a meteorite impact on mars (or earth) could eject sizable rocks into space. there's not a lot of doubt about this.
a 1.7 km wide boulder screaming into earth at roughly 1/1000 the speed of light would make an estimated impact equivalant to a 100,000 megaton explosion. this would destroy a land area the size of California. collisions of this magnitude are thought to occur every hundred million years or so, and more frequently in the earliest history of earth. these are "small". the K/T event that many (with good evidence) believe ended the dinosaurs is estimated to have been a 10-20km rock that made the oceans boil and ejected huge amounts of material into low-earth orbit (and therefore faster bits could escape).
in contrast, the largest volcanic eruption in the history of earth is thought to be Fish Canyon, where 28 million years ago more than 5000 cubic km of magma was ejected with a force of maybe a few thousand megatons. this is enough material to cover california like 12m deep, but most stuff goes sideways not up, and the plume of such an event would not likley reach higher than the stratosphere (i.e. not reach orbit, let alone escape orbit). granted, mars has bigger volcanoes, lower gravity, etc.
nonetheless, I guess all I'm trying to say is that I think volcanoes ejecting rocks into space is orders of magnitude unlikely or at least far less likely than meteorites, which we think knock lots of stuff into space.
this is probably why hollywood has come out with a lot more meteor-impact end-of-the-world scenarios (a la "Deep Impact", "Armageddon"), but "Volcano" only destroyed L.A.;)
a good paper: N. H. Sleep, K. Zahnle. "Refugia from asteroid impacts on early Mars and the early earth." Journal of Geophysical Research. vol 103, No. E12, p. 529 (1998).
some of the other numbers: http://www.nineplanets.org/meteorites.ht ml http://www.decadevolcano.net/photos/keywords/c alde ra.htm
a meteorite impact on mars (or earth) could eject sizable rocks into space. there's not a lot of doubt about this.
a 1.7 km wide boulder screaming into earth at roughly 1/1000 the speed of light would make an estimated impact equivalant to a 100,000 megaton explosion. this would destroy a land area the size of California. collisions of this magnitude are thought to occur every hundred million years or so, and more frequently in the earliest history of earth. these are "small". the K/T event that many (with good evidence) believe ended the dinosaurs is estimated to have been a 10-20km rock that made the oceans boil and ejected huge amounts of material into low-earth orbit (and therefore faster bits could escape).
in contrast, the largest volcanic eruption in the history of earth is thought to be Fish Canyon, where 28 million years ago more than 5000 cubic km of magma was ejected with a force of maybe a few thousand megatons. this is enough material to cover california like 12m deep, but most stuff goes sideways not up, and the plume of such an event would not likley reach higher than the stratosphere (i.e. not reach orbit, let alone escape orbit). granted, mars has bigger volcanoes, lower gravity, etc.
nonetheless, I guess all I'm trying to say is that I think volcanoes ejecting rocks into space is orders of magnitude unlikely or at least far less likely than meteorites, which we think knock lots of stuff into space.
this is probably why hollywood has come out with a lot more meteor-impact end-of-the-world scenarios (a la "Deep Impact", "Armageddon"), but "Volcano" only destroyed L.A.;)
a good paper:
N. H. Sleep, K. Zahnle. "Refugia from asteroid impacts on early Mars and the early earth." Journal of Geophysical Research. vol 103, No. E12, p. 529 (1998).
some of the other numbers:
http://www.nineplanets.org/meteorites.html
http://www.decadevolcano.net/photos/keywords/calde ra.htm
I heard physicist and astrobiologist Paul Davies give a talk on this subject just yesterday;)
Davies proposes that the lower gravity of Mars makes it more likely for Martian rocks to reach earth, than vice versa, though transit both ways is statistically viable.
He also suggests that the faster cooling rate of the Mars crust, the lack of a global ocean, and some of the largest volcanoes in the solar system made Mars a more favorable place for microbial life to form.
http://aca.mq.edu.au/Research/research2003.html
Slashdot Mirror
in the laser lab where I work:
solid state diode laser, 5W at 532nm: $40,000
YLF laser, 20W at 532nm: $40,000
Titanium doped sapphire crystal: $1000
optics to make 400mW ultrafast laser: $10,000+
cost of buying comparable kit from KML: priceless!
no, actually $100-300k
not that these lasers are exactly general use.
I'm just pointing out that lasers and materials can be very expensive.
sorry I posted this twice...
;)
t mlc alde ra.htm
a meteorite impact on mars (or earth) could eject sizable rocks into space. there's not a lot of doubt about this.
a 1.7 km wide boulder screaming into earth at roughly 1/1000 the speed of light would make an estimated impact equivalant to a 100,000 megaton explosion. this would destroy a land area the size of California. collisions of this magnitude are thought to occur every hundred million years or so, and more frequently in the earliest history of earth. these are "small". the K/T event that many (with good evidence) believe ended the dinosaurs is estimated to have been a 10-20km rock that made the oceans boil and ejected huge amounts of material into low-earth orbit (and therefore faster bits could escape).
in contrast, the largest volcanic eruption in the history of earth is thought to be Fish Canyon, where 28 million years ago more than 5000 cubic km of magma was ejected with a force of maybe a few thousand megatons. this is enough material to cover california like 12m deep, but most stuff goes sideways not up, and the plume of such an event would not likley reach higher than the stratosphere (i.e. not reach orbit, let alone escape orbit). granted, mars has bigger volcanoes, lower gravity, etc.
nonetheless, I guess all I'm trying to say is that I think volcanoes ejecting rocks into space is orders of magnitude unlikely or at least far less likely than meteorites, which we think knock lots of stuff into space.
this is probably why hollywood has come out with a lot more meteor-impact end-of-the-world scenarios (a la "Deep Impact", "Armageddon"), but "Volcano" only destroyed L.A.
a good paper:
N. H. Sleep, K. Zahnle. "Refugia from asteroid impacts on early Mars and the early earth." Journal of Geophysical Research. vol 103, No. E12, p. 529 (1998).
some of the other numbers:
http://www.nineplanets.org/meteorites.h
http://www.decadevolcano.net/photos/keywords/
a meteorite impact on mars (or earth) could eject sizable rocks into space. there's not a lot of doubt about this. a 1.7 km wide boulder screaming into earth at roughly 1/1000 the speed of light would make an estimated impact equivalant to a 100,000 megaton explosion. this would destroy a land area the size of California. collisions of this magnitude are thought to occur every hundred million years or so, and more frequently in the earliest history of earth. these are "small". the K/T event that many (with good evidence) believe ended the dinosaurs is estimated to have been a 10-20km rock that made the oceans boil and ejected huge amounts of material into low-earth orbit (and therefore faster bits could escape). in contrast, the largest volcanic eruption in the history of earth is thought to be Fish Canyon, where 28 million years ago more than 5000 cubic km of magma was ejected with a force of maybe a few thousand megatons. this is enough material to cover california like 12m deep, but most stuff goes sideways not up, and the plume of such an event would not likley reach higher than the stratosphere (i.e. not reach orbit, let alone escape orbit). granted, mars has bigger volcanoes, lower gravity, etc. nonetheless, I guess all I'm trying to say is that I think volcanoes ejecting rocks into space is orders of magnitude unlikely or at least far less likely than meteorites, which we think knock lots of stuff into space. this is probably why hollywood has come out with a lot more meteor-impact end-of-the-world scenarios (a la "Deep Impact", "Armageddon"), but "Volcano" only destroyed L.A. ;)
a good paper:
N. H. Sleep, K. Zahnle. "Refugia from asteroid impacts on early Mars and the early earth." Journal of Geophysical Research. vol 103, No. E12, p. 529 (1998).
some of the other numbers:
http://www.nineplanets.org/meteorites.html
http://www.decadevolcano.net/photos/keywords/calde ra.htm
I heard physicist and astrobiologist Paul Davies give a talk on this subject just yesterday ;)
Davies proposes that the lower gravity of Mars makes it more likely for Martian rocks to reach earth, than vice versa, though transit both ways is statistically viable.
He also suggests that the faster cooling rate of the Mars crust, the lack of a global ocean, and some of the largest volcanoes in the solar system made Mars a more favorable place for microbial life to form.
http://aca.mq.edu.au/Research/research2003.html