The rim of the crater is illuminated by the Sun, which for good part of the month lights up the crater interior brighter than full Moon on Earth, and prevents it from getting colder than about 70 K.
Never have had to think about solar cells on the moon's poles:)
Lots of people have been. There are regions of the rim of Shackleton Crater which are never out of the Sun*, so solar power could be collected there and beamed down into the crater. This is the reason why NASA selected power beaming for a Game Changing Technology award.
* Well, maybe never, or maybe never except for a few days every few years. There are still arguments about the terrain models, so I believe the point is still uncertain. And, of course, you will lose the Sun every time there is a Lunar eclipse (i.e., when the Earth gets in the way).
You are mixing up albedo / reflectivity with ranging. Skin depth / surface detail info is not the same as geodetic accuracy (which is at the 10 cm level at best without a corner cube retroreflector).
Here is an example - suppose I shine a flashlight on my car at night. Can I tell if it is wet ? Yes, because I can see specular reflection from a thin layer of water if it is. That layer may be 100 microns thick; seeing it doesn't mean that I know where I am, or where my car is, or the relative distance between us, to anything like 100 microns.
The LRO has a multi-beam altimeter, with fiber optics to send out 5 shots simultaneously from each laser pulse - see Dave Smith's LEAG presentation, page 6. Each spot is 5 meters across (actually, less now as the orbit has been lowered); with 5 spots they can get the local slope and estimate the terrain roughness per shot. They estimate that they can get 10 cm height accuracy with these multiple beams, when the local slope is less than 3 degrees.
Eat it ? You would die if you even tried to touch it (unprotected).
Of course, the metallic snow is a hypothesis, to explain the high radar reflectivity observed in the Venusian highlands. There are other explanations. To find out, someone needs to send a lander (but don't hold your breath on that one).
Coldest temperature ever recorded : -89.2 C, in Antarctica
Sublimation temperature of Dry ice (solid CO2) : -78.5 C (-109.3 F) at atmospheric pressure.
So, there are places on the Earth where occasionally the temperature gets low enough to precipitate out CO2. I have always wondered if anyone has ever thought to look for it.
Range, Doppler, and VLBI, all from Earth (and all done by the DSN). I don't believe that this mission is using Optical Navigation. No (other) Mars spacecraft participate directly in this, although of course the Mars ephemeris is dominated by data from them. It is an iterative process, where an initial trajectory is refined by course corrections and monitored more or less continuously, with the measurement tempo increasing as Mars entry gets near.
If you want to drill down into this, here is a good starting point focusing on Mars entry navigation.
Curiosity is the biggest Hail Mary play since Cassini/Huygens. It is already going to take either divine intervention or help from the Martians to get that thing down right side up and in one piece. So this doesn't sound like too big a risk, considering everything else that they've had to account for.
Cassini/Huygens presumably being helped by the Sirens of Titan.
I was told that are plans to have the Mars Reconnaissance Orbiter image the landing. If anything goes wrong, this might provide the only knowledge of what failed and, if it works, the pictures should be pretty spectacular.
Its not like curiosity will be doing anything that is time sensitive. Who cares if you arrive at the site a few months early? It definitely is not worth the risk of destroying the lander.
If the lander fails before it gets to the primary target, you have a partially or even mostly failed mission. MSL will be a long way from Earth, and many things can happen, so, yes, there is pressure to get there sooner.
It astounds me that Linkedin and eHarmony used unsalted password hashes. That's much worse than using md5 (and, yes, you shouldn't use md5, but, still, first things first).
From the Linkedin Press Release :
The passwords are stored as unsalted SHA-1 hashes,
Come on, guys, get up to at least 1978 in your security policy.
Ok, so now that my post was modded down to -1,with 48 replies, I'm going to make another point.
I've obviously touched a nerve with the amount and content of the replies to this post. People are passionate about what they believe, and want to make sure that there is significant discussion around this topic. Yet, the post was modded down to -1. Why? Because it challenges the status quo?
What are we so passionate about defending, yet we're trying to silence critics. If the critics are wrong, lets move their arguments to the forefront and let them stand/fall on their own merit.
No, because it is stupid. Seriously, the same old tired analogies and false equivalences and willful misperceptions are trotted out, again and again, often word for word. There is really no significant discussion whatsoever, just an attempt to make sure that the other side doesn't have the playing field all to themselves.
There are no scientists who believe in a young universe. There haven't been any in a long time, over a century. You have obviously been listening to con-men and grifters.
If you want to believe that the universe was created, go ahead. I certainly know scientists who do. (That could be at the big bang, or even before it, in the multiverse theories.) In that case, your statement about origins is valid.
But, evolution is not about origins. It is about the middle past, or even the recent past, of the story of the universe, i.e., about events that happened long (billions of years) after the origin. It (and the panoply of evidence from astronomy, physics and geology that also describe the size and age of our universe) are based on facts, which can be, have been and are being tested scientifically.
And, as a very wise man (Daniel Patrick Moynihan) once said, "Everyone is entitled to his own opinion but not his own facts."
From our results we place an upper limit of 7 MW Hz1 on the power output of any isotropic emitter located in the Gliese 581 system, within this frequency range.
.
That means they could detect a 7 megawatt carrier tone with very narrow bandwidth of 1 HZ (or a 70 MW signal spread over 10 HZ, etc.) BUT, that is isotropic power. If the ETI was using something like the DSN antennas, much less something like Arecibo, they might have a gain of 60 dB, which means we could detect a signal down in the 10 Watt range. This search has enough sensitivity that there are lots of broadcasters on Earth (weather radar and airport radars, for example), that could be detected by this survey, if there happened to be a clone of our civilization at Gliese 581.
Ah, but the advantage of VLBI is that, even if they were just putting out noise, it would cross-correlate between antennas and be detected (if strong enough).
the first very long baseline interferometry (VLBI) campaign has been carried out on a SETI target star:
Here is a rare case where a Slashdot summary is better than the original article, which simply claims to be "The First" VLBI SETI, which it isn't, not by a long shot.
This is spectral line VLBI, and I bet almost everyone who has correlated spectral line VLBI has thought "maybe this time..." they will get lucky and see an ETI signal. I know that when Demetrios Matsakis was doing ultra-narrow band spectral line searches for the US Navy in the early 1990's, we used to joke that it was "applied SETI," as it was hard to see how you could get Hz bandwidth spectral lines without an ETI behind it. (And, of course, he didn't find any, or else you would have heard about it then.)
This result isn't surprising [...] but it does validate VLBI as a very exciting means
I'm a little confused as how a negative result validates the excitement-quotient. Or how this could even be validated in a more meaningul sense -- there's no way of checking the data. Maybe it was a false negative and there's oodles of aliens there.
The biggest technical problem in radio SETI is RFI. A signal from the star in question would have a very specific Doppler shift between the VLBI antennas, different from the relative Doppler shifts from any terrestrial RFI, even spill-over from a satellite. You can still have a saturated receiver if the RFI is too strong, but that is less of problem (it's easy to detect), and VLBI really reduces the chance of a false positive to almost nil. You also don't need an actual signal to show that this technique works.
Slashdot Mirror
The rim of the crater is illuminated by the Sun, which for good part of the month lights up the crater interior brighter than full Moon on Earth, and prevents it from getting colder than about 70 K.
Never have had to think about solar cells on the moon's poles :)
Lots of people have been. There are regions of the rim of Shackleton Crater which are never out of the Sun*, so solar power could be collected there and beamed down into the crater. This is the reason why NASA selected power beaming for a Game Changing Technology award.
* Well, maybe never, or maybe never except for a few days every few years. There are still arguments about the terrain models, so I believe the point is still uncertain. And, of course, you will lose the Sun every time there is a Lunar eclipse (i.e., when the Earth gets in the way).
You are mixing up albedo / reflectivity with ranging. Skin depth / surface detail info is not the same as geodetic accuracy (which is at the 10 cm level at best without a corner cube retroreflector).
Here is an example - suppose I shine a flashlight on my car at night. Can I tell if it is wet ? Yes, because I can see specular reflection from a thin layer of water if it is. That layer may be 100 microns thick; seeing it doesn't mean that I know where I am, or where my car is, or the relative distance between us, to anything like 100 microns.
The LRO has a multi-beam altimeter, with fiber optics to send out 5 shots simultaneously from each laser pulse - see Dave Smith's LEAG presentation, page 6. Each spot is 5 meters across (actually, less now as the orbit has been lowered); with 5 spots they can get the local slope and estimate the terrain roughness per shot. They estimate that they can get 10 cm height accuracy with these multiple beams, when the local slope is less than 3 degrees.
Shackleton is a sink for ice (i.e., it traps it there), not a source.
Eat it ? You would die if you even tried to touch it (unprotected).
Of course, the metallic snow is a hypothesis, to explain the high radar reflectivity observed in the Venusian highlands. There are other explanations. To find out, someone needs to send a lander (but don't hold your breath on that one).
Coldest temperature ever recorded : -89.2 C, in Antarctica
Sublimation temperature of Dry ice (solid CO2) : -78.5 C (-109.3 F) at atmospheric pressure.
So, there are places on the Earth where occasionally the temperature gets low enough to precipitate out CO2. I have always wondered if anyone has ever thought to look for it.
The 1% don't do drug tests. What more do you need to know?
No, but MRO should be.
And, if you want to know how we know where Mars is to within 10's of meters in real time, read this.
Range, Doppler, and VLBI, all from Earth (and all done by the DSN). I don't believe that this mission is using Optical Navigation. No (other) Mars spacecraft participate directly in this, although of course the Mars ephemeris is dominated by data from them. It is an iterative process, where an initial trajectory is refined by course corrections and monitored more or less continuously, with the measurement tempo increasing as Mars entry gets near.
If you want to drill down into this, here is a good starting point focusing on Mars entry navigation.
Curiosity is the biggest Hail Mary play since Cassini/Huygens. It is already going to take either divine intervention or help from the Martians to get that thing down right side up and in one piece. So this doesn't sound like too big a risk, considering everything else that they've had to account for.
Cassini/Huygens presumably being helped by the Sirens of Titan.
I was told that are plans to have the Mars Reconnaissance Orbiter image the landing. If anything goes wrong, this might provide the only knowledge of what failed and, if it works, the pictures should be pretty spectacular.
Why risk it?
Its not like curiosity will be doing anything that is time sensitive. Who cares if you arrive at the site a few months early?
It definitely is not worth the risk of destroying the lander.
If the lander fails before it gets to the primary target, you have a partially or even mostly failed mission. MSL will be a long way from Earth, and many things can happen, so, yes, there is pressure to get there sooner.
I always get lost with these references to ancient history.
It astounds me that Linkedin and eHarmony used unsalted password hashes. That's much worse than using md5 (and, yes, you shouldn't use md5, but, still, first things first).
From the Linkedin Press Release :
The passwords are stored as unsalted SHA-1 hashes,
Come on, guys, get up to at least 1978 in your security policy.
I could see the point of this in '96-'97. Now, not so much.
We still use astronomical observations from Baghdad in that period (800 to 1000 CE).
Would you prefer to be a Nautilus then?
Don't know. Never having been one, I am not qualified to judge.
Ok, so now that my post was modded down to -1,with 48 replies, I'm going to make another point.
I've obviously touched a nerve with the amount and content of the replies to this post. People are passionate about what they believe, and want to make sure that there is significant discussion around this topic. Yet, the post was modded down to -1. Why? Because it challenges the status quo?
What are we so passionate about defending, yet we're trying to silence critics. If the critics are wrong, lets move their arguments to the forefront and let them stand/fall on their own merit.
No, because it is stupid. Seriously, the same old tired analogies and false equivalences and willful misperceptions are trotted out, again and again, often word for word. There is really no significant discussion whatsoever, just an attempt to make sure that the other side doesn't have the playing field all to themselves.
There are no scientists who believe in a young universe. There haven't been any in a long time, over a century. You have obviously been listening to con-men and grifters.
If you want to believe that the universe was created, go ahead. I certainly know scientists who do. (That could be at the big bang, or even before it, in the multiverse theories.) In that case, your statement about origins is valid.
But, evolution is not about origins. It is about the middle past, or even the recent past, of the story of the universe, i.e., about events that happened long (billions of years) after the origin. It (and the panoply of evidence from astronomy, physics and geology that also describe the size and age of our universe) are based on facts, which can be, have been and are being tested scientifically.
And, as a very wise man (Daniel Patrick Moynihan) once said, "Everyone is entitled to his own opinion but not his own facts."
FTA :
From our results we place an upper limit of 7 MW Hz1 on the power output of any isotropic emitter located in the Gliese 581 system, within this frequency range.
.
That means they could detect a 7 megawatt carrier tone with very narrow bandwidth of 1 HZ (or a 70 MW signal spread over 10 HZ, etc.) BUT, that is isotropic power. If the ETI was using something like the DSN antennas, much less something like Arecibo, they might have a gain of 60 dB, which means we could detect a signal down in the 10 Watt range. This search has enough sensitivity that there are lots of broadcasters on Earth (weather radar and airport radars, for example), that could be detected by this survey, if there happened to be a clone of our civilization at Gliese 581.
Ah, but the advantage of VLBI is that, even if they were just putting out noise, it would cross-correlate between antennas and be detected (if strong enough).
You have obviously never worked at a VLBI correlator. Trust me, if they found something, you would know.
the first very long baseline interferometry (VLBI) campaign has been carried out on a SETI target star:
Here is a rare case where a Slashdot summary is better than the original article, which simply claims to be "The First" VLBI SETI, which it isn't, not by a long shot.
This is spectral line VLBI, and I bet almost everyone who has correlated spectral line VLBI has thought "maybe this time..." they will get lucky and see an ETI signal. I know that when Demetrios Matsakis was doing ultra-narrow band spectral line searches for the US Navy in the early 1990's, we used to joke that it was "applied SETI," as it was hard to see how you could get Hz bandwidth spectral lines without an ETI behind it. (And, of course, he didn't find any, or else you would have heard about it then.)
This result isn't surprising [...] but it does validate VLBI as a very exciting means
I'm a little confused as how a negative result validates the excitement-quotient. Or how this could even be validated in a more meaningul sense -- there's no way of checking the data. Maybe it was a false negative and there's oodles of aliens there.
The biggest technical problem in radio SETI is RFI. A signal from the star in question would have a very specific Doppler shift between the VLBI antennas, different from the relative Doppler shifts from any terrestrial RFI, even spill-over from a satellite. You can still have a saturated receiver if the RFI is too strong, but that is less of problem (it's easy to detect), and VLBI really reduces the chance of a false positive to almost nil. You also don't need an actual signal to show that this technique works.