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Comments on Liquid Mirror Telescope For Moon Studied By NASA
Liquid Mirror Telescopes are cool enough - but putting one on the moon? (Read the complete story)

"There's no need to place the LLMT on a surface. Put the thing in Earth orbit. When you want to use it, extend a conducting tether in the approptiate direction and run a current. The resulting acceleration lets you spin up the mirror."
(BobD 2/6/2006 7:59:23 AM)
"Hi Bob, not sure that would work as the LMT concent relies on gravity pulling the mercury down onto a surface that is then spun. how would you get the gravitational effect to hold th mercury on the surface?"
(Delster 2/6/2006 8:27:55 AM)
"That's what the conducting tether is for. Run a current through it, it interacts with the Earth's magnetic field and accelerates the LMT radially. The change in altitude (hopefully away from the Earth) without change in orbital volocity produces microgravity so you can spin up the dish. It has the added advantage of being somewhat pointable. The tether technology is well understood and already in use to produce microgravity in orbit"
(BobD 2/6/2006 12:42:18 PM)
"You might also be interested in the comments on Gallun's Martian liquid mirror telescope."
(Bill Christensen 2/8/2006 6:04:45 PM)
"ok, but why couldn't you tip it? wouldn't the centrifical forces that spread the liquid also keep it in place as you tip it?"
( 2/9/2006 12:12:31 AM)
"Somebody's not thinking here: a LMT at a pole could only see one thing in the sky. There would have to be a series of them at different latitudes in order to cover the whole sky."
(Bill Parkyn 2/9/2006 10:03:40 AM)
"Bill - You're partly right. A liquid mirror telescope points straight up and cannot tilt ... but, the rotation of the planet (or body!) that it is built on will point it at a long ribbon of sky over time. This makes LMTs suitable for lots of different kinds of astronomy - but not for all. "
(Bill Christensen 2/9/2006 7:33:08 PM)
"It seems to me that altho gravity is indeed the force against which centrifugal force works, that certain amounts of tilt could have the resultant 'warp' of the fluid compensated for by digital analysis.. similiar to how the Hubble had its optics 'fixed' by digital correction of its physically warped view. The placement at a (physical as opposed to magnetic) pole would maintain a steady view."
(bobby 2/12/2006 8:09:21 PM)
"why do you use mercury in the bowl.
(Two reasons - the optical reflectivity of mercury is 73 percent [quite good] and best of all, it stays a liquid down to abut 240K.)"
( 3/1/2006 3:37:14 PM)
"This is a very interesting thread and all have good points. The easiest solution is not to tilt the LMT at all but to leave it perfectly level and move the imaging unit above the spinning mercury mirror (like the tremendous radio telescope located in Puerto Rico) and incorporate distortable lensatic adaptive optics in the light path between the mirror and the imaging unit. There are two choices for this adaptive lens: one that is made of a distortable matrix or one made of two or more solid lenses that can be shifted against each other to correct for the off-axis distortion caused by the parabola of the liquid mirror being off center. Aiming of the telescope in right ascention would not necessarily have to be far in any direction as planned observing sessions would make use of the moon's slow rotation to aim the telescope. The only drawback is that if one is to take in the entire heavens, several telescopes would need to be set up along the meridian as the practical north-south movement of the imaging unit would be limited to something in the area of just a few degrees from zenith (twenty would probably be the very maximum). Energy consumption of the entire aparatus would be far less than that if it were installed on earth due to the lower gravity of the moon (1/8 that of earth). The less gravity, the fewer RPMs required to form the mirror and the less energy needed to operate the movable imaging unit. Just a few bones to chew on :) "
(Jeff the Great 3/4/2006 10:06:06 PM)
"Makes me want to spincast a 30" substrate out of JB-Weld epoxy and then high speed spincast a coat of Gallium for a quick and dirty home brew large aperture Dobsonian. Good food for thought :-)"
(Dave 8/27/2006 3:25:29 PM)
( 10/6/2006 1:12:00 AM)
"So when was the first liquid mirror telescope used? and by whom?"
( 10/12/2006 4:56:46 PM)
"If such a mirror were built in space wouldn't it be possible to tilt it in any direction?"
(jerry t. searcy 11/16/2006 9:07:49 AM)
"True, but you would need something like gravity to get the liquid to settle into the right shape for the mirror to work..."
(Bill Christensen 11/18/2006 10:35:59 AM)
"Why not mount an Ion drive on the telescope and use acceleration instead of gravity, at some point near L3 or such. Point and accelerate towards a distant galaxy, spin up, take pictures. Refuel as needed."
(Ion Tichy 11/20/2006 2:26:00 AM)
"If a mercury coated bowl is used on the moon, wouldn't the cold "temperature" cause the liquid to freeze? Would that change the reflective quality of the now-solid mercury?"
(Jim Shirey 11/21/2006 3:55:57 AM)
"No. This is entirely bogus. All liquids sublime in a vacuum. That is, at earth's air pressure, carbon dioxide is "dry ice" and goes from a solid to a gaseous state with no intermediate state. Nevertheless carbon dioxide has been used as liquid in some industrial cooling systems at least as early as the 1960s. As long as it was pressurized enough it could have a liquid state. On the moon liquid mercury would boil away. Also, _Amateur Telescope Making_, the trilogy published by Scientific American in the 1930s had reports of further experiments. The next problem is that mercury, like all liquids, is not really mirror like. It has ripples. Any vibration ripples its surface. A related idea is rotating a pan (shall we call it) of molten metal while it cools. "
(dhm 12/21/2006 4:55:55 PM)
"I don't think that I implied in the article that mercury would be the liquid of choice on the moon. First, it's not true that 'all liquids sublime in a vacuum' - temperature is an important consideration. I'm pretty sure that mercury would freeze at lunar night temperatures; the freezing point of mercury is about -38 degrees C. Materials like ethane, methane and other small hydrocarbons would work. Unfortunately, these materials are not reflective, so a small layer of something shiny would have to be deposited onto the surface of the liquid. This has actually been done, but not at the requisite low temperature. See this article for more information on using a liquid telescope: A Pristine View of the Universe"
(Bill Christensen 12/21/2006 6:36:22 PM)
" The moon is moving away from Earth Due to the tidal forces of weight [gravity] and the tangential component [vortex force] two parts, vortex force to the moon is of increasing angular momentum away from the Earth, this process of angular momentum conservation, therefore slowing down the Earth's rotation cycle. In recent years, some countries in the world after scientists and technical workers in-depth observation and research, found that the moon is gradually away from us, and will be increasingly dark. The United States and France scientists use astronauts landing on the moon in 1969 when the United States placed in the mirror on the moon to measure the results showed that in 28years to the distance between the Earth and the moon increased 1 m, The United States and France the two scientists is the use of accurate time measurement to measurement, the distance between the change, This method of pulsed laser projection, and then to the mirror reflection back on the ground detector, a return of about 2.5 seconds, Constantly measuring return by the time the changes on the distance that can change. Repeated measurements show that the earth and the moon because of the distance between the earth's surface tidal friction role annual increase of nearly 4 cm. using gravitational& vortex force the formula to calculate the moon from Earth: Cos а ≈ 1 Me = 6 × 10 ^ 24kg; month - the distance r = 38.4 × 10 ^ 7M Mgh = mv^2 / 2 ① V = at ② Moon average week: v-= 1 / π ∫ vsin ω td ω t = 2v / π ③ Angular velocity difference: q = 29/30 = 1-1/30 V-= 2at / π; ω = 1 / T a = KGM ω/ r ^ 2 ④ Mg = GMm / r ^ 2 ⑤ Daily the moon away from us: h = 2GK ^ 2Mq / π ^2 r ^ 2 = 2 × 6.67 × 10^-11 × 0.16 × 6 × 10 ^ 24 × 29 / [38.4 × 10 ^ 7] ^ 2 × 3.14 ^ 2× 30 = 8.51 × 10 ^ 5m From a year: 8.51 × 365 × 10 ^ 5 = 0.031m This is close the measured value Reference: “ mysterious vortex force - gravity partner ”Books Author: Zhuyonghuan Publisher: 21st Century Publishing House - China 2005-3 "
(zyh 4/20/2008 7:07:28 PM)
" vortex force Introduction of In the beginning of the last century, Astrophysicists face a problem, Mercury recently at the precession (Newton's theory deviation of: 43 angle seconds per century ), This is the quote the classics scholars can not explain, and it is not Newton's theory of classical mechanics adopted by a storm. Then only 37-year-old in 1916 Einstein published the《〈basis of general relativity〉》,Schwarzschild Metric German mathematician in the field equations of general relativity to the Mercury precession of the mystery,Mercury precession was therefore established the general theory of relativity early as the first major experiment. Later measured the Earth, Venus and other planets has also point precession of the general theory of relativity and the calculation of anastomosis with good results. Mercury precession and in the light deflection in the gravitational field, the gravitational redshift spectra of the three major criterion known as general relativity. In the beginning of the new century, have an astrophysicist at the problems facing the front ,This is NASA launched the "pioneers 10" "Galilean slightly," four spacecraft speed reduction. American scientists through 10 years of observation, found space for the role of a slowdown The effect is tiny - only about one part in 10bn of that due to the Earth's gravity acting on you right now - but it is definitely there. So some scientists questioned Newton's Law of Universal Gravitation, However, while some scientists believe that the best flight path is based on the parameters calculated, it is too early to doubt the basic law. We explore the long-term, in 2001, with Cavendish balance is measured not only by gravity to the component (that is, Newton's gravity), but also the existence of the tangential component, and that formula. To our planet, as an example, in addition to the original gravity (ie to the component), with the rotation of the earth, there are around in the vortex force of its (tangential component) the existence of ,The vortex force of (that is tangential component) and the Earth's rotation rate is proportional relationship. In the gravitational theory to elect representatives, it seems that non-Kepler, Newton and Einstein to my mind. It is worth noting that three representatives in the two agree that planets or stars in the rotation around a vortex. Kepler's idea of the same gravity as the car spoke, on the one hand to maintain the planets in their orbits can not run away (ie the components), on the other hand, with the sun's rotation around the sun forced planetary rotation (that is tangential component) . Einstein's general theory of relativity in there is a little-known forecast to be tested, the framework called gravitational drag [frame dragging]. When a planet or star rotation in space, it will drag space-time in its surrounding. This is very like the following example, when you filled with water in the bowl, one ball, and their rotation, the surface will be generated by the friction of water along the direction of rotation drag ball, the ball near the water in the rotation faster, the farther away from the ball, the friction of water drag effect will be weak. Newton's theory does not recognize the planet's rotation a scroll, so could not pass on Newton's theory of the "Mercury precession," this hurdle, a spacecraft can slow down this hurdle, Not only that, in many helpless astronomical phenomena, such as the angular momentum of the solar system, Venus reverse rotation problems…… . Practice is the sole criterion for testing theory, laboratory come to the conclusion also subject to the test of practice can rise to the theory. use of vortex & gravitational force formula, explain and calculate the following questions. vortex force of 12 major criterion [quantitative calculation, high school students can master] 1. Mercury precession 43 "per century. (Newton's theory of deviation values.) 2. Venus precession 8.4 "± 4.8" per century. (Newton's theory of deviation values.) 3. Earth's precession 5.0 "± 1.2" per century. (Newton's theory of deviation values.) 4. "Pioneers 10" four spacecraft speed reduction. ( slowdown by the the acceleration : one part in 10 billion of gravity at Earth's surface ) 5.the moon Away from the Earth (3 cm per year). 6. Cycle of the Earth's rotation slows down. (Per hundred years 0.00164 s] , 7. Coriolis force whereabouts eastward. 8. Around Mars Phobos campaign cycle to slow down the week 0.1 ms 9. Sun-synchronous orbit satellite orbital plane precession; altitude of 900 km polar orbit satellite orbital plane precession of the daily 1 degree. The orbital plane of the vertical scroll relatively static, the situation in order to prove Scroll of the accuracy of the vortex force and an excellent opportunity. 10. Oblate of the Earth , 5 × 10-5m/s2. On the Global Positioning System GPS satellite orbit produces nearly 10,000 meters every day the impact of this phenomenon of vortex theory can be used to explain and calculate. Satellite orbit calculation of the largest perturbation of the - non-perturbation of the ball, not the flat rate from the Earth, but the role of the vortex. 11. Solar wind acceleration: time to reach the Earth, usually in the jet speed of 450 kilometers per second around. 12. With near 20years explore the more than 300 people each repeated verification; used Cavendish torsion balance measured vortex force of existence, and that formula New gravitational formula in the 2001 : F = Fn + Ft To the weight of Fn = GMm / r ^ 2 - Tangential component [vortex force] Ft = kGMm ω Cos α / r ^ 2 K = 0.4 for one factor,the unit: sec/Band ; ω is the angular velocity rotating ball, the unit: Band / sec; α to the orbital inclination. Reference: “mysterious vortex force- gravity partner ”Books Author: Zhuyonghuan Publisher: 21st Century Publishing House - China 2005-3 "
(zyh 4/20/2008 7:12:18 PM)
"= 8.51 × 10 ^ -5m From a year: 8.51 × 365 × 10 ^- 5 = 0.031m This is close the measured value "
(zyh 4/20/2008 7:17:22 PM)
"I seem to recall an SF story that included an interferometer in Earth orbit that acted as a 186-million-mile-wide lens...the narrative had the heroes zooming in on individual continents on planets in the Andromeda Galaxy...aside from the financial or technical aspects, is such resolution theoretically possible?"
( 8/8/2008 11:01:43 AM)

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