项研制工作正有序推进，已完成发动机试车台选址、建台方案论证设计，今年将完成半系统试验和整机试验验证。220吨级补燃循环氢氧发动机性能和技术指标刷新了我国氢氧发动机的纪录，其研制能够填补我国氢氧发动机型谱和技术空白，并对诸多基础科学和工业领域有巨大的牵引带动作用。

First engineering prototype of the 220ton YF-90 staged-combustion cycle LH2/LOX engine. This will be the second stage engine for the Long March 9 (2011).

What are these engines going to be used for now? On 24 June 2021, the chief designer of the Long March series, Long Lehao, presented a new design of Long March 9 which uses 4 new 120-tonne hydrolox engines for the second stage, instead of 2 YF-90 engines used in earlier design. Or are they going to build two completely different types of Long March 9?

 

[FairAndUnbiased]

This is dumb sense objects in space can only lose heat via radiation, so they stand out against the background like a sore thumb if you use thermals. No matter how low the RCS is they can still be easily tracked.

But with low resolution sensors they won't be able to be positively IDed and thermal sensors only give a bearing, not bearing and range. Radar gives both bearing and range. This is important because in space range can be thousands of km.

In addition radar has vast swath size while IR sensors field of view is much more limited.

That means maneuver could defeat long range IR guided weapons in a way they can't for radar.

 

[siegecrossbow]

you could make sure the object in space radiates heat strongly in directions away from the IR sensor, while presenting only a cool, or even an actively cooled, surface to the IR sensor.

Yeah you have to have bulky radiators for that. Guess what, additional launch mass.

 

[Richard Santos]

Yeah you have to have bulky radiators for that. Guess what, additional launch mass.

If you want a stealthy satellite, you have to pay the price.

 

[Quickie]

Wow... What if they lose control of the thrusters?