Author Topic: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011  (Read 427580 times)

Offline sdsds

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #900 on: 11/12/2011 07:34 PM »
The high-speed, 34 m antenna at Goldstone, (the "HSB" antenna) has the fastest tracking and slew rates of any DSN antenna.  Its slew rates (in deg/s) are 3.0 (AZ) 2.0 (EL).  I haven't done the math, but the attached graph seems to imply tracking FG on at least some passes would be within its capabilities.  (Info and graphic from: http://deepspace.jpl.nasa.gov/dsndocs/810-005/302/302B.pdf.)
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Offline iamlucky13

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #901 on: 11/12/2011 07:47 PM »
According to some people in NK (ones that have to do with space, including some Lavochkin guys) the other problem is that the spacecraft uses X band and from all the ground antennas available configured to woek with the craft, the smallest one is 64m wide.
If this is true, it seems like a case where US or other outside parties could possibly help. NASA, ESA, and JAXA all have X band grounds stations AFAIK.

I'm sure there's lots of parties with X-band transmitters that could potentially help. However, there's no detail about what "configured to work with" F-G means.

Also, by "the smallest one is 64m wide," can we assume that means the one and only? How many antennas bigger than 64 meters are there around the world? I know of the DSN 70m dishes. I'm not familiar with whatever antennas are run by the Russians or ESA.

I wonder if it means raising the orbit on purpose
Seems unlikely something it would decide to do on it's own in safe mode, but possibly a side effect of maintaining attitude.

That was my thought, too - net translational components in the attitude control. Or As suggested by the satobs poster who originally pointed out the apparent rise, it could be a leak/venting.

That could be an additional mission concern if the spacecraft is recovered. I presume for an 11-month cruise it is either spin or reaction-wheel stabilized, so there probably was not much fuel budgeted for attitude control. An extended period of fixed attitude control could further reduce the fuel margin.
« Last Edit: 11/12/2011 07:48 PM by iamlucky13 »

Offline joek

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #902 on: 11/12/2011 07:54 PM »
According to some people in NK (ones that have to do with space, including some Lavochkin guys) the other problem is that the spacecraft uses X band and from all the ground antennas available configured to woek with the craft, the smallest one is 64m wide. This means that it could not possibly track a spacecraft so close and hitting the spacecraft with the beam (it is very narrow from that antenna) is quite difficult and requires precise knowledge of the orbit and a lot of luck. Even if you hit FG with the beam, it will pass out of it quickly, so you cannot get telemetry down or commands up. S band receiver/transmitter would have been a nice addition. Although after so many attempts people are beginning to think that at least once the craft should have got the commands from the ground, so possibly something physically went wrong with the craft and that caused some damage to the comms system.
I have no idea if that makes any sense.

Thanks; that makes sense and helps explain some of the delay and silence.  The big deep space antennas aren't generally designed to track fast low-flying SC such as FG.  Instead of actively tracking to maintain an extended comm window, it would be more like pointing the dish at where you think the SC will be, wait for it to intersect, and try to get as much up/down during a few seconds as possible (which may not be enough time).

Understandably that takes precise knowledge of the SC orbit and a bit of luck.  Given enough shots you might expect one to get through, but apparently none have.  I wonder how many they've tried?

Offline ChileVerde

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #903 on: 11/12/2011 08:17 PM »

Seems unlikely something it would decide to do on it's own in safe mode, but possibly a side effect of maintaining attitude.


I agree. The small orbital changes (which also are giving rise to weird SatEvo decay predictions) are likely to be an unintended effect of something else. I think that the speculations that "something else" is likely to be attitude thrusters or venting are probably correct.  All in all, they don't really provide any reason for optimism about recovering the mission -- though I hope that, somehow, it does rise from the near-dead.
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Offline Blackstar

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #904 on: 11/12/2011 08:29 PM »

Let's use our automobile analogy again...It's equivalent to saying that the steering wheel is apparently working and the front tires move but the engine is dead, the radio and horn don't seem to work, we don't know if the A/C is good and there are some other unknown problems that keep the car from starting.  I don't think I would describe this automobile as "OK".


How about a runaway train with an incapacitated engineer and the dead man switch isn't working.

How about a runaway train run by a... zombie!

(This is fun!)

Offline mike-shevchenko

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #905 on: 11/12/2011 08:57 PM »
My 5 cents to fantastic rescue scenarios: maybe it is still feasible to give some appropriate portable antenna/codec to the upcoming Soyuz crew to be launched on Monday? The ISS has got plenty of kilowatts, and maybe could reach FG.

About Russian programmers (as being one of them): there are lots of strong ones; the majority of us just can't _afford_ to work for the space industry (being all governmental) for about 1/3 of a commercial job market salary, though many of us have always dreamt of. Give us competitive compensation, and I will be the first one to apply.
« Last Edit: 11/12/2011 08:58 PM by mike-shevchenko »

Offline hop

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #906 on: 11/12/2011 09:14 PM »
My 5 cents to fantastic rescue scenarios: maybe it is still feasible to give some appropriate portable antenna/codec to the upcoming Soyuz crew to be launched on Monday? The ISS has got plenty of kilowatts, and maybe could reach FG.
Sigh. No chance.
1) design + build + test the equipment in a weekend. It needs to be installed on the outside of the station, so there's no way it's off the shelf.
2) Plan and carry out an EVA to install it.

Once that's done, ISS is at very similar inclination to FG but a different plane, so you still have quick encounters like a ground station.

Offline manboy

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #907 on: 11/12/2011 10:55 PM »
Latest article from AFP:

Quote
"All attempts to obtain telemetric information from the Phobos-Grunt probe and activate its command system have failed. The probe must be considered lost," Interfax quoted a source in the Russian space sector as saying.

The source said Russia's space agency would announce the failure of the mission in the next few days.

http://www.google.com/hostednews/afp/article/ALeqM5gMW4kePeuEcETL4ubT0UUDyRBoww?docId=CNG.cbc3ed79698bb9cab8ad6a92169ceb0c.01
I was really looking forward to this mission. Here's hoping re-entry doesn't occur over any populated areas.
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Offline Liss

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #908 on: 11/12/2011 11:05 PM »
Quote
"All attempts to obtain telemetric information from the Phobos-Grunt probe and activate its command system have failed. The probe must be considered lost," Interfax quoted a source in the Russian space sector as saying.

The source said Russia's space agency would announce the failure of the mission in the next few days.

Fortunately this is not correct. The attempts continue, the hope is still with operators and designers of FG, but the situation is difficult.

They use one or two 12-meters X-band antennae located at Baikonur and Medvezhyi Ozera (aka Bear Lakes). In theory, these cannot follow FG due to slow slew rate. But there could be passes and modes when commanding is possible.

Small orbital changes are probably the side effect of PM engines firings to keep the attitude. At least it's the current thinking.

Once more I advise you to discard all agencies reports unless they have a signed quote, or extraordinary level of details, or being the final official report.
« Last Edit: 11/12/2011 11:06 PM by Liss »
This message reflects my personal opinion based on open sources of information.

Offline Liss

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #909 on: 11/12/2011 11:17 PM »
By the way, extremely interesting article about the probe's control and communication system, however it is in Russian and does not describe the final configuration.
http://www.novosti-kosmonavtiki.ru/phpBB2/viewtopic.php?t=12378

Well, it differs in the number of orbit corrections.
But I hope it is similar in part of communications on LEO at least before the 1st engine burn.
Word is that the final choice of two-burn departure vs. three-burn is the only error in it.
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Offline sdsds

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #910 on: 11/12/2011 11:20 PM »
They use one or two 12-meters X-band antennae located at Baikonur and Medvezhyi Ozera (aka Bear Lakes). In theory, these cannot follow FG due to slow slew rate. But there could be passes and modes when commanding is possible.

It would be informative to compare the capabilities of these antennae with those used by the DSN.  It appears the DSS 24 BWG antenna has a mode which provides 18.2 kW of power for X-band uplink, though that antenna is also hampered by a slow slew rate.  (I can't find evidence of the DSS 27 HSB high speed antenna supporting X-band.  Sigh.)

These are 34-meter diameter antennae.  How do their transmit power compare with the antennae at Baikonur and Medvezhyi Ozera?

FWIW http://deepspace.jpl.nasa.gov/dsndocs/810-005/104/104F.pdf provides what looks to be an up to date description of 34-m BWG Stations Telecommunications Interfaces.
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Offline klausd

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #911 on: 11/12/2011 11:21 PM »

Did we have that one? watch 3min and 1 sec... failed burn?

« Last Edit: 11/12/2011 11:22 PM by klausd »

Offline hop

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #912 on: 11/12/2011 11:28 PM »
They use one or two 12-meters X-band antennae located at Baikonur and Medvezhyi Ozera (aka Bear Lakes). In theory, these cannot follow FG due to slow slew rate. But there could be passes and modes when commanding is possible.
Thanks for this. Do you know if they receive any transmission or telemetry in these passes ? I would expect safe mode should broadcast something ?

Quote
Once more I advise you to discard all agencies reports unless they have a signed quote, or extraordinary level of details, or being the final official report.
Very sound advice!

Offline i2000s

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #913 on: 11/12/2011 11:33 PM »

Did we have that one? watch 3min and 1 sec... failed burn?


Do you believe it?

Offline klausd

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #914 on: 11/12/2011 11:40 PM »

Look @ the upload time. It could be true. A Fake, just to baffle you, would have been uploaded later. The title of a youtube video can be changed any time.

And i know of a guy in Rio who had linked a livestream on http://www.satview.org to watch for fobos-grunt.

Offline Liss

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #915 on: 11/12/2011 11:43 PM »
I would expect safe mode should broadcast something ?

We would expect too. Life would be much better if FG did. Listening resulted in nothing (as of Nov 12, 16:00 UTC). Commanding is being made to try to switch transmitters on.
This message reflects my personal opinion based on open sources of information.

Offline kevin-rf

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #916 on: 11/12/2011 11:50 PM »

Look @ the upload time. It could be true. A Fake, just to baffle you, would have been uploaded later. The title of a youtube video can be changed any time.

And i know of a guy in Rio who had linked a livestream on http://www.satview.org to watch for fobos-grunt.

All I am seeing at 3:01 is is going behind a telephone pole ... Can someone better explain?
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Offline klausd

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #917 on: 11/12/2011 11:53 PM »

Hm, you are right.   :-\

Offline hop

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #918 on: 11/12/2011 11:58 PM »

Look @ the upload time. It could be true. A Fake, just to baffle you, would have been uploaded later. The title of a youtube video can be changed any time.

And i know of a guy in Rio who had linked a livestream on http://www.satview.org to watch for fobos-grunt.
Let's say it's real, what does it show ? I see a point of light going in and out of focus, and then fades out around 3:00, which would be consistent with no burn taking place, and PG eventually going into eclipse. Or being eclipsed by something local such as a telephone pole, but to me it fades out a bit slow for that. He picks something up at the end but that looks like a light to me.

Looking at the maps here: http://phobos.cosmos.ru/index.php?id=312&L=2 this appears consistent with expectation for an observer in Sao Palo, although of course without any reference points, we can't say.
« Last Edit: 11/13/2011 01:07 AM by hop »

Offline kevin-rf

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Re: LIVE: Zenit-2SB launch with Phobos-Grunt - November 8, 2011
« Reply #919 on: 11/13/2011 01:04 AM »

Hm, you are right.   :-\

For anything more than an aborted engine start I think we would be seeing more in the two TLE's. I was hoping for a flash, or sudden brightening in the video, I think this video actually was posted several pages back the night of the launch (or soon there-after).
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