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#520
by
Rocket Science
on 24 Nov, 2011 15:31
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Why are people asking about rescue missions? The whole probe cost <$200 million. Does anyone really think a rescue would be cheaper than a straight up replacement, especially now that the design for the probe is set (except for fixes to the problems revealed this time around)?
An interesting question. I think it is a genuine lack of knowledge of what a rescue mission would cost and how long it would take to plan and prepare for.
I blame Hollywood. No, seriously; Armageddon is a good example of a film in which a major HSF mission is planned, prepared and executed in a few weeks when it would actually take years. I think that people honestly think that a Soyuz could be prepped and a crew launched to trouble-shoot the probe with a few days' lead time because that's the way it happens in the movies.
I agree with you Ben. I occasionally show Apollo 13 to my students and when I ask them for comments I usually hear the word “boring”… Then I tell them that this is “science fact not science fiction”… So in a sense reality is boring for them. That’s what you get when they spend most of their life immersed in some video game… Sad really and explains the lack of interest in “real” space exploration and HSF.
Regards
Robert
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#521
by
baldusi
on 24 Nov, 2011 15:52
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Obviously uplink needs to be seriously encrypted. That downlink encrypting is thought to be "simply an impediment to troubleshooting", shows that the impediment then can "simply" be the proximate cause of some types of failure.
Uplink should be authenticated. You can do unencrypted authentication, with PKI. You are giving away your formatting, and might give some proprietary info. But the fundamental is the authentication. The desirable is encryption on top of that. Making it encrypted but unauthenticated is a recipe for disaster. And you'd be surprised at how may "security systems" are vulnerable to such basic attacks as Man-in-the-Middle and Replay.
On the other hand, the Russians have some of the best, if not the very best hackers. If I were Russian I would use very aggressive encryption and authentication, just to keep some bored hacker from trying to make the ultimate hack, just for the publicity of it. And wrt efficiency, encryption tries to keep everything as close to white noise as possible. As such, it usually implements a compression scheme to reduce any pattern. And, for a deep space probe, I'm sure cpu cycles are more abundant than TX/RX bandwidth. So, in that sense should be free, too.
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#522
by
Hurrikansaison
on 24 Nov, 2011 15:58
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Hello everybody!
I'm no expert at all but I haven't found a better board/thread to ask my question(s). If you consider my post doesn't belong here please just delete and forget it.
Let's suppose Roskosmos actually will reach control of the probe.
In this case we'll see a conflict of interests. Russian's very own (best use of PG), Chinese (Yinghuo-1) and the LIFExperiment. I know this is no place to discuss political detail and that isn't my intention.
But wouldn't it be a priority to try to take all the 3 missions onboard PG to success?
If I understand things well: Right now PG could still reach Mars (Phobos) but would be unable to return to Earth. Reaching Mars orbit could make Chinese happy because Yinghuo-1 isn't meant to come back. On the other hand I have the impression Roskosmos isn't willing to use PG only as a transportation service for the Chinese satellite. You know that some sources indicate Russian interest in different targets already.
LIFExperiment experts on their part appear to be fine with almost everything, as long as PG really leaves earth orbit and travels through space.
If it's true - and only IF it's true - that the next Go-and-Return-Window to Mars opens in about 26 months .... Are there any reasons why Roskosmos couldn't wait until 2013 to finally bring PG on its track?
A simple mind like me is just thinking:
- Gain the control
- Send PG into a (much) higher orbit to improve communications (time-window) and keep the probe there
- Wait until the next Mars-window opens ... and use the time - lots of time - you bought well and carefully.
What kind of circumstances would probably avoid success or make this idea pure nonsens?
Is fuel a problem?
Is there anything onboard with a limited time factor?
Hardware, materials?
Would launch (from orbit)-, ignition-, constellation- or travel conditions be too different to make it possible?
As I said at the beginning: If you think this "theory" is quite absurd, please just ignore and delete it. On the other hand I'd be greatful if someone could answer briefly.
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#523
by
savuporo
on 24 Nov, 2011 16:16
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Uplink should be authenticated. You can do unencrypted authentication, with PKI.
Very good observation, a lot of people mix up the functions of authentication, authorization and encryption.
As such, it usually implements a compression scheme to reduce any pattern. And, for a deep space probe, I'm sure cpu cycles are more abundant than TX/RX bandwidth. So, in that sense should be free, too.
If you are talking power efficiency, you are absolutely correct : keeping the cpu awake for a few microseconds to compress a packet is always cheaper in watts consumed, than keeping the antenna powered ( the same applies for all battery-powered wireless electronics .. )
However, you do not always want compression, sometimes/often quite the opposite, you add forward error correction bits, which is basically the opposite of compression.
A good protocol is flexible with the environment changes : in known to be lossy transmission environment you may want to add lots of FEC, in other cases you may want to do a lot of compression to save every milliwatt.
EDIT: of course, spectral efficiency is what most deep space protocols would optimize for.
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#524
by
joek
on 24 Nov, 2011 16:17
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Obviously uplink needs to be seriously encrypted. That downlink encrypting is thought to be "simply an impediment to troubleshooting", shows that the impediment then can "simply" be the proximate cause of some types of failure.
Uplink should be authenticated. You can do unencrypted authentication, with PKI. You are giving away your formatting, and might give some proprietary info. But the fundamental is the authentication. The desirable is encryption on top of that. Making it encrypted but unauthenticated is a recipe for disaster. And you'd be surprised at how may "security systems" are vulnerable to such basic attacks as Man-in-the-Middle and Replay.
On the other hand, the Russians have some of the best, if not the very best hackers. If I were Russian I would use very aggressive encryption and authentication, just to keep some bored hacker from trying to make the ultimate hack, just for the publicity of it. And wrt efficiency, encryption tries to keep everything as close to white noise as possible. As such, it usually implements a compression scheme to reduce any pattern. And, for a deep space probe, I'm sure cpu cycles are more abundant than TX/RX bandwidth. So, in that sense should be free, too.
Agree uplink authentication is minimum requirement, for safety if nothing else (aka message authentication code "MAC" or message integrity code "MIC"). However, you don't need asymmetric key scam ("public key", "PKI"); it can and is done with symmertic key scam ("shared key") which is considerably more efficient than asymmetric key scam.
In any case, most (all?) downlink typically includes forward error correction (FEC). Likely the problems were (are?) due to error/noise level which exceeded the capability of the FEC.
p.s. scam typically does not include compression. However, you always want to perform compression before encryption, as compression relies on repetitive data patterns. Good scam will produce ciphertext which does not have repetitive patterns (i.e., it is incompressible).
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#525
by
edkyle99
on 24 Nov, 2011 16:34
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An English-language story about Rodionov's ravings is here:
Did US 'climate weapon' knock-out Russian probe?
http://rt.com/news/phobos-grunt-climate-weapon-129/
In particular don't miss the comments section.
Funny, due to the launch inclination, I think it was closest Alaska just before T-0. The burn was supposed to happen over south america.
Location doesn't matter! HAARP has been blamed for the downing of TWA Flight 800, Gulf War syndrome, earthquakes in South America, and so on.
Russia has, or had, super-powerful radars bouncing across the arctic too.
- Ed Kyle
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#526
by
Ben the Space Brit
on 24 Nov, 2011 16:41
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Location doesn't matter! HAARP has been blamed for the downing of TWA Flight 800, Gulf War syndrome, earthquakes in South America, and so on.
FWIW, HAARP has been blamed for the collapse of the Twin Towers too.
Is there any word about whether the probe has any power over the night-side? If not, then any trouble-shooting will be an exercise in frustration.
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#527
by
Kaputnik
on 24 Nov, 2011 16:44
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Hello everybody!
I'm no expert at all but I haven't found a better board/thread to ask my question(s). If you consider my post doesn't belong here please just delete and forget it.
Let's suppose Roskosmos actually will reach control of the probe.
In this case we'll see a conflict of interests. Russian's very own (best use of PG), Chinese (Yinghuo-1) and the LIFExperiment. I know this is no place to discuss political detail and that isn't my intention.
But wouldn't it be a priority to try to take all the 3 missions onboard PG to success?
If I understand things well: Right now PG could still reach Mars (Phobos) but would be unable to return to Earth. Reaching Mars orbit could make Chinese happy because Yinghuo-1 isn't meant to come back. On the other hand I have the impression Roskosmos isn't willing to use PG only as a transportation service for the Chinese satellite. You know that some sources indicate Russian interest in different targets already.
LIFExperiment experts on their part appear to be fine with almost everything, as long as PG really leaves earth orbit and travels through space.
If it's true - and only IF it's true - that the next Go-and-Return-Window to Mars opens in about 26 months .... Are there any reasons why Roskosmos couldn't wait until 2013 to finally bring PG on its track?
A simple mind like me is just thinking:
- Gain the control
- Send PG into a (much) higher orbit to improve communications (time-window) and keep the probe there
- Wait until the next Mars-window opens ... and use the time - lots of time - you bought well and carefully.
What kind of circumstances would probably avoid success or make this idea pure nonsens?
Is fuel a problem?
Is there anything onboard with a limited time factor?
Hardware, materials?
Would launch (from orbit)-, ignition-, constellation- or travel conditions be too different to make it possible?
As I said at the beginning: If you think this "theory" is quite absurd, please just ignore and delete it. On the other hand I'd be greatful if someone could answer briefly.
Some of these ideas have been mooted earlier in the thread. Although I think you have stated them a bit more clearly than others.
The problems with putting the mission on a 2-year hiatus involve at least three potential problems:
- the 2013 launch window will have different delta-v requirements; I don't know whether PG can meet these or not
- because the TMI burn has to be made during a low altitude pass, the parking orbit would need to retain a perigee of c.300km; there is unlikely to be sufficient delta-v budget to raise it and then lower it again. This means the orbit will still suffer some drag, and more importantly could end up crossing the Van Allen belts
- Soviet/Russian unmanned deep-space hardware is not known for its longevity. Even their most succesful Mars missions of the past have only lasted a few weeks after arrival. So, some people have expressed doubts about the probe's ability to operate over such an extended mission
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#528
by
rnc
on 24 Nov, 2011 16:46
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Suspect FG would be difficult to hack for practical reasons - big antenna, need for knowledge of rf data formatting,accurate tracking of the fast moving object, orbit parameters, Doppler compensation. Before u even get to scam. Look how hard it was for Roscosmos who built it to get comms.
Crossing fingers for plucky little FG being rescued from certain doom at clutching hands of gravity.
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#529
by
Hurrikansaison
on 24 Nov, 2011 16:57
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Some of these ideas have been mooted earlier in the thread. Although I think you have stated them a bit more clearly than others.
The problems with putting the mission on a 2-year hiatus involve at least three potential problems:
- the 2013 launch window will have different delta-v requirements; I don't know whether PG can meet these or not
- because the TMI burn has to be made during a low altitude pass, the parking orbit would need to retain a perigee of c.300km; there is unlikely to be sufficient delta-v budget to raise it and then lower it again. This means the orbit will still suffer some drag, and more importantly could end up crossing the Van Allen belts
- Soviet/Russian unmanned deep-space hardware is not known for its longevity. Even their most succesful Mars missions of the past have only lasted a few weeks after arrival. So, some people have expressed doubts about the probe's ability to operate over such an extended mission
That's exactly what I wanted to know. Thanks a lot.
And I really apologize if I have "warmed up" topics you've already talked about.
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#530
by
savuporo
on 24 Nov, 2011 17:22
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The problems with putting the mission on a 2-year hiatus involve at least three potential problems: ..
The very remote upside would be that you could, in theory, mount a servicing/rescue mission.
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#531
by
JWag
on 24 Nov, 2011 17:30
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The very remote upside would be that you could, in theory, mount a servicing/rescue mission.
That's been covered in this thread MANY times. The top reason it won't happen: A rescue mission would cost more than a replacement probe.
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#532
by
kevin-rf
on 24 Nov, 2011 17:31
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The problems with putting the mission on a 2-year hiatus involve at least three potential problems: ..
The very remote upside would be that you could, in theory, mount a servicing/rescue mission.
It is a giant bomb, non starter for any manned servicing mission...
Besides the drop tank was not designed for an extended stay in LEO. It most likely does not have heaters to keep the props from freezing.
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#533
by
Kaputnik
on 24 Nov, 2011 17:33
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The problems with putting the mission on a 2-year hiatus involve at least three potential problems: ..
The very remote upside would be that you could, in theory, mount a servicing/rescue mission.
For a spacecraft with unknown flaws, which was never designed for orbital servicing, or for being grappled or approached, and which barely costs any more than any hypothetical 'servcing' mission itself, and which belongs to a nation whose manned space program is fully committed and also lacks a manned craft capable of grappling and working on another spacecraft.
No offence, but you might as well hope for the Buran to be brought back to life so that they can bring PG back to Earth. Which is not going to happen either.
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#534
by
mr. mark
on 24 Nov, 2011 17:34
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Quick question, could the spacecraft land on the Moon and launch from the lunar surface? Phobos and the Moon having different variables, what would the requirements be on the spacecraft for lunar landing and return vs. Phobos landing and return?
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#535
by
Skylab
on 24 Nov, 2011 17:47
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#536
by
alk3997
on 24 Nov, 2011 17:50
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Quick question, could the spacecraft land on the Moon and launch from the lunar surface? Phobos and the Moon having different variables, what would the requirements be on the spacecraft for lunar landing and return vs. Phobos landing and return?
What is the difference in mass between Phobos and the Moon? You'll have your answer when you see the difference. Not to mention the thermal differences between long term operations in Earth orbit and Mars orbit.
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#537
by
alk3997
on 24 Nov, 2011 17:56
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Some of these ideas have been mooted earlier in the thread. Although I think you have stated them a bit more clearly than others.
The problems with putting the mission on a 2-year hiatus involve at least three potential problems:
- the 2013 launch window will have different delta-v requirements; I don't know whether PG can meet these or not
- because the TMI burn has to be made during a low altitude pass, the parking orbit would need to retain a perigee of c.300km; there is unlikely to be sufficient delta-v budget to raise it and then lower it again. This means the orbit will still suffer some drag, and more importantly could end up crossing the Van Allen belts
- Soviet/Russian unmanned deep-space hardware is not known for its longevity. Even their most succesful Mars missions of the past have only lasted a few weeks after arrival. So, some people have expressed doubts about the probe's ability to operate over such an extended mission
Keep in mind the different environments between going to Mars over eleven months and staying in low Earth (or even higher Earth) orbit. The thermal differences are certainly the constant night/day passes and the heat coming off Earth's surface (even at night). This is another thing people are overlooking when they talk about staying in Earth orbit long-term. Also the lifetime of the upper stage components. They are designed for a day of use, not months of use.
And then, above all, is we still don't know what was wrong with the spacecraft initially that caused the lack of a burn. Even the idea of a partial power failure is based on very little data, although it fits the facts as we know them right now.
Andy
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#538
by
alk3997
on 24 Nov, 2011 17:59
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Suspect FG would be difficult to hack for practical reasons - big antenna, need for knowledge of rf data formatting,accurate tracking of the fast moving object, orbit parameters, Doppler compensation. Before u even get to scam. Look how hard it was for Roscosmos who built it to get comms.
Crossing fingers for plucky little FG being rescued from certain doom at clutching hands of gravity.
Really - so the supposed hackers would have forseen that the probe would remain in low Earth orbit?? How about if the spacecraft was on its way to Mars.
In any event there is a lot of confusion between the translated words between encrypted and encoded. All data is encoded but there are different types of encoding schemes.
And, yes, encryption can be used to protect scientific data and pretty much any other type of data that someone would consider valuable. Usually when encryption is done it is an all data or no data choice. Otherwise you might be giving some information away (what isn't encrypted can provide clues about what is encrypted).
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#539
by
savuporo
on 24 Nov, 2011 18:05
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It is a giant bomb, non starter for any manned servicing mission...
You and others here, nobody said anything about manned.
Its entirely possible that someone could come up with a makeshift way of boosting or closing the required delta-v gap by a simple propulsion module launched on one of many russias cheap small launchers, assuming other longevity problems could be solved and the probe can at least regain attitude hold capability.
This is obviously all very hypothetical, which is why i said "very remote" from the outset, but i'm betting Roscosmos will be evaluating every single way of salvaging whats possible out of their investment. The reported mission cost is $170M, so no small change.
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