Let’s all just kind of take a moment to soak this in … for the first time ever, humanity has changed the orbit [of a celestial body].
Lori Glaze
Director of planetary science at NASA
October 11, 2022
Smashing success: NASA asteroid strike results in big nudge
[It is a remarkably big deal. Imagine firing a bullet even one 1/1000th of that distance at an object about 500 feet in diameter and moving thousands of miles per hour and hitting it. Now think about what this technology could mean for our planet. It could save millions or even billions of lives and prevent incalculable amounts of property damage. It could even prevent the extinction of hundreds or thousands of species.
Now NASA should contract with private enterprise to put a bunch of rock pushers on the moon or in orbit and be ready to push threats away from us on short notice.—Joe]
SF writer L. Neil Smith postulated such a private enterprise, in his novel “Pallas”. Along the way he also points out that such a thing can’t be entrusted to governments, because the power to divert asteroids away from earth implies the power to divert them towards earth.
Among the tools used by Neil’s group is a large observatory set on the back side of the moon, known as the “Far Side Observatory”. Yes, with a Gary Larson cartoon mural in the lobby. 🙂
The “Dims” have lots of toys that I don’t trust anyone with. Who knows who they consider a threat to their lifestyle.
The ability to save Earth from asteroids has always been accompanied by the ability to destroy it with those same asteroids. What isn’t usually mentioned is the
“screw up effect”. Where we pushed this asteroid from the direction it was going into a new direction….that a century or two from now might actually cause it to hit Earth when otherwise it wouldn’t. Because asteroid orbits are NOT stable. They DO change. Experimentation has risks. We need more and different ways to counter the threat of asteroids/comets.
Consider smaller objects than earth-killing asteroids. City killers perhaps which are more common and easier to deflect. Suppose we have incoming that is aimed at NYC. We nudge it and it hits Beijing. Act of war? I suspect the Chinese would see it that way.
” We need more and different ways to counter the threat of asteroids/comets.”
This.
The recent effort is “Asteroid Orbit Control 1.0.” I expect that by about 2.5 we’ll be accomplishing soft landings and orbital change with thruster engines rather than simple impact of moving mass. By which time one hopes the math and computational power necessary for extremely long term orbit analysis has become old hat, even for those orbits predominantly outside our solar system.
Which raises the question “if we don’t know precisely what is out there, and where, orbital analysis cannot be complete. One more argument for humanity developing multiple Egg Baskets throughout the universe.
I hate the comparison to firing a bullet to how accurately you can place a spacecraft. Bullets don’t have dozens of people tracking them so they can make mid-course corrections and to tweak the final trajectory like a spacecraft does
True. It’s still a non-trivial problem. Just observing the spacecraft at that distance has to be tough.
Hmmmmm….. maybe they didn’t observe it. They could have used cameras on the craft to locate it.
Absolutely it’s a non-trivial problem. It’s just that the bullet comparison irritates my inner Sheldon Cooper. 🙂
>>Francisco- My thoughts too. Why just hit it if you can own it. 2 gimbaled engines placed 90* apart could do any sort of twisting, turning or shoving needed. High efficiency thrusters, designed to use local material as fuel. But absolutely, positively under no circumstances use nuclear power *). Space is a harsh mistress too, such a mobile mountain could be a marvelous resource or a marvelous weapon. It always goes back to a management problem.
Given the probable number of objects “out there” there are certainly some which contain valuable material, some which are essentially worthless, and some which appear worthless but under the exterior shell offer great value, and some just the opposite. “Owning” those would be worthwhile, assuming we can tell which is which and there is a cost effective way to get the value to someplace where it can be manipulated to advantage. Maybe that is earth, maybe it is an orbiting lab/manufacturing facility, maybe it’s a site on the moon or even Mars.
Right now we’re concerned with “just change the orbit enough so it doesn’t hit us” which is, quite reasonably, the highest order value. For now. Next year, next decade, next century, things will change as we learn and develop more options, assuming we have that time available.
I would think shooting rocks in space is much simpler than shooting long range on earth.
As gravity, wind, and coriolis wouldn’t be a factor.
I would suppose the angle at which one wants to hit something would pose greater difficulties.
As for moving thing around in space seems to me to be more a factor of fuel availability? As H2 and O2 have to be brought from earth. As liquid, they are heavy.
There is lots of gravity “out there”. The sun, planets, moons, and asteroids all contribute a variable direction and magnitude force to be accounted for.
Indeed. The earlier comment about the difficulty of long range orbit calculation is tied directly to all the gravitational sources out there. Not all are known, and the computation is hard. As I recall, the three-body problem has no closed form solution but can only be solved iteratively. What is the computational complexity of the n-body problem? O(n)? O(exp(n))?
One reason long range calculation is so hard is the increased impact of tolerances and rounding errors. Rounding errors can be handled, just throw more bits at the problem. But tolerances can be dealt with only so much; at some point you’re up against the limitations of the best instruments. Just from the reproducibility limits of the current primary standards you’re up against a 10^-14 or so bound, probably worse in most cases depending on which units are involved.
I would also consider that they are somewhat able to make mid-flight corrections?
But I can surely see the problems one would face in the enterprise.
Mid-flight corrections, exactly. The right analogy is not a bullet, but a Sidewinder.