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-------------------------- 1859 - Will a rocket ever reach the stars? -
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- We assemble a laser array the size of Manhattan in low-earth orbit. We use a sail propelled by laser light. The large laser array orbiting the Earth would gather energy via solar panels. The laser beam would push the tiny probes to 26% the speed of light, 17,000,000 miles per hour, and reach the nearest stars in 20 years.
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- How close is our nearest star? Not the Sun, it is 93 million miles away. The next star is Alpha Centauri. It is 4.37 lightyears away, that is 25,000,000,000,000 miles. If we send today’s spacecraft at 20,000 miles per hour it would take 30,000 years to reach our nearest star.
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- What if we could reach the star in 20 years? Would it be worth it? Is it really even possible? My grandkids should be able to prove it is possible.
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- The mission is even in the design phase today. Small, light-weight, nano-spacecraft, powered by lasers that could reach speeds 1,000 times faster than today’s spacecraft, could reach 20% the speed of light
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- The nanocraft could carry cameras, photon thrusters, power supplies, navigation and communications instruments. The propulsion would use “ light sails”. The sails would be very thin, only a few hundred atoms thick. Laser arrays could pus them to 17,000,000 miles per hour, 26% the speed of light, 4,756 miles per second.
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- 20 years after launch these nanocraft would be gathering scientific data and transmitting back to Earth. The communications at the speed of light would take 4.36 years to reach us. It would be received by the same laser array that launched the mission. My grandkids might be writing reviews about this event.
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- The laser array would be on the scale of kilometers. It would need to be able to store or receive several gigawatt-hours of energy. The mother ship would put thousands of nanocraft into high altitude orbit, loaded with instruments ready for launch.
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- This “ Starshot” could really be possible. Light beams, light sails, light spacecraft only imagined until now. Now the design for the mission has started.
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- Alpha-Centauri is really a system of 2 stars. The closest star , Proxima, and a larger binary star system. We have yet to learn if the star system is supporting planets and moons. But, what our own Solar System has told us, and what over 2,000 exoplanets discovered orbiting other stars has told us, Starshot is very likely to discover planets as well.
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- The Starshot project assembles a laser array the size of Manhattan in low-earth orbit. The lasers are powered by solar panels so that solves the “bring your own fuel problem”. Today’s rockets use fuel as “reaction mass” Action equals reaction. On the launch pad fuel makes up 90% of the mass of the rocket. The thrust generated to lift the rocket is working it lift the fuel not the small payload.
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- Today the farthest space craft is Voyager I, the only spacecraft to reach interstellar space beyond our Solar System. It took Voyager 40 years and it is only 10 light hours away, not lightyears away. At Voyager’s speed it would take 40,000 more years to reach these nearest stars.
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- We need a new approach to space propulsion if we are ever going to reach the stars. An obvious answer is to use an external source for power and don’t depend on carrying it with you.
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- This new approach uses large and light weight mirrors to generate thrust from photons coming from the Sun. Even that miniscule force , slowly and continually builds up to enormous speeds.
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- To accelerate 100,000 times faster than using the Sun, the sails could use powerful lasers that are focused and perfectly synchronized. Ideally the laser array would be in space as well, in near-earth orbit.
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- Laser arrays can be modular and assembled to 10 meters on a side generating 30 kilowatts. Or, 10 kilometers on a side generating 70,000 kilowatts. That is an array 6 miles on a side.
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- The wavelength of the laser light is 1 micron. The lower wattage, smaller arrays could launch “ CubeSats” and nano-satellites. The larger arrays are powerful enough to send a CubeSat to Mars in 8 hours. If the payload is 22,000 pounds the trip to Mars would take one month. Using current technology it takes seven months.
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- The mass of the largest laser array would be 100 times the mass of the International Space Station. So, we are talking about a 50 year timescale to accomplish the more ambitious missions. A CubeSat that could reach Mars in 8 hours traveling at 2% the speed of light would still take 200 years to reach these nearest stars.
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- To get to the stars even faster we need to have smaller payloads, maybe wafer-scale spacecraft weighing only a few grams. To carry miniaturization further we need nano-photonics, a nano-radio thermal generator (1 watt), nano-camera, nano-thruster, and thin-film super capacitors for energy storage. A one meter laser sail propelled by a 70,000 kilowatt laser array to 26% light speed would reach Alpha Centauri in 15 years.
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- Even these tiny spacecraft could send data and low-resolution pictures back to Earth. The mirror sail and transmitter could send data at 100 kilobytes per second.
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- Another mission to consider is the discovery of exoplanets up to 100 lightyears away. Stationed at 600 Astronomical Units distance a telescope could use the Sun mass as a gravitational lens that could image exoplanets to 1 pixel per square kilometer. Today a planet image is a single pixel.
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- The first missions gong to Mars will need fuel used to slowdown. Once a laser array could be assembled in Mars orbit we could send payloads back and forth like a commuter service. If we can’t slow down early missions will be “ fly-bys” .
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- This is challenging engineering but within reach of our rapidly developing technologies. Reaching a 20 lightyear radius from Earth would reach 150 stars, 17 known planetary systems, 14 of which could support planets in the “ habitable zone“. Who knows what we might find?
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- Request these Reviews to learn more about stars:
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- #1822 - The largest stars, the oldest stars. The dark sky contains the entire electromagnetic spectrum outside our eye’s ability to see it.
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- The #1822 Review contains references to 12 other reviews about stars, #1116 to #907.
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- You can see Alpha Centauri on a clear night. It is one of the most brilliant stars in the southern sky, Magnitude = 0. Centaurus is in the Constellation “ Crux of the Southern Cross”.
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- Alpha Cen A is slightly larger than our Sun.
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- Alpha Cen B is slightly smaller and dimmer, orange in color.
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- Proxima is a small red star 10% the mass of the Sun, but, 129 times the mass of the planet Jupiter. Proxima orbits its two larger companions once ever 500,000 years.
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----- 707-536-3272 ---------------- Monday, April 18, 2016 -----
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