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Stuff in orbit is always falling down toward the planet, but always missing on account of its sideways motion. The closer the orbiter is to the planet, the harder it is to miss it as it is falling. But it is still possible, provided there is enough sideways motion.
I propose that a VLO {very
low orbit) device be constructed and set into orbit around the moon. I choose the moon for its lack of atmosphere, which otherwise would slow the VLO and make it crash. The VLO would be set into orbit about 2 feet (or 1 meter) off the ground. A path would need to be carefully cleared and marked, as a rock in the way would have tragic consequences. The device would need to be very shiny, to reflect rays which might push it down toward the surface.
A railgun might be used to start the VLO. The railgun would need to be quickly moved out of the way as the VLO completed its first orbit. The VLO would be good for all the usual sort of things very low lunar satellites are good for, except it would be better, because it is lower.
Earth Space Web
http://www.halfbake...a/Earth-Space_20Web
Inspiration! [bungston, Oct 05 2004, last modified Oct 17 2004]
Light mill
http://math.ucr.edu...ill/light-mill.html
That's how they chop light rays into photons. [kbecker, Oct 05 2004, last modified Oct 17 2004]
Annotation:
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Wonderfully weird and directionless. Have a pastry. |
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The thing would be going at about 6000 km/h and complete a circle every hour and 50 minutes. |
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It would take a big rail gun. You could also start it in a high orbit and gradually decrease the altitude. |
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Make one end shiny and other end black. Launch it in a plane that is parallel to the plane of the earth orbit, but still around the moon. Now you have a light mill (link) circling the moon.
To launch float it on magnetic rails and let the sun do the acceleration until orbital speed is achieved. Then pull off the carriage real fast to make it fly. |
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"The device would need to be very shiny, to reflect rays which might push it down toward the surface."
Hello? |
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And after you answer that one: Why? |
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[phoenix] is technically correct, absorbing a photon in a black surface just picks up a single push. Reflecting it gives a double push because of the recoil when it goes back. To eliminate the push make the device from a cylinder of glass with just coated ends.
Will look nice from earth when the device just comes around the moon: "Ahhh, look, Bungston's rod is rising" |
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To answer [phoenix]' last question: Because! |
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I for one don't need to see [bungston]'s rod rising. |
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I've seen the videos. It's not much, really... |
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A very low orbit baby.. I love what you've got
Let's get constructing, we can... Weld hot
No more atmosphere, baby.. Tide is today
Girl, I can clear and mark...Okay
This thing is very shiny, baby..To reflect the sun
You pull the trigger of my gun
Rail gun, (rail gun), rail gun
Rail gun, (rail gun), rail gun... |
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"all the usual sort of things very low lunar satellites are good for" - name one! (Especially given that we don't currently have anyone on the Moon.) |
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I really like the glass rod concept, and the physics assistance. Much better. I highly recommend the light mill link. [Deathninja], I am cancelling your membership to my website. Don't care if you're paid up for this month. |
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Ahh, [Curry, Curry, Curry]. The myriad uses of a very low lunar satellite. Where to begin? |
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The sky is falling....the sky is falling... |
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On reading the light mill paper, I am not sure that this would work on the moon since it seems that a small amount of residual gas is necessary for the vanes to turn. Or perhaps the lunar atmosphere is not actually a vacuum, but just very thin, so that this small amount of gas exists there? |
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The undisturbed lunar atmosphere exists, but is much more rarified than anything we've managed to create on earth. There are details in the "light mill" article that more deeply explain the physics of the radiometer (that it doesn't have much to do with thermal pressure, but rather thermal creep at the edges). |
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Please, enlighten us on the multiple uses of an extremely low orbit lunar satellite moving at 6000 km/hr? |
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You could play that game where you stand on the moon as the satellite approaches and jump just before it hits you. |
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1: Anyone able to view the VLO could use it as a clock.
2: The VLO could be used to relay messages to the far side of the moon and vice versa, without stringing up cumbersome phone lines.
3: An LED strip on the VLO could change such that as it sped by, the illusion of a message would be left on the viewer's eye (like those strips which appear to be an eye of seen while turning the head). This could be used for advertising purposes.
4. Slight orbital variations of the VLO could be used as a rapid meteor impact detector.
5. The VLO would be a mascot for the new lunar program, and would be depicted on T-shirts, caps and stationery. Elementary school sports teams would be named the V-Los, or maybe the VLO Riders.
6. The VLO would invigorate the "space race", stimulating nations to invest money into building and launching lower, faster VLO devices. To save on clearing the paths, these would orbit in parallel.
7. Once VLO technology had matured, different companies could offer objects which could be launched along the VLO trajectory. Sports cars, golf clubs, candy bars and other consumer goods would be set into very low orbit as publicity stunts, as well as to test durability at very high speeds under lunar conditions.
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That's all I have right now. I think it adequately makes the case. Like the personal computer and internet, other uses for the VLO will be devised once it exists. |
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2 feet off the ground. Ha! I'd expect at least under an inch for a _real_ low orbit device. |
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This might entail extensive excavations (beyond moving mountains) as the moon is probably not perfectly round +/- 2 feet. |
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If the transparent cylinder model is used, excavations might be limited to a simple tunnel the diameter of the VLO. Mountains would be left in place. In addition, rocks weigh considerably less on the moon, making excavations less difficult. I grant that some extensive survey work will be needed before setting the VLO in motion. |
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Or you could have just said you meant 2 feet off the highest point. |
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where is the fun in that? |
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Explosive VLOs would help with that plan. Although at 6000 km/h explosives might be superfluous. |
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If you use a laser to very precisely determine the orbital altitude at various points along the path, it seems you could produce an extremely sensitive gravity wave detector. If you're serious about making such a detector, the lunar VLO may actually be more cost-effective than an earth based solution for a similar sensitivity. |
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Ooooooh. There you go. Application. |
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Go to NASA if you want to throw around applications. This site is reserved for avant garde engineers and scientists. |
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I don't know the exact maths (never my strong point), but considering Kepler's third law, I think 6000 klicks per hour is being very conservative. |
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The formula you want is v = sqrt(G * M / R) where v is orbital velocity, G is the universal gravitational constant, M is the mass of the moon, and R is the radius of the orbit. |
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M = 7.349 * 10^22 kg
R = 1738.1 km
G = 6.67300 * 10^-11 m^3 kg^-1 s^-2
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It goes slower than a low earth orbit because the mass is not very big in this case. |
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[AO] - It took me 9 months to revisit this idea, but thank you for the equation. I did the math and found a speed of 53117 meters/second, or 191222 km/ hour. Which means a full circuit would take 32 seconds. |
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I was thinking about the VLO orbiter because I was pondering how to illuminate the inside of Pellucidar, or some other celestial-sized hollow body, and still have day and night. An object inside a very large sphere should still orbit the center of mass of that sphere. Thus a lunimous device like the VLO orbiter, orbiting about 1 km inwards from the inner surface of the sphere should provide a change of night and day for the inhabitants. Very short nights and days. |
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Umm... how exactly will this lumnous body produce a day and night? I mean I suppose the inverse square law and all proves that it will be somwhat darker on the far side than on the near side... |
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Or will this luminous body be illuminated on only one side? I'd imagine you'd have as much luck setting it up so it's got a polar orbit, and shines in through the 800 mile wide holes above the north and south poles. |
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In general, orbiting inside a hollow body is dangerous, as the masscons would be killer. |
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A one sided luminosity would be necessary. Given that each day would be only a few minutes long, I agree that a different mechanism for illumination would be necessary. |
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//An object inside a very large sphere should still orbit the center of mass of that sphere.// Actually, an object inside of a hollow sphere experiences no gravity, and thereby has nothing to orbit. I'll refrain from the math demo unless it is requested. |
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//I did the math and found a speed of 53117 meters/second, or 191222 km/ hour. Which means a full circuit would take 32 seconds.// You neglected to convert the radius of the moon from kilometers to meters. Had you done so, you would have come up with about 6026 km/hr, as [AO] said. (A professor used to tell me: "Nothing screws up a good math problem like a bit of arithmetic.") |
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