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#640
by
Comga
on 27 Nov, 2011 17:57
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difficult to understand their string of failures with mars, when they succeeded with the much more challenging venus landers...
my understanding is that the temperature & atmospheric pressure makes descent , landing and survival after landing for any length of time a real tough job @ venus.
That's the point, but for the opposite reasons. The wonderfully successful Venera landers only had to last minutes before their relays went out of sight, and were designed to last just longer than that in the intense heat. The dense atmosphere DID help with descent and landing. All they had was a drag disk and a crash ring. Terminal velocity was low and they may not even have had parachutes. Venus is an environment that favors ruggedness and brute force over subtlety and complexity.
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#641
by
savuporo
on 27 Nov, 2011 18:03
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Many Venus missions failed and at least six of them was because of problems with the escape stage. Without waving the flag, I can say the United States is fortunate to have a fairly reliable and flexible booster in the Centaur.
Many of the missions
failed in the early days period, on both sides. But there were also a lot more frequent mission attempts. In the historical context, Venera ( and Luna , and Zond, and Lunokhod ) were a relatively successful series.
EDIT: i think there was a quip on zarya.info Phobos page before, something along the lines of "In the early days, after losing contact, PG would have been assigned a next number in the Cosmos- series and quickly and quietly forgotten"
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#642
by
olasek
on 27 Nov, 2011 18:13
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Mission duration is the common factor with the Soviet unmanned successes.
You might have hit a nail on the head. Overall reliability and longevity of systems might be the underlying cause and it is more of a factor in missions to Mars. Only a few days ago some Russian space official complained (talking about Phobos-Grunt) that their satellites quit working usually within a year whereas a typical NASA satellite lasts 10 years or more.
Venus is an environment that favors ruggedness and brute force over subtlety and complexity.
I agree, very well stated.
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#643
by
FinalFrontier
on 27 Nov, 2011 20:23
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Well this is quite sad. Seems to me they have little to no chance of utilizing this spacecraft at this point. I wish them luck in continuing attempts to command the vehicle, but I do not think it will work or matter at this stage. Seems like they lost another one
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#644
by
gospacex
on 27 Nov, 2011 20:31
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difficult to understand their string of failures with mars, when they succeeded with the much more challenging venus landers...
Soviet electronics had pathetic reliability record. They did manage to make one durable enough for Venus transit times, but anything longer than that never worked. Note total absence of Soviet missions to any destination farther than Mars.
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#645
by
JimO
on 27 Nov, 2011 22:46
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Aren't we due some new Perth tracking passes?
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#646
by
tolis
on 27 Nov, 2011 22:53
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Hi All,
I'm a new user.
On the subject of Soviet successes on Venus vs mixed
success at Mars, perhaps the answer may be found in persistence
and timing. Soviet Russia kept shooting probes to Venus
at almost every launch window until 1984 simply because they could
afford to (not a capitalist system back then). Lessons learned
propagated forwards to the next attempt and eventually
this led to a string of successes (Veneras 9-16+Vega 1-2).
For Mars, things were different. There, the string of missions
was cut short at 1973, presumably before the technology had a chance
to mature.
Then, in 1989, when Phobos 1&2 were launched, the USSR was
already cracking at the seams (although the rest of the world did
not know about it). Apart from that, the Mars "learning curve" was
essentially starting from scratch.
Since then, Russia has been trying to pick up where it left off
(Mars 96, P-G) but I suspect the solution is accept that past glories are
past and start again from scratch (or not far from it) with a modest but scientifically valuable mission.
Tolis.
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#647
by
hop
on 27 Nov, 2011 22:57
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#648
by
Spacenick
on 27 Nov, 2011 23:35
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If the Russians were that bad at producing reliable electronics, how come the Russian ISS and Mir modules function that reliable? Is it the expertise in satellite design in general or has it to do with their lack of deep space competence that's at play here?
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#649
by
Jim
on 27 Nov, 2011 23:42
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If the Russians were that bad at producing reliable electronics, how come the Russian ISS and Mir modules function that reliable? Is it the expertise in satellite design in general or has it to do with their lack of deep space competence that's at play here?
The avionics boxes are in the inhabited volumes; and can and been replaced.
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#650
by
DaveS
on 27 Nov, 2011 23:43
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If the Russians were that bad at producing reliable electronics, how come the Russian ISS and Mir modules function that reliable? Is it the expertise in satellite design in general or has it to do with their lack of deep space competence that's at play here?
Russian ISS/Mir hardware reliable? Not at all! I have lost count how many times Vozduk/Elektron in Zvezda has failed over and over again, only to be brought back to life thanks to a hard-working crew! Prior Expedition 1's arrival, Zarya had some battery failures that was fixed by a shuttle crew!
And Mir wasn't exactly much better!
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#651
by
Andy USA
on 28 Nov, 2011 01:48
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Seriously, can we keep this on the spacecraft.
It's not about the Russian government, it's not about ISS. It's about Fobos Grunt.
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#652
by
Ben the Space Brit
on 28 Nov, 2011 08:24
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It's not about the Russian government, it's not about ISS. It's about Fobos Grunt.
Well, in fairness, Andy, the reliability (or not) of the ISS Russian Segment's equipment might have a bearing on the success or failure of FG.
That said, I would agree that it is a bit too early for post-mortems, especially as all the information known is not yet in the public domain. We have no way of knowing whether this was an electronic malfunction. It could just as easily be mechanical. For example defective fuel valves and/or tank pressurisation systems would be one way that could lead to the observed affects.
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#653
by
John Duncan
on 28 Nov, 2011 09:32
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We'll probably never know what happened.
With some of the new members this mission has attracted, it would be good time to start a thread on Russian spacecraft design, if there already isn't one. There's a chance for some new perspectives on their program and I am very interested to hear about them.
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#654
by
JimO
on 28 Nov, 2011 11:16
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I just noticed two visual observations described the color of the vehicle as 'orange'.
Here:
http://satobs.org/seesat/Nov-2011/0308.htmlhttp://satobs.org/seesat/Nov-2011/0342.htmlDo we have closeout photos of exterior surfaces that are orange [or gold] in hue?
Or are the observations of 'orange' connected with the color of stains from venting hydrazine [or from thruster plumes]? We saw that effect on Mir.
Has the reported color changed over the past two weeks? Let's go back and check.
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#655
by
JimO
on 28 Nov, 2011 11:21
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An Interfax report on Nov28/0705 UT states that the Baykonur comm pass 'on Friday' was unsuccessful, according to 'a cosmodrome source'.
It also clarified that the next ESA attempt will not occur 'before the early hours of Tuesday'.
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#656
by
glanmor05
on 28 Nov, 2011 11:23
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Seriously, can we keep this on the spacecraft.
It's not about the Russian government, it's not about ISS. It's about Fobos Grunt.
Absolutely agree! I keep checking this thread for the "LIVE Troubleshooting Latest" to be met with a load of other stuff.
I appreciate that there isn't much (official) new information, I don't even mind hearing rumour regarding this mission, but this thread is sooooo off track it's unbelievable.
Edit - and now I've added to it.
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#657
by
notsorandom
on 28 Nov, 2011 11:30
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I just noticed two visual observations described the color of the vehicle as 'orange'.
Here:
http://satobs.org/seesat/Nov-2011/0308.html
http://satobs.org/seesat/Nov-2011/0342.html
Do we have closeout photos of exterior surfaces that are orange [or gold] in hue?
Or are the observations of 'orange' connected with the color of stains from venting hydrazine [or from thruster plumes]? We saw that effect on Mir.
Has the reported color changed over the past two weeks? Let's go back and check.
The pre-launch photographs I saw showed it covered in a gold foil or Mylar like material. There are other satellites that have an orangish hue to them which are covered in a similar material, Lacrosse 4 comes to mind.
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#658
by
plutogno
on 28 Nov, 2011 13:06
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getting back in topic, according to the French newspaper "Le Monde", if contacts are re-established with F-G, it could be put in a high parking orbit between the Earth and the Moon, where it would wait for the 2013 window to open while engineers complete debugging its software.
http://www.lemonde.fr/planete/article/2011/11/26/espoir-pour-la-sonde-russe-phobos-grunt_1609001_3244.html (in French, evidemment...)
this is the most sensitive proposal so far (and I discussed here first a few days ago
I imagine F-G could be sent to fly by the moon like that old comm sat Asiasat 3 or Nozomi and be perturbed in a distant resonant orbit or even a solar orbit returning to fly by the moon and Earth in late 2013 and resume the original mission as planned. I guess this could be done with the available fuel. The only problem I see (beside the non-trivial need to re-establish full control over the probe) is that Russian hardware is not known for its reliability and 2 more years in space may be too much.
I hope that orbital mechanics gurus like Farquhar and Bellbruno will be working on this
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#659
by
Michael J
on 28 Nov, 2011 13:28
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getting back in topic, according to the French newspaper "Le Monde", if contacts are re-established with F-G, it could be put in a high parking orbit between the Earth and the Moon, where it would wait for the 2013 window to open while engineers complete debugging its software.
http://www.lemonde.fr/planete/article/2011/11/26/espoir-pour-la-sonde-russe-phobos-grunt_1609001_3244.html (in French, evidemment...)
this is the most sensitive proposal so far (and I discussed here first a few days ago
I imagine F-G could be sent to fly by the moon like that old comm sat Asiasat 3 or Nozomi and be perturbed in a distant resonant orbit or even a solar orbit returning to fly by the moon and Earth in late 2013 and resume the original mission as planned. I guess this could be done with the available fuel. The only problem I see (beside the non-trivial need to re-establish full control over the probe) is that Russian hardware is not known for its reliability and 2 more years in space may be too much.
I hope that orbital mechanics gurus like Farquhar and Bellbruno will be working on this
I am not an engineer, but the modified Fregat stage may not last that long in the extremes of outer space, especially the external propellant tank, which was supposed to be expended immediately and jettisoned. I am unsure of the engineering and physics involved, but the fuel within that tank could potentially explode sitting in orbit that long creating additional space debris.
At the expense of being a party-pooper, my personal opinion is that it coming back with a time frame calculated to be January 14 plus or minus 9 days. If they can regain some control, it could be used to try and maneuver the craft such that it does not impact land or any populated areas.
.
