NROL-76 – Falcon 9 – Кеннеди LC-39A – 01.05.2017 11:15 UTC

[SGS_67]

Старый пишет:
Возврат ступени к месту пуска - значит спутник маааааленький.

Параметры орбиты также имеют значение.
Дятел.

[SGS_67]

silentpom пишет:
а есть подтверждение, что видео ступени с земли - это от вояк?

Вообще-то, от Сатурнов до Шаттлов, есть много качественного видео-материала из этой точки.
Коллеги высказали предположение, что была использована наземная аппаратура космодрома.
То ли подновлённая, то ли просто расконсервированная.

Спойлер

Лично мне казалось, что именно от вояк.
Потому, как Маск у них выиграл право запускать КА военного назначения по суду.
А это есть нарушение монополии, и потому пасут.

[свернуть]

[SGS_67]

tnt22 пишет:
   

SpaceX - Best Landing - NROL76 05-01-2017
 
 
 USLaunchReport

Извиняюсь, а что вызвало Ваше такое смущение?
Нонче такое видео можно снять аппаратурой даже "любительского" качества.

За "ловлю", и не только здесь - огромное спасибо!
ПМСМ, крайне ценная информация.

[SGS_67]

Старый пишет:
Спутник-разведчик на наклонении 50 градусов? 

Что не так?

Старый пишет:
А что, при наклонении 50 градусов перигей не прецессирует?  

Он прецессирует при любом наклонении.
Дятел.

[Прол]

SGS_67 пишет:
потому, что полёт 2-й ступени - топ сикрет.

Именно так и объясняли прекращение трансляции выведения.

[Старый]

SGS_67 пишет: 

Старый пишет:
А что, при наклонении 50 градусов перигей не прецессирует?    

Он прецессирует при любом наклонении.
Дятел.

Перигей не прецессирует при наклонении 63.4 градуса. Неужели это можно не знать? 
 Дебил, б#"@ (с) Лавров 

[Старый]

Я так и не смог понять что Молчан понимает под "замороженой орбитой" и какую связь NROL-76 он видит со всеми этими аппаратами:

Frozen orbits are intended to maintain as nearly a constant altitude above geoid as possible around the entire orbit.The argument of perigee may be frozen near 90 deg or 270 deg.

Below is a partial of list of satellites that have employed frozen orbits that I compiled in Jan 2007:

GEOS-3 radar altimeter
Seasat 1 SAR, radar altimeter
GEOSAT radar altimeter
Spot Earth resources imaging
Lacrosse SAR
UARS various Earth sensors
JERS 1 SAR
Topex/Poeidon radar altimeter
ERS SAR, radar altimeter
RadarSat SAR
GEOSAT FO radar altimeter
Landsat 7 Earth resources imaging
Terra spectroradiometers, radiometer
EO-1 Earth resources imaging
Jason 1 radar altimeter
Envisat SAR, radar altimeter, radiometers
Aqua radiometers, microwave sounder
Icesat altimeter, radiometer
ALOS SAR, radiometer
USA 193 classified

The known sensors of the above payloads predominantly employed radio waves, but some were optical. A frozen orbit isstrong evidence of an imaging payload, but not all imagers employ frozen orbits.

[Старый]

Вот как трактует этот вопрос Педивикия:

In orbital mechanics , a frozen orbit is an orbit for an artificial satellite in which natural drifting due to the central body 's shape has been minimized by careful selection of theorbital parameters . Typically this is an orbit where, over a long period of time, the altitude remains constant at the same point in each orbit [1] — changes in the inclination , position of the lowest point of the orbit , and eccentricity have been minimized by choosing initial values so that their perturbations cancel out. [2] This results in a long-term stable orbit that minimizes the use of stationkeeping propellant.

Однако ясно что при высоте 400 км основное возмущение будет от сопротивления атмосферы, так что "замороженной" орбиты никак не получится. 

 И при чём тут вообще аргумент перигея?

[tnt22]

Dr Marco Langbroek‏ @Marco_Langbroek 19 ч. назад

Video of a pass of recently launched spy sat USA 276 (NROL-76) over Leiden, NL

https://vimeo.com/218875925

19 ч. назад

Going to try to image the second pass (01:06 UT, an hour from now) as well

16 ч. назад

Observed 2nd USA 276 (NROL-76) pass as well. It was brighter, mag +3. Imagery tomorrow: sleep now.

8 ч. назад

Spy satellite USA 276 launched as #NROL76 by @SpaceX on May 1, over my house in #Leiden, NL, last night, plus 3 gratuit old r/b. @SSC_NL

[tnt22]

Dr Marco Langbroek‏ @Marco_Langbroek 3 ч. назад

New blog post: Observing USA 276, the odd NROL-76 payload fr om the May 1 @SpaceX launch: https://sattrackcam.blogspot.nl/2017/05/observing-usa-276-odd-nrol-76-payload.html ... @SSC_NL

https://sattrackcam.blogspot.ru/2017/05/observing-usa-276-odd-nrol-76-payload.html

Thursday, 25 May 2017

Observing USA 276, the odd NROL-76 payload
 

click image to enlarge

The image above shows USA 276 passing over the roof of my house last night. USA 276 is the mystery payload of the May 1 SpaceX NROL-76 launch from Cape Canaveral.
 
Also visible in the image are three rocket boosters: the r/b of the classified Milstar 3 launch, and two Russian objects. Skies surely are crowded these days...

Спойлер

The photograph above was shot near 3:07 local time (1:07 UT) during the second of two consecutive passes. During the first pass, near 1:30 local time (23:30 UT), I obtained this video record:



USA 276 was quite faint during the first pass (I could not see it by naked eye from Leiden town center). During the second pass it was brighter, attaining mag. +3 near culmination, visible to the naked eye without problem. Due to its low orbital altitude it was very fast: the object is in a 389 x 409 km, 50.0 degree inclined orbit.

After its May 1 launch, there was a lot of discussion among our observers. The launch azimuth seemed to suggest a 50 degree orbital inclination. That would be odd (see below), so not everybody was willing to believe this. Some suggested a dog-leg manoeuvre towards a 63.4 HEO orbit. Because of the lack of precedent, orbital altitudes could only be guessed, making a quick recovery by observers more troublesome.

It took a while (23 days) before the payload was finally observed and the orbit could be confirmed. On May 23-24, the night before I obtained the imagery above, Leo Barhorst in the Netherlands finally found the payload. And it was in a 50 degree inclination, 389 x 409 km Low Earth Orbit.

The purpose of this payload in this odd orbit is a bit of a mystery. The orbital inclination of 50.0 degrees does not match common orbital inclinations attached to specific functions: US military radar satellites (ONYX, TOPAZ) tend to be in 57 degree LEO orbits or their 123 degree retrograde equivalents; SIGINT sats in 63.4 degree orbits (either LEO or HEO); optical reconnaissance satellites in 98 degree sun-synchronous LEO orbits; the X-37B space plane was in a 39-degree inclined very Low Earth Orbit. An orbital inclination of 50.0 degrees, as shown by USA 276, is odd and unusual.
 
The common opinion is that USA 276 is some technology demonstrator, somewhat similar to the ill-fated USA 193 from 2006, blown from the sky with a SM-3 in 2008. But what technology does it demonstrate?


click map to enlarge

Orbital inclination and orbital altitude are in fact very (some would say oddly) similar to the ISS (see diagrams above and below, showing how close the orbits currently are): the two objects in theory (and based on the current USA 276 orbit) can potentially even make quite close approaches, to within a few km (!), as Ted Molczan showed in a private communication.


click image to enlarge

I have found that on June 4, USA 276 will in fact be very close by when (if all goes according to plan)  the SpaceX DRAGON CRS-11 should arive at the ISS at this date. That is, if USA 276 doesn't change its current orbit before then.

Observers in Europe might see the three objects close together in their evening twilight of June 3, with USA 276 some 15 degrees distant from the ISS.

The diagram below shows the position of USA 276 relative to the ISS on the European evening of June 3, if USA 276 has not manoeuvered by then:

click image to enlarge

Due to slightly different rates of precession of their orbital nodes, the orbits will slowly diverge from their current close coincidence over time, unless USA 176 makes a corrective manoeuvre.

I have pondered the question whether this all is coincidental or not. I can in fact think of a potential goal wh ere this all would be on purpose, but that would be a very wild thing to do, so perhaps is not so likely. For the moment, let's better chalk it up to coincidence until new developments seem to point otherwise.

[свернуть]

[SGS_67]

Старый пишет:

SGS_67 пишет:

Старый пишет:
А что, при наклонении 50 градусов перигей не прецессирует?    

Он прецессирует при любом наклонении.
Дятел.

Перигей не прецессирует при наклонении 63.4 градуса. Неужели это можно не знать?    
 Дебил, б#"@ (с) Лавров

Перигей прецессирует при любом наклонении. Любого спутника Земли.
Как и перицентр движущегося по орбите любого космического тела. А в таковые можно записать абсолютно всё.
Баран.

ЗЫ. Линия апсид околоземного КА имеет наименьшую прецессию примерно на полярной орбите.
Но всё равно имеет.

Спойлер

Последнее - манок на дятелов.

[свернуть]

[SGS_67]

Старый пишет:
Однако ясно что при высоте 400 км основное возмущение будет от сопротивления атмосферы...

Это ты в педивикиях вычитал, экселенц?
Или просто пукнул в лужу?

[tnt22]

http://www.satobs.org/seesat/May-2017/0134.html

From: Ted Molczan via Seesat-l <seesat-l_at_satobs.org>
 Date: Thu, 25 May 2017 06:47:43 -0400

The following elements are derived from observations by Leo Barhorst, Kevin Fetter, Sergey Guryanov, Marco Langbroek, Scott Tilley, Brad Young, and Mike Waterman:

USA 276 | 389 X 410 km
1 42689U 17022A 17145.09297211 .00007006 00000-0 97415-4 0 06
2 42689 50.0009 159.4241 0015293 79.4326 280.8364 15.56135339 04
Arc 20170523.76-0525.1 WRMS resid 0.047 totl 0.012 xtrk

The decay term is of doubtful accuracy, due to the shortness of the arc.

In my previous post to this thread, I speculated on the possibility that the orbit may be frozen, and the implications. Propagating the above elements with GMAT 2015a, using a gravity model of degree and order 41, reveals that the orbit is not frozen.

Ted Molczan

[Старый]

tnt22 пишет:
http://www.satobs.org/seesat/May-2017/0134.html

In my previous post to this thread, I speculated on the possibility that the orbit may be frozen, and the implications. Propagating the above elements with GMAT 2015a, using a gravity model of degree and order 41, reveals that the orbit is not frozen .

Ted Molczan

Ну слава богу!

Осталось теперь только понять какую связь он увидел между этим аппаратом и всеми прочими которые он привёл выше. 

[Apollo13]

https://elvperf.ksc.nasa.gov/Pages/Query.aspx

Orbit Class:	LEO Circular
Graph Type:	Altitude (km) vs. Mass (kg)
Altitude (km):	400
Inclination (deg):	51.6

Vehicle	Capability, kg
Falcon 9 (Full Thrust, RTLS )	10860

[Брабонт]

Так понимаю, 3-го июня он будет брать МКС на абордаж

[Старый]

Я смотрю он летает в районе терминатора таким образом что в северном полушарии оказывается над неосвещённой поверхностью земли. 
 Но в дальнейшем ситуация изменится. 

[tnt22]

https://sattrackcam.blogspot.ru/2017/05/brightness-variation-of-usa-276-nrol-76.html

Friday, 26 May 2017

Brightness variation of USA 276 (NROL-76)


click image to enlarge

Last night was very clear again. I observed two passes of the new USA 276 (2017-022A) satellite, also known under its NRO launch number NROL-76. It was launched early this month by SpaceX, and I wrote in detail about this mystery payload in my post fr om yesterday.

The image above, taken with a Canon EOS 60D and EF 2.0/35 mm lens, shows the satellite passing over the roof of my house during the first pass (00:36 local time, 22:36 UT). It was bright and an easy naked eye object at mag +2.5 near culmination.

Спойлер

During the second pass, 02:06 local time (00:06 UT) it was somewhat fainter, mag +3 to +3.5, but still visible naked eye. Below are two images from this pass:


click image to enlarge


click image to enlarge

During this second pass, I visually seemed to note some brightness variation, notably after culmination.

Analysis of the pixel brightness of the trails in my imagery seems to confirm this. They show an irregular brightness variation, notably in the third image (the last of the images above), that looks like it is a combination of several periods.

The diagrams below show the curve obtained from 4 images, and a detail curve of the third image wh ere brightness variation seems most pronounced. Pixel values of the trails were measured with IRIS.


click diagram to enlarge


click diagram to enlarge

This variation could hint at some form of spin stabilization, or alternatively the presence of some rotating element perhaps.

I did not note this variation during earlier passes, so  it could perhaps strongly depend on the viewing angle.

[свернуть]

[tnt22]

http://satobs.org/seesat/May-2017/0151.html

From: Ted Molczan via Seesat-l <seesat-l_at_satobs.org>
 Date: Fri, 26 May 2017 10:18:16 -0400

The following elements have been derived from observations by Leo Barhorst, Kevin Fetter, Sergey Guryanov, David Hopkins, Marco Langbroek, Alberto Rango, Scott Tilley, Brad Young, and Mike Waterman:

USA 276 | 390 X 410 km
1 42689U 17022A 17146.05615742 .00004806 00000-0 66833-4 0 01
2 42689 49.9996 154.4553 0014810 91.7985 268.4680 15.56142385 01
Arc 20170523.76-0526.08 WRMS resid 0.054 totl 0.015 xtrk

As Marco Langbroek alerted yesterday, USA 276 will pass within tens of kilometres of ISS on Jun 3, unless either one changes its orbit. Below is some data for the closest approaches with range <= ~100 km.



The time and range of closest approach is fairly sensitive to the decay rate of USA 276, which may not yet have settled down to its actual value, due to the still short observational arc.

After each conjunction, the objects move apart, typically reaching a range of around 400 km, before closing in for the next encounter.

I have not made a close evaluation of visibility. A cursory review of the above does not reveal favourable observing circumstances for any of the regular contributors to the list.

For USA 276, I used the above TLE. For ISS, I used NASA's current estimated TLE for June 3:

https://spaceflight.nasa.gov/realdata/sightings/SSapplications/Post/JavaSSOP/orbit/ISS/SVPOST.html

1 25544U 98067A 17154.59567142 .00016717 00000-0 10270-3 0 9127
2 25544 51.6394 106.0762 0004802 233.4052 126.6659 15.53976959 19638

Ted Molczan

[tnt22]

Уточнение TLE сабжа
http://satobs.org/seesat/May-2017/0165.html

From: Ted Molczan via Seesat-l <seesat-l_at_satobs.org>
 Date: Sun, 28 May 2017 11:37:47 -0400

The following elements have been derived from observations by Leo Barhorst, Kevin Fetter, Sergey Guryanov, David Hopkins, Marco Langbroek, Alberto Rango, Scott Tilley, Brad Young, and Mike Waterman:

USA 276 | 389 X 410 km
1 42689U 17022A 17147.98252060 .00003853 00000-0 53546-4 0 02
2 42689 50.0003 144.4680 0014878 97.4263 262.8397 15.56155710 08
Arc 20170524.02-05271 WRMS resid 0.096 totl 0.018 xtrk

Ted Molczan