注册 登录  
 加关注
   显示下一条  |  关闭
温馨提示!由于新浪微博认证机制调整,您的新浪微博帐号绑定已过期,请重新绑定!立即重新绑定新浪微博》  |  关闭

长缨在手 敢缚苍龙

 
 
 
 
 

日志

 
 

“光明星四号”开始运转?  

2016-03-01 19:19:10|  分类: 半岛风云 |  标签: |举报 |字号 订阅

  下载LOFTER 我的照片书  |
俄联邦国防部:朝鲜卫星设备仪器开始运转
02:04 2016年02月23日(更新 02:08 2016年02月23日)

俄联邦国防部空天部队航天设备侦察中心长官 - 安德烈·卡柳塔上校星期一(22日)表示,朝鲜确实将其地球遥控探测侦察卫星送入了轨道。
人造卫星“光明星-4号”是由朝鲜于2月7日发射的。朝鲜各邻国将此视为是其洲际弹道导弹发射的试验。本周,美联社援引美国政府消息表示,卫星在一段短暂的稳定期后,继续在轨道上“翻跟头”。西方媒体也写道,并未收到从卫星上发出的无线电信号。
卡柳塔表示,“主中心的设备发现朝鲜航天器进入轨道。我们在此次发射过程中发现了两枚航天对象:三级运载导弹和航天器本身。从对收到的信息分析来看,可以得出结论,这一航天器为地球遥控探测卫星,也就是说这一卫星能够完成侦察任务。”他补充表示,航天器的功能显示出这个卫星上的仪器已经包含在内,开始运转。

俄文报道:http://special.tass.ru/politika/2688450


俄罗斯国防部机构:朝鲜卫星在宇宙正常运转

    朝中社平壤2月28日电 俄罗斯国防部空天防御部队中央航天状况监视中心负责任安德烈·卡柳塔22日在参加俄罗斯新闻服务广播电台一栏节目时确认,当前朝鲜对地观测卫星“光明星四号”运转正常。
    卡柳塔指出,根据对所收到的轨道情报,即公转周期和航天器进入的轨道斜角、高度的分析,可以得出结论:这一航天器是遥感对地观测卫星。也就是说,它能够发挥观测功能。其装置正在正常运转。(完)

===

荷兰业余卫星观测者Marco Langbroek报告,2月28日从地面观测到了“光明星4号”卫星以及发射所用的火箭第三级。

Imaging North Korea's new Kwangmyongsong-4 satellite, and the flash period of its UNHA-3 rb

“光明星四号”开始运转? - kktt - 长缨在手  敢缚苍龙
Kwangmyongsong-4 on 28 Feb 2016

North Korea's recently launched new satellite (see a  previous post), Kwangmyongsong-4 (KMS-4: 2016-009A), is finally starting to make visible evening passes here at Leiden.

Yesterday evening, 28 Feb 2016 near 19:45 UT (20:45 local time), I shot the image above, one of two images showing the satellite passing near the Celestial pole. It is a short exposure of 2 seconds with the 2.8/180 mm Zeiss Sonnar lens on my Canon EOS 60D.

Below is the same image, but in black-and-white negative, showing the trail a bit better:

“光明星四号”开始运转? - kktt - 长缨在手  敢缚苍龙
Kwangmyongsong-4 on 28 Feb 2016
 
The object is very faint (probably near mag +7). It needs a rather big lens (the Zeiss 2.8/180 mm has a lens diameter of 6.4 cm), which unfortunately also means a small FOV. Over the two images, a total imaging arc of ~6 seconds, it however appeared to be stable in brightness with no sign of a periodicity due to tumble. So either it is not tumbling, or if it is tumbling at all it must be a very slow tumble.

Some 16 minutes earlier, near 19:28 UT, I also imaged the upper stage of the Kwangmyongsong/UNHA-3 rocket (2016-009B) that was used to launch the satellite. This object is brighter and shows a nice tumble resulting in periodic flashes. Below are crops from three images spanning 19:28:32 - 19:28:44 UT. The brightness variation is well visible (the bright star it passes in the first image is beta Umi):

“光明星四号”开始运转? - kktt - 长缨在手  敢缚苍龙
brightness variation of UNHA-3 r/b 2016-009B on 28 Feb 2016

A fit to the measured brightness variation over these three images shows several specular peaks at regular intervals, with a slightly asymetric profile:

“光明星四号”开始运转? - kktt - 长缨在手  敢缚苍龙
 
The fit shown in red is the result of two combined sinusoids: a major period of 2.39 seconds with a minor period of 1.195 seconds superimposed (resulting in the slight asymmetry). Pixel brightness over the trails was measured with IRIS. The data were fitted using PAST.

posted by SatTrackCam Leiden at 2/29/2016 11:48:00 AM


UPDATE 1 March 2016:

I imaged both the UNHA-3 r/b and Kwangmy?ngs?ng-4 again in the evening of 29 Feb 2016. The sky conditions wer less good, and the pass was much lower in the sky. I used the 1.4/85 mm SamYang lens this time, to get a larger FOV in order to try to capture a larger arc.

KMS-4 was captured on four images (2 second exposures) between 19:19:17 - 19:19:34 UT. It was barely visible on the images, but again the brightness appeared to be stable over this 17 second time span.

The UNHA-3 r/b was also captured, and 3 images (5 second exposures) between 18:58:42 - 18:59:07 UT again showed a very nice flash pattern, fitting (like the observations of Feb 28) a flash period of 2.39 seconds:

“光明星四号”开始运转? - kktt - 长缨在手  敢缚苍龙
 
The image below is a stack of these three images. The rocket stage moves from upper right to lower left in the image.

“光明星四号”开始运转? - kktt - 长缨在手  敢缚苍龙

===

Kwangmyongsong 4 - Not So Dead?

It is possible to look at the compensated/corrected plot and draw some tentative conclusions as to what the distribution of readings is telling us. This is one view and there will be others with equal validity. However, the overall conclusion stays the same - there was change in the way Kwangmyongsong 4 was oriented in space and it probably managed to get rid of any significant spinning or tumbling.

“光明星四号”开始运转? - kktt - 长缨在手  敢缚苍龙
 
Initally the satellite was probably rotating slowly (a number of seconds per revolution) rather than tumbling rapidly, or even spinning as some would have seen it. There is a lot of scatter in the Ndot2 values but the trend is to stay roughly constant, just below 0.00008. it implies that Kwangmyongsong's average cross sectional area stayed constant. Around February 13 there is a relatively fast transition to 0.00010 where it stays constant for a while.

The implication of the change is that air drag increased. Air drag is determined by the cross sectional area presented towards the direction of travel. Kwangmyongsong is a cuboid about 1.3 times as long as it is wide. It will experience a little more drag if one of the larger surfaces is facing the forward direction than it will if one of the square-shaped ends is leading. With a tumble, drag will appear to be constant based on an average of the large and small faces of the shape as they are presented alternately to the oncoming air.

KMS-4 solar panelsThe February 13 change could be related to deployment of the solar panel. At launch, Kwangmyonsong 4 had solar panels covering three of the longer sides. Two of them were hinged so that they could swing out either side of the third to form a single flat surface covered in solar cells. Opening the panel itself would have reduced the satellite's rotation speed through conservation of angular momentum. The average cross sectional area would have increased, leading to higher drag, hence the exhibited rise in value of Ndot2.

Kwangmyongsong 4's design is similar to Kwangmyongsong 3. There is a discussion of the solar panel deployment mechanism in Zarya.info's pages covering the earlier launch. The picture here depicts the fully-opened panel on Kwangmyongsong 4.

The change around February 17 is distinct and suggests that the stabilisation mechanism kicked in. The two possibilities are that it extended a gravity-gradient stabilisation boom or that gyros were spun-up. Whichever, it seems to have settled into a relatively stable regime with a fluctuation that has a period of 7-8 days. The fluctuation seems to be damped as the second peak is significantly less than the first. It may eventiually settle down to a constant value when all rotation is damped out.

It may explain the Russian comment on February 22. Russia has its own tracking network that produces observations similar to those that feed the Twoline Orbital Elements. Its analysts will have seen this pattern and could justifiably have concluded that Kwangmyongsong 4 had been "activated".
  评论这张
 
阅读(1554)| 评论(0)
推荐

历史上的今天

评论

<#--最新日志,群博日志--> <#--推荐日志--> <#--引用记录--> <#--博主推荐--> <#--随机阅读--> <#--首页推荐--> <#--历史上的今天--> <#--被推荐日志--> <#--上一篇,下一篇--> <#-- 热度 --> <#-- 网易新闻广告 --> <#--右边模块结构--> <#--评论模块结构--> <#--引用模块结构--> <#--博主发起的投票-->
 
 
 
 
 
 
 
 
 
 
 
 
 
 

页脚

网易公司版权所有 ©1997-2016