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Showing posts with label space travel. Show all posts
Showing posts with label space travel. Show all posts

Monday, October 06, 2014

Science: A warp bubble drive for interstellar travel

image: illustration of USS Enterprise (Star Trek) at warp
USS Enterprise at warp (Paramount Pictures/CBS Studios), Universe Today
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To travel beyond our solar system and flyby the nearest star system, Alpha Centauri (4.3 light years distant), is a journey estimated to take 40 years one way, depending on the mode of propulsion used. That's a road trip with possibly no return. Wikipedia's article on interstellar travel is truly an eye-opener.

It's known that we cannot travel faster than light in spacetime, as explained on NASA's Status of "Warp Drive" page. After a reference to special relativity, the NASA author says:
One of the consequences of this Special Relativity is the light speed barrier [compared to the sound barrier earlier in the article]. Here’s another way to look at it. To move faster, you add energy. But when you get going near the speed of light, the amount of energy you need to go faster balloons to infinity! To move a mass at the speed of light would take infinite energy. It appears that there is a distinct barrier here.
Note that this barrier is an effect of being in the spacetime matrix. But what if we consider altering the matrix itself? Then we are looking at ideas like the warp bubble drive (Alcubierre drive) and wormhole transportation.

Since first coming across the idea of warp bubble drive, I've been intrigued by it.  Here's a diagram that might help.
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image: illustration of warp drive bubble
Warp drive bubble (NASA), Gizmag
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According to an article in Gizmag, "Warp drive looks more promising than ever in recent NASA studies:"
The warp drive broke away from being a wholly fictional concept in 1994, when physicist Miguel Alcubierre suggested that faster-than-light (FTL) travel was possible if you remained still on a flat piece of spacetime inside a warp bubble that was made to move at superluminal velocity. Rather like a magic carpet. The main idea here is that, although no material objects can travel faster than light, there is no known upper speed to the ability of spacetime itself to expand and contract. The only real hint we have is that the minimum velocity of spacetime expansion during the period of cosmological inflation was about 30 million billion times the speed of light.
In describing how the warp bubble would work, author Brian Dodson says:
The warp effect uses gravitational effects to compress the spacetime in front of a spacecraft, then expand the spacetime behind it. The bit of spacetime within the warp bubble is flat, so that the spacecraft would float at zero-g along the wave of compressed and expanded spacetime. The net effect is rather like surfing, where you are nearly stationary with respect to the wave, but are traveling with the speed of the wave. Whereas many of the theoretical studies consider a warp bubble moving at ten times the speed of light, there is no known limit to the potential speed.
All is not rosy with this shiny new idea, though. Universe Today warns:
Planning a little space travel to see some friends on Kepler 22b? Thinking of trying out your newly-installed FTL3000 Alcubierre Warp Drive to get you there in no time? Better not make it a surprise visit — your arrival may end up disintegrating anyone there when you show up.
In closing Wikipedia's article on the Alcubierre Warp Drive includes a snapshot of the math.

-- Marge


Monday, September 15, 2014

Science: space travel without fuel

image: cartoon by Eric Allie
Eric Allie, Cagle
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At the current stage of development, dreams of space travel start in the range of 30 and 50 micro-Newtons in thrust (NASA reporting on the Cannae drive). Currently there are two candidates for space propulsion that don't require tons of fuel to launch and propel. Keep in mind interstellar travel (going outside our solar system) will require more time than a human is currently allotted in a lifetime. Take a look at Kate Mulcahy's "Top 10 Problems with Interstellar Travel" for more information.
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image: NASA's Gravity Probe B
Gravity Probe B, ListVerse
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Still, developing propulsion without fuel is an important step.

The first candidate is the EmDrive, developed by Roger Shawyer, and introduced in 2010. This drive has been validated by NASA and built and tested by the Chinese.
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image: photo by Elvis Popovic of the EmDrive
EmDrive (photo by Elvis Popovic), DVICE
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The other candidate is the Cannae Drive, reportedly a 'reactionless' engine. As reported by The Independent,
A NASA study has recently concluded that the "Cannae Drive," a disruptive new method of space propulsion, can produce small amounts of thrust without the use of propellant, in apparent discordance with Newton's third law. According to its inventor, the device can harness microwave radiation inside a resonator, turning electricity into a net thrust.
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image: photo of the Cannae Drive
Cannae Drive, gizmag
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Wired includes the Cannae and EmDrive engines in "10 questions about Nasa's 'impossible' space drive answered."

Travel within our solar system using one of these fuelless drives is being discussed, but to me the most interesting stuff lies beyond the heliosphere.

-- Marge