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Cryosat Mission Feared Lost
Guest_BruceMoomaw_*
post Oct 16 2005, 10:34 PM
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Unfortunately, that Wikipedia article still leaves wide open whether the Mars 6 failure was due to the retrorockets exploding, or to their failing to fire at all, or simply to the lander touching down by bad luck in rough terrain: "Contact with the descent module was lost at 09:11:05 UT in " 'direct proximity to the surface', probably either when the retrorockets fired or when it hit the surface at an estimated 61 m/s." (The latter presumably would have happened if the retrorockets had not fired at all.) Nor can I find anything more in McDowell's very brief description. Aviation Week said at the time that contact was lost 2 seconds before the planned landing, although I've never seen this anywhere else.

However, the Wikipedia article does contain two interesting notes that are new to me. First: "The [Mars 6] descent module transmitted 224 seconds of data before transmissions ceased, the first data returned from the atmosphere of Mars. Unfortunately [this is new to me], much of the data were unreadable due to a flaw in a computer chip which led to degradation of the system during its journey to Mars." (That transistor error really loused up the Soviets disastrously -- it seems likely that it may also have caused the retros to fail to fire, and even if the lander had touched down it might have transmitted only gibberish.)

Second: " Due to a problem in the operation of one of the onboard systems (attitude control or retro-rockets) the [Mars 7] landing probe separated prematurely (4 hours before encounter) and missed the planet by 1300 km. The early separation was probably due to a computer chip error which resulted in degradation of the systems during the trip to Mars. The intended landing site was 50 S, 28 W." I'm a bit skeptical of part of this -- 4 hours before closest approach actually sounds about right for such a lander's separation, and it may be that the only failure was the failure of its course-diversion rocket to fire. But in any case I had no idea that its intended landing site had ever been announced.

By the way, Perminov's account provides no new information at all on the possible cause of the Mars 6 failure -- he just says he doesn't know. (We will likely never know, even if some future traveller in that antique land stumbles across its remains.) But he does provide, as I say, a lot of interesting new stuff -- including confirmation, after three decades, of my suspicion that while the 1970s Soviet Mars landers carried no biological experiments, they DID carry an X-ray spectrometer to analyze the elemental composition of Mars soil (presumably like the one on the Lunokhods). He also says that the addition of that new radio transmission channel to send data during the descent itself was virtually the only difference between the 1971 and 1973 landers -- and that he had to fight like hell to get it added.
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ljk4-1
post Oct 17 2005, 12:01 AM
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QUOTE (BruceMoomaw @ Oct 16 2005, 05:34 PM)
However, the Wikipedia article does contain two interesting notes that are new to me.  First: "The [Mars 6] descent module transmitted 224 seconds of data before transmissions ceased, the first data returned from the atmosphere of Mars. Unfortunately [this is new to me], much of the data were unreadable due to a flaw in a computer chip which led to degradation of the system during its journey to Mars."  (That transistor error really loused up the Soviets disastrously -- it seems likely that it may also have caused the retros to fail to fire, and even if the lander had touched down it might have transmitted only gibberish.) 

Second: " Due to a problem in the operation of one of the onboard systems (attitude control or retro-rockets) the [Mars 7] landing probe separated prematurely (4 hours before encounter) and missed the planet by 1300 km. The early separation was probably due to a computer chip error which resulted in degradation of the systems during the trip to Mars. The intended landing site was 50 S, 28 W."  I'm a bit skeptical of part of this -- 4 hours before closest approach actually sounds about right for such a lander's separation, and it may be that the only failure was the failure of its course-diversion rocket to fire.  But in any case I had no idea that its intended landing site had ever been announced.
*


Mars 7 was supposed to land on Mars at 50 degrees south/28 degrees west, which I believe came from Kenneth Gatland's 1971 book Robot Explorers.

The Mars 6 atmosphere data, which said there was a larger amount of argon in the Red Planet's atmosphere than expected, caused the Viking team to actually attune the Viking lander sensors for this gas. It later turned out to be faulty data.

In a letter by Bart Hendrixx in the BIS Spaceflight magazine around 1991, he wrote that they had planned to put life detection equipment on the first Mars landers in the 1960s. They tested them out on the Kazahk steppes. The detectors failed to find life and the devices were not included, as the scientists assumed that if they could not find life on Earth, they certainly wouldn't find any on Mars.


--------------------
"After having some business dealings with men, I am occasionally chagrined,
and feel as if I had done some wrong, and it is hard to forget the ugly circumstance.
I see that such intercourse long continued would make one thoroughly prosaic, hard,
and coarse. But the longest intercourse with Nature, though in her rudest moods, does
not thus harden and make coarse. A hard, sensible man whom we liken to a rock is
indeed much harder than a rock. From hard, coarse, insensible men with whom I have
no sympathy, I go to commune with the rocks, whose hearts are comparatively soft."

- Henry David Thoreau, November 15, 1853

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Guest_BruceMoomaw_*
post Oct 17 2005, 02:52 AM
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Yes, I read that. (As I understand it, it's still uncertain whether the 1964 Zond 2 mission carried a lander or not; if it did, it would have been predicated on the assumption that Mars' atmosphere was dense enough to allow a soft landing with just a parachute.)
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edstrick
post Oct 17 2005, 06:22 AM
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Regarding the Mars 6 descent data. 2 sets of science results were published from that.

There was very low sample-rate deceleration data, I do not recall if it was from doppler through the relaying flyby vehicle or onboard accelerometers, but it provided a crude atmosphere temperature structure profile that was totally eclipsed ni quality by the Viking entry data.

The other data was engineering data from the pump-down of a mass spectrometer that was going to take atmosphere mass-spectra as the first science task after landing, instead of an image. The data indicated that the mass spectrometer pump was "laboring" and having problems reducing in-instrument pressure to the level needed for the science data after landing. Their inferred cause was an estimated 30% argon in the atmosphere.

This value was large, but not outside the range of some models for the composition of the martian atmosphere, and caused concern for successful operation of the already designed Viking Lander mass spectrometers. Viking had a simple mass spectrometer or ion-spectrometer on the entry heat shield as part of an atmosphere structure experiment, and I think it was able to confirm a much lower limit on argon fraction, enabling normal planned operation of the lander instruments.

The limited Mars 6 results, if I recall, were published in an article in the journal "Icarus" maybe a year before the Vikings got to Mars.
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ljk4-1
post Oct 17 2005, 02:41 PM
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QUOTE (BruceMoomaw @ Oct 16 2005, 09:52 PM)
Yes, I read that.  (As I understand it, it's still uncertain whether the 1964 Zond 2 mission carried a lander or not; if it did, it would have been predicated on the assumption that Mars' atmosphere was dense enough to allow a soft landing with just a parachute.)
*


Andrew Lepage wrote about Zond 2 in the April, 1991 issue of the EJASA. His conclusion was that the probe did have a landing capsule, but that the Soviets assumed Mars had a thicker atmosphere than it did, so that even if Zond 2 did release its lander, the craft would have likely crashed on the Martian surface.

The issue and article can be found here:

ftp://ftp.seds.org/pub/info/newsletters/e...91/jasa9104.txt


--------------------
"After having some business dealings with men, I am occasionally chagrined,
and feel as if I had done some wrong, and it is hard to forget the ugly circumstance.
I see that such intercourse long continued would make one thoroughly prosaic, hard,
and coarse. But the longest intercourse with Nature, though in her rudest moods, does
not thus harden and make coarse. A hard, sensible man whom we liken to a rock is
indeed much harder than a rock. From hard, coarse, insensible men with whom I have
no sympathy, I go to commune with the rocks, whose hearts are comparatively soft."

- Henry David Thoreau, November 15, 1853

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OWW
post Oct 19 2005, 12:00 PM
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QUOTE (Rakhir @ Oct 9 2005, 12:32 PM)
Actually, the launch of Monitor-E was a success, the satellite suffered a communication glitch shortly after launch, but communication with the satellite was restored shortly after.


Unfortunately not for long:
http://en.rian.ru/russia/20051019/41821700.html
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Rakhir
post Oct 26 2005, 11:35 AM
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Ban On Russian Rokot Launches Lifted

"The cause of the crash of the Rokot booster that was used to launch the CryoSat satellite has been determined.

It was the improper flight program that resulted in the failure of the Briz-KM upper stage's control system to give a command to shut down the engine of the second stage of the carrier rocket."


http://www.spacedaily.com/news/launchers-05zzzq.html
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