Re: [meteorite-list] Could Venus Watch For Earth-Bound Asteroids?
Hi Larry, all - I will be reading Don and Lindley's report today. Don has always spent the publics' money wisely, so it will be interesting to see his reasoning for this detector. The Russians proposed telescopes in Earth orbit, one leading the Earth, another following. Asd you point out, heat in Venus orbit is a real problem. The Moon would make a great cooling sink for IR detectors, and there is a convenient site in the current proposal which could be used. Detection radars on the Moon could also be used for SETI. Assuming that the collisions with fragments of Comet Encke over tha lawt 10,000 years are the norm, and not a one off, then the way to go is with a Moon based lidar system with a 1 AU detection radius. That's where China is heading. with this bum left hamd, I have really got to get a spell checker - sorry for the typos. Ed E.P. Grondine Man and Impact in the Americas --- [EMAIL PROTECTED] wrote: Hello List: I have observer a few asteroids in my life and have some problems with this article. I am away from home, so I am going mostly on memory and so these are only estimates; 1. If you are to put a telescope at the orbit of Venus, it would have to be in the same orbit as Venus, but not near Venus. If you are planning to observe in the infrared, you would want a Spitzer-type telescope. The Earth is hot and Venus would be hotter (so is the Sun)! Spitzer has a lifetime of about 5 years thanks to shielding from the Sun and Earth. I am not sure how much more of a problem there would be at the distance of Venus. HST with it CCDs is much easier to cool so does not have the limits of an infrared telescope. 2. Yes, asteroids are brighter in the infrared: but this is sunlight absorbed and re-emitted (heat). So, yes, you could observe asteroids at these wavelengths, but as stated about would need a cooled telescope. 3. While the idea of an asteroid coming at us out of the sunlight (worked in war movies), statistically, there are fewer of these asteroid (at least known). There are over 2000 known Apollo asteroids (cross Earth orbit, but mean solar distance greater than Earth's) and less than 400 Aten asteroids (cross Earth's orbit, but mean distance less than Earth's). There are known known asteroids with orbits wholly within Earth's orbit (at least none discovered). So, there are more things coming in from outside in than inside out. Yes, it would be better to look from closer to the Sun, but would have the bigger, brighter, hotter Sun to deal with (visible or infrared). 4. You would also be better off with more than one telescope. There is always the chance that the asteroid with our name on it would hit us at its first close pass (might not be able to do anything about it). But if that is so, you would want a telescope that is looking in the direction of the Earth at any given time. 5. Now, something that I just thought about that I cannot calculate here in my hotel room (in Disney World). How many asteroids have perihelion (closest distance to the Sun) that get anywhere near Venus? Most near Earth asteroids (NEOs) can only be detected when they are close to Earth (they are very small). These may never be detected from far away Venus. That is all I can think of at the moment. Larry -Ursprüngliche Nachricht- Von: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Im Auftrag von Ron Baalke Gesendet: Freitag, 9. März 2007 22:50 An: Meteorite Mailing List Betreff: [meteorite-list] Could Venus Watch For Earth-Bound Asteroids? http://space.newscientist.com/article/dn11356-could-venus-watch-for-earth bou nd-asteroids.html Could Venus watch for Earth-bound asteroids? David L Chandler New Scientist 09 March 2007 A dedicated space-based telescope is needed to achieve a congressionally mandated goal of discovering 90% of all near-Earth asteroids down to a size of 140 metres by the year 2020, says a report NASA sent to the US Congress on Thursday. Asteroids of that size are large enough to destroy a major city or region if they strike the planet - but NASA says it does not have the money to pay for the project. The study says Venus is the best place for the telescope. That is because space rocks within Earth's orbit - where Venus lies - are most likely to be lost in the Sun's glare, potentially catching astronomers off guard. The telescope could be placed either behind or ahead of Venus in its orbit by about 60° - the stable Lagrange points, known as L4 or L5, where the gravity of the Sun and Venus are in balance. There are quite a few [objects] that are interior to Earth's orbit, NASA's Lindley Johnson told New Scientist. Those are really hard to detect [from Earth]; the opportunities to see them are very limited. From the orbit of Venus, however, you're always looking away from the Sun, always looking out, he says
Re: [meteorite-list] Could Venus Watch For Earth-Bound Asteroids?
Hello List: I have observer a few asteroids in my life and have some problems with this article. I am away from home, so I am going mostly on memory and so these are only estimates; 1. If you are to put a telescope at the orbit of Venus, it would have to be in the same orbit as Venus, but not near Venus. If you are planning to observe in the infrared, you would want a Spitzer-type telescope. The Earth is hot and Venus would be hotter (so is the Sun)! Spitzer has a lifetime of about 5 years thanks to shielding from the Sun and Earth. I am not sure how much more of a problem there would be at the distance of Venus. HST with it CCDs is much easier to cool so does not have the limits of an infrared telescope. 2. Yes, asteroids are brighter in the infrared: but this is sunlight absorbed and re-emitted (heat). So, yes, you could observe asteroids at these wavelengths, but as stated about would need a cooled telescope. 3. While the idea of an asteroid coming at us out of the sunlight (worked in war movies), statistically, there are fewer of these asteroid (at least known). There are over 2000 known Apollo asteroids (cross Earth orbit, but mean solar distance greater than Earth's) and less than 400 Aten asteroids (cross Earth's orbit, but mean distance less than Earth's). There are known known asteroids with orbits wholly within Earth's orbit (at least none discovered). So, there are more things coming in from outside in than inside out. Yes, it would be better to look from closer to the Sun, but would have the bigger, brighter, hotter Sun to deal with (visible or infrared). 4. You would also be better off with more than one telescope. There is always the chance that the asteroid with our name on it would hit us at its first close pass (might not be able to do anything about it). But if that is so, you would want a telescope that is looking in the direction of the Earth at any given time. 5. Now, something that I just thought about that I cannot calculate here in my hotel room (in Disney World). How many asteroids have perihelion (closest distance to the Sun) that get anywhere near Venus? Most near Earth asteroids (NEOs) can only be detected when they are close to Earth (they are very small). These may never be detected from far away Venus. That is all I can think of at the moment. Larry -Ursprüngliche Nachricht- Von: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Im Auftrag von Ron Baalke Gesendet: Freitag, 9. März 2007 22:50 An: Meteorite Mailing List Betreff: [meteorite-list] Could Venus Watch For Earth-Bound Asteroids? http://space.newscientist.com/article/dn11356-could-venus-watch-for-earth bou nd-asteroids.html Could Venus watch for Earth-bound asteroids? David L Chandler New Scientist 09 March 2007 A dedicated space-based telescope is needed to achieve a congressionally mandated goal of discovering 90% of all near-Earth asteroids down to a size of 140 metres by the year 2020, says a report NASA sent to the US Congress on Thursday. Asteroids of that size are large enough to destroy a major city or region if they strike the planet - but NASA says it does not have the money to pay for the project. The study says Venus is the best place for the telescope. That is because space rocks within Earth's orbit - where Venus lies - are most likely to be lost in the Sun's glare, potentially catching astronomers off guard. The telescope could be placed either behind or ahead of Venus in its orbit by about 60° - the stable Lagrange points, known as L4 or L5, where the gravity of the Sun and Venus are in balance. There are quite a few [objects] that are interior to Earth's orbit, NASA's Lindley Johnson told New Scientist. Those are really hard to detect [from Earth]; the opportunities to see them are very limited. From the orbit of Venus, however, you're always looking away from the Sun, always looking out, he says. And, of course, you can observe 24 hours a day - you don't have to worry about night and day. Even from Earth orbit, a telescope's view of any given part of the sky is blocked about half the time by the Earth itself. In addition, because Venus orbits the Sun in about two-thirds the time the Earth does, a telescope in that orbit would catch up with any near-Earth asteroids in their orbits more frequently than Earth does, offering more opportunities for discovery. You're able to sample that population more rapidly in the same amount of time, Johnson says. Missed deadline An infrared telescope would be more effective than one that studies visible light, because asteroids reflect sunlight more strongly at infrared wavelengths. The background sky is also much less bright in the infrared, providing better contrast for discovering even small, faint asteroids. With the Venus-orbit IR telescope, NASA could exceed its goal by three years, finding 90% of the most dangerous space rocks by 2017. But the space telescope is estimated to cost $1.1
Re: [meteorite-list] Could Venus Watch For Earth-Bound Asteroids?
But the space telescope is estimated to cost $1.1 billion for 15 years of operation Hmm, what does cost a F-22 and a B2 Spirit? -Ursprüngliche Nachricht- Von: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Im Auftrag von Ron Baalke Gesendet: Freitag, 9. März 2007 22:50 An: Meteorite Mailing List Betreff: [meteorite-list] Could Venus Watch For Earth-Bound Asteroids? http://space.newscientist.com/article/dn11356-could-venus-watch-for-earthbou nd-asteroids.html Could Venus watch for Earth-bound asteroids? David L Chandler New Scientist 09 March 2007 A dedicated space-based telescope is needed to achieve a congressionally mandated goal of discovering 90% of all near-Earth asteroids down to a size of 140 metres by the year 2020, says a report NASA sent to the US Congress on Thursday. Asteroids of that size are large enough to destroy a major city or region if they strike the planet - but NASA says it does not have the money to pay for the project. The study says Venus is the best place for the telescope. That is because space rocks within Earth's orbit - where Venus lies - are most likely to be lost in the Sun's glare, potentially catching astronomers off guard. The telescope could be placed either behind or ahead of Venus in its orbit by about 60° - the stable Lagrange points, known as L4 or L5, where the gravity of the Sun and Venus are in balance. There are quite a few [objects] that are interior to Earth's orbit, NASA's Lindley Johnson told New Scientist. Those are really hard to detect [from Earth]; the opportunities to see them are very limited. From the orbit of Venus, however, you're always looking away from the Sun, always looking out, he says. And, of course, you can observe 24 hours a day - you don't have to worry about night and day. Even from Earth orbit, a telescope's view of any given part of the sky is blocked about half the time by the Earth itself. In addition, because Venus orbits the Sun in about two-thirds the time the Earth does, a telescope in that orbit would catch up with any near-Earth asteroids in their orbits more frequently than Earth does, offering more opportunities for discovery. You're able to sample that population more rapidly in the same amount of time, Johnson says. Missed deadline An infrared telescope would be more effective than one that studies visible light, because asteroids reflect sunlight more strongly at infrared wavelengths. The background sky is also much less bright in the infrared, providing better contrast for discovering even small, faint asteroids. With the Venus-orbit IR telescope, NASA could exceed its goal by three years, finding 90% of the most dangerous space rocks by 2017. But the space telescope is estimated to cost $1.1 billion for 15 years of operation, and NASA says there is currently no money in its budget to pursue any of the search proposals it studied. That means it would take until at least 2026 to achieve its goal - and that is assuming a large telescope in Chile called the LSST (Large Synoptic Survey Telescope) is completed. But the LSST, which would be funded through the National Science Foundation, itself has not had final approval (see Unique wide-field telescope will make 'sky movies' http://space.newscientist.com/article/dn9200-unique-widefield-telescope-wil l-make-sky-movies.html). Without the LSST, as well, the goal would slip beyond 2030. Former Apollo astronaut Rusty Schweickart says NASA's analysis was a good examination of the options, and showed that the space option ... is most effective in dealing with the danger of an unexpected impact. But Schweickart says NASA failed to deliver on an additional analysis that Congress had asked for, which included an examination of the relative merits of different proposals for deflecting an asteroid found to be on a collision course with Earth. [NASA] did nothing, they declined to respond. That's pretty disappointing, Schweickart told New Scientist. __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
Re: [meteorite-list] Could Venus Watch For Earth-Bound Asteroids?
Hi, Martin! The cost of a series production item includes on the cost of development and depends on how many copies you have made. Based on the current planned production of F-22 Raptors, the cost is $380 to $390 million apiece. Had the originally planned number of planes been built the cost would have been about $130 million each. However, it's never that simple. The follow-on F-35 Lightning II will use much of the technology developed for the F-22, but the F-35 will have a much lower cost per plane than the F-22 could ever have. Without that technological development, the cost of the F-35 would be much greater. The B-2 Spirit, built in the numbers presently contemplated, will cost $2,200 million per copy! Again, and to an even greater degree, the cost of developing the technology in the first is staggering. The actual material and man-hour manufacturing cost of building one B-2 bomber is about $120 million, one heck of a bargain. Conceived of in the 1970's, developed in the 1980's, then completely re-designed to change it from a high altitude penetrating bomber to a low altitude penetrating bomber (will you make up your mind?), it was first displayed about the instant the Cold War sublimated Instead of the 136 that were planned, even without a Cold War, we decided to settle for 75 and more recently our Defender and Decider, Mr. Bush, decided that twenty were plenty, which raises the cost/plane to about $2.2 billion a bump. It is now said to be fully operational, but I cannot find out exactly how many planes have been built. (Why are you following me and where is your warrant?) However, you may live to see more B-2's or at least B-2-lookalikes, as the design engineer in charge of the propulsion system was arrested on October 2005 for selling classified information to China and possibly other countries as well. Those B-2 copies would cost considerably less, I imagine, and have a different in-flight menu. So, one B-2 equals TWO space telescopes, but it takes about three F-22's to pay for one space telescope. Of course, IF the B-2 could fly to and destroy an incoming asteroid, it would be worth $22 billion, or $22 trillion --- name your price. Sterling K. Webb -- - Original Message - From: Martin Altmann [EMAIL PROTECTED] To: meteorite-list@meteoritecentral.com Sent: Saturday, March 10, 2007 6:31 PM Subject: Re: [meteorite-list] Could Venus Watch For Earth-Bound Asteroids? But the space telescope is estimated to cost $1.1 billion for 15 years of operation Hmm, what does cost a F-22 and a B2 Spirit? -Ursprüngliche Nachricht- Von: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Im Auftrag von Ron Baalke Gesendet: Freitag, 9. März 2007 22:50 An: Meteorite Mailing List Betreff: [meteorite-list] Could Venus Watch For Earth-Bound Asteroids? http://space.newscientist.com/article/dn11356-could-venus-watch-for-earthbou nd-asteroids.html Could Venus watch for Earth-bound asteroids? David L Chandler New Scientist 09 March 2007 A dedicated space-based telescope is needed to achieve a congressionally mandated goal of discovering 90% of all near-Earth asteroids down to a size of 140 metres by the year 2020, says a report NASA sent to the US Congress on Thursday. Asteroids of that size are large enough to destroy a major city or region if they strike the planet - but NASA says it does not have the money to pay for the project. The study says Venus is the best place for the telescope. That is because space rocks within Earth's orbit - where Venus lies - are most likely to be lost in the Sun's glare, potentially catching astronomers off guard. The telescope could be placed either behind or ahead of Venus in its orbit by about 60° - the stable Lagrange points, known as L4 or L5, where the gravity of the Sun and Venus are in balance. There are quite a few [objects] that are interior to Earth's orbit, NASA's Lindley Johnson told New Scientist. Those are really hard to detect [from Earth]; the opportunities to see them are very limited. From the orbit of Venus, however, you're always looking away from the Sun, always looking out, he says. And, of course, you can observe 24 hours a day - you don't have to worry about night and day. Even from Earth orbit, a telescope's view of any given part of the sky is blocked about half the time by the Earth itself. In addition, because Venus orbits the Sun in about two-thirds the time the Earth does, a telescope in that orbit would catch up with any near-Earth asteroids in their orbits more frequently than Earth does, offering more opportunities for discovery. You're able to sample that population more rapidly in the same amount of time, Johnson says. Missed deadline An infrared telescope would be more effective than one that studies visible light, because asteroids reflect sunlight more strongly at infrared wavelengths. The background sky is also much less bright
[meteorite-list] Could Venus Watch For Earth-Bound Asteroids?
http://space.newscientist.com/article/dn11356-could-venus-watch-for-earthbound-asteroids.html Could Venus watch for Earth-bound asteroids? David L Chandler New Scientist 09 March 2007 A dedicated space-based telescope is needed to achieve a congressionally mandated goal of discovering 90% of all near-Earth asteroids down to a size of 140 metres by the year 2020, says a report NASA sent to the US Congress on Thursday. Asteroids of that size are large enough to destroy a major city or region if they strike the planet - but NASA says it does not have the money to pay for the project. The study says Venus is the best place for the telescope. That is because space rocks within Earth's orbit - where Venus lies - are most likely to be lost in the Sun's glare, potentially catching astronomers off guard. The telescope could be placed either behind or ahead of Venus in its orbit by about 60° - the stable Lagrange points, known as L4 or L5, where the gravity of the Sun and Venus are in balance. There are quite a few [objects] that are interior to Earth's orbit, NASA's Lindley Johnson told New Scientist. Those are really hard to detect [from Earth]; the opportunities to see them are very limited. From the orbit of Venus, however, you're always looking away from the Sun, always looking out, he says. And, of course, you can observe 24 hours a day - you don't have to worry about night and day. Even from Earth orbit, a telescope's view of any given part of the sky is blocked about half the time by the Earth itself. In addition, because Venus orbits the Sun in about two-thirds the time the Earth does, a telescope in that orbit would catch up with any near-Earth asteroids in their orbits more frequently than Earth does, offering more opportunities for discovery. You're able to sample that population more rapidly in the same amount of time, Johnson says. Missed deadline An infrared telescope would be more effective than one that studies visible light, because asteroids reflect sunlight more strongly at infrared wavelengths. The background sky is also much less bright in the infrared, providing better contrast for discovering even small, faint asteroids. With the Venus-orbit IR telescope, NASA could exceed its goal by three years, finding 90% of the most dangerous space rocks by 2017. But the space telescope is estimated to cost $1.1 billion for 15 years of operation, and NASA says there is currently no money in its budget to pursue any of the search proposals it studied. That means it would take until at least 2026 to achieve its goal - and that is assuming a large telescope in Chile called the LSST (Large Synoptic Survey Telescope) is completed. But the LSST, which would be funded through the National Science Foundation, itself has not had final approval (see Unique wide-field telescope will make 'sky movies' http://space.newscientist.com/article/dn9200-unique-widefield-telescope-will-make-sky-movies.html). Without the LSST, as well, the goal would slip beyond 2030. Former Apollo astronaut Rusty Schweickart says NASA's analysis was a good examination of the options, and showed that the space option ... is most effective in dealing with the danger of an unexpected impact. But Schweickart says NASA failed to deliver on an additional analysis that Congress had asked for, which included an examination of the relative merits of different proposals for deflecting an asteroid found to be on a collision course with Earth. [NASA] did nothing, they declined to respond. That's pretty disappointing, Schweickart told New Scientist. __ Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list
