Devin Crowe gave an update on the NASA NIAC study on one-kilometer space bubble telescopes.
The plan is bring liquid and gas and blow a large spherical bubble and then shine a wavelength to solify the material. They would spray part of the bubble with a very thin metal layer to make a reflective telescope.
They have simulated that a one-kilometer telescope would be able to image Jupiter and its four largest moons from a distance of 7 parsecs.
There has been work done with one meter metalized glass spheres as a telescope in the stratosphere. There is follow up work for a ten meter metalized mylar sphere as a telescope.
A cubesat would be able to hold the bubble liquid and gas to inflate a 2-meter diameter metalized sphere.
They would want to create a 30 meter space bubble telescope and then a 100 meter and then a 1000 meter space telescope.
Brian Wang is a Futurist Thought Leader and a popular Science blogger with 1 million readers per month. His blog Nextbigfuture.com is ranked #1 Science News Blog. It covers many disruptive technology and trends including Space, Robotics, Artificial Intelligence, Medicine, Anti-aging Biotechnology, and Nanotechnology.
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Propulsion systems are interesting, but even the best systems on the drawing boards would take centuries to get a human to the nearest stars. Spend 10 years to build a better telescope and you can instantly learn more about the nearest stars, as well as stars completely out of reach of our travel. Better yet, do both. Which we are doing of course, to some extent. If we didn’t blow hundreds of millions of dollars on government-subsidized sports stadiums, or totally redundant nuclear weapons, we’d be a lot farther along by now.
Why on Earth we need more telescopes, if we are not able to reach the closest planet, let alone a star. In the meantime companies which work on propulsion are starved of funds.
Very ingenious idea!
Propulsion systems are interesting but even the best systems on the drawing boards would take centuries to get a human to the nearest stars. Spend 10 years to build a better telescope and you can instantly learn more about the nearest stars as well as stars completely out of reach of our travel.Better yet do both. Which we are doing of course to some extent. If we didn’t blow hundreds of millions of dollars on government-subsidized sports stadiums or totally redundant nuclear weapons we’d be a lot farther along by now.
Why on Earth we need more telescopes if we are not able to reach the closest planet let alone a star. In the meantime companies which work on propulsion are starved of funds.
Very ingenious idea!
space has a lot of…space.
It worked for Sauron.
so, after centuries of building telescopes, the best we can come up with is a giant EYEBALL in space? Not that I’m complaining, if it works then Great! Just odd that we still can’t do better than evolution in some aspects.
It’s always been about *knowing,* not necessarily about *going.* Telescopes generally don’t care if they’re looking at objects in this solar system (where there’s a chance of eventual human missions), or galaxies billions of light years away. For space probes however, those are rather different challenges…
I would really be shocked if they could get a good enough figure on that bubble to make it work. We’re talking fractional wavelengths over a kilometer, after all.
So they want to put this 1 km telescope in EML2. China put a satellite there recently, NASA wants (wanted?) a manned outpost there, it’s a good place for a fuel depot, and maybe some other things. How much room is there in EML2? I understand these objects would be in halo orbits, but how big are these orbits? How many? At what spacings?
space has a lot of…space.
It worked for Sauron.
so after centuries of building telescopes the best we can come up with is a giant EYEBALL in space? Not that I’m complaining if it works then Great! Just odd that we still can’t do better than evolution in some aspects.
It’s always been about *knowing* not necessarily about *going.*Telescopes generally don’t care if they’re looking at objects in this solar system (where there’s a chance of eventual human missions) or galaxies billions of light years away.For space probes however those are rather different challenges…
I would really be shocked if they could get a good enough figure on that bubble to make it work. We’re talking fractional wavelengths over a kilometer after all.
So they want to put this 1 km telescope in EML2. China put a satellite there recently NASA wants (wanted?) a manned outpost there it’s a good place for a fuel depot and maybe some other things. How much room is there in EML2? I understand these objects would be in halo orbits but how big are these orbits? How many? At what spacings?
Yah. That’s not going to happen. I can think of almost a dozen reasons why… • (1) electric charge anisotropies • (2) film tension anisotropies • (3) film thickness variation • (4) film metalization effects • (5) chaotic cosmic ray degradation • (6) local micro-heating • (7) positioning shear and strain • (8) unsuppressable inertial wobble (1) ELECTRIC CHARGE ANISOTROPIES: Space is full of protons. We know that the flux varies a LOT. Implied is the same ion flux also varies substantially over macroscopic scales… Such variations will definitely “attract the film” variously. (2) FILM TENSION ANISOTROPIES: As parts of the film harden, the film will come under varying tension gradients. These in turn work directly to pull the spherical ideal out of shape. • (3) FILM THICKNESS VARIATION: most easily seen on the playground, using “big fuzzy hoops” to blow a big soap bubble. Remember how as it floats about, a stage is reached where it is madly swirling with various ranbow colors? These come from interference of light from the extremely thin film losing water vapor. DIFFERENT colors shows anisotropic thickness evolution. • (4) FILM METALIZATION EFFECTS: similar to (3), the metalization of the film will not be isotropic. Since the film is very thin, the metalization will be a larger fraction of the film’s mass. Thus, its variation will vary the local film tension. • (5) CHAOTIC COSMIC RAY DEGRADATION: Over time incoming cosmic rays vary. Indirectly they also vary, unpredictably, spatially spatially. This will cause radiation-absorbed hardening and both polymerization and depolymerization of the underlying prime focus film. • (6) LOCAL MICRO-HEATING: That great big sun-shade will be good — arguably perfect — but the entropy of the local interplanetary medium will heat-and-cool the film. Chaotically, due to small differences in density, in local ionization : neutral atom ratios, and so forth. • (7) POSITIONING SHEAR AND STRAIN: It isn’t likely to po
Yah. That’s not going to happen. I can think of almost a dozen reasons why…• (1) electric charge anisotropies• (2) film tension anisotropies• (3) film thickness variation• (4) film metalization effects• (5) chaotic cosmic ray degradation• (6) local micro-heating• (7) positioning shear and strain• (8) unsuppressable inertial wobble(1) ELECTRIC CHARGE ANISOTROPIES: Space is full of protons. We know that the flux varies a LOT. Implied is the same ion flux also varies substantially over macroscopic scales… Such variations will definitely attract the film”” variously.(2) FILM TENSION ANISOTROPIES: As parts of the film harden”” the film will come under varying tension gradients. These in turn work directly to pull the spherical ideal out of shape. • (3) FILM THICKNESS VARIATION: most easily seen on the playground”” using “”””big fuzzy hoops”””” to blow a big soap bubble. Remember how as it floats about”” a stage is reached where it is madly swirling with various ranbow colors? These come from interference of light from the extremely thin film losing water vapor. DIFFERENT colors shows anisotropic thickness evolution. • (4) FILM METALIZATION EFFECTS: similar to (3) the metalization of the film will not be isotropic. Since the film is very thin the metalization will be a larger fraction of the film’s mass. Thus its variation will vary the local film tension.• (5) CHAOTIC COSMIC RAY DEGRADATION: Over time incoming cosmic rays vary. Indirectly they also vary unpredictably spatially spatially. This will cause radiation-absorbed hardening and both polymerization and depolymerization of the underlying prime focus film. • (6) LOCAL MICRO-HEATING: That great big sun-shade will be good — arguably perfect — but the entropy of the local interplanetary medium will heat-and-cool the film. Chaotically due to small differences in density in local ionization : neutral atom ratios and so forth. • (7) POSITIONING SHEAR AND STRAIN”
Good. I just don’t think we will EVER be getting “humans to the local stars”, in the “live today, landing tomorrow” sense. Interstellar distances are profoundly huge. Almost beyond comprehension to the likes of us “mere mortals”. EVEN in the case of a “fly-by”, the timeframes and numbers are huge. At least for semi-conventional rocket propulsion. ______ As you might have followed here (or at dozens of other sites), the choice is either “conventional physics”, or “magic wand physics” to accelerate a space probe. Further, at the outset, you either have a choice of sending something big-and-human (and all her life-support requirements), or something presumabaly relatively compact, small, electronic… a rich assortment of tiny optical and physics “package” sensors on board. These are essentially binary design decisions. Using “max physics, with realistic expectations…” Well, ISP = 200,000 implies mv = 2,000,000 newton-seconds of thrust per kilogram of fully realized burned fuel. That’s quite nice. Assuming that one could build a spacecraft with multiple expendable (just to get rid of overhead mass) stages, say 5 of them, and starting with a payload of just 1000 kg (i.e. a very sophisticated physics package, no humans), then … Doesn’t matter whether you use Tsiolkovsky’s rocket equation or piecewise integration of declining rest masses, it all works out the same. 5 stages, respectively with (450, 2,000, 9,500, 44,000 and finally 200,000 ISP) per stage (recognizing scaling issues), delivers the final 1,000 kg probe at 1.5% of c, able to make it to Alpha Cen in 270 years. ± of course. And that’s depressing. Because it is 100× to 250× too small, and at least 5× too slow. For humans. Just saying. GoatGuy
Good.I just don’t think we will EVER be getting humans to the local stars”””” in the “”””live today”””” landing tomorrow”””” sense. Interstellar distances are profoundly huge. Almost beyond comprehension to the likes of us “”””mere mortals””””. EVEN in the case of a “”””fly-by”””””” the timeframes and numbers are huge. At least for semi-conventional rocket propulsion. ______As you might have followed here (or at dozens of other sites)”” the choice is either “”””conventional physics”””””””” or “”””magic wand physics”””” to accelerate a space probe. Further”” at the outset you either have a choice of sending something big-and-human (and all her life-support requirements) or something presumabaly relatively compact small”” electronic… a rich assortment of tiny optical and physics “”””package”””” sensors on board. These are essentially binary design decisions. Using “”””max physics”””” with realistic expectations…””””Well”” ISP = 200000 implies mv = 20000 newton-seconds of thrust per kilogram of fully realized burned fuel. That’s quite nice. Assuming that one could build a spacecraft with multiple expendable (just to get rid of overhead mass) stages say 5 of them and starting with a payload of just 1000 kg (i.e. a very sophisticated physics package no humans) then …Doesn’t matter whether you use Tsiolkovsky’s rocket equation or piecewise integration of declining rest masses it all works out the same. 5 stages respectively with (45020950044000 and finally 200000 ISP) per stage (recognizing scaling issues) delivers the final 1000 kg probe at 1.5{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} of c able to make it to Alpha Cen in 270 years. ± of course.And that’s depressing. Because it is 100× to 250× too small”” and at least 5× too slow.For humans. Just saying.GoatGuy”””””””
In college I had the idea of using a photoconductive film as a rapidly focusable zone plate for terrahertz radiation, by projecting an image of the desired zone plate on the film. A variation of that concept could work here, using a photosensitive film converted into a zone plate by an interference pattern of light of a frequency different from what the zone plate was meant to focus. Perhaps you could use a bilayer film, with the light that generated the zones blocked by the second, supporting layer.
I think manned interstellar flight in a ‘reasonable” (less than a lifespan) flight time could be possible using beamed propulsion, but the infrastructure requirements would be astronomical. Terra watts of power would be needed. I do think we’ll have Von Neumann machines before the end of the century, (Before the middle of it if we really try.) and “shortly” after astronomical amounts of infrastructure would be available, if the will is there to apply it in that manner. Such technology is necessary to a lot of space applications, because life in space is so infrastructure intensive.
If you want to do something like this, you need an approach that doesn’t require fractional wavelength precision. I’m not certain, but a zone plate might satisfy that requirement.
In college I had the idea of using a photoconductive film as a rapidly focusable zone plate for terrahertz radiation by projecting an image of the desired zone plate on the film. A variation of that concept could work here using a photosensitive film converted into a zone plate by an interference pattern of light of a frequency different from what the zone plate was meant to focus. Perhaps you could use a bilayer film with the light that generated the zones blocked by the second supporting layer.
I think manned interstellar flight in a ‘reasonable (less than a lifespan) flight time could be possible using beamed propulsion but the infrastructure requirements would be astronomical. Terra watts of power would be needed.I do think we’ll have Von Neumann machines before the end of the century” (Before the middle of it if we really try.) and “”shortly”””” after astronomical amounts of infrastructure would be available”” if the will is there to apply it in that manner.Such technology is necessary to a lot of space applications”” because life in space is so infrastructure intensive.”””
If you want to do something like this you need an approach that doesn’t require fractional wavelength precision. I’m not certain but a zone plate might satisfy that requirement.
Obligatory: That’s no moon!
Obligatory: That’s no moon!
… possible using beamed propulsion … Dunno. I will have to map beamed-energy stored-and-beamed neutral matter. It is wickedly expensive to neutral-beam matter by the kiloton around. Doesn’t matter how you go about it, it takes exawatts of juice to beam kilograms-per-second of neutral matter at basically relativistic speed. No, even more than that. E = ½mv² … v = 10% c = 30,000,000 m/s, m = 1 kg/s E = 450 terawatts That’s the kinetic energy of a continuous beam. One might conceive of beaming along a similar amount of optical power (since our hapless space flyer doesn’t carry prodigious power, and is going to need a bunch of it to take the intercepted beam and turn it backward, to accelerate it away in the Ultimate ΔV caper. Well, those are huge numbers. Around 1,000,000,000,000,000 watts of invested power. Who knows how much additional to MAKE the collimated beam, to pump the lasers. 3× that? 5×? 10×? The sky’s the limit. However, this kind of beam would have bâhlls, baby. Big cajunas. Mayhaps our rocket flyer weighs in at what, 1,000 tons … to carry enough stuff for its entourage of bumpkins and for-pay sciencey types to be aboard, and “live” for the nearly indefinite trip? And it carries at leat 10,000 tons of reaction mass — the part you’d just not want to waste the money accelerating. From the neutral beam, we’re probably good out to 2 AU. 30,000,000 N-s/s of neutral beam, fully deflected “out there”. (0.1) … F = ma (0.2) … a = F/m (0.3) … a = 30,000,000 ÷ 12,500,000 kg (0.4) … a = 2.4 m/s². Wicked cool. And that’s before employing much of the piggy-backed laser. Just working with that and 2 AU (and not the onboard mass, nor the incoming laser), (1.1) … D = ½at² (1.2) … t = √( 2D/a ) (1.3) … t = √( 2 × ( 2 × 149,500,000,000 ) ÷ 2.4 m/s² ) (1.4) … t = 500,000 sec (2.1) … v = at (2.2) … v = 2.4 × 500,000 sec (2.3) … v = 1,200,000 m/s (2.4) … v = 100,000,000 km/day (2.5) … v = 0.69 AU/day (3.1) … Centauri = 4.1 LY × 63
… possible using beamed propulsion … Dunno. I will have to map beamed-energy stored-and-beamed neutral matter. It is wickedly expensive to neutral-beam matter by the kiloton around. Doesn’t matter how you go about it it takes exawatts of juice to beam kilograms-per-second of neutral matter at basically relativistic speed. No even more than that. E = ½mv² … v = 10{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} c = 30000000 m/s m = 1 kg/sE = 450 terawattsThat’s the kinetic energy of a continuous beam. One might conceive of beaming along a similar amount of optical power (since our hapless space flyer doesn’t carry prodigious power and is going to need a bunch of it to take the intercepted beam and turn it backward to accelerate it away in the Ultimate ΔV caper. Well those are huge numbers. Around 1000000000000000 watts of invested power. Who knows how much additional to MAKE the collimated beam to pump the lasers. 3× that? 5×? 10×? The sky’s the limit. However this kind of beam would have bâhlls baby. Big cajunas. Mayhaps our rocket flyer weighs in at what 1000 tons … to carry enough stuff for its entourage of bumpkins and for-pay sciencey types to be aboard and live”” for the nearly indefinite trip? And it carries at leat 10″”000 tons of reaction mass — the part you’d just not want to waste the money accelerating. From the neutral beam we’re probably good out to 2 AU. 300000 N-s/s of neutral beam”” fully deflected “”””out there””””. (0.1) … F = ma(0.2) … a = F/m (0.3) … a = 30″”0000 ÷ 12500000 kg (0.4) … a = 2.4 m/s². Wicked cool. And that’s before employing much of the piggy-backed laser. Just working with that and 2 AU (and not the onboard mass nor the incoming laser) (1.1) … D = ½at²(1.2) … t = √( 2D/a )(1.3) … t = √( 2 × ( 2 × 1495000000 ) ÷ 2.4 m/s² )(1.4) … t = 500000 sec(2.1) … v = at(2.2) … v = 2.4 × 500000 sec(2.3) … v = 1200000 m/s (2.4) … v = 1000″
A spherical mirror doesn’t focus on a point. It would need a smaller correction mirror.
A spherical mirror doesn’t focus on a point. It would need a smaller correction mirror.
Everything interstellar is very difficult. You’re assuming the beam can be held together for 2 AU, I’m assuming it can be held together for more like thousands of them. After all, Doppler cooling can take atoms down to temperatures well under a mK, the perpendicular component of the beam velocity is measured in centimeters per second. If the beam is relativistic, it will only spread a few meters per AU. So, what you do is put additional beam focusing/cooling (You can Doppler focus, too.) stations along the beam, which will intercept any leakage, and be pulled along by it. Eventually you’ve got a beam as long as a light year, with stations along it cooling and focusing. And, because the interaction with the beam is optical, *the stations have a big hole the beam goes through.* Your starship goes through that hole, too… However, I would rather make the “particles” large enough, as I said upthread, to have their own guidance and propulsion systems. This Project Starshot is better thought of as a mass beamer than a way of sending probes. Even after the tiny sails aren’t being pushed along much, they can still do course corrections by using the beam, and home in on a beacon on the starship. Once your particles are capable of course corrections, they don’t diverge at all. But, yes, all these schemes require many terawatts of power to accomplish for manned ships. Let’s get started on that statite array to power it.
Everything interstellar is very difficult.You’re assuming the beam can be held together for 2 AU I’m assuming it can be held together for more like thousands of them. After all Doppler cooling can take atoms down to temperatures well under a mK the perpendicular component of the beam velocity is measured in centimeters per second. If the beam is relativistic it will only spread a few meters per AU.So what you do is put additional beam focusing/cooling (You can Doppler focus too.) stations along the beam which will intercept any leakage and be pulled along by it. Eventually you’ve got a beam as long as a light year with stations along it cooling and focusing. And because the interaction with the beam is optical *the stations have a big hole the beam goes through.*Your starship goes through that hole too…However I would rather make the particles”” large enough”” as I said upthread to have their own guidance and propulsion systems. This Project Starshot is better thought of as a mass beamer than a way of sending probes. Even after the tiny sails aren’t being pushed along much they can still do course corrections by using the beam and home in on a beacon on the starship.Once your particles are capable of course corrections they don’t diverge at all.But yes”” all these schemes require many terawatts of power to accomplish for manned ships. Let’s get started on that statite array to power it.”””
I wish I had GoatGuy’s analytical math ability. If I had to design this system I would have a central focal/processing module with 60 playground “soap bubbles.” This is a camera not a video machine, so I decide to look at something of interest, blow the bubble (necessarily spherical, not parabolic), cut the bubble in the direction of interest, calibrate the bubble with a known object in the desired field, then “photograph” the desired image/field. Computing is cheap, bandwidth is getting cheaper, possibly do the computing on the ground if less than 1 light second to bubble, don’t look at this as a permanent machine like Hubble.
I wish I had GoatGuy’s analytical math ability. If I had to design this system I would have a central focal/processing module with 60 playground soap bubbles.””This is a camera not a video machine”” so I decide to look at something of interest blow the bubble (necessarily spherical not parabolic) cut the bubble in the direction of interest calibrate the bubble with a known object in the desired field”” then “”””photograph”””” the desired image/field. Computing is cheap”” bandwidth is getting cheaper possibly do the computing on the ground if less than 1 light second to bubble”” don’t look at this as a permanent machine like Hubble.”””
I wish I had GoatGuy’s analytical math ability. If I had to design this system I would have a central focal/processing module with 60 playground “soap bubbles.”
This is a camera not a video machine, so I decide to look at something of interest, blow the bubble (necessarily spherical, not parabolic), cut the bubble in the direction of interest, calibrate the bubble with a known object in the desired field, then “photograph” the desired image/field. Computing is cheap, bandwidth is getting cheaper, possibly do the computing on the ground if less than 1 light second to bubble, don’t look at this as a permanent machine like Hubble.
Everything interstellar is very difficult. You’re assuming the beam can be held together for 2 AU, I’m assuming it can be held together for more like thousands of them. After all, Doppler cooling can take atoms down to temperatures well under a mK, the perpendicular component of the beam velocity is measured in centimeters per second. If the beam is relativistic, it will only spread a few meters per AU. So, what you do is put additional beam focusing/cooling (You can Doppler focus, too.) stations along the beam, which will intercept any leakage, and be pulled along by it. Eventually you’ve got a beam as long as a light year, with stations along it cooling and focusing. And, because the interaction with the beam is optical, *the stations have a big hole the beam goes through.* Your starship goes through that hole, too… However, I would rather make the “particles” large enough, as I said upthread, to have their own guidance and propulsion systems. This Project Starshot is better thought of as a mass beamer than a way of sending probes. Even after the tiny sails aren’t being pushed along much, they can still do course corrections by using the beam, and home in on a beacon on the starship. Once your particles are capable of course corrections, they don’t diverge at all. But, yes, all these schemes require many terawatts of power to accomplish for manned ships. Let’s get started on that statite array to power it.
Everything interstellar is very difficult.You’re assuming the beam can be held together for 2 AU I’m assuming it can be held together for more like thousands of them. After all Doppler cooling can take atoms down to temperatures well under a mK the perpendicular component of the beam velocity is measured in centimeters per second. If the beam is relativistic it will only spread a few meters per AU.So what you do is put additional beam focusing/cooling (You can Doppler focus too.) stations along the beam which will intercept any leakage and be pulled along by it. Eventually you’ve got a beam as long as a light year with stations along it cooling and focusing. And because the interaction with the beam is optical *the stations have a big hole the beam goes through.*Your starship goes through that hole too…However I would rather make the particles”” large enough”” as I said upthread to have their own guidance and propulsion systems. This Project Starshot is better thought of as a mass beamer than a way of sending probes. Even after the tiny sails aren’t being pushed along much they can still do course corrections by using the beam and home in on a beacon on the starship.Once your particles are capable of course corrections they don’t diverge at all.But yes”” all these schemes require many terawatts of power to accomplish for manned ships. Let’s get started on that statite array to power it.”””
A spherical mirror doesn’t focus on a point. It would need a smaller correction mirror.
A spherical mirror doesn’t focus on a point. It would need a smaller correction mirror.
Everything interstellar is very difficult.
You’re assuming the beam can be held together for 2 AU, I’m assuming it can be held together for more like thousands of them. After all, Doppler cooling can take atoms down to temperatures well under a mK, the perpendicular component of the beam velocity is measured in centimeters per second. If the beam is relativistic, it will only spread a few meters per AU.
So, what you do is put additional beam focusing/cooling (You can Doppler focus, too.) stations along the beam, which will intercept any leakage, and be pulled along by it. Eventually you’ve got a beam as long as a light year, with stations along it cooling and focusing. And, because the interaction with the beam is optical, *the stations have a big hole the beam goes through.*
Your starship goes through that hole, too…
However, I would rather make the “particles” large enough, as I said upthread, to have their own guidance and propulsion systems. This Project Starshot is better thought of as a mass beamer than a way of sending probes. Even after the tiny sails aren’t being pushed along much, they can still do course corrections by using the beam, and home in on a beacon on the starship.
Once your particles are capable of course corrections, they don’t diverge at all.
But, yes, all these schemes require many terawatts of power to accomplish for manned ships. Let’s get started on that statite array to power it.
… possible using beamed propulsion … Dunno. I will have to map beamed-energy stored-and-beamed neutral matter. It is wickedly expensive to neutral-beam matter by the kiloton around. Doesn’t matter how you go about it, it takes exawatts of juice to beam kilograms-per-second of neutral matter at basically relativistic speed. No, even more than that. E = ½mv² … v = 10% c = 30,000,000 m/s, m = 1 kg/s E = 450 terawatts That’s the kinetic energy of a continuous beam. One might conceive of beaming along a similar amount of optical power (since our hapless space flyer doesn’t carry prodigious power, and is going to need a bunch of it to take the intercepted beam and turn it backward, to accelerate it away in the Ultimate ΔV caper. Well, those are huge numbers. Around 1,000,000,000,000,000 watts of invested power. Who knows how much additional to MAKE the collimated beam, to pump the lasers. 3× that? 5×? 10×? The sky’s the limit. However, this kind of beam would have bâhlls, baby. Big cajunas. Mayhaps our rocket flyer weighs in at what, 1,000 tons … to carry enough stuff for its entourage of bumpkins and for-pay sciencey types to be aboard, and “live” for the nearly indefinite trip? And it carries at leat 10,000 tons of reaction mass — the part you’d just not want to waste the money accelerating. From the neutral beam, we’re probably good out to 2 AU. 30,000,000 N-s/s of neutral beam, fully deflected “out there”. (0.1) … F = ma (0.2) … a = F/m (0.3) … a = 30,000,000 ÷ 12,500,000 kg (0.4) … a = 2.4 m/s². Wicked cool. And that’s before employing much of the piggy-backed laser. Just working with that and 2 AU (and not the onboard mass, nor the incoming laser), (1.1) … D = ½at² (1.2) … t = √( 2D/a ) (1.3) … t = √( 2 × ( 2 × 149,500,000,000 ) ÷ 2.4 m/s² ) (1.4) … t = 500,000 sec (2.1) … v = at (2.2) … v = 2.4 × 500,000 sec (2.3) … v = 1,200,000 m/s (2.4) … v = 100,000,000 km/day (2.5) … v = 0.69 AU/day (3.1) … Centauri = 4.1 LY × 63
… possible using beamed propulsion … Dunno. I will have to map beamed-energy stored-and-beamed neutral matter. It is wickedly expensive to neutral-beam matter by the kiloton around. Doesn’t matter how you go about it it takes exawatts of juice to beam kilograms-per-second of neutral matter at basically relativistic speed. No even more than that. E = ½mv² … v = 10{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} c = 30000000 m/s m = 1 kg/sE = 450 terawattsThat’s the kinetic energy of a continuous beam. One might conceive of beaming along a similar amount of optical power (since our hapless space flyer doesn’t carry prodigious power and is going to need a bunch of it to take the intercepted beam and turn it backward to accelerate it away in the Ultimate ΔV caper. Well those are huge numbers. Around 1000000000000000 watts of invested power. Who knows how much additional to MAKE the collimated beam to pump the lasers. 3× that? 5×? 10×? The sky’s the limit. However this kind of beam would have bâhlls baby. Big cajunas. Mayhaps our rocket flyer weighs in at what 1000 tons … to carry enough stuff for its entourage of bumpkins and for-pay sciencey types to be aboard and live”” for the nearly indefinite trip? And it carries at leat 10″”000 tons of reaction mass — the part you’d just not want to waste the money accelerating. From the neutral beam we’re probably good out to 2 AU. 300000 N-s/s of neutral beam”” fully deflected “”””out there””””. (0.1) … F = ma(0.2) … a = F/m (0.3) … a = 30″”0000 ÷ 12500000 kg (0.4) … a = 2.4 m/s². Wicked cool. And that’s before employing much of the piggy-backed laser. Just working with that and 2 AU (and not the onboard mass nor the incoming laser) (1.1) … D = ½at²(1.2) … t = √( 2D/a )(1.3) … t = √( 2 × ( 2 × 1495000000 ) ÷ 2.4 m/s² )(1.4) … t = 500000 sec(2.1) … v = at(2.2) … v = 2.4 × 500000 sec(2.3) … v = 1200000 m/s (2.4) … v = 1000″
Obligatory: That’s no moon!
Obligatory: That’s no moon!
A spherical mirror doesn’t focus on a point. It would need a smaller correction mirror.
… possible using beamed propulsion …
Dunno. I will have to map beamed-energy stored-and-beamed neutral matter. It is wickedly expensive to neutral-beam matter by the kiloton around. Doesn’t matter how you go about it, it takes exawatts of juice to beam kilograms-per-second of neutral matter at basically relativistic speed. No, even more than that.
E = ½mv² … v = 10% c = 30,000,000 m/s, m = 1 kg/s
E = 450 terawatts
That’s the kinetic energy of a continuous beam. One might conceive of beaming along a similar amount of optical power (since our hapless space flyer doesn’t carry prodigious power, and is going to need a bunch of it to take the intercepted beam and turn it backward, to accelerate it away in the Ultimate ΔV caper.
Well, those are huge numbers. Around 1,000,000,000,000,000 watts of invested power. Who knows how much additional to MAKE the collimated beam, to pump the lasers. 3× that? 5×? 10×? The sky’s the limit.
However, this kind of beam would have bâhlls, baby. Big cajunas.
Mayhaps our rocket flyer weighs in at what, 1,000 tons … to carry enough stuff for its entourage of bumpkins and for-pay sciencey types to be aboard, and “live” for the nearly indefinite trip? And it carries at leat 10,000 tons of reaction mass — the part you’d just not want to waste the money accelerating.
From the neutral beam, we’re probably good out to 2 AU. 30,000,000 N-s/s of neutral beam, fully deflected “out there”.
(0.1) … F = ma
(0.2) … a = F/m
(0.3) … a = 30,000,000 ÷ 12,500,000 kg
(0.4) … a = 2.4 m/s².
Wicked cool. And that’s before employing much of the piggy-backed laser. Just working with that and 2 AU (and not the onboard mass, nor the incoming laser),
(1.1) … D = ½at²
(1.2) … t = √( 2D/a )
(1.3) … t = √( 2 × ( 2 × 149,500,000,000 ) ÷ 2.4 m/s² )
(1.4) … t = 500,000 sec
(2.1) … v = at
(2.2) … v = 2.4 × 500,000 sec
(2.3) … v = 1,200,000 m/s
(2.4) … v = 100,000,000 km/day
(2.5) … v = 0.69 AU/day
(3.1) … Centauri = 4.1 LY × 63,072 AU/LY (nice number to remember)
(3.2) … Centauri = 259,000 AU
(3.3) … T = D/v
(3.4) … T = 259,000 AU ÷ 0.69 AU/day
(3.5) … T = 374,770 days.
Or about a thousand years. No, this is not yet going to get us to The Stars. Not on mass-chucking-and-capture alone. What’s really going to be needed will be to use the prodigious energy attendant with the beam of neutral ions. (Is “neutral ion” an oxymoronic statement?)
Blast ’em out at a higher mass … plus that 10,000 tons of starting mass … and you’ll not only get lighter in mass, but will accelerate faster. Maybe out to 4 AU? Maybe.
Instead of 1,200 km/s (which is 0.4% c), you might get to 10,000 km/s. Hey, 3% of c is pretty darn good. To make the Centauri Run in less than 40 parsecs (ahem… years), you still would need to zing along at 10% of c or better. And that’d take some dâhmned fine neutral ion mass throwing.
GoatGuy
Obligatory: That’s no moon!
In college I had the idea of using a photoconductive film as a rapidly focusable zone plate for terrahertz radiation, by projecting an image of the desired zone plate on the film. A variation of that concept could work here, using a photosensitive film converted into a zone plate by an interference pattern of light of a frequency different from what the zone plate was meant to focus. Perhaps you could use a bilayer film, with the light that generated the zones blocked by the second, supporting layer.
In college I had the idea of using a photoconductive film as a rapidly focusable zone plate for terrahertz radiation by projecting an image of the desired zone plate on the film. A variation of that concept could work here using a photosensitive film converted into a zone plate by an interference pattern of light of a frequency different from what the zone plate was meant to focus. Perhaps you could use a bilayer film with the light that generated the zones blocked by the second supporting layer.
I think manned interstellar flight in a ‘reasonable” (less than a lifespan) flight time could be possible using beamed propulsion, but the infrastructure requirements would be astronomical. Terra watts of power would be needed. I do think we’ll have Von Neumann machines before the end of the century, (Before the middle of it if we really try.) and “shortly” after astronomical amounts of infrastructure would be available, if the will is there to apply it in that manner. Such technology is necessary to a lot of space applications, because life in space is so infrastructure intensive.
I think manned interstellar flight in a ‘reasonable (less than a lifespan) flight time could be possible using beamed propulsion but the infrastructure requirements would be astronomical. Terra watts of power would be needed.I do think we’ll have Von Neumann machines before the end of the century” (Before the middle of it if we really try.) and “”shortly”””” after astronomical amounts of infrastructure would be available”” if the will is there to apply it in that manner.Such technology is necessary to a lot of space applications”” because life in space is so infrastructure intensive.”””
If you want to do something like this, you need an approach that doesn’t require fractional wavelength precision. I’m not certain, but a zone plate might satisfy that requirement.
If you want to do something like this you need an approach that doesn’t require fractional wavelength precision. I’m not certain but a zone plate might satisfy that requirement.
Good. I just don’t think we will EVER be getting “humans to the local stars”, in the “live today, landing tomorrow” sense. Interstellar distances are profoundly huge. Almost beyond comprehension to the likes of us “mere mortals”. EVEN in the case of a “fly-by”, the timeframes and numbers are huge. At least for semi-conventional rocket propulsion. ______ As you might have followed here (or at dozens of other sites), the choice is either “conventional physics”, or “magic wand physics” to accelerate a space probe. Further, at the outset, you either have a choice of sending something big-and-human (and all her life-support requirements), or something presumabaly relatively compact, small, electronic… a rich assortment of tiny optical and physics “package” sensors on board. These are essentially binary design decisions. Using “max physics, with realistic expectations…” Well, ISP = 200,000 implies mv = 2,000,000 newton-seconds of thrust per kilogram of fully realized burned fuel. That’s quite nice. Assuming that one could build a spacecraft with multiple expendable (just to get rid of overhead mass) stages, say 5 of them, and starting with a payload of just 1000 kg (i.e. a very sophisticated physics package, no humans), then … Doesn’t matter whether you use Tsiolkovsky’s rocket equation or piecewise integration of declining rest masses, it all works out the same. 5 stages, respectively with (450, 2,000, 9,500, 44,000 and finally 200,000 ISP) per stage (recognizing scaling issues), delivers the final 1,000 kg probe at 1.5% of c, able to make it to Alpha Cen in 270 years. ± of course. And that’s depressing. Because it is 100× to 250× too small, and at least 5× too slow. For humans. Just saying. GoatGuy
Good.I just don’t think we will EVER be getting humans to the local stars”””” in the “”””live today”””” landing tomorrow”””” sense. Interstellar distances are profoundly huge. Almost beyond comprehension to the likes of us “”””mere mortals””””. EVEN in the case of a “”””fly-by”””””” the timeframes and numbers are huge. At least for semi-conventional rocket propulsion. ______As you might have followed here (or at dozens of other sites)”” the choice is either “”””conventional physics”””””””” or “”””magic wand physics”””” to accelerate a space probe. Further”” at the outset you either have a choice of sending something big-and-human (and all her life-support requirements) or something presumabaly relatively compact small”” electronic… a rich assortment of tiny optical and physics “”””package”””” sensors on board. These are essentially binary design decisions. Using “”””max physics”””” with realistic expectations…””””Well”” ISP = 200000 implies mv = 20000 newton-seconds of thrust per kilogram of fully realized burned fuel. That’s quite nice. Assuming that one could build a spacecraft with multiple expendable (just to get rid of overhead mass) stages say 5 of them and starting with a payload of just 1000 kg (i.e. a very sophisticated physics package no humans) then …Doesn’t matter whether you use Tsiolkovsky’s rocket equation or piecewise integration of declining rest masses it all works out the same. 5 stages respectively with (45020950044000 and finally 200000 ISP) per stage (recognizing scaling issues) delivers the final 1000 kg probe at 1.5{22800fc54956079738b58e74e4dcd846757aa319aad70fcf90c97a58f3119a12} of c able to make it to Alpha Cen in 270 years. ± of course.And that’s depressing. Because it is 100× to 250× too small”” and at least 5× too slow.For humans. Just saying.GoatGuy”””””””
Yah. That’s not going to happen. I can think of almost a dozen reasons why… • (1) electric charge anisotropies • (2) film tension anisotropies • (3) film thickness variation • (4) film metalization effects • (5) chaotic cosmic ray degradation • (6) local micro-heating • (7) positioning shear and strain • (8) unsuppressable inertial wobble (1) ELECTRIC CHARGE ANISOTROPIES: Space is full of protons. We know that the flux varies a LOT. Implied is the same ion flux also varies substantially over macroscopic scales… Such variations will definitely “attract the film” variously. (2) FILM TENSION ANISOTROPIES: As parts of the film harden, the film will come under varying tension gradients. These in turn work directly to pull the spherical ideal out of shape. • (3) FILM THICKNESS VARIATION: most easily seen on the playground, using “big fuzzy hoops” to blow a big soap bubble. Remember how as it floats about, a stage is reached where it is madly swirling with various ranbow colors? These come from interference of light from the extremely thin film losing water vapor. DIFFERENT colors shows anisotropic thickness evolution. • (4) FILM METALIZATION EFFECTS: similar to (3), the metalization of the film will not be isotropic. Since the film is very thin, the metalization will be a larger fraction of the film’s mass. Thus, its variation will vary the local film tension. • (5) CHAOTIC COSMIC RAY DEGRADATION: Over time incoming cosmic rays vary. Indirectly they also vary, unpredictably, spatially spatially. This will cause radiation-absorbed hardening and both polymerization and depolymerization of the underlying prime focus film. • (6) LOCAL MICRO-HEATING: That great big sun-shade will be good — arguably perfect — but the entropy of the local interplanetary medium will heat-and-cool the film. Chaotically, due to small differences in density, in local ionization : neutral atom ratios, and so forth. • (7) POSITIONING SHEAR AND STRAIN: It isn’t likely to po
Yah. That’s not going to happen. I can think of almost a dozen reasons why…• (1) electric charge anisotropies• (2) film tension anisotropies• (3) film thickness variation• (4) film metalization effects• (5) chaotic cosmic ray degradation• (6) local micro-heating• (7) positioning shear and strain• (8) unsuppressable inertial wobble(1) ELECTRIC CHARGE ANISOTROPIES: Space is full of protons. We know that the flux varies a LOT. Implied is the same ion flux also varies substantially over macroscopic scales… Such variations will definitely attract the film”” variously.(2) FILM TENSION ANISOTROPIES: As parts of the film harden”” the film will come under varying tension gradients. These in turn work directly to pull the spherical ideal out of shape. • (3) FILM THICKNESS VARIATION: most easily seen on the playground”” using “”””big fuzzy hoops”””” to blow a big soap bubble. Remember how as it floats about”” a stage is reached where it is madly swirling with various ranbow colors? These come from interference of light from the extremely thin film losing water vapor. DIFFERENT colors shows anisotropic thickness evolution. • (4) FILM METALIZATION EFFECTS: similar to (3) the metalization of the film will not be isotropic. Since the film is very thin the metalization will be a larger fraction of the film’s mass. Thus its variation will vary the local film tension.• (5) CHAOTIC COSMIC RAY DEGRADATION: Over time incoming cosmic rays vary. Indirectly they also vary unpredictably spatially spatially. This will cause radiation-absorbed hardening and both polymerization and depolymerization of the underlying prime focus film. • (6) LOCAL MICRO-HEATING: That great big sun-shade will be good — arguably perfect — but the entropy of the local interplanetary medium will heat-and-cool the film. Chaotically due to small differences in density in local ionization : neutral atom ratios and so forth. • (7) POSITIONING SHEAR AND STRAIN”
In college I had the idea of using a photoconductive film as a rapidly focusable zone plate for terrahertz radiation, by projecting an image of the desired zone plate on the film. A variation of that concept could work here, using a photosensitive film converted into a zone plate by an interference pattern of light of a frequency different from what the zone plate was meant to focus. Perhaps you could use a bilayer film, with the light that generated the zones blocked by the second, supporting layer.
I think manned interstellar flight in a ‘reasonable” (less than a lifespan) flight time could be possible using beamed propulsion, but the infrastructure requirements would be astronomical. Terra watts of power would be needed.
I do think we’ll have Von Neumann machines before the end of the century, (Before the middle of it if we really try.) and “shortly” after astronomical amounts of infrastructure would be available, if the will is there to apply it in that manner.
Such technology is necessary to a lot of space applications, because life in space is so infrastructure intensive.
If you want to do something like this, you need an approach that doesn’t require fractional wavelength precision. I’m not certain, but a zone plate might satisfy that requirement.
Good.
I just don’t think we will EVER be getting “humans to the local stars”, in the “live today, landing tomorrow” sense. Interstellar distances are profoundly huge. Almost beyond comprehension to the likes of us “mere mortals”.
EVEN in the case of a “fly-by”, the timeframes and numbers are huge.
At least for semi-conventional rocket propulsion.
______
As you might have followed here (or at dozens of other sites), the choice is either “conventional physics”, or “magic wand physics” to accelerate a space probe. Further, at the outset, you either have a choice of sending something big-and-human (and all her life-support requirements), or something presumabaly relatively compact, small, electronic… a rich assortment of tiny optical and physics “package” sensors on board.
These are essentially binary design decisions.
Using “max physics, with realistic expectations…”
Well, ISP = 200,000 implies mv = 2,000,000 newton-seconds of thrust per kilogram of fully realized burned fuel. That’s quite nice. Assuming that one could build a spacecraft with multiple expendable (just to get rid of overhead mass) stages, say 5 of them, and starting with a payload of just 1000 kg (i.e. a very sophisticated physics package, no humans), then …
Doesn’t matter whether you use Tsiolkovsky’s rocket equation or piecewise integration of declining rest masses, it all works out the same. 5 stages, respectively with (450, 2,000, 9,500, 44,000 and finally 200,000 ISP) per stage (recognizing scaling issues), delivers the final 1,000 kg probe at 1.5% of c, able to make it to Alpha Cen in 270 years. ± of course.
And that’s depressing.
Because it is 100× to 250× too small, and at least 5× too slow.
For humans.
Just saying.
GoatGuy
Yah. That’s not going to happen. I can think of almost a dozen reasons why…
• (1) electric charge anisotropies
• (2) film tension anisotropies
• (3) film thickness variation
• (4) film metalization effects
• (5) chaotic cosmic ray degradation
• (6) local micro-heating
• (7) positioning shear and strain
• (8) unsuppressable inertial wobble
(1) ELECTRIC CHARGE ANISOTROPIES: Space is full of protons. We know that the flux varies a LOT. Implied is the same ion flux also varies substantially over macroscopic scales… Such variations will definitely “attract the film” variously.
(2) FILM TENSION ANISOTROPIES: As parts of the film harden, the film will come under varying tension gradients. These in turn work directly to pull the spherical ideal out of shape.
• (3) FILM THICKNESS VARIATION: most easily seen on the playground, using “big fuzzy hoops” to blow a big soap bubble. Remember how as it floats about, a stage is reached where it is madly swirling with various ranbow colors? These come from interference of light from the extremely thin film losing water vapor. DIFFERENT colors shows anisotropic thickness evolution.
• (4) FILM METALIZATION EFFECTS: similar to (3), the metalization of the film will not be isotropic. Since the film is very thin, the metalization will be a larger fraction of the film’s mass. Thus, its variation will vary the local film tension.
• (5) CHAOTIC COSMIC RAY DEGRADATION: Over time incoming cosmic rays vary. Indirectly they also vary, unpredictably, spatially spatially. This will cause radiation-absorbed hardening and both polymerization and depolymerization of the underlying prime focus film.
• (6) LOCAL MICRO-HEATING: That great big sun-shade will be good — arguably perfect — but the entropy of the local interplanetary medium will heat-and-cool the film. Chaotically, due to small differences in density, in local ionization : neutral atom ratios, and so forth.
• (7) POSITIONING SHEAR AND STRAIN: It isn’t likely to point the Sauron’s Eye at someplace in the heavens on Day 1, and leave it. It’ll be repositioned. move a kilometer “of stuff” around, and you’ve got to tug (or push) on it substantially. This will tend to “de-circularize” the thing in unexpected ways.
• (8) UNSUPPRESSABLE INERTIAL WOBBLE: Again, like the soap bubbles. They really aren’t inclined to be exactly round, are they? They wobble a lot, even on the most calm days, in various non-spherical ways. Sure, interplanetary space is MUCH less ‘thick’ as a medium compared to Earth’s atmosphere. But… over kilometer scale films?
Anyway, those were the low-hanging fruit. I’m sure the space scientists can cup another dozen-plus things that’d have to be dealt with, engineering wise.
Just saying,
GoatGuy
space has a lot of…space.
space has a lot of…space.
It worked for Sauron.
It worked for Sauron.
so, after centuries of building telescopes, the best we can come up with is a giant EYEBALL in space? Not that I’m complaining, if it works then Great! Just odd that we still can’t do better than evolution in some aspects.
so after centuries of building telescopes the best we can come up with is a giant EYEBALL in space? Not that I’m complaining if it works then Great! Just odd that we still can’t do better than evolution in some aspects.
It’s always been about *knowing,* not necessarily about *going.* Telescopes generally don’t care if they’re looking at objects in this solar system (where there’s a chance of eventual human missions), or galaxies billions of light years away. For space probes however, those are rather different challenges…
It’s always been about *knowing* not necessarily about *going.*Telescopes generally don’t care if they’re looking at objects in this solar system (where there’s a chance of eventual human missions) or galaxies billions of light years away.For space probes however those are rather different challenges…
I would really be shocked if they could get a good enough figure on that bubble to make it work. We’re talking fractional wavelengths over a kilometer, after all.
I would really be shocked if they could get a good enough figure on that bubble to make it work. We’re talking fractional wavelengths over a kilometer after all.
So they want to put this 1 km telescope in EML2. China put a satellite there recently, NASA wants (wanted?) a manned outpost there, it’s a good place for a fuel depot, and maybe some other things. How much room is there in EML2? I understand these objects would be in halo orbits, but how big are these orbits? How many? At what spacings?
So they want to put this 1 km telescope in EML2. China put a satellite there recently NASA wants (wanted?) a manned outpost there it’s a good place for a fuel depot and maybe some other things. How much room is there in EML2? I understand these objects would be in halo orbits but how big are these orbits? How many? At what spacings?
Propulsion systems are interesting, but even the best systems on the drawing boards would take centuries to get a human to the nearest stars. Spend 10 years to build a better telescope and you can instantly learn more about the nearest stars, as well as stars completely out of reach of our travel. Better yet, do both. Which we are doing of course, to some extent. If we didn’t blow hundreds of millions of dollars on government-subsidized sports stadiums, or totally redundant nuclear weapons, we’d be a lot farther along by now.
Propulsion systems are interesting but even the best systems on the drawing boards would take centuries to get a human to the nearest stars. Spend 10 years to build a better telescope and you can instantly learn more about the nearest stars as well as stars completely out of reach of our travel.Better yet do both. Which we are doing of course to some extent. If we didn’t blow hundreds of millions of dollars on government-subsidized sports stadiums or totally redundant nuclear weapons we’d be a lot farther along by now.
Why on Earth we need more telescopes, if we are not able to reach the closest planet, let alone a star. In the meantime companies which work on propulsion are starved of funds.
Why on Earth we need more telescopes if we are not able to reach the closest planet let alone a star. In the meantime companies which work on propulsion are starved of funds.
Very ingenious idea!
Very ingenious idea!
space has a lot of…space.
It worked for Sauron.
so, after centuries of building telescopes, the best we can come up with is a giant EYEBALL in space? Not that I’m complaining, if it works then Great! Just odd that we still can’t do better than evolution in some aspects.
It’s always been about *knowing,* not necessarily about *going.*
Telescopes generally don’t care if they’re looking at objects in this solar system (where there’s a chance of eventual human missions), or galaxies billions of light years away.
For space probes however, those are rather different challenges…
I would really be shocked if they could get a good enough figure on that bubble to make it work. We’re talking fractional wavelengths over a kilometer, after all.
So they want to put this 1 km telescope in EML2. China put a satellite there recently, NASA wants (wanted?) a manned outpost there, it’s a good place for a fuel depot, and maybe some other things. How much room is there in EML2? I understand these objects would be in halo orbits, but how big are these orbits? How many? At what spacings?
Propulsion systems are interesting, but even the best systems on the drawing boards would take centuries to get a human to the nearest stars. Spend 10 years to build a better telescope and you can instantly learn more about the nearest stars, as well as stars completely out of reach of our travel.
Better yet, do both. Which we are doing of course, to some extent. If we didn’t blow hundreds of millions of dollars on government-subsidized sports stadiums, or totally redundant nuclear weapons, we’d be a lot farther along by now.
Why on Earth we need more telescopes, if we are not able to reach the closest planet, let alone a star. In the meantime companies which work on propulsion are starved of funds.
Very ingenious idea!