"In case you don't already know, the Mossbauer spectrometer is a rediculously cool instrument..."
I knew.:-)
Your post was still very informative though, and the part about the software you're developing for the mission...cool!
There is something I don't understand however. I thought that since the linewidth of metastable iron 57's hyperfine transition was so incredibly narrow that unless the nuclei are fixed in a crystal and the crystal lattice vibrations(phonons) are quantized by cooling it to cryogenic temps. then the frequency shift imparted by the recoil of the emitting nuclei destroy any resonance with potentially absorbing sample Fe nuclei. How is the emitter cryogenically cooled on mars!?
Anyway, cool talking to you, I work here so if you have any questions about giant lasers...:-)
I'm not sure exactly how they plan to fix the spectrometer but I'm sure they're not lying when they say it's an option. Remember the Galileo space probe was recently fixed from hundreds of millions of miles away. Since a Mossbauer spectrometer uses a moving radioactive source to take a spectrum I would guess it might be put through it's paces several times to try to work out a glitch(speculation). The Japanese Mars probe with a failing circuit breaker is currently undergoing repairs to fix it remotely too.
Heh, interesting that you would mention that, kind troll. Since coincidentally, Frist is actively supporting a constitutional amendment to officially ban gay marriage. This would effectively be the first constitutional amendment since the 18th(prohibition), ratified in 1919, that is specifically intended to revoke the rights of citizens instead of granting new ones. If this is any indication of the behavior his cronies are prone to, well we're in for a real treat then!
"Oh, and interesting to note that when SETI@home first started up, they ran out of data to process. So you know what they did? They just fed the same data back to clients, over and over and over again, without telling people- acting like they still had new data to process."
Hello? SETI@home is a scientific endeavour. Accuracy of results matters, and as long as hacking the client to produce false results is possible(always will be), rechecking work units for authenticity by sending them out to more than one client is necessary, duh.
I have a sneaking suspicion that Prof. Gold will, once the solar sail spacecraft flies and works, attempt to invoke the solar wind as an explanation for the observed effects. This assertion should be easy to discredit by calculating the expected pressure of the solar wind on a sail of X area and then comparing that to the actual observed forces acting on the sail but for some people will never believe thier dragon dosen't exist[credit to Carl Sagan].
They're probably using "visible" to mean visible to the telescope, due to the fact that Arecibo is a fixed dish with only movable antennas, it can only see a fraction of the entire sky.
SOHO has served us well. That said, it's only made of metal plastic and silicon parts and after being blasted by the solar wind for so many years, it's bound to fail eventually. SOHO's replacement is called the STEREO mission. It will actually be 2 separate spacecraft that view the sun simultaneously, in order to acquire STEREOscopic observations of the corona and coronal mass ejections. It was sometimes difficult for SOHO to tell what direction a CME was traveling in because it had only one point of view. STEREO launches in 2005. In the meantime TRACE can do a few of the things SOHO did and while at it, do some things SOHO could never do, like take these SPECTACULAR movies and images of the corona and photosphere at very high spatial and temporal resolution.
The effect only works with single walled carbon nanotubes, and even then only when in air. The effect actually happens because the tubes are very black and very porus, absorbing a large amount of light and rapidly converting it to a violent expansion of the surrounding Oxygen in the air igniting the nanotube. This will never occur if the tubes are incorporated into an epoxy string.
I doubt this technology would have helped you. Your cochlear implant probably uses a magnet to hold the external transmitting coil (which also contanis a magnet) against your head. This new technology reduces the ohmic heating susceptibility in metal implants induced by the RF excitation pulse in the MRI by using some special coating but does nothing to mitigate magnetic field effects. Your implant will always be vulnerable to very strong (>1 Tesla I guess)external magnetic fields ripping it out (OW!) because it contains a magnet.:(
It is probable that the above poster was making a tangential reference to the old homoerotic game of Soggy Cracker or Soggy Biscuit, wherein a group of males (usu. used in initiation rites and the like) will masturbate in a circle upon a cracker and the last one to "finish" is made to eat said cracker. Aren't you glad that now you know!?
If the mechanism of self destruction is a chemical reaction between an added layer of dye(or whatever) and the Oxygen in the atmosphere (almost definitely how it works), then that means there will very likely be a stong unavoidable lifetime dependence on heat. DVD PLAYERS ARE HOT! And some more so than others....that =class action lawsuit from people who happen to have a brand of DVD player that runs particularly hot and whose "EZ-D's"(puke) are viewable for a much shorter time than the average.
The 60 beams are arranged around the target exactly opposite eachother to maximize irradiation uniformity on target. Sometimes the target breaks or something goes wrong with the expected amount of plasma opacity of the imploding target and the beam exits the opposite side of the chamber(at off angles). Other times they are simply mispointed, which can happen when more than 8 shots are done in a day and each one requires a slightly different setup.
They aren't low power. There are 60 beams on the laser with an average Omega beam being around 30cm in diameter and assuming 1TW pulse/beam you would be exposed to several Gigawatts per square cm. Im guessing now, but I would think if you were exposed to the infrared beam(before it gets converted to UV) you would be very severely burned but if you were hit with the UV side it might not be so bad since it is so readily absorbed by the upper layer of your skin it might just blow off a few top layers. I definitly would not want to try it though, there are scary looking burn marks all over the laser target chamber and walls of the containment room.
(I'll point you to my previous post first, which may clear some things up) Actually the Omega Laser dosen't use Nd:YLF it uses Nd:glass which is much MUCH cheaper to make. Other than than the only real difference is going to be that the new laser uses the "NIF style" beam amplification which makes use of a "PEPC" or plasma electrode pockles cell to reflect the beam back through the same Nd:glass slabs more than once, squeezing more energy out of them with each pass. Also the diffraction gratings for the re-compression of the chirped pulse will have to be HUGE and endure extremely high electric fields at the surface; this has never been done before on such a scale and will be a challenge to make for the laser.
As a technician on the Omega Laser I guess have a bit of an inside track on what's going on around the LLE.
First you must make a distinction between most powerful(energy/time) laser and most energetic(energy per pulse) laser, this is a distinction not made in the article. The Omega laser is currently the most energetic ultraviolet(frequency tripled Neodymium:Glass) laser in the world now at ~25 Kilojoules per pulse, very soon to be eclipsed by the preliminary first light of the National Ignition Facility. However each "shot" on the system, as they are called, is only a couple hundred picoseconds to a couple nanoseconds long (depending on the shot pulse shape) making it's peak power around a maximum of about 60 Terawatts. This is not the most powerful laser in the world. The Rutherford Appelton laboratory in England has a "Petawatt" system they just commissioned which is capable of at least hundreds of Terawatts of power albeit only with a couple hundred joules of energy per shot.
It is interesting to note that the mechanism the Petawatt upgrade at the LLE will use to achieve it's million billion watts of power in a pulse time of a few picoseconds to hundreds of femtoseconds is called Optical Parametric Chirped Pulse Amplification(OPCPA) and was invented right at THE UofR in the late 1980's!! Chirped Pulse Amplification lasers are the only means to get to petawatt intensities and they are interesting because they are the first technology to allow nuclear reactions to be directly caused by intense light radiation(ie. no implosion/ heating stage as in ICF). This is really interesting because in addition to the spark plug type inertial confinement fusion catalyzing experiments that are planned, the intensity fluences allowed by petawatt lasers approaches (possibly >10^21 watts/sq. inch) what is necessary to do an experiment called "sparking the vacuum" whereby enough energy is placed in a small enough volume of space in a short enough period of time to cause a spontaneous transformation of energy directly into particles(via E=Mc^2). Neat eh?
Actually, it is possible to make software bug free, it's just very expensive/hard to do. For instance the Mars Pathfinder mission had exactly 3 bugs in it's code. All but one were fixed with a patch because of priorities they were working with and that caused the the landers failure after 90 days on the surface.
score 4 insightful? I don't know who's more clueless, the poster or the moderators. I swear the quickest way to spot a conspiracy theorist moron on slashdot is to look for a post saying essentially that 'no it wasn't unfeasible schemes due to the laws of physics, it was the power companies and the MAN who kept him down!!' or some such. Please get a clue. The reason it was impossible is becasue of the inverse square law of radiating electromagnetic radiation. In other words if you double your distance from the power generating station you will only recieve 1/4th the power (for non directed beams, which Tesla's station was) using the same power gathering area(antenna size). You would have to generate unbelieveably intense EM fields at the transmission station just to light a light bulb a mile away! It would be so wasteful a means of power transmission that a mere few percent at most of the generated electricity would ever be used by the customer. By the way your other non-sequitor comment about the "Tunduska" (sic. Tunguska) event belies your ignorance as well, everyone knows by now that it almost certainly was either a comet or asteroid.
"Oh no! My coffee cu..NOOOOOO!!! OH THE HUMANITY! OH! THIS IS THE WORST OF THE WORST!"
------- [this space to be filled with the usual complaints about the lameness filter in order to circumvent it's wrath, which is itself lame for blocking "too many caps" in my opinion.]
Slashdot Mirror
I have a question! someone thought it was funny though apparently :-(
"In case you don't already know, the Mossbauer spectrometer is a rediculously cool instrument..."
:-)
:-)
I knew.
Your post was still very informative though, and the part about the software you're developing for the mission...cool!
There is something I don't understand however. I thought that since the linewidth of metastable iron 57's hyperfine transition was so incredibly narrow that unless the nuclei are fixed in a crystal and the crystal lattice vibrations(phonons) are quantized by cooling it to cryogenic temps. then the frequency shift imparted by the recoil of the emitting nuclei destroy any resonance with potentially absorbing sample Fe nuclei. How is the emitter cryogenically cooled on mars!?
Anyway, cool talking to you, I work here so if you have any questions about giant lasers...
I'm not sure exactly how they plan to fix the spectrometer but I'm sure they're not lying when they say it's an option. Remember the Galileo space probe was recently fixed from hundreds of millions of miles away. Since a Mossbauer spectrometer uses a moving radioactive source to take a spectrum I would guess it might be put through it's paces several times to try to work out a glitch(speculation). The Japanese Mars probe with a failing circuit breaker is currently undergoing repairs to fix it remotely too.
Heh, interesting that you would mention that, kind troll. Since coincidentally, Frist is actively supporting a constitutional amendment to officially ban gay marriage. This would effectively be the first constitutional amendment since the 18th(prohibition), ratified in 1919, that is specifically intended to revoke the rights of citizens instead of granting new ones. If this is any indication of the behavior his cronies are prone to, well we're in for a real treat then!
"Oh, and interesting to note that when SETI@home first started up, they ran out of data to process. So you know what they did? They just fed the same data back to clients, over and over and over again, without telling people- acting like they still had new data to process."
Hello? SETI@home is a scientific endeavour. Accuracy of results matters, and as long as hacking the client to produce false results is possible(always will be), rechecking work units for authenticity by sending them out to more than one client is necessary, duh.
This has already been done! (at the request of Carl Sagan in the early 90's)
Goodnight. :-]
I have a sneaking suspicion that Prof. Gold will, once the solar sail spacecraft flies and works, attempt to invoke the solar wind as an explanation for the observed effects. This assertion should be easy to discredit by calculating the expected pressure of the solar wind on a sail of X area and then comparing that to the actual observed forces acting on the sail but for some people will never believe thier dragon dosen't exist[credit to Carl Sagan].
They're probably using "visible" to mean visible to the telescope, due to the fact that Arecibo is a fixed dish with only movable antennas, it can only see a fraction of the entire sky.
Gee, I guess that's why it ISN'T WRITTEN THAT WAY IN THE POST, huh? Idiot.
SOHO has served us well. That said, it's only made of metal plastic and silicon parts and after being blasted by the solar wind for so many years, it's bound to fail eventually. SOHO's replacement is called the STEREO mission. It will actually be 2 separate spacecraft that view the sun simultaneously, in order to acquire STEREOscopic observations of the corona and coronal mass ejections. It was sometimes difficult for SOHO to tell what direction a CME was traveling in because it had only one point of view. STEREO launches in 2005. In the meantime TRACE can do a few of the things SOHO did and while at it, do some things SOHO could never do, like take these SPECTACULAR movies and images of the corona and photosphere at very high spatial and temporal resolution.
The effect only works with single walled carbon nanotubes, and even then only when in air. The effect actually happens because the tubes are very black and very porus, absorbing a large amount of light and rapidly converting it to a violent expansion of the surrounding Oxygen in the air igniting the nanotube. This will never occur if the tubes are incorporated into an epoxy string.
I doubt this technology would have helped you. Your cochlear implant probably uses a magnet to hold the external transmitting coil (which also contanis a magnet) against your head. This new technology reduces the ohmic heating susceptibility in metal implants induced by the RF excitation pulse in the MRI by using some special coating but does nothing to mitigate magnetic field effects. Your implant will always be vulnerable to very strong (>1 Tesla I guess)external magnetic fields ripping it out (OW!) because it contains a magnet. :(
It is probable that the above poster was making a tangential reference to the old homoerotic game of Soggy Cracker or Soggy Biscuit, wherein a group of males (usu. used in initiation rites and the like) will masturbate in a circle upon a cracker and the last one to "finish" is made to eat said cracker. Aren't you glad that now you know!?
If the mechanism of self destruction is a chemical reaction between an added layer of dye(or whatever) and the Oxygen in the atmosphere (almost definitely how it works), then that means there will very likely be a stong unavoidable lifetime dependence on heat. DVD PLAYERS ARE HOT! And some more so than others....that =class action lawsuit from people who happen to have a brand of DVD player that runs particularly hot and whose "EZ-D's"(puke) are viewable for a much shorter time than the average.
The 60 beams are arranged around the target exactly opposite eachother to maximize irradiation uniformity on target. Sometimes the target breaks or something goes wrong with the expected amount of plasma opacity of the imploding target and the beam exits the opposite side of the chamber(at off angles). Other times they are simply mispointed, which can happen when more than 8 shots are done in a day and each one requires a slightly different setup.
They aren't low power. There are 60 beams on the laser with an average Omega beam being around 30cm in diameter and assuming 1TW pulse/beam you would be exposed to several Gigawatts per square cm. Im guessing now, but I would think if you were exposed to the infrared beam(before it gets converted to UV) you would be very severely burned but if you were hit with the UV side it might not be so bad since it is so readily absorbed by the upper layer of your skin it might just blow off a few top layers. I definitly would not want to try it though, there are scary looking burn marks all over the laser target chamber and walls of the containment room.
(I'll point you to my previous post first, which may clear some things up) Actually the Omega Laser dosen't use Nd:YLF it uses Nd:glass which is much MUCH cheaper to make. Other than than the only real difference is going to be that the new laser uses the "NIF style" beam amplification which makes use of a "PEPC" or plasma electrode pockles cell to reflect the beam back through the same Nd:glass slabs more than once, squeezing more energy out of them with each pass. Also the diffraction gratings for the re-compression of the chirped pulse will have to be HUGE and endure extremely high electric fields at the surface; this has never been done before on such a scale and will be a challenge to make for the laser.
such as......?
As a technician on the Omega Laser I guess have a bit of an inside track on what's going on around the LLE.
First you must make a distinction between most powerful(energy/time) laser and most energetic(energy per pulse) laser, this is a distinction not made in the article. The Omega laser is currently the most energetic ultraviolet(frequency tripled Neodymium:Glass) laser in the world now at ~25 Kilojoules per pulse, very soon to be eclipsed by the preliminary first light of the National Ignition Facility. However each "shot" on the system, as they are called, is only a couple hundred picoseconds to a couple nanoseconds long (depending on the shot pulse shape) making it's peak power around a maximum of about 60 Terawatts. This is not the most powerful laser in the world. The Rutherford Appelton laboratory in England has a "Petawatt" system they just commissioned which is capable of at least hundreds of Terawatts of power albeit only with a couple hundred joules of energy per shot.
It is interesting to note that the mechanism the Petawatt upgrade at the LLE will use to achieve it's million billion watts of power in a pulse time of a few picoseconds to hundreds of femtoseconds is called Optical Parametric Chirped Pulse Amplification(OPCPA) and was invented right at THE UofR in the late 1980's!! Chirped Pulse Amplification lasers are the only means to get to petawatt intensities and they are interesting because they are the first technology to allow nuclear reactions to be directly caused by intense light radiation(ie. no implosion/ heating stage as in ICF). This is really interesting because in addition to the spark plug type inertial confinement fusion catalyzing experiments that are planned, the intensity fluences allowed by petawatt lasers approaches (possibly >10^21 watts/sq. inch) what is necessary to do an experiment called "sparking the vacuum" whereby enough energy is placed in a small enough volume of space in a short enough period of time to cause a spontaneous transformation of energy directly into particles(via E=Mc^2). Neat eh?
Actually, it is possible to make software bug free, it's just very expensive/hard to do. For instance the Mars Pathfinder mission had exactly 3 bugs in it's code. All but one were fixed with a patch because of priorities they were working with and that caused the the landers failure after 90 days on the surface.
score 4 insightful? I don't know who's more clueless, the poster or the moderators. I swear the quickest way to spot a conspiracy theorist moron on slashdot is to look for a post saying essentially that 'no it wasn't unfeasible schemes due to the laws of physics, it was the power companies and the MAN who kept him down!!' or some such.
Please get a clue. The reason it was impossible is becasue of the inverse square law of radiating electromagnetic radiation. In other words if you double your distance from the power generating station you will only recieve 1/4th the power (for non directed beams, which Tesla's station was) using the same power gathering area(antenna size). You would have to generate unbelieveably intense EM fields at the transmission station just to light a light bulb a mile away! It would be so wasteful a means of power transmission that a mere few percent at most of the generated electricity would ever be used by the customer.
By the way your other non-sequitor comment about the "Tunduska" (sic. Tunguska) event belies your ignorance as well, everyone knows by now that it almost certainly was either a comet or asteroid.
...right here(scroll down to the bottom for mpeg)[warning! not for the squeamish!].
So I'm guessing the worst that could happen is:
"Oh no! My coffee cu..NOOOOOO!!! OH THE HUMANITY! OH! THIS IS THE WORST OF THE WORST!"
-------
[this space to be filled with the usual complaints about the lameness filter in order to circumvent it's wrath, which is itself lame for blocking "too many caps" in my opinion.]
"(not knowing being a worry not actually the worry of being)"
Oh! That certainly clears things up.