Solar-pumped laser power transmission, a way to dramatically decrease launch costs?
in [Physics]
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From: William Mook on 19 Feb 2010 10:56 On Feb 16, 3:12 am, Pat Flannery <flan...(a)daktel.com> wrote: > Scott M. Kozel wrote: > > > Mercury at 35 million miles is 800 F ... at 2 million miles it might > > be hot enough to melt tungsten ... i.e. a satellite would melt or > > maybe even vaporize long before it got that close. > > The radiation flux at that distance is going to be ferocious also. > You would be well inside the Sun's corona, and the first time a major > flare erupted underneath it it would be like sticking it inside of a > nuclear reactor. > At least as of 2008, JPL was planning to send a spacecraft to 4.1 > million miles from the Sun's surface, and just designing that was > driving them nuts:http://www.astronomy.com/asy/default.aspx?c=a&id=6917 > > > "The metal with the highest melting point is tungsten (W) at 3410 > > degrees Celcius (6170 degrees Fahrenheit). However, technically Carbon > > has a higher melting point, though not under normal atmospheric > > conditions. This is because it sublimates (turns directly from a solid > > to a gas) at 6740 degrees Fahrenheit under normal circumstances." > > Temperature at 4.1 million miles is 2,160F according to the above > article, so assuming halving the distance increases the temperature four > times over (I think that's how it works, though the large solar radius > may screw this up; it's going to at least double) that makes the temp it > could be facing over 8,000 F. > So unless you are building it out of Larry Niven's Puppeteer Hull > Metal... another problem at this distance is that you aren't going to be > orbiting it in vacuum, but rather in the very thin superheated gas of > its outer atmosphere. That's going to generate drag on the solar array, > and given its extremely high orbital velocity it's probably going to end > up falling into the Sun in fairly short order. > > Pat Radiation flux from the Sun at 3.5 million km is 2.58 million watts per square meter. Since an object has a larger surface area than its shadow and since not 100% of the energy is absorbed by the structure, then the radiative surfaces will be well below 1,600 K (2,420 F) which is well within the operating range of diamond based semiconductors and other carbon based structures like graphite. So, a thin panel of MEMS elements that consist of solar cells facing the sun, and a laser emitter facing the sky may be constructed and operated at this distance. An object like this massing only 430 grams per square meter - and less than a millimeter thick - would cover 20,000 square meters and mass only 8.6 tons. It would intercept 50 billion watts of solar energy and beam a portion of it to a companion satellite on orbit. The pair would easily be carrried within the Space Shuttle payload bay. Once released on orbit the panels would unfold - to over 500 feet in diameter - and solar pressure would drive them to their respective orbits. One would rise to GEO over the course of three months. Another would continue onward for 4.6 months - and be headed for Jupiter. Two and a half years later, at Jupiter, the spacecraft would execute a gravity boost maneuver to drop its speed to nearly zero. It would then fall directly into the sun. After another two years and four months the spacecraft would deploy at 3.5 million km above the sun, and use light pressure to hover above the solar surface - directly beneath the Earth - and beam UV laser energy at 200 nm to the companion satellite at GEO. The GEO satellite receives the energy from the SUNSAT and beams IR laser energy at 1,000 nm to multiple receivers simultaneously. A higher power system should be possible. One that operates at 2 million km from the sun - would have 3x the energy density as the one at 3.5 million km - but only operate at 31% higher temperature (the fourth root of 3 is 1.31) At this distance the LASER energy is around 63 billion watts - equal to all the nation's nuclear power plants combined. Beamed to Earth holographically to millions of users simultaneously, this energy provides tremendous value. Thirty such satellite pairs would provide ALL the world's energy without burning any fuels. Our current space shuttle fleet is capable of operating at 20x per year. So, our current space shuttle fleet would be able to deploy enough infrastructure to REPLACE ALL THE WORLDS ENERGY NEEDS in 18 months. Which is pretty damn amazing - and shows the value of getting close to the source.
From: William Mook on 19 Feb 2010 11:17 PROPULSION POSSIBILITIES 63 billion watt IR laser beam collimated into a single beam from a power satellite on GEO to drive a laser powered rocket engine capable of 5,000 sec Isp produces 2.57 mega-newtons (262,280 kgf or 577,020 lbf) thrust. With a take off weight of 71% of its maximum thrust we have a vehicle of 186.2 tons. A flight to the moon and back requires a vehicle delta vee of 17 km/sec. This requires a propellant fraction at this Isp of 29.4% take off mass or 54.6 tons. This is a high density polymer massing about 1.5 tons per cubic meter provides a compact coating to place on the laser energized propulsive surface. Subtract off 28.6 tons of structure and that leaves 103 tons of payload. With 30 passengers, and 100 tons of cargo, this is a very interesting spacecraft as a follow on to the Space Shuttle. So, the program here would be to; (1) Acquire United Space Alliance and other Space Shuttle related Assets from NASA (2) Operate them to deploy advanced solar power satellites described here (3) Use the revenue stream to develop a propulsive laser satellite and spacecraft fleet (4) Deploy the satellite and fleet and retire the shuttle (5) Build a lunar village with the new fleet of spacecraft. I takes four days to get to the moon along a minimum energy orbit. And four days to get back. If we allow six days on the lunar surface, and two weeks to refurbish the spacecraft at Earth, we can support 1 flight per vehicle per month. A fleet of five vehicles would support one flight every six days. 60 flights per year. This allows 1,800 people per year, and 6,000 tons of cargo per year to be brought to the moon. Since it takes 1 ton of consumables to support 1 person for a year, this small fleet of vehicles can support a town of 6,000 on the moon. With 5 tons of capital equipment per person, this will take 5 years to deploy with the fleet as we build up capability. At $5 million per ton, this village will cost $30 billion - less than the cost of the Space Shuttle per day. This program would cost $6 billion per year and at $0.08 per kWh be paid for by the operation of 8.6 GW generator (about 15% of a single power sat)
From: William Mook on 19 Feb 2010 11:59 INTERPLANETARY LASER LIGHT SAIL The 63 GW beam bouncing off a laser light sail that's 99.9% reflective at the operating wavelength (1 micron in this case) beaming energy at a 20,000 sq m disc (500 ft diam) that masses 1 metric ton and operates at 420 Kelvin. This boosts a 103 ton payload at nearly 1 gee without consuming ANY propellant!! So, the more compact vehicle lands and takes off using laser propelled rockets. The vehicle then deploys a laser light sail to boost at 1 gee through interplanetary space! So our 103 ton payload module equipped with a laser light sail, operating in conjunction with our advanced solar power satellite network, is capable of sending payloads efficiently across the solar system. At 1 gee the moon is only 3 and a half hours away. The planets are nearly all less than 2 weeks away using this fleet; Mercury 2 days 5 hours Venus 1 days 15 hours Mars 2 days Ceres 3 days 20 hours Jupiter 5 days 20 hours Saturn 8 days 8 hours Uranus 12 days 8 hours Neptune 15 days 10 hours Though efficiencies (and thrust) fall off far from the Sun - without some sort of lens system in place to recollimate the beams. Alternatively, larger diameter emitters may be built - and higher energy levels - which mean larger thrusts. Which gets us into the realm of travel to the Kuiper Belt, to Pluto and Beyond. As well as nearby star systems. Larger diameter emitters close in to the sun, combined with larger diameter mirrors - 20 sq km and more - operating at the TW levels - provide a means to send 1,000 ton payloads to nearby stars and slow them down using 1,000 ton mirror sheets using methods first described by Bob Forward of Hughes Aircraft. 6 months at 1 gee gets to half light speed. After 8.6 years of travel time - assuming Alpha Centuari is our destination then, 6 months at 1 gee slows the payload to rest in the target star system, while accelerating the larger portion of the laser light sail to over 87% the speed of light. The payload deploys a laser power satellite into the Centauri System, which then uses light from the Cenauri star to sail to a convenient spot above the stellar surface - to create a counter-propagating beam back toward Earth. This beam is used by the spacecraft to visit locations in the Centauri system and then return home. Accelerating for 6 months at 1 gee to get up to half light speed. After another 8.6 years of cruising the spacecraft arrive near Sol. The solar laser power satellite beams energy to the spacecraft for six months, slowing it at a 1 gee rate for 6 months - bringing it to rest relative to the Solar system - and then driving it to whatever planet its returning to (presumably Earth)
From: Brad Guth on 19 Feb 2010 15:52 On Feb 19, 8:59 am, William Mook <mokmedi...(a)gmail.com> wrote: > INTERPLANETARY LASER LIGHT SAIL > > The 63 GW beam bouncing off a laser light sail that's 99.9% reflective > at the operating wavelength (1 micron in this case) beaming energy at > a 20,000 sq m disc (500 ft diam) that masses 1 metric ton and operates > at 420 Kelvin. This boosts a 103 ton payload at nearly 1 gee without > consuming ANY propellant!! > > So, the more compact vehicle lands and takes off using laser propelled > rockets. The vehicle then deploys a laser light sail to boost at 1 > gee through interplanetary space! > > So our 103 ton payload module equipped with a laser light sail, > operating in conjunction with our advanced solar power satellite > network, is capable of sending payloads efficiently across the solar > system. > > At 1 gee the moon is only 3 and a half hours away. The planets are > nearly all less than 2 weeks away using this fleet; > > Mercury 2 days 5 hours > Venus 1 days 15 hours > Mars 2 days > Ceres 3 days 20 hours > Jupiter 5 days 20 hours > Saturn 8 days 8 hours > Uranus 12 days 8 hours > Neptune 15 days 10 hours > > Though efficiencies (and thrust) fall off far from the Sun - without > some sort of lens system in place to recollimate the beams. > > Alternatively, larger diameter emitters may be built - and higher > energy levels - which mean larger thrusts. > > Which gets us into the realm of travel to the Kuiper Belt, to Pluto > and Beyond. As well as nearby star systems. > > Larger diameter emitters close in to the sun, combined with larger > diameter mirrors - 20 sq km and more - operating at the TW levels - > provide a means to send 1,000 ton payloads to nearby stars and slow > them down using 1,000 ton mirror sheets using methods first described > by Bob Forward of Hughes Aircraft. > > 6 months at 1 gee gets to half light speed. > > After 8.6 years of travel time - assuming Alpha Centuari is our > destination then, > > 6 months at 1 gee slows the payload to rest in the target star system, > while accelerating the larger portion of the laser light sail to over > 87% the speed of light. > > The payload deploys a laser power satellite into the Centauri System, > which then uses light from the Cenauri star to sail to a convenient > spot above the stellar surface - to create a counter-propagating beam > back toward Earth. This beam is used by the spacecraft to visit > locations in the Centauri system and then return home. > > Accelerating for 6 months at 1 gee to get up to half light speed. > > After another 8.6 years of cruising the spacecraft arrive near Sol. > > The solar laser power satellite beams energy to the spacecraft for six > months, slowing it at a 1 gee rate for 6 months - bringing it to rest > relative to the Solar system - and then driving it to whatever planet > its returning to (presumably Earth) I can't say if your math is correct, though I happen to like it, and I'd even help fund its R&D with my 50/50 matching of public loot to that of your private loot. However, why are there so few if any serious topic contributions by others? ~ BG
From: Brad Guth on 19 Feb 2010 15:57
On Feb 19, 8:17 am, William Mook <mokmedi...(a)gmail.com> wrote: > PROPULSION POSSIBILITIES > > 63 billion watt IR laser beam collimated into a single beam from a > power satellite on GEO to drive a laser powered rocket engine capable > of 5,000 sec Isp produces 2.57 mega-newtons (262,280 kgf or 577,020 > lbf) thrust. With a take off weight of 71% of its maximum thrust we > have a vehicle of 186.2 tons. A flight to the moon and back requires > a vehicle delta vee of 17 km/sec. This requires a propellant fraction > at this Isp of 29.4% take off mass or 54.6 tons. This is a high > density polymer massing about 1.5 tons per cubic meter provides a > compact coating to place on the laser energized propulsive surface. > Subtract off 28.6 tons of structure and that leaves 103 tons of > payload. With 30 passengers, and 100 tons of cargo, this is a very > interesting spacecraft as a follow on to the Space Shuttle. > > So, the program here would be to; > > (1) Acquire United Space Alliance and other Space Shuttle related > Assets from NASA > (2) Operate them to deploy advanced solar power satellites described > here > (3) Use the revenue stream to develop a propulsive laser satellite > and spacecraft fleet > (4) Deploy the satellite and fleet and retire the shuttle > (5) Build a lunar village with the new fleet of spacecraft. > > I takes four days to get to the moon along a minimum energy orbit. > And four days to get back. If we allow six days on the lunar surface, > and two weeks to refurbish the spacecraft at Earth, we can support 1 > flight per vehicle per month. A fleet of five vehicles would support > one flight every six days. 60 flights per year. > > This allows 1,800 people per year, and 6,000 tons of cargo per year to > be brought to the moon. Since it takes 1 ton of consumables to > support 1 person for a year, this small fleet of vehicles can support > a town of 6,000 on the moon. With 5 tons of capital equipment per > person, this will take 5 years to deploy with the fleet as we build up > capability. At $5 million per ton, this village will cost $30 billion > - less than the cost of the Space Shuttle per day. > > This program would cost $6 billion per year and at $0.08 per kWh be > paid for by the operation of 8.6 GW generator (about 15% of a single > power sat) I happen to have a good location for that IR laser cannon, Selene L1. I'd planned on having my platform of a dozen 100 GW laser cannons, but if all you need is 63 GW, we're good to go. ~ BG |