CLCACS "klickacs"
Posted: Thu Mar 05, 2015 4:11 pm
Cis-Lunar Collision Avoidance and Communications System: CLCACS "klickacs"
If anyone here is interested, I'm curious to see the numbers of what it would take to install a single facility at Lunar L1, that can provide interesting levels of surveillance, tracking and communications throughout cislunar space.
In order to launch a radar and communications array that can promote future space development and watch for Near Earth Objects, one needs a dielectric that can shrink the size and mass of a metallic antenna array hugely, and even that of a normal dielectric array by a serious factor. We're talking about the kind of array that one could compare to the ALTAIR array on Kwajalein--something on the order of a 10 MW installation. Even using a dielectric with astonishing qualities, we're talking about a BIG array. So here's what I'm wondering.
One wants to look at the mass a Falcon 9, a Falcon Heavy and SLS can loft to Lunar L1 and see if it is feasible to put several tons up with a single launch, then use several launches. If for example, one of these launch vehicles can lift 5T to LL1, then one could conceivably build a very large array with 6 launches.
In such an array, you might for example stipulate a hexagon assembly. each of the six trusses of that assembly could be launched as a single, light weight carbon fiber, hexagonal cross section craft of about 70 meters long and 5 meters diameter and storing PV panels and power equipment inside for launch; that when unfolded at LL1, would provide ~20? X 70 ~=1,400 square meters surface area facing one direction. Six such trusses could then be connected in a hexagon that lies radially on the plane of the Earth's orbit around the sun, at LL1. If one placed a light-weight ceramic dielectric antenna every 10cm on such a surface, they'd have an array of about 140,000 elements per truss. Such an array would be able to scan in all the important directions at once, send and receive both radar and VHF/UHF communications (300 Mhz) and could be capable of some astonishing feats.
For example, it appears to me possible such an array could track objects across all cislunar space down to a reasonable limit defined by their distance, but perhaps on the order of a golfball at greatest range. It is possible, such an array could repeat UHF communications from a lunar astronaut's suit, back to any lunar surface vehicle, any vehicle in cislunar space and even direct back to Earth. It's possible such an array could even track a Chinese lunar rover on the surface of the Moon--something DoD would take an interest in.
The point, is to consider what is in the realm of the possible and what is not. If we stipulate we have a next generation ceramic with a dielectric constant of 40,000 at 300 Mhz, this can be used to shrink a full wave antenna from 1 meter, to 0.5cm. A 1cm diameter antenna of this sort could send and receive with astonishing power. Put 840,000 of them into a single installation at the right point, and even one in the top of an astronaut's helmet, and there's no telling what is possible, at least without some calculation.
Certainly, such an array truss as proposed would weigh on the order of several tons. So first things first. Can Falcon 9, Falcon Heavy, or SLS loft several tons to LL1?
Secondly, given the distance between Earth and Luna, ~406,000 km; and the Lagrangian point between them as defined here in the first equation under "Mathematical details":
http://en.wikipedia.org/wiki/Lagrangian_point
how far would a transmitter on the Moon need to send to such an installation? How far would the installation need to be able to sense objects in space of sufficient size to be considered great threats to future spacecraft? 300,000 km? Is is reasonable to presume an array on the order of 50 MW transmitter power could cover all cislunar space in useful fashion? (Remember, radar transmitters only transmit periodically, so there is no trouble with collecting power at far less rate than using it to transmit. 1 MW installed PV power is likely more than necessary for a 50 MW array, and if each installation truss holds 2, 5mX65m PV panels, that is a lot of installed power. Just guessing but probably more than ISS by a factor or more.)
These are the kinds of questions I'm asking myself since this is the kind of project one could sell both NASA and DoD on, and that would eventually make it possible to build the spaceships. So it's a serious consideration. Anyone who wants to play with the numbers, please do share. I can't afford an engineer for this right now, and it would be great if there were enough answers to at least spark the interest of a radar and communications antenna miniaturization specialist I have in mind.
Falcon 9 launched the Deep Space Climate Observatory to Solar L1 and it weighs 570 kg. Is the energy requirement to Solar L1 smaller, larger or the same as to Lunar L1?
Note NASA's interest here:
http://www.nasa.gov/pdf/604657main_4-%2 ... bskill.pdf
If anyone here is interested, I'm curious to see the numbers of what it would take to install a single facility at Lunar L1, that can provide interesting levels of surveillance, tracking and communications throughout cislunar space.
In order to launch a radar and communications array that can promote future space development and watch for Near Earth Objects, one needs a dielectric that can shrink the size and mass of a metallic antenna array hugely, and even that of a normal dielectric array by a serious factor. We're talking about the kind of array that one could compare to the ALTAIR array on Kwajalein--something on the order of a 10 MW installation. Even using a dielectric with astonishing qualities, we're talking about a BIG array. So here's what I'm wondering.
One wants to look at the mass a Falcon 9, a Falcon Heavy and SLS can loft to Lunar L1 and see if it is feasible to put several tons up with a single launch, then use several launches. If for example, one of these launch vehicles can lift 5T to LL1, then one could conceivably build a very large array with 6 launches.
In such an array, you might for example stipulate a hexagon assembly. each of the six trusses of that assembly could be launched as a single, light weight carbon fiber, hexagonal cross section craft of about 70 meters long and 5 meters diameter and storing PV panels and power equipment inside for launch; that when unfolded at LL1, would provide ~20? X 70 ~=1,400 square meters surface area facing one direction. Six such trusses could then be connected in a hexagon that lies radially on the plane of the Earth's orbit around the sun, at LL1. If one placed a light-weight ceramic dielectric antenna every 10cm on such a surface, they'd have an array of about 140,000 elements per truss. Such an array would be able to scan in all the important directions at once, send and receive both radar and VHF/UHF communications (300 Mhz) and could be capable of some astonishing feats.
For example, it appears to me possible such an array could track objects across all cislunar space down to a reasonable limit defined by their distance, but perhaps on the order of a golfball at greatest range. It is possible, such an array could repeat UHF communications from a lunar astronaut's suit, back to any lunar surface vehicle, any vehicle in cislunar space and even direct back to Earth. It's possible such an array could even track a Chinese lunar rover on the surface of the Moon--something DoD would take an interest in.
The point, is to consider what is in the realm of the possible and what is not. If we stipulate we have a next generation ceramic with a dielectric constant of 40,000 at 300 Mhz, this can be used to shrink a full wave antenna from 1 meter, to 0.5cm. A 1cm diameter antenna of this sort could send and receive with astonishing power. Put 840,000 of them into a single installation at the right point, and even one in the top of an astronaut's helmet, and there's no telling what is possible, at least without some calculation.
Certainly, such an array truss as proposed would weigh on the order of several tons. So first things first. Can Falcon 9, Falcon Heavy, or SLS loft several tons to LL1?
Secondly, given the distance between Earth and Luna, ~406,000 km; and the Lagrangian point between them as defined here in the first equation under "Mathematical details":
http://en.wikipedia.org/wiki/Lagrangian_point
how far would a transmitter on the Moon need to send to such an installation? How far would the installation need to be able to sense objects in space of sufficient size to be considered great threats to future spacecraft? 300,000 km? Is is reasonable to presume an array on the order of 50 MW transmitter power could cover all cislunar space in useful fashion? (Remember, radar transmitters only transmit periodically, so there is no trouble with collecting power at far less rate than using it to transmit. 1 MW installed PV power is likely more than necessary for a 50 MW array, and if each installation truss holds 2, 5mX65m PV panels, that is a lot of installed power. Just guessing but probably more than ISS by a factor or more.)
These are the kinds of questions I'm asking myself since this is the kind of project one could sell both NASA and DoD on, and that would eventually make it possible to build the spaceships. So it's a serious consideration. Anyone who wants to play with the numbers, please do share. I can't afford an engineer for this right now, and it would be great if there were enough answers to at least spark the interest of a radar and communications antenna miniaturization specialist I have in mind.
Falcon 9 launched the Deep Space Climate Observatory to Solar L1 and it weighs 570 kg. Is the energy requirement to Solar L1 smaller, larger or the same as to Lunar L1?
Note NASA's interest here:
http://www.nasa.gov/pdf/604657main_4-%2 ... bskill.pdf