This is mostly true, at least for flagship missions like Cassini. Almost every system has a full backup. (Except the high-gain antenna, apparently.) The instruments, not so much, but only one of those is mission-critical. (Maybe two, depending how you count things.)
Having finally gotten to the Cosmos story, I'm going to repeat my recommendation to head to the source. (Which is almost always a good idea, anyway.) The Cosmos story managed to mangle the quote and you might as well get the original story before the telephone game has taken hold.
It's not so much the Scotty factor as standard engineering procedure for years. If you're told to design an elevator to life 5 people, you make sure it can hold 10 just to be safe. If the design requirements from NASA say "Four years", you design for 6 or 8. You don't want to be penalized for early failure, after all.
And I don't know how the engineers estimate life expectancies, but most components aren't mission-enders. You worry mostly about things like fuel/reaction mass and power sources, first. These are relatively predictable. Other parts that fail generally seem to do so gradually. (Electronics degradation, the reaction wheels on Cassini, etc.) So while you wouldn't necessarily have predicted that a priori, you can track it once it starts to happen.
We have to apply for extended missions by putting together a plan and pitching what we're going to do. ("More of the same," is generally frowned upon, naturally.) If the mission is healthy and the plan seems reasonable, they'll approve it. From what I've seen (I'm still pretty young in the field), they tend to be pretty favorable to healthy missions, though, so odds seem good of extension. It's pretty much expected that missions will survive their prime missions since those tend to be conservative estimates for life expectancy.
I am involved with planning the Cassini mission and, in fact, helped plan the images in the current story.
Yet only now are we beginning to receive imagery of detailed ring structure.
You're starting from a mistaken premise. We've been getting detailed images of the rings for the entire mission. In fact, the highest resolution images of the rings to date (probably ever) occurred during orbit insertion at the very beginning of the prime mission.
Since the primary mission has ended it is apparent that obtaining detailed images of ring structure was never a priority.
Nope, rings is a major priority and drives the mission around 20%. (Depending on how you quantify that.)
All of the time has been spent on the moons, Saturn and relatively wide shots of the rings.
Again, blatantly false. Any time we're out of the equatorial plane of Saturn (as we are now and have been many times during the mission to date), we're studying the rings and the magnetosphere (and Saturn, but they tend to be a bit less insistent on this geometry). There are many close-ups of the rings available. Have you looked for them? They're all over at CICLOPS, if you do a search. Or even browse images, really.
Is resolving the ring constituents even feasible for Cassini?
No, we can't get close enough to resolve a 1-m body.
I can see from the flight schedule that close up passes of some sheppard moons will occur in 2010. Will attempts be made to image the detailed structure of the rings at this time?
Yes and no. At the time of flyby, we're in the ringplane and cannot see the rings very well at all. Near that time, I'm sure we'll take images of the rings. As we have always done.
I know the rings are largely particulate; a fog of ice particles.
Not the main rings, no. The main rings are ~30-cm to ~3-m bodies. And there is almost no way to get close enough to image these. It's not even a matter of risk, it's a matter of having to be far, far too close to what amounts to a solid wall of ring. And what good would imaging a few particles in one location do compared to destroying the spacecraft in the process? Apart from satisfying you need to see even closer up to the rings?
Well we DO know that there is liquid iron and rock in the Earth's interior. Volcanos spew the stuff out all the time.
To be fair, that stuff coming out of volcanoes isn't from the core. At the deepest, you might be seeing the mantle. (I can't recall how deep material comes from.)
And the inner core is solid, for the record. The outer core? Liquid.
If secular variation is caused by the ocean flow, the entire concept of the dynamo operating in the Earthâ(TM)s core is called into question: there exists no other evidence of hydrodynamic flow in the core.
--From the article
Er, dude, no. We are pretty certain that the outer core is a liquid from seismic wave data. "So what?" you say, "Couldn't the core not be flowing?" Perhaps, but our understanding of how heat moves in a fluid is pretty good. And we know that at some point, in order to move the heat out, the fluid has to convect (as the dynamo model requires). So while we haven't directly measured the flow of fluid in the core, arguing that it isn't happening requires at least some explanation of the lack of convection we have every reason to expect.
That said, let's look at the notion that the oceans are responsible. This ought to be measurable if it's worth talking about. We can get close enough to the oceans that we should easily be able to measure variations in the local field due to the oceans. Heck, tides and changes in circulation patterns ought to manifest temporal variations that we could measure. No, I don't know that anyone has done these measurements, I would be a bit surprised if no one had. (In fact, if no one has, I ask: why hasn't the author?)
Also, I'm skeptical by comparison to Europa. That body is in a changing magnetic field that is much more powerful than Earth's (and which changes much more rapidly, every 11 hrs). The ocean required to produce the induced field has something like 3 times (from memory) the salinity of our ocean and only produces a response of ~100 nT. (Our magnetic field is around 50 mT.) I'm... skeptical.
Actually, it *is* pretty well supported by the anecdotes. There have a been a few reports of hot meteorites (I'm not sure how many of those were later confirmed to BE meteorites, either; I've seen hot slag get confused with meteorites.), but also quite a few of warm or even frosty ones. Take, for example, the case where a ricochet struck a woman in the leg; I know of no reports adding that she was burned by the meteorite at the same time. Doesn't sound like an "extremely hot" rock to me. And the fact that there are NO known reports of fires being started by meteorites also suggests that your protestations are off base. (I notice that you provide no evidence or calculations to back up your rather definitive assertions, incidentally. Care to?)
Exactly right. I work for a contractor to JPL and I was up for these same security checks to get my NASA badge (which is, I think, on hold). I've been following this case fairly closely, needless to say.
Er, yes and no. JPL is NASA when it wants to be and Caltech at other times. For example, the new badges are general NASA badges. (I've technically got a contractor badge application pending with them and I'm told that the same badge would get me into other centers as well.)
It's an odd relationship and that leads to some... quirky?... interactions.
Actually, to dirty water ice enough to darken it considerably takes only a very small proportion of contaminants. Next winter, collect one of those dirty, nasty tire-bergs off of a car and melt it down. See how much of it is water and how much is dirt. For all it's nastiness, it's almost all water. (More broadly, this is true of planetary surfaces. The colors we generally associate with various surfaces are often due to trace components on otherwise white material.)
HST isn't that based on military models, given what I've heard about interesting problems that HST encountered. (Problems that the military and spy outfits *knew* about, but never told NASA.)
And yes, it's true that contractors want more contracts. But I think you're over-estimating how likely they are to LOSE contracts when they screw up. Look at the Mars failures from the last 15 years. A Martian researcher friend of mine is fond to tracing the source of every since US loss in that time straight back to one company. The company, one of the few that can actually build and operate large components and spacecraft, keeps getting contracts though precisely because NASA has little choice.
(This has little to do with the engineers' pride in their work, by the way. I've known some of those engineers --- even dated one --- and they are a bright, hard-working bunch. But when you're on a tight time-table and limited budget, there's only so much a reasonable person can and should do.)
NASA doesn't really build much of its stuff. That's contracted out... oh, yes: corporations.
(It does do the final assembly on quite a few spacecraft, so they're also involved. But still: if the corporations are building in short life-spans to their components, NASA's final assembly ain't going to fix that.)
If Chekov had been a cadet, his rank would have been "midshipman". (See: Wrath of Khan)
And the amount of influence a single captain can wield there is limited. I mean, if Kirk had been a commander (or even a lt. commander) with a solid record, I can believe the assignment. But jumping him from midshipman (with a disciplinary hearing in process) to captain of the flagship?
Yes! Thank you! This point SO pissed me off. Everyone on the Enterprise outranked Kirk (who wasn't even supposed to be there). Every. Fucking. Person. Even a 17-year-old Chekov (how the hell does he get a commission on 17!?) outranks the guy, let alone Spock. Yet the promote him PAST around five ranks to give him command thanks to one incident. (Wherein he was only in command because Pike served with Kirk's daddy, I might add. Pike had no business leaving him as first officer.)
Actually, that's not entirely true. The poles gets the most solar insolation over any given 24 period of any place on the globe. (The given period is the summer solstice, of course.) So they *do* get quite a lot of heat from the Sun sometimes. The trouble is that the snow reflects much (most?) of the incident energy and the energy that they receive is never enough to undo the rest of the year's lack of heating.
Hell, I'd use it for Denver->the Twin Cities. I've tried, but the only way to do it takes well over 24 hours to get there (not inclusive of transit to/from stations) and at that point, it's worth it to fly. But if they could get the travel time down to even ~10 hrs, I'd take the train over flying almost any time, even at a similar price. The airlines are getting too obnoxious for words, but are getting away with it because for most of the country, there's no realistic alternative.
Slashdot Mirror
This is mostly true, at least for flagship missions like Cassini. Almost every system has a full backup. (Except the high-gain antenna, apparently.) The instruments, not so much, but only one of those is mission-critical. (Maybe two, depending how you count things.)
And you know dragons, what can you do?
Except I've never taught Physics 2 to you or to anyone else.
Although I do love me my potatoes. Maybe you're from the future? Did you bring back stock tips? Or future-potatoes?
Having finally gotten to the Cosmos story, I'm going to repeat my recommendation to head to the source. (Which is almost always a good idea, anyway.) The Cosmos story managed to mangle the quote and you might as well get the original story before the telephone game has taken hold.
It's not so much the Scotty factor as standard engineering procedure for years. If you're told to design an elevator to life 5 people, you make sure it can hold 10 just to be safe. If the design requirements from NASA say "Four years", you design for 6 or 8. You don't want to be penalized for early failure, after all.
And I don't know how the engineers estimate life expectancies, but most components aren't mission-enders. You worry mostly about things like fuel/reaction mass and power sources, first. These are relatively predictable. Other parts that fail generally seem to do so gradually. (Electronics degradation, the reaction wheels on Cassini, etc.) So while you wouldn't necessarily have predicted that a priori, you can track it once it starts to happen.
We have to apply for extended missions by putting together a plan and pitching what we're going to do. ("More of the same," is generally frowned upon, naturally.) If the mission is healthy and the plan seems reasonable, they'll approve it. From what I've seen (I'm still pretty young in the field), they tend to be pretty favorable to healthy missions, though, so odds seem good of extension. It's pretty much expected that missions will survive their prime missions since those tend to be conservative estimates for life expectancy.
I am involved with planning the Cassini mission and, in fact, helped plan the images in the current story.
Yet only now are we beginning to receive imagery of detailed ring structure.
You're starting from a mistaken premise. We've been getting detailed images of the rings for the entire mission. In fact, the highest resolution images of the rings to date (probably ever) occurred during orbit insertion at the very beginning of the prime mission.
Since the primary mission has ended it is apparent that obtaining detailed images of ring structure was never a priority.
Nope, rings is a major priority and drives the mission around 20%. (Depending on how you quantify that.)
All of the time has been spent on the moons, Saturn and relatively wide shots of the rings.
Again, blatantly false. Any time we're out of the equatorial plane of Saturn (as we are now and have been many times during the mission to date), we're studying the rings and the magnetosphere (and Saturn, but they tend to be a bit less insistent on this geometry). There are many close-ups of the rings available. Have you looked for them? They're all over at CICLOPS, if you do a search. Or even browse images, really.
Is resolving the ring constituents even feasible for Cassini?
No, we can't get close enough to resolve a 1-m body.
I can see from the flight schedule that close up passes of some sheppard moons will occur in 2010. Will attempts be made to image the detailed structure of the rings at this time?
Yes and no. At the time of flyby, we're in the ringplane and cannot see the rings very well at all. Near that time, I'm sure we'll take images of the rings. As we have always done.
I know the rings are largely particulate; a fog of ice particles.
Not the main rings, no. The main rings are ~30-cm to ~3-m bodies. And there is almost no way to get close enough to image these. It's not even a matter of risk, it's a matter of having to be far, far too close to what amounts to a solid wall of ring. And what good would imaging a few particles in one location do compared to destroying the spacecraft in the process? Apart from satisfying you need to see even closer up to the rings?
No, but I'd expect Cosmo to do better journalism.
(I'm assuming that the quote that Slashdot has at the end of the summary is straight from Cosmos magazine. It's fairly mangled.)
Oh, an other versions:
Discovery Channel
Bad Astronomy
But CICLOPS has the main story. (And should be able to take a reasonable Slashdotting, these days.)
Thanks for the link. I considered submitting the story myself, but it seemed to much self-advertisement.
Gah, correct. I mean microT but forgot to try to find the character code for mu. My fault for being lazy/forgetful.
The point stands, however.
Well we DO know that there is liquid iron and rock in the Earth's interior. Volcanos spew the stuff out all the time.
To be fair, that stuff coming out of volcanoes isn't from the core. At the deepest, you might be seeing the mantle. (I can't recall how deep material comes from.)
And the inner core is solid, for the record. The outer core? Liquid.
He says,
If secular variation is caused by the ocean flow, the entire concept of the dynamo operating in the Earthâ(TM)s core is called into question: there exists no other evidence of hydrodynamic flow in the core.
--From the article
Er, dude, no. We are pretty certain that the outer core is a liquid from seismic wave data. "So what?" you say, "Couldn't the core not be flowing?" Perhaps, but our understanding of how heat moves in a fluid is pretty good. And we know that at some point, in order to move the heat out, the fluid has to convect (as the dynamo model requires). So while we haven't directly measured the flow of fluid in the core, arguing that it isn't happening requires at least some explanation of the lack of convection we have every reason to expect.
That said, let's look at the notion that the oceans are responsible. This ought to be measurable if it's worth talking about. We can get close enough to the oceans that we should easily be able to measure variations in the local field due to the oceans. Heck, tides and changes in circulation patterns ought to manifest temporal variations that we could measure. No, I don't know that anyone has done these measurements, I would be a bit surprised if no one had. (In fact, if no one has, I ask: why hasn't the author?)
Also, I'm skeptical by comparison to Europa. That body is in a changing magnetic field that is much more powerful than Earth's (and which changes much more rapidly, every 11 hrs). The ocean required to produce the induced field has something like 3 times (from memory) the salinity of our ocean and only produces a response of ~100 nT. (Our magnetic field is around 50 mT.) I'm... skeptical.
Better example: Mercury.
Actually, it *is* pretty well supported by the anecdotes. There have a been a few reports of hot meteorites (I'm not sure how many of those were later confirmed to BE meteorites, either; I've seen hot slag get confused with meteorites.), but also quite a few of warm or even frosty ones. Take, for example, the case where a ricochet struck a woman in the leg; I know of no reports adding that she was burned by the meteorite at the same time. Doesn't sound like an "extremely hot" rock to me. And the fact that there are NO known reports of fires being started by meteorites also suggests that your protestations are off base. (I notice that you provide no evidence or calculations to back up your rather definitive assertions, incidentally. Care to?)
Another link, if you're curious: http://www.amsmeteors.org/fireball/faqf.html#9
And the author of that page, had you bothered to check, isn't an arm-chair astronomer. He's a PhD'ed astronomer and a well-known science advocate.
Yes, they're not hot. http://www.badastronomy.com/bad/misc/meteoric.html
Be careful using that bold.
http://blogs.discovermagazine.com/badastronomy/2009/06/12/a-boy-claims-he-was-hit-by-a-meteorite/
Short story is that it's possible (although not as presented in the media right now), but be skeptical.
Exactly right. I work for a contractor to JPL and I was up for these same security checks to get my NASA badge (which is, I think, on hold). I've been following this case fairly closely, needless to say.
Er, yes and no. JPL is NASA when it wants to be and Caltech at other times. For example, the new badges are general NASA badges. (I've technically got a contractor badge application pending with them and I'm told that the same badge would get me into other centers as well.)
It's an odd relationship and that leads to some... quirky?... interactions.
Actually, to dirty water ice enough to darken it considerably takes only a very small proportion of contaminants. Next winter, collect one of those dirty, nasty tire-bergs off of a car and melt it down. See how much of it is water and how much is dirt. For all it's nastiness, it's almost all water. (More broadly, this is true of planetary surfaces. The colors we generally associate with various surfaces are often due to trace components on otherwise white material.)
HST isn't that based on military models, given what I've heard about interesting problems that HST encountered. (Problems that the military and spy outfits *knew* about, but never told NASA.)
And yes, it's true that contractors want more contracts. But I think you're over-estimating how likely they are to LOSE contracts when they screw up. Look at the Mars failures from the last 15 years. A Martian researcher friend of mine is fond to tracing the source of every since US loss in that time straight back to one company. The company, one of the few that can actually build and operate large components and spacecraft, keeps getting contracts though precisely because NASA has little choice.
(This has little to do with the engineers' pride in their work, by the way. I've known some of those engineers --- even dated one --- and they are a bright, hard-working bunch. But when you're on a tight time-table and limited budget, there's only so much a reasonable person can and should do.)
NASA doesn't really build much of its stuff. That's contracted out... oh, yes: corporations.
(It does do the final assembly on quite a few spacecraft, so they're also involved. But still: if the corporations are building in short life-spans to their components, NASA's final assembly ain't going to fix that.)
If Chekov had been a cadet, his rank would have been "midshipman". (See: Wrath of Khan)
And the amount of influence a single captain can wield there is limited. I mean, if Kirk had been a commander (or even a lt. commander) with a solid record, I can believe the assignment. But jumping him from midshipman (with a disciplinary hearing in process) to captain of the flagship?
Yes! Thank you! This point SO pissed me off. Everyone on the Enterprise outranked Kirk (who wasn't even supposed to be there). Every. Fucking. Person. Even a 17-year-old Chekov (how the hell does he get a commission on 17!?) outranks the guy, let alone Spock. Yet the promote him PAST around five ranks to give him command thanks to one incident. (Wherein he was only in command because Pike served with Kirk's daddy, I might add. Pike had no business leaving him as first officer.)
Actually, that's not entirely true. The poles gets the most solar insolation over any given 24 period of any place on the globe. (The given period is the summer solstice, of course.) So they *do* get quite a lot of heat from the Sun sometimes. The trouble is that the snow reflects much (most?) of the incident energy and the energy that they receive is never enough to undo the rest of the year's lack of heating.
Hell, I'd use it for Denver->the Twin Cities. I've tried, but the only way to do it takes well over 24 hours to get there (not inclusive of transit to/from stations) and at that point, it's worth it to fly. But if they could get the travel time down to even ~10 hrs, I'd take the train over flying almost any time, even at a similar price. The airlines are getting too obnoxious for words, but are getting away with it because for most of the country, there's no realistic alternative.