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#720
by
alk3997
on 29 Nov, 2011 14:14
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Are there no on-orbit sats that would allow transmission of commands towards F-G more frequently eg a TDRS type sat ?
Just a thought..
A-P
The Soviets used to have such a network called Luch, but it fell out of service after the Cold War. The Russians are planning to rebuild the system, however, and if I recall, the first launch is scheduled for December 11th. I'm not sure that it is capable of transmitting X-band, however.
As I recall it was not reliable when it was used with Mir. The new Luch has Ku-Band and S-Band antennas for telecommunications along with P-Band and L-Band for geonavigation relay, according to a very unofficial source.
X-Band is used for interplanetary spacecraft so there would be no reason to have it on a relay satellite. Optical relay would be a much more useful function for a satellite with an interplanetary spacecraft, but I digress.
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#721
by
SiberianTiger
on 29 Nov, 2011 14:20
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Can any of our fluent Russian-speakers who are watching the NK and other blogs on Fobos-Grunt provide any summaries of what is known about three items:
1. What exactly IS the orbit-raising plan? Presumably it is just the first of the two planned insertion burns from Flight Day 1, the one that depletes and drops the toroid aft propellant tank complex. But specifically, what was the commanded ignition time? This can tell us how they are planning to shape the orbit on future maneuvers. It also can help us alert ground observers who may be able to witness the plume [or its absence] and the tank propellant venting.
No information or even informed speculations on that, except for what the ESA representatives told.
2. What if anything has been learned about vehicle status from the short bursts of telemetry?
From NK (
http://www.novosti-kosmonavtiki.ru/phpBB2/viewtopic.php?p=845868#845868):
Analysis of the emergency frame from the cruise stage was not too fruitful. It contained:
* Status of several specific devices from the radio assembly itself;
* Working voltages on the assembly's buses;
* Temperature readings in severals spots of the assembly;
* Confirmation of nominal state of the bus for data exchange with the CPU;
* History track of switching between the primary and emergency transmitters.
3. What is the speculation about the remarkable "apogee creep" exhibited for several days early in the mission, and hypothetically attributed to propellant venting, thruster firing, or some combination? The apparent cessation of this effect shortly before radio contact was first established may be a significant clue about vehicle status, but how has it been interpreted?
That was perigee creep, not apogee creep. Posters at NK speculated it might happen due to:
* An error in interpretation of TLE data, not taking into account perigee argument's precession into higher latitude where Earth is bulged less;
* Regular repeating of prograde attitude taking, ullage and main thruster start sequence, broken each time short of burning the main engine;
* A disturbance introduced by leak from a propellant or pressured gas tank;
* A disturbance introduced by leak from a blown up battery.
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#722
by
SiberianTiger
on 29 Nov, 2011 14:31
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The Soviets used to have such a network called Luch, but it fell out of service after the Cold War. The Russians are planning to rebuild the system, however, and if I recall, the first launch is scheduled for December 11th. I'm not sure that it is capable of transmitting X-band, however.
No, only C and Ku band.
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#723
by
kevin-rf
on 29 Nov, 2011 14:32
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* A disturbance introduced by leak from a blown up battery.
That is the first I have seen mention of that possibility, can you provide more on this?
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#724
by
Confusador
on 29 Nov, 2011 14:34
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The Soviets used to have such a network called Luch, but it fell out of service after the Cold War. The Russians are planning to rebuild the system, however, and if I recall, the first launch is scheduled for December 11th. I'm not sure that it is capable of transmitting X-band, however.
As I recall it was not reliable when it was used with Mir. The new Luch has Ku-Band and S-Band antennas for telecommunications along with P-Band and L-Band for geonavigation relay, according to a very unofficial source.
X-Band is used for interplanetary spacecraft so there would be no reason to have it on a relay satellite. Optical relay would be a much more useful function for a satellite with an interplanetary spacecraft, but I digress.
One of the things that occurred to me watching MSL was that it had a video feed all the way up past TMI so that they could watch spacecraft sep; I doubt that would have been possible without TDRSS. That doesn't affect anything now with F-G, of course, but I suspect that if the new Luch had been operational then they would have designed the communication system differently, so that they could have gotten telemetry all the way through. Since they couldn't the data down even if they wanted to, there didn't seem to be any reason to design it with an antenna for use in LEO, and here we are.
Again, none of that is germane to the current attempts at troubleshooting, but it does give me hope that the fact that they are replacing Luch (albeit slowly) may allow the avoidance of this problem on future probes.
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#725
by
alk3997
on 29 Nov, 2011 14:36
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Interesting...so there is a separate transmitter for safe mode along with a backup single-use battery which had a 1/2 day supply when new.
From reading the original article it looks like what was received were "emergency frames" not regular telemetry which is why there was so little information.
A battery explosion would explain a lot - it all goes back to a power issue of some type causing all of these problems. The battery would vent. The only thing it wouldn't explain is why there wasn't more damage in that instance.
It seems very strange to try to "do a burn" when all you've received are a few emergency frames of data. Not really planned but more, "if you're listening start your burn". It has a feeling of despiration from the outside looking in.
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#726
by
Jim
on 29 Nov, 2011 14:43
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One of the things that occurred to me watching MSL was that it had a video feed all the way up past TMI so that they could watch spacecraft sep; I doubt that would have been possible without TDRSS.
That wasn't through TDRSS, but a ground station.
ELV's use TDRSS for telemetry. Video thru TDRSS would require a pointing antenna, that is why a ground station is used, it is only a few hundred miles away.
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#727
by
alk3997
on 29 Nov, 2011 14:47
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Keep in mind that up until the last 10-15 years, the use of video cameras on a rocket or to watch separation wasn't done, even though the first TDRS was launched in 1983.
Video is usually done on UHF and small ground terminals, not with TDRS. Remember for video TDRS requires a Ku-Band dish with pointing accuracy. So that isn't very practical
However UHF is not difficult to implement. So, if the Russians had wanted to have a video feed on PG, it could have been done.
However, most engineers will tell you that a properly designed telemetry system with the proper measurements makes video redundant at best. It was useful for determining if any shedding events occurred for Shuttle since there was no way to "measure" those events, despite some "science fair projects" that attempted to. So, video was useful there.
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#728
by
SiberianTiger
on 29 Nov, 2011 14:49
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* A disturbance introduced by leak from a blown up battery.
That is the first I have seen mention of that possibility, can you provide more on this?
Not really, it's difficult to search for sunken posts at NK. Somebody came up with a speculation that a shirt circuiting might cause a battery to blow up, and subsequent outgassing caused some influence on the orbit's shape.
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#729
by
Stan Black
on 29 Nov, 2011 15:57
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The Soviets used to have such a network called Luch, but it fell out of service after the Cold War. The Russians are planning to rebuild the system, however, and if I recall, the first launch is scheduled for December 11th. I'm not sure that it is capable of transmitting X-band, however.
As I recall it was not reliable when it was used with Mir. The new Luch has Ku-Band and S-Band antennas for telecommunications along with P-Band and L-Band for geonavigation relay, according to a very unofficial source.
X-Band is used for interplanetary spacecraft so there would be no reason to have it on a relay satellite. Optical relay would be a much more useful function for a satellite with an interplanetary spacecraft, but I digress.
One of the things that occurred to me watching MSL was that it had a video feed all the way up past TMI so that they could watch spacecraft sep; I doubt that would have been possible without TDRSS. That doesn't affect anything now with F-G, of course, but I suspect that if the new Luch had been operational then they would have designed the communication system differently, so that they could have gotten telemetry all the way through. Since they couldn't the data down even if they wanted to, there didn't seem to be any reason to design it with an antenna for use in LEO, and here we are.
Again, none of that is germane to the current attempts at troubleshooting, but it does give me hope that the fact that they are replacing Luch (albeit slowly) may allow the avoidance of this problem on future probes.
What about Garpun 14F136 Kosmos 2473?
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#730
by
scpc
on 29 Nov, 2011 16:58
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#731
by
JimO
on 29 Nov, 2011 17:31
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#732
by
Comga
on 29 Nov, 2011 18:46
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#733
by
Prober
on 29 Nov, 2011 18:48
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#734
by
bolun
on 29 Nov, 2011 19:25
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From
http://twitter.com/#!/esaoperationsesaoperations ESA Operations
ESA teams at #ESOC have received request from #PhobosGrunt mission controllers to uplink orbit-boosting commands again tonight via #Perth
3 hours ago
esaoperations ESA Operations
More details on #ESA activities in support of #PhobosGrunt mission control later. Teams on all sides working with #goodwill & #dedication.
4 hours ago
esaoperations ESA Operations
Timeslots avilable for sending Russian telecommands to #phobosgrunt tonight via #Perth & in daytime via #Maspalomas, once ready
4 hours ago
esaoperations ESA Operations
ESA's #Maspalomas station being modified w/feedhorn antenna similar to what enabled #Perth to establish #PhobosGrunt contact last week
4 hours ago
esaoperations ESA Operations
Teams at #ESA/ESOC now prep'ing alternate communication possibility using #ESTRACK 15m station at #Maspalomas (Spain)
4 hours ago
esaoperations ESA Operations
ESA informed by #PhobosGrunt controllers that last night's orbit-boosting commands did not execute #Perth
4 hours ago
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#735
by
iamlucky13
on 29 Nov, 2011 19:28
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One of the things that occurred to me watching MSL was that it had a video feed all the way up past TMI so that they could watch spacecraft sep; I doubt that would have been possible without TDRSS.
That wasn't through TDRSS, but a ground station.
ELV's use TDRSS for telemetry. Video thru TDRSS would require a pointing antenna, that is why a ground station is used, it is only a few hundred miles away.
To add to Jim's post, if you look back at the full launch video, you will see that there were long periods of the 2nd stage burn during which no video was provided. Instead we had the animation based on telemetry.
The PAO called out loss and acquisition by several ground stations during the launch. I forget at the moment which one covered the video feed of spacecraft separation.
Interestingly, there was some TDRSS telemetry dropout for that launch, but that's another topic.
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#736
by
hop
on 29 Nov, 2011 20:01
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#737
by
kevin-rf
on 29 Nov, 2011 20:07
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#738
by
hop
on 29 Nov, 2011 20:28
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#739
by
Vladi
on 29 Nov, 2011 20:32
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If the top of the spacecraft is bottom left, then the arrays are open - otherwise there shouldn't be the faint bluish glow there. However what is sticking from after the toroidal droptank if my interpretation is correct?