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redneckgaijinhttp://www.cnn.com/2005/TECH/space/06/22/russia.cosmos.reut/index.html
Evidently, the retooled Russian nuclear missile misfired. The odds are that Cosmos 1, the second attempt to put a solar sail into operation, crashed into the ocean, but there's a tiny chance that it's in a low and unstable orbit.
In either case, there's practically zero chance that the experiment will actually go forward. Athmospheric drag plus the Earth's magnetic field will likely render the experiment ineffective in low Earth orbit.
Which means that someone will try again, eventually.
And I personally think that's a bad idea, because solar sails are, to my mind, not an effective means of propulsion.
The theory is that, if you have a surface big enough and lightweight enough, it can catch the photons, ions, and other radiation from the sun- the "solar wind"- and propel a tiny ship with no engine, no reaction mass, no nothing.
In reality, even if everything possible goes right, force is equal to mass times acceleration. Photons have no mass at all, solar wind particles have negligible mass, and even going at significant fractions of lightspeed their ability to push things around is limited. Using a solar sail to get from Earth to Mars? Good luck- leaving Earth's gravitational pull would take months at best, provided Earth's magnetic field doesn't divert away so much of the solar wind that you can't get propulsion. Once you're away from Earth, the travel time would still be over a year.
As for interstellar travel? The theory persumes constant acceleration, but we've already found the point in space, more or less, where solar wind no longer has the power to push out the interstellar dust clouds which partially surround our solar system. It's a LOT closer in than we thought- light-days away rather than light-years. Beyond that point, acceleration will no longer be possible.
Solar sails may be more efficient in theory, but they just don't address the single greatest obstacle to space travel- FLIGHT DURATION.
This flight should have proved that, but it looks like it's gone Beagle 2 on us, which means someone else will sink millions into this.
Come on, Rutan, put that brain in gear, and find us a solution before this happens again...
Evidently, the retooled Russian nuclear missile misfired. The odds are that Cosmos 1, the second attempt to put a solar sail into operation, crashed into the ocean, but there's a tiny chance that it's in a low and unstable orbit.
In either case, there's practically zero chance that the experiment will actually go forward. Athmospheric drag plus the Earth's magnetic field will likely render the experiment ineffective in low Earth orbit.
Which means that someone will try again, eventually.
And I personally think that's a bad idea, because solar sails are, to my mind, not an effective means of propulsion.
The theory is that, if you have a surface big enough and lightweight enough, it can catch the photons, ions, and other radiation from the sun- the "solar wind"- and propel a tiny ship with no engine, no reaction mass, no nothing.
In reality, even if everything possible goes right, force is equal to mass times acceleration. Photons have no mass at all, solar wind particles have negligible mass, and even going at significant fractions of lightspeed their ability to push things around is limited. Using a solar sail to get from Earth to Mars? Good luck- leaving Earth's gravitational pull would take months at best, provided Earth's magnetic field doesn't divert away so much of the solar wind that you can't get propulsion. Once you're away from Earth, the travel time would still be over a year.
As for interstellar travel? The theory persumes constant acceleration, but we've already found the point in space, more or less, where solar wind no longer has the power to push out the interstellar dust clouds which partially surround our solar system. It's a LOT closer in than we thought- light-days away rather than light-years. Beyond that point, acceleration will no longer be possible.
Solar sails may be more efficient in theory, but they just don't address the single greatest obstacle to space travel- FLIGHT DURATION.
This flight should have proved that, but it looks like it's gone Beagle 2 on us, which means someone else will sink millions into this.
Come on, Rutan, put that brain in gear, and find us a solution before this happens again...
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no subject
Date: 2005-06-22 08:57 pm (UTC)For long-term propulsion, yeah, you need to point a laser at the solar sail rather than assuming that the solar radiation will be sufficient - if you want constant acceleration. If you're sending out a probe that doesn't have to be anywhere by any particular time, eventually it'll stop accelerating, but it'll still keep going at whatever speed it reached.
Without the laser propulsion, it's an idea better used for probes and data-gathering devices than for ships carrying any kind of a payload. But it's not an inherently silly idea overall.
no subject
Date: 2005-06-22 09:10 pm (UTC)As for sending probes that don't have to be anywhere in any particular timeframe... there's no such. Mechanisms have lifespans, as do the scientists who designed them, planned them, and know how to operate them, as do the budgets such programs operate from. In order to be superior to chemical or ion thrust propulsion, solar sails must be -faster-, not just cheaper...
... especially since, in space travel, there's no such thing as guaranteed cheaper. As we have seen with Cosmos 1 and Beagle 2, among others.