Yes, I do hope cheap advanced propulsion concepts get used sometime in our lifetime. Then we can start "Buck Rogering" around the solar system rather than worrying about every drop of fuel. That's when the real fun'll begin.
celestial classification based on birth order
on
Defining "Planet"
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· Score: 1
I think one (perhaps) unambiguous way to define planets, asteroids, etc. is in terms of the order of formation of the objects. The asteroid and Kuiper belts are believed to be remnants of planetesimals (or protoplanets) that formed very early from the primordial nebula. Some planetesimals grew during a runaway growth phase to become planets.
But our knowledge of the timeline of planet formation is far from complete. So this way classifying may not be feasible for now.
It would be cool though, because then it be similar to the biological classification, where "relatedness" of two species (in terms of similar DNA) is strongly correlated with how early they diverged from one another.
As one of the scientists mentioned in the article (my website), I think the author of the article, who's a journalist and not a dynamicist, is slightly wrong about material "collecting" at L4.
Material typiclly doesn't come from elsewhere in the solar system and get stuck in some system's L4 points (like the Earth-Moon L4 or L5 points). The material that is there, if any, would have existed in that location since the formation of the system, i.e., anything near the Earth-Moon L4 or L5 points was there when the Moon formed.
Regarding the killer asteroids, you're totally right about deflecting them with small forces. There will be a conference next year,
Planetary Defense Conference: Protecting Earth from Asteroids, where people will propose technical plans associated with defending Earth from approaching near Earth objects (comets and asteroids). The threat will be approached from three warning levels: short-term (less than ten years warning); medium-term (ten to 30 years warning); and long-term (more than 30 years warning). The more time we have to deflect it, the smaller the force needs to be.
Thanks Heisenburg! It's good to know some people appreciate our work. It's bloody hard to explain to NASA managers, much less the general public. This article is a sort of first attempt.
Although I guess I am in some sense a "rocket scientist," I think the truly cool aspect of the work is the light that it sheds on the mechanisms of "interplanetary cross-fertilization." This
understanding contributes to fields such as astrobiology, for
example, where comet impact rates are key for determining the delivery of
water to the Earth and impact ejecta exchange rates are important for investigating the transportation of microbes between
Mars and Earth.
By the way, the fastest that a piece of impact ejecta has been able to get between Earth and Mars in any simulation is 10,000 years. This would be a piece of debris which, due to nonlinear effects, repeately encountered Mars and Earth with just the right geometry that it made the trip in the fastest time. The average transit time for bits of debries is a few million years.
Thanks for enjoying the article. I'm the grad student who did much of the work that the paper speaks of; a friend let me know that slashdot was discussing it, which is cool. There seem to be a lot of questions. People have to remember that the level of the article is "Popular Science"-esque, which always involves some glossing over important mathematical concepts.
Slashdot Mirror
There are several helpful animations here
Yes, I do hope cheap advanced propulsion concepts get used sometime in our lifetime. Then we can start "Buck Rogering" around the solar system rather than worrying about every drop of fuel. That's when the real fun'll begin.
But our knowledge of the timeline of planet formation is far from complete. So this way classifying may not be feasible for now.
It would be cool though, because then it be similar to the biological classification, where "relatedness" of two species (in terms of similar DNA) is strongly correlated with how early they diverged from one another.
Good observation. This is exactly what we hope to do for a multi-moon orbiter mission which "jumps" between the planet-sized moons of Jupiter (e.g., the proposed Jupiter Icy Moons Orbiter).
Material typiclly doesn't come from elsewhere in the solar system and get stuck in some system's L4 points (like the Earth-Moon L4 or L5 points). The material that is there, if any, would have existed in that location since the formation of the system, i.e., anything near the Earth-Moon L4 or L5 points was there when the Moon formed.
Regarding the killer asteroids, you're totally right about deflecting them with small forces. There will be a conference next year, Planetary Defense Conference: Protecting Earth from Asteroids, where people will propose technical plans associated with defending Earth from approaching near Earth objects (comets and asteroids). The threat will be approached from three warning levels: short-term (less than ten years warning); medium-term (ten to 30 years warning); and long-term (more than 30 years warning). The more time we have to deflect it, the smaller the force needs to be.
Although I guess I am in some sense a "rocket scientist," I think the truly cool aspect of the work is the light that it sheds on the mechanisms of "interplanetary cross-fertilization." This understanding contributes to fields such as astrobiology, for example, where comet impact rates are key for determining the delivery of water to the Earth and impact ejecta exchange rates are important for investigating the transportation of microbes between Mars and Earth.
By the way, the fastest that a piece of impact ejecta has been able to get between Earth and Mars in any simulation is 10,000 years. This would be a piece of debris which, due to nonlinear effects, repeately encountered Mars and Earth with just the right geometry that it made the trip in the fastest time. The average transit time for bits of debries is a few million years.
Thanks for enjoying the article. I'm the grad student who did much of the work that the paper speaks of; a friend let me know that slashdot was discussing it, which is cool. There seem to be a lot of questions. People have to remember that the level of the article is "Popular Science"-esque, which always involves some glossing over important mathematical concepts.
We have some papers at my website here.