Author Topic: Fobos-Grunt Troubleshooting Latest (Part 2)  (Read 447076 times)

Offline Chris Bergin

The main thread, at 460 posts and 160,000 reads, is too long and convoluted to be managed, so we're starting this new thread for troubleshooting updates.

This thread will convert to a mission thread if efforts are successful (I know that's not likely). Otherwise the thread will convert into a failure thread through to the spacecraft's re-entry.

Resources:

Pre-Launch:
http://forum.nasaspaceflight.com/index.php?topic=15610.0

Launch Updates:
http://forum.nasaspaceflight.com/index.php?topic=15610.165

Launch Article:
http://www.nasaspaceflight.com/2011/11/live-zenit-2launch-fobos-grunt-sample-return-mission-to-phobos/

Post S/C Sep, leading into notes of a problem:
http://forum.nasaspaceflight.com/index.php?topic=15610.330

Fobos-Grunt Issue Article:
http://www.nasaspaceflight.com/2011/11/russian-engineers-stricken-fobos-grunt-spacecraft/


This thread follows on from the problem notes thread. All posts need to be worthwhile and specific to spaceflight. Any posts which are rambling, political, or armwavey and not to the standard of this thread will be removed, but also should be reported to mod to draw attention to the need for action.

Come on Fobos-Grunt! Say something!!
« Last Edit: 12/24/2013 06:58 PM by Jester »

Offline Chris Bergin

Re: LIVE: Fobos-Grunt Troubleshooting Latest (Part 2)
« Reply #1 on: 11/13/2011 08:16 PM »
Some recent update notes:




http://www.novosti-kosmonavtiki.ru/content/news.shtml

The Russian interplanetary probe Phobos-Grunt is able to correct its orbit using its own engines, says Igor Lisov, an editor of Novosti Kosmonavtika.

A source from the space industry has informed RIA Novosti that during the last three days the height of the apogei has been lowered to 6.5 kilometers, while the height of the perigee (which had to lower too), had risen to a kilometer due to unknown reason.

The observed data is best explained bu the fact the probe keeps its own orientation due to periodic activation of the engine. This is not something that's commanded from Earth - Phobos-Grunt lives its own life. But it cannot talk.

Very interesting!

From ISS On-Orbit Status Report for 13/11/2011.

Phobos-Grunt Visibility:
The ISS crew was notified of viewing/photographing opportunities for the stranded Phobos-Grunt Mars probe from the DC-1 VL-1 and MRM-2 windows as it crossed the ISS trajectory this morning at 4:06:16 AM GMT and 4:52 AM GMT.

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Re: LIVE: Fobos-Grunt Troubleshooting Latest (Part 2)
« Reply #2 on: 11/13/2011 09:17 PM »
...
Very interesting!

From ISS On-Orbit Status Report for 13/11/2011.

Phobos-Grunt Visibility:
The ISS crew was notified of viewing/photographing opportunities for the stranded Phobos-Grunt Mars probe from the DC-1 VL-1 and MRM-2 windows as it crossed the ISS trajectory this morning at 4:06:16 AM GMT and 4:52 AM GMT.
Interesting, indeed. Did they snap any photos, and how far was the closest approach?
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Re: LIVE: Fobos-Grunt Troubleshooting Latest (Part 2)
« Reply #3 on: 11/13/2011 09:33 PM »
I don't understand what could possibly be gained by attempting to photograph it from ISS. They won't be able to resolve it any more than ground observers can without a powerful telescope.

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Re: LIVE: Fobos-Grunt Troubleshooting Latest (Part 2)
« Reply #4 on: 11/13/2011 09:42 PM »
I don't understand what could possibly be gained by attempting to photograph it from ISS. They won't be able to resolve it any more than ground observers can without a powerful telescope.
Depends on how close the pass is, though, doesn't it? Earth-based telescopes are usually limited by seeing to usually worse than the large telephoto lenses on ISS, and the ones that aren't limited by seeing usually have far lower slew-rates than required, whereas I think ISS has a system set up for higher slew-rates (do they still have that set up? okay, probably not, but it was a kludge anyway... an awesome kludge).

If it's a very close pass, it could be several times closer than any ground observation, thus possibly allowing several times greater resolution, if they can track it well enough.
« Last Edit: 11/13/2011 09:46 PM by Robotbeat »
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Offline Lee Jay

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Re: LIVE: Fobos-Grunt Troubleshooting Latest (Part 2)
« Reply #5 on: 11/13/2011 09:46 PM »
I don't understand what could possibly be gained by attempting to photograph it from ISS. They won't be able to resolve it any more than ground observers can without a powerful telescope.
Depends on how close the pass is, though, doesn't it? Earth-based telescopes are usually limited by seeing to usually worse than the large telephoto lenses on ISS, and the ones that aren't limited by seeing usually have far lower slew-rates than required, whereas I think ISS has a system set up for higher slew-rates (do they still have that set up? okay, probably not, but it was a kludge anyway... an awesome kludge).

System?  Not sure about that, but a person holding a camera can do 90 per second or so.

Offline robertross

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Re: LIVE: Fobos-Grunt Troubleshooting Latest (Part 2)
« Reply #6 on: 11/13/2011 10:05 PM »
I don't understand what could possibly be gained by attempting to photograph it from ISS. They won't be able to resolve it any more than ground observers can without a powerful telescope.

I can't see it proving any useful information either, even with an image stabilized lens with, IIRC, 1200mm max effective focal length with current assets, which when hand held and 1/8 sec maximum shutter speed (which is borderline, better with 1/30 sec).
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Offline hop

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Re: LIVE: Fobos-Grunt Troubleshooting Latest (Part 2)
« Reply #7 on: 11/13/2011 10:09 PM »
Depends on how close the pass is, though, doesn't it?
The orbits cross at almost right angles, so the time of closest approach will be tiny. I haven't worked out what the closest possible approach is, but if the perigee and apogee lined up perfectly (which I'm sure they don't), it would be ~40km. Now think about when visiting Soyuz and Progress start to be visible...

The only values I can see to this are
1) Sentimental. I'd certainly give it a try if I was on ISS.
2) Video could possibly provide confirmation of whether the spacecraft was tumbling.

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Re: LIVE: Fobos-Grunt Troubleshooting Latest (Part 2)
« Reply #8 on: 11/13/2011 10:13 PM »
Also, F-G would pass under the ISS when it's near so unless you want to lose it in the clouds, the ground below should be in the darkness while F-G is not.

Offline clongton

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Re: LIVE: Fobos-Grunt Troubleshooting Latest (Part 2)
« Reply #9 on: 11/13/2011 10:13 PM »
I don't understand what could possibly be gained by attempting to photograph it from ISS. They won't be able to resolve it any more than ground observers can without a powerful telescope.

I can't see it proving any useful information either, even with an image stabilized lens with, IIRC, 1200mm max effective focal length with current assets, which when hand held and 1/8 sec maximum shutter speed (which is borderline, better with 1/30 sec).

It's always possible that the inability to communicate may be due to a broken antennae or cable. A close-up photo from ISS may be able to provide that data. In any case a telephoto lens photo from the ISS will be better than any ground-based telescope could provide.

I'm really pulling for our Russian friends. I hope they can save this mission.
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Re: LIVE: Fobos-Grunt Troubleshooting Latest (Part 2)
« Reply #10 on: 11/13/2011 10:15 PM »
It's always possible that the inability to communicate may be due to a broken antennae or cable. A close-up photo from ISS may be able to provide that data.

My 2c? No frickin' way.

I'll also add that even if they managed to pull off a miracle an regain control of it, the orbital plane its in by now is probably too far out of alignment with the desired TMI asymptote to be able to salvage the mission. The 180 deg nodal rotation on the other hand could happen too late to catch the end of the Mars launch period.
« Last Edit: 11/13/2011 10:19 PM by ugordan »

Offline robertross

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Re: LIVE: Fobos-Grunt Troubleshooting Latest (Part 2)
« Reply #11 on: 11/13/2011 10:17 PM »

I'm really pulling for our Russian friends. I hope they can save this mission.

Oh don't get me wrong, I am too, 100% (selfishly thinking of the science lost more than the hardware at this point).

I would only add that I wish there was a way to 'boost' the signal if the antenna is indeed being obstructed in any way, perhaps that being enough to get through to the spacecraft.
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Re: LIVE: Fobos-Grunt Troubleshooting Latest (Part 2)
« Reply #12 on: 11/13/2011 10:19 PM »
40km is far closer than the ~200km elevation Phobos-Grunt orbits (though obviously 40km is a best-case scenario).

This is what I was thinking about, by the way:
http://spaceflight.nasa.gov/gallery/images/station/crew-6/html/iss006e44305.html
This is an old photo, and I believe that has been long disassembled, but it is a little better than just hand-tracking.
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Offline Space Pete

Re: LIVE: Fobos-Grunt Troubleshooting Latest (Part 2)
« Reply #13 on: 11/13/2011 10:32 PM »
This is what I was thinking about, by the way:
http://spaceflight.nasa.gov/gallery/images/station/crew-6/html/iss006e44305.html
This is an old photo, and I believe that has been long disassembled, but it is a little better than just hand-tracking.

Yup, that was mounted in the Lab window, where the WORF rack now resides. Phobos-Grunt was only visible out of the Pirs and Poisk module windows - which are angled forward-starboard, forward-port, aft-starboard, and aft-port.
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Offline JimO

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Re: LIVE: Fobos-Grunt Troubleshooting Latest (Part 2)
« Reply #14 on: 11/14/2011 12:17 AM »
Let me add my 2 kopecks to the mystery of the orbit rise and its hypothetical connection with attitude control firings.


The effect that is being postulated was called 'cross-coupling' in the MCC when I worked there, and reflects the fact that small thrusters which are dedicated to specific translational or rotational modes are rarely 'pure' in their force. Along with major intended contribution to specific roll/pitch/yaw and X/Y/Z translation, they induce forces in other modes as well, sometimes minor, but not always so.

Best example: attitude hold for the Orbiter using vernier jets. Since the verniers used are all down-firing, an attitude deadband is maintained by the autopilot alternately firing nose down jets, then tail down jets. The result was a 'creep' in the +X direction, in translation. Such an unexpected creep, overlooked by some consoles, was actually at the root of a major navigation crisis while I was on duty on a mission I am not yet at liberty to disclose -- a crisis I'm happy to brag that I solved as the lead 'Rendezvous and Guidance Procedures Officer'.

Translational cross-coupling was also at the heart of the loss of Mars Climate Orbiter in 1999, when the outbound cruise experienced higher-than-planned effects due to the assymetry of the solar array, requiring frequent rotational correction burns that added up to a significant translational deviation. It was THAT deviation, which was mis-entered into cruise navigation based on the tables being in the wrong units, that created the navigation error that [together with management's refusal to listen to the navigators' intuitive concern based on their DETECTION of the cumulative error but their inability to spend enough manpower to chase down its root cause] that led to flying the perfectly-good spacecraft into the martian atmosphere.

Now, here's how this reflects on Phobos-Grunt. Translational cross-coupling is most in evidence when the spacecraft attitude profile is such that the series of small extraneous forces are cumulative -- that is, adding up in the effectively same direction.

For orbital altitude effects, that direction is posigrade [or retrograde], along the velocity vector. That was the case for STS-[oops, almost typed it in!], and for MCO.

But we are given to understand that Phobos-Grunt may be holding attitude in solar inertial orientation, to maximize power. This is NOT the LVLH [local vertical local horizontal] attitude of the shuttle, or for that matter, ISS.

In practice, solar inertial pointing clocks completely around the sky once every rev.

This suggests to me that any translational cross coupling from such repeated burns would for the most part cancel out. Those that fell far off the velocity vector would not alter orbital energy and hence not affect altitude/period.

Or at least they would cancel if the sun were nearly in the probe parking orbital plane. If the probe-sun vector is significantly out of plane, some assymetry could indeed be occurring.

Does anybody have the 'beta angle' for the probe -- the angle of the line-of-sight to the sun based on the orbital plane [with time tag]? An easier question -- what's the delta RAAN between PhG and ISS, since we know the beta angle of the latter.

 

   

Offline FinalFrontier

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Re: LIVE: Fobos-Grunt Troubleshooting Latest (Part 2)
« Reply #15 on: 11/14/2011 12:24 AM »
Okay. So If I have this straight their going to try taking a video or pictures of the spacecraft from ISS to see if its tumbling or is otherwise damaged? Did they actually take pictures?
« Last Edit: 11/14/2011 12:26 AM by FinalFrontier »
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Offline Lee Jay

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Re: LIVE: Fobos-Grunt Troubleshooting Latest (Part 2)
« Reply #16 on: 11/14/2011 12:32 AM »
But we are given to understand that Phobos-Grunt may be holding attitude in solar inertial orientation, to maximize power.

Are we?  I wasn't under that impression.  Could it be that it is holding LVLH in anticipation of the burns that didn't occur?

Offline Nickolai

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Re: LIVE: Fobos-Grunt Troubleshooting Latest (Part 2)
« Reply #17 on: 11/14/2011 12:43 AM »
Okay. So If I have this straight their going to try taking a video or pictures of the spacecraft from ISS to see if its tumbling or is otherwise damaged? Did they actually take pictures?

I don't think there was any indication that ISS personnel were going to inspect for damage. As far as I understand it, ground controllers were simply informing the crew that there will be a close pass, and it's up to the crew to decide what they want to do with that information.

Offline JimO

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Re: LIVE: Fobos-Grunt Troubleshooting Latest (Part 2)
« Reply #18 on: 11/14/2011 12:46 AM »
But we are given to understand that Phobos-Grunt may be holding attitude in solar inertial orientation, to maximize power.

Are we?  I wasn't under that impression.  Could it be that it is holding LVLH in anticipation of the burns that didn't occur?

Well, that's possible -- but if so, why, and with what sensors? Too bad neither Roskosmos nor Lavochkin are providing such basic information.

Visual tracking strikes me as highly important, as often as possible, to watch for any plumes that suggest prop release from one of the dozens of tanks. There seems to be no other way to detect such an eventuality.

Not that there's anything to be done about it, of course.


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Re: LIVE: Fobos-Grunt Troubleshooting Latest (Part 2)
« Reply #19 on: 11/14/2011 01:08 AM »
Jim, Can I make a suggestion, and feel free to shot it down.

Quote
In practice, solar inertial pointing clocks completely around the sky once every rev.

True, it should, but the rub is, part of each orbit is in earths shadow.

What does it do at that point? Go searching for the sun? Just hang out making no adjustments? Could the "shadow" behavior be why the adjustments are not fully canceling?
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