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#1020 by rdale on 19 Dec, 2011 13:59
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Of course ~2/3 of the earths surface is ocean, but we had two large water re-entrys in the last few months. So when you start taking odds, we are overdue for one coming down on land...
Nothing personal - but that is not how odds work...
If you flip a coin twice and get heads, the odds of getting heads on the next flip are still 50/50. The last two water reentries have no impact on where FG might end up. Still have better than even odds of a water entry. -
#1021 by JimO on 19 Dec, 2011 14:20
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No need to worry about it either. There is no way of knowing, and odds are extremely high that even if so it will fall harmlessly away, so don't stress...
Of course ~2/3 of the earths surface is ocean, but we had two large water re-entrys in the last few months. So when you start taking odds, we are overdue for one coming down on land...
What is the proper emoticon symbol for slapping somebody about the head for a very Un-mathematical silly claim [unless it was made in jest]? Kevin, you've got it coming!
Entry events are stochastic -- they have no memory of previous performance of similar events. But you knew that, and I'm being hyper-sensitive.
There ARE trends from past performance that MIGHT be useful in predicting future human behavior, which is definitely NON stochastic.
As described in links on my home page www.jamesoberg.com, previous Moscow performance regarding honesty and disclosure for potentially hazardous entries in the past, are not encouraging [Salyut-3 (?), RORSATs, Polyus, Mars-96]. And the public information performance of space officials THIS time has been pure 'old-thinking' Soviet style, alas. They even extended their blackout to ESA, which was required, to earn the right to help the Russians, to restrict release of specifics on their OWN activities regarding the comm attempts.
Since Nick Johnson is not having any heartburn over the aluminum tanks, I won't either. My question remains -- are ALL the tanks aluminum? The modified fregat hardware, OK. But the special tanks custom-built for the spacecraft itself? titanium?
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#1022 by kevin-rf on 19 Dec, 2011 14:46
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You are right, the bogus math was in jest, the last several large reentry's have not hurt anyone, but our luck is bound to run out sometime. Especially if the tanks are frozen and survive...
Of course something that has always bugged me on reentries, we all know that earth is an oblate spheroid, I have always wondered if that extra drag in the tropics has any impact on distribution reentry impact locations. -
#1023 by Ben the Space Brit on 19 Dec, 2011 15:11
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Of course something that has always bugged me on reentries, we all know that earth is an oblate spheroid, I have always wondered if that extra drag in the tropics has any impact on distribution reentry impact locations.
You might be onto something there. Offhand, I seem to recall that most re-entries of this type (high but sub-polar inclination) tend to occur towards middle latitudes. -
#1024 by Michael J on 19 Dec, 2011 16:31
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Why are you proposing that they will ever admit it? Even if it happens the probabilities of actually falling on someone they would have to actually take care of (i.e. world power or so), are nil.From Ria Novosti (Google translated): No further attempts to activate engines until controllers know the spacecraft's orientation; up to 200kg of debris is expected to survive reentry. And the saga continues.
http://translate.google.com/translate?sl=ru&tl=en&js=n&prev=_t&hl=en&ie=UTF-8&layout=2&eotf=1&u=http%3A%2F%2Fria.ru%2Fscience%2F20111219%2F520737471.html&act=url
A cynical and worried part of me suspects that the possibility of a serious incident will only be admitted by the authorities at the last possible moment. I'm praying that I'm wrong.
Well, they did have to deal with it when Cosmos 954 crashed in Canada. Of course, at first they denied the debris belonged to that spacecraft until they were shown that the Canadian government had proof that they could not deny diplomatically or in front of an arbiter at the Claims Commission. Then they were in a position where they had to admit liability, but only paid a fraction of the actual settlement reached with the Canadian government.
The whole liability issue is a tricky one, and like most governments they will not admit liability unless they have to. For example, the United States to my knowledge never admitted that the debris that fell in Esperance, Australia belonged to Skylab and hence did not assume liability. In that case there was no appreciable damage from the debris, except that it needed to be collected, for which the United States received a fine for littering.
Interestingly, an official from DLR came out shortly before ROSAT reentered and stated that liability for any damage belonged to everyone involved with the spacecraft. Similarly, a NASA official stated before the reentry of UARS that any surviving debris remained the property of the United States government. Making this statement set the stage for liability if any of the debris from that spacecraft had survived. -
#1025 by baldusi on 19 Dec, 2011 17:01
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And what about the Bolivian case? If the country is not strong enough, or has public servants that might look the other way, why should they admit any liability?
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#1026 by kevin-rf on 19 Dec, 2011 17:28
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A bit off topic, but there has been recent buzz on how spills are (not) handled in russia: http://hosted.ap.org/dynamic/stories/E/EU_RUSSIA_OIL_CALAMITY?SITE=ILMOL&SECTION=HOME&TEMPLATE=DEFAULT
It might give us some insight into what to expect as a reaction if Phobos-Grunt comes down in the wrong place. -
#1027 by Michael J on 19 Dec, 2011 17:55
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And what about the Bolivian case? If the country is not strong enough, or has public servants that might look the other way, why should they admit any liability?
I presume you are talking about the pressurization tanks from a U.S. rocket booster that landed in Bolivia. In answer to your question, they may have a legal obligation under the Liability Convention to do so. This presumes any damage has occurred that requires compensation. -
#1028 by baldusi on 19 Dec, 2011 18:03
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I was referring to the 200 grams of plutonium of the Mars-96 probe.And what about the Bolivian case? If the country is not strong enough, or has public servants that might look the other way, why should they admit any liability?
I presume you are talking about the pressurization tanks from a U.S. rocket booster that landed in Bolivia. In answer to your question, they may have a legal obligation under the Liability Convention to do so. This presumes any damage has occurred that requires compensation. -
#1029 by kevin-rf on 19 Dec, 2011 18:23
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Quote
I presume you are talking about the pressurization tanks from a U.S. rocket booster that landed in Bolivia. In answer to your question, they may have a legal obligation under the Liability Convention to do so. This presumes any damage has occurred that requires compensation.
I was referring to the 200 grams of plutonium of the Mars-96 probe.
Which they have yet to admit to falling there, and has not yet been found... -
#1030 by Michael J on 19 Dec, 2011 20:17
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Quote
I presume you are talking about the pressurization tanks from a U.S. rocket booster that landed in Bolivia. In answer to your question, they may have a legal obligation under the Liability Convention to do so. This presumes any damage has occurred that requires compensation.
I was referring to the 200 grams of plutonium of the Mars-96 probe.
Which they have yet to admit to falling there, and has not yet been found...
There is the problem: it hasn't been found yet. -
#1031 by JimO on 19 Dec, 2011 20:36
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You might be onto something there. Offhand, I seem to recall that most re-entries of this type (high but sub-polar inclination) tend to occur towards middle latitudes.
While the question is a good one, the concentration of impact points in 'middle latitudes' is an artifact of geometry. As a rule, orbital inclinations create a spherical geometry situation where an orbiter simply spends a lot more time between latitude x and x+10 than it does between X-10 and X. The ground track chord traced across the two bands is shorter for the band closer to the equator.
Go play with a globe and string at home to convince yourself of this. No, I'm not trying to be snide -- it's one of conceptual tools I use a lot when considering orbital motion, to get the 'big picture' first. -
#1032 by JimO on 19 Dec, 2011 20:42
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I was referring to the 200 grams of plutonium of the Mars-96 probe.
Which they have yet to admit to falling there, and has not yet been found...
Sadly, we have no grounds for making that last statement. All we can say is that nobody is known to have REPORTED finding debris from the satellite. Debris could easily have been found -- the altiplano is IDEAL terrain to detect 'junk' on the ground, third world countries have a tradition of recovering and selling scrap metal whenever found, and people could indeed have been injured by exposure to the plutonium batteries, as the 'daughter product' isotopes begin cooking off more dangerous gamma rays while the warm-to-the-touch small canisters are attractive magic boxes to warm cold hands, or a cold crib.
Just nit-picking.
Also, no reports of glowing alpacas, either. -
#1033 by Comga on 19 Dec, 2011 20:55
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I was referring to the 200 grams of plutonium of the Mars-96 probe.
Which they have yet to admit to falling there, and has not yet been found...
Sadly, we have no grounds for making that last statement. All we can say is that nobody is known to have REPORTED finding debris from the satellite. Debris could easily have been found -- the altiplano is IDEAL terrain to detect 'junk' on the ground, third world countries have a tradition of recovering and selling scrap metal whenever found, and people could indeed have been injured by exposure to the plutonium batteries, as the 'daughter product' isotopes begin cooking off more dangerous gamma rays while the warm-to-the-touch small canisters are attractive magic boxes to warm cold hands, or a cold crib.
Just nit-picking.
Also, no reports of glowing alpacas, either.
A book by Peter Takeda documents an expedition that placed a Plutonium RTG near the summit of Nanda Devi. The porters would huddle around it during the brutally cold nights. That is, it was an "attractive magic box to warm cold hands" as JimO said. -
#1034 by ChileVerde on 19 Dec, 2011 22:13
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Go play with a globe and string at home to convince yourself of this. No, I'm not trying to be snide -- it's one of conceptual tools I use a lot when considering orbital motion, to get the 'big picture' first.
Seconded. I've gotten a lot of mileage out of some string and a globe, though have tended to use the ruler tool in Google Earth more these days. Also excellent for looking at longish-range ballistic missile trajectories. -
#1035 by iamlucky13 on 19 Dec, 2011 22:55
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I was referring to the 200 grams of plutonium of the Mars-96 probe.
Which they have yet to admit to falling there, and has not yet been found...
Sadly, we have no grounds for making that last statement. All we can say is that nobody is known to have REPORTED finding debris from the satellite. Debris could easily have been found -- the altiplano is IDEAL terrain to detect 'junk' on the ground, third world countries have a tradition of recovering and selling scrap metal whenever found, and people could indeed have been injured by exposure to the plutonium batteries, as the 'daughter product' isotopes begin cooking off more dangerous gamma rays while the warm-to-the-touch small canisters are attractive magic boxes to warm cold hands, or a cold crib.
Just nit-picking.
Also, no reports of glowing alpacas, either.
I'm not sure the hazard increases appreciably over time. Pu-238 has a fairly lengthy decay chain through other alpha-producing isotopes with similar decay energies but much longer half-lives before it reaches gamma-emitting isotopes.
So I think the bigger concern is someone deciding to make a couple smaller heaters out of a big one, cracking it open, fragmenting the fuel, and possibly inhaling or ingesting the dust.
The really scary cases of RTG theft are the strontium-90 powered lighthouses dotting the Siberian coast that have often been vandalized for scrap metal.
By the way, the Associated Press published an article on Friday erroneously stating F-G was carrying 10 kilograms of Cobalt-57, instead of the believed actual amount of roughly 10 micrograms.
http://www.msnbc.msn.com/id/45698240/ns/technology_and_science-space/#.Tu_LqPKyHlx
At 8600 Curies/gram, that would work out to more radioactivity on that single spacecraft than was released by the entire Fukushima accident, as opposed to roughly 100,000 smoke detectors, or the amount of radioactive material in chunk of typical granite 15 meters on a side.
Only a billion-fold mistake. Oh well. -
#1036 by kevin-rf on 19 Dec, 2011 23:44
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Sadly, we have no grounds for making that last statement. All we can say is that nobody is known to have REPORTED finding debris from the satellite. Debris could easily have been found -- the altiplano is IDEAL terrain to detect 'junk' on the ground, third world countries have a tradition of recovering and selling scrap metal whenever found, and people could indeed have been injured by exposure to the plutonium batteries, as the 'daughter product' isotopes begin cooking off more dangerous gamma rays while the warm-to-the-touch small canisters are attractive magic boxes to warm cold hands, or a cold crib.
Just nit-picking.
Also, no reports of glowing alpacas, either.
Good point, remember the 1987 "Goiânia accident". Scrap metal scavengers stole a radiation source from an abandoned hospital and contaminated over 200 in Brazil.
What scares me most, even in the US people sell magnets as magic cures. Image what people will do with a magic charred box that puts out it's own heat? I am amazed more do not make bigger messes with ionizing smoke detectors. -
#1037 by Ben the Space Brit on 20 Dec, 2011 12:13
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I just want to clear things up. In The Independent of the UK over the weekend, it was claimed that there were over 10 kilogrammes of some radioactive cobalt isotope aboard PG. That doesn't sound right to me; have they got kilogrammes and grammes mixed up here?
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#1038 by bolun on 20 Dec, 2011 12:42
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I just want to clear things up. In The Independent of the UK over the weekend, it was claimed that there were over 10 kilogrammes of some radioactive cobalt isotope aboard PG. That doesn't sound right to me; have they got kilogrammes and grammes mixed up here?
Don't worry, perhaps they don't know the metric system.
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#1039 by ChileVerde on 20 Dec, 2011 13:51
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I just want to clear things up. In The Independent of the UK over the weekend, it was claimed that there were over 10 kilogrammes of some radioactive cobalt isotope aboard PG. That doesn't sound right to me; have they got kilogrammes and grammes mixed up here?
Micrograms. A mere factor of 1e9 in error.
Add: Actually, 10 micrograms is still quite a bit more than I'd calculated earlier (0.036 micrograms) from the strength given for the source.
