From the original blog post : "over this timescale, the Martian atmosphere has been too cold and thin for liquid water."
I read something like this frequently, and yet it is simply wrong and I wish people would stop repeating it.
Liquid water is not magic, but governed by physics. For there to be liquid water on Mars, all that is needed is that water be present, that the surface pressure be above the triple point of water, and that the temperature be above the freezing point. (Actually, this can be relaxed somewhat for brines and the like, but let's put that aside for the moment.) We know that Mars has water. What about the other two conditions ?
Much of the surface of Mars is above the triple point of water (i.e., at a low enough elevation that the surface pressure is higher than 611.7 pascals). Any low lying region is. The Viking 2 landing site is (some of the time) and the Phoenix landing site is (all of the time). The entire Hellas basin is, and it is highly likely to have liquid water at times (as the surface temperature there is warm enough during the day). Remember, peak surface soil temperatures on Mars can reach 27 C, even under current climate conditions.
Further, the atmospheric pressure on Mars varies greatly during its obliquity cycle, and it is highly likely that the entire planet (except for the high volcanoes of Tharsis) can support liquid water at times during each obliquity cycle. During those phases of the cycle, the atmospheric temperatures will be generally warmer, as well.
Now, this does not prove or disprove that these gullies are formed by water rather than sand, but you don't need unusually strong brines or geothermal vents to have liquid water on Mars (even though both of those probably exist as well), and it is quite reasonable to expect its presence in places, even under current atmospheric conditions.
What this is is an experimental spacecraft that NASA gave up, and should reclaim in my opinion. Turning this into a manned flight precursor would be a good way for President Obama to regain status in the astronaut community.
I assume most corporate speech recognition is intended to get people to hang up in frustration, thereby saving the cost of the call. Same thing with entering in account information. If you keep pushing zero, you will generally eventually get a person, so (if I need to talk to an actual person), that's what I do.
Robotic exploration of the planets has been tried, and found to be incredibly slow. This is partially technology, and partially politics, but the experiment has been tried, and that's the result.
Here is an example - the Viking Mars orbiters were assumed to not need biological sterilization and were put in an orbit with a 50 year lifetime, because surely in 50 years we would know if there was life on Mars, right ? 50 years from Viking is 2025, which is now not that far off. (And, incidentally, the satellite orbit people are worried that the orbiters orbit may not have the expected life-time , and may have already decayed.) We are highly unlikely to know if there is life on Mars by 2025. 50 years to answer a basic question.
Heck, we don't even know if there is liquid water on the surface (which there should be, in places at times). We don't know what the soil is made of.
One week after the first manned mission arrives at Mars, its robotic exploration will become a footnote.
H.264 is licensed by MPEG-LA and has most of the heavy hitters in this area in the patent pool. So
- you know that none of these parties will come after you if you pay MPEG-LA's rates (as they can't, by the agreements they sign to join the pool) and
- if some other company does (say a patent troll), they are effectively taking on all of the companies in the pool, and had better have really deep pockets.
Now, I would rather it be unencumbered, but these are not inconsiderable advantages. Remember, just saying that another codec doesn't have any patent encumbrances doesn't make it so.
I have spent, by now, several years abroad in a variety of places (including Canada and China). I have never gotten in any trouble for not having my passport on me.
By the way, I have been in more than one place where the hotel kept my passport while I was staying there.
Because (unlike the case with Satellite Laser Ranging), the expected return per shot is actually less than one photon. So, a shot returns either zero or one photons.
They do lots of shots and gate (time filter) the returns to get a single range estimate, based on maybe 1000 photon returns. But, each shot still returns only one photon at most at a time. (With the appropriate color filter, and a nanosecond size time gate, there is rarely a photon from the solar illumination of the Moon, and those that get through add only a little noise.)
The new Apollo system will have better statistics, and may get above 1 photon per shot, but there are actually pretty good reasons to only take the first photon from a shot, so I suspect that they will continue to only use 1 at a time.
We left 3 LLR retroreflector arrays, at the Apollo 11, 14 and 15 landing sites. (That is 3 out of 6, so exactly 1/2 of the landings.)
Apollo 15's LLR array is by far the biggest, and so it is used the most often for ranging. But, to get the rotation (librations) of the Moon, you need a distribution in both latitude and longitude. The Apollo LLR arrays form a nice, but not especially large, triangle centered around the center of Near Side, Lunakhod 2 is usefully separated from them to the North-East, but Lunakhod 1 is all the way across Mare Imbrium in the North-West quadrant of the Near Side of the Moon. Ranging from Lunakhod 1 will substantially help the determination of Lunar librations.
Transparency threatens closed institutions, and the Vatican (run in much the same way as the Holy Roman Empire of the Middle Ages) is a closed institution.
This is not a comment on the Roman Catholic faith one way or the other, but on the Curia.
You know, it would be nice to have a reflector on mars. I wonder if it is possible to go that distance.
Distance is a problem (ranging sensitivity is proportional to 1/distance to the fourth power), but aberration makes this sort of passive Laser ranging to the planets impossible. (The retroreflector arrays return photons towards the direction they were received from, which is not the direction the Earth will be at one round-trip time later.)
There have been several proposals to do active laser ranging to spacecraft or to landers on the planets. Ranging accuracies in the tens of picoseconds should be available from this, and I regard this as inevitable in the long run as interplanetary communications moves from radio to optical lasers to get higher bandwidth.
History is against you. The 10 years (1962-1972) of manned space exploration has never been matched by unmanned probes. Partly this is capabilities, partly this is politics, but the experiment has been tried and the results are against you.
You are correct. No one knows if there is anything to be returned. I myself would bet for at least a few micrograms, which would be enough to do some real science.
as little credence can be placed in the report as in those criticised by the US GAO
That's not the point. The point of these studies is not to find out anything, and it's not really even to convince anyone of anything, it's to show that the problem has been exhaustively studied, and that "our" research is more exhaustive than the other side. When I was in government, we used to call this "science by the pound," and it could literally devolve into "my study is thicker than yours" type of arguments.
As a simple rule of thumb, if the body funding the study has a interest in obtaining a particular result, and the study supports that result, it should just be ignored.
Slashdot Mirror
From the original blog post : "over this timescale, the Martian atmosphere has been too cold and thin for liquid water."
I read something like this frequently, and yet it is simply wrong and I wish people would stop repeating it.
Liquid water is not magic, but governed by physics. For there to be liquid water on Mars, all that is needed is that water be present, that the surface pressure be above the triple point of water, and that the temperature be above the freezing point. (Actually, this can be relaxed somewhat for brines and the like, but let's put that aside for the moment.) We know that Mars has water. What about the other two conditions ?
Much of the surface of Mars is above the triple point of water (i.e., at a low enough elevation that the surface pressure is higher than 611.7 pascals). Any low lying region is. The Viking 2 landing site is (some of the time) and the Phoenix landing site is (all of the time). The entire Hellas basin is, and it is highly likely to have liquid water at times (as the surface temperature there is warm enough during the day). Remember, peak surface soil temperatures on Mars can reach 27 C, even under current climate conditions.
Further, the atmospheric pressure on Mars varies greatly during its obliquity cycle, and it is highly likely that the entire planet (except for the high volcanoes of Tharsis) can support liquid water at times during each obliquity cycle. During those phases of the cycle, the atmospheric temperatures will be generally warmer, as well.
Now, this does not prove or disprove that these gullies are formed by water rather than sand, but you don't need unusually strong brines or geothermal vents to have liquid water on Mars (even though both of those probably exist as well), and it is quite reasonable to expect its presence in places, even under current atmospheric conditions.
What this is is an experimental spacecraft that NASA gave up, and should reclaim in my opinion. Turning this into a manned flight precursor would be a good way for President Obama to regain status in the astronaut community.
I assume most corporate speech recognition is intended to get people to hang up in frustration, thereby saving the cost of the call. Same thing with entering in account information. If you keep pushing zero, you will generally eventually get a person, so (if I need to talk to an actual person), that's what I do.
If there is one thing we have learned from 60 years of AI research, it's to never bet on AI fulfilling its promises.
Not ultimate. Next.
Robotic exploration of the planets has been tried, and found to be incredibly slow. This is partially technology, and partially politics, but the experiment has been tried, and that's the result.
Here is an example - the Viking Mars orbiters were assumed to not need biological sterilization and were put in an orbit with a 50 year lifetime, because surely in 50 years we would know if there was life on Mars, right ? 50 years from Viking is 2025, which is now not that far off. (And, incidentally, the satellite orbit people are worried that the orbiters orbit may not have the expected life-time , and may have already decayed.) We are highly unlikely to know if there is life on Mars by 2025. 50 years to answer a basic question.
Heck, we don't even know if there is liquid water on the surface (which there should be, in places at times). We don't know what the soil is made of.
One week after the first manned mission arrives at Mars, its robotic exploration will become a footnote.
They've done pretty well with solar.
What they considered was nuclear - the upcoming Mars Science Laboratory (MSL) will be nuclear powered, and so will not have to rest for the winter.
The security implications of carrying a nuclear battery do substantially increase the mission cost, however.
H.264 is licensed by MPEG-LA and has most of the heavy hitters in this area in the patent pool. So
- you know that none of these parties will come after you if you pay MPEG-LA's rates (as they can't, by the agreements they sign to join the pool) and
- if some other company does (say a patent troll), they are effectively taking on all of the companies in the pool, and had better have really deep pockets.
Now, I would rather it be unencumbered, but these are not inconsiderable advantages. Remember, just saying that another codec doesn't have any patent encumbrances doesn't make it so.
I hadn't heard that Widows Media had end-of-lifed - does this mean that it is dead ?
Oh, and he apparently doesn't like our state seal, either.
He is just another Republican carpetbagger (from New Jersey). These grifters evidently think that everyone in the South is an easy mark.
I have spent, by now, several years abroad in a variety of places (including Canada and China). I have never gotten in any trouble for not having my passport on me.
By the way, I have been in more than one place where the hotel kept my passport while I was staying there.
What if it's not kosher for others to shoot lasers at the reflectors that other scientists use?
They are mirrors. Everyone who does this (US, French, Germans, Russians, so far) has used all the ones up there.
Because (unlike the case with Satellite Laser Ranging), the expected return per shot is actually less than one photon. So, a shot returns either zero or one photons.
They do lots of shots and gate (time filter) the returns to get a single range estimate, based on maybe 1000 photon returns. But, each shot still returns only one photon at most at a time. (With the appropriate color filter, and a nanosecond size time gate, there is rarely a photon from the solar illumination of the Moon, and those that get through add only a little noise.)
The new Apollo system will have better statistics, and may get above 1 photon per shot, but there are actually pretty good reasons to only take the first photon from a shot, so I suspect that they will continue to only use 1 at a time.
Oh, by the way, while the Lunakhod's were Soviet, the French actually built the retroreflectors, so this is a Soviet-French experiment.
We left 3 LLR retroreflector arrays, at the Apollo 11, 14 and 15 landing sites. (That is 3 out of 6, so exactly 1/2 of the landings.)
Apollo 15's LLR array is by far the biggest, and so it is used the most often for ranging. But, to get the rotation (librations) of the Moon, you need a distribution in both latitude and longitude. The Apollo LLR arrays form a nice, but not especially large, triangle centered around the center of Near Side, Lunakhod 2 is usefully separated from them to the North-East, but Lunakhod 1 is all the way across Mare Imbrium in the North-West quadrant of the Near Side of the Moon. Ranging from Lunakhod 1 will substantially help the determination of Lunar librations.
Transparency threatens closed institutions, and the Vatican (run in much the same way as the Holy Roman Empire of the Middle Ages) is a closed institution.
This is not a comment on the Roman Catholic faith one way or the other, but on the Curia.
You know, it would be nice to have a reflector on mars. I wonder if it is possible to go that distance.
Distance is a problem (ranging sensitivity is proportional to 1/distance to the fourth power), but aberration makes this sort of passive Laser ranging to the planets impossible. (The retroreflector arrays return photons towards the direction they were received from, which is not the direction the Earth will be at one round-trip time later.)
There have been several proposals to do active laser ranging to spacecraft or to landers on the planets. Ranging accuracies in the tens of picoseconds should be available from this, and I regard this as inevitable in the long run as interplanetary communications moves from radio to optical lasers to get higher bandwidth.
This is way cool. The LLR (Lunar Last Ranging) people have been looking for this for a long, long time.
This (by providing a new fiducial point on the Moon) will significantly help Lunar geodesy.
Note, by the way, that LLR returns are always exactly 1 photon per shot, so this flash was no fainter than any other LLR return.
History is against you. The 10 years (1962-1972) of manned space exploration has never been matched by unmanned probes. Partly this is capabilities, partly this is politics, but the experiment has been tried and the results are against you.
You are correct. No one knows if there is anything to be returned. I myself would bet for at least a few micrograms, which would be enough to do some real science.
Yes, you missed a lot. They recovered it and are getting back, after a real "Perils of Pauline" type adventure.
There is no actual guarantee that there is a sample in the chamber (as the pellets misfired).
It's a remarkable achievement to get it back; let's hope that there is something inside.
as little credence can be placed in the report as in those criticised by the US GAO
That's not the point. The point of these studies is not to find out anything, and it's not really even to convince anyone of anything, it's to show that the problem has been exhaustively studied, and that "our" research is more exhaustive than the other side. When I was in government, we used to call this "science by the pound," and it could literally devolve into "my study is thicker than yours" type of arguments.
As a simple rule of thumb, if the body funding the study has a interest in obtaining a particular result, and the study supports that result, it should just be ignored.
The library went to a lot of trouble to prove that their records from the 18th century are probably a bit inaccurate.
Got them in the press, didn't it ?