RE: Oh no! Another alien probe
December 15, 2017 at 12:08 am
(This post was last modified: December 15, 2017 at 12:53 am by Anomalocaris.)
Actually, ejecting small objects from stellar systems is dynamically much easier than you might think.
Certainly if the object started in a circular orbit deep inside the star's gravitational well, say where the major planets in our solar system are, it would take one hell of an energy boost to kick the object out of the system. But if the layout of our solar system is any guide, in terms of numbers, but not mass, the vast majority of discrete objects that orbits the sun orbits in an very extended Oort cloud hundreds to thousands of times further from the sun than the farthest major planet. They are near the edge of the sun's gravity well to start with and are very loosely bound by the sun's gravity. The dekta V required to boost them into a hyperbolic trajectory could be just a few dozen meters per second. These objects require only a small influence on their orbital speed, say gravitational purtrbation of a star that passes with 1-2 light years, to get either sent them into the inner solar system, or ejecting completely out of the solar system.
As an order of magnitude estimate, you might say approximately for every comet that was sent into the inner solar system for us to see and catalogue, another was ejected from our solar system by the same event that sent the comet we catalogue in from the Oort cloud.
So even today, our solar system is probably still shedding objects similar to the one we detected into interstellar space In spurts with each relatively close encounter with nearby stsrs, or even rogue interstellar planets, which averages out to an long term average rate of at least several, possibly up to several hundred comets shed, a year.
There are probably still somewhere between a trillion and quadrillion meter sized object or above in the port cloud. So our sun won't run out of comets to shed into interstelar space during the remaining life of the sun.
Certainly if the object started in a circular orbit deep inside the star's gravitational well, say where the major planets in our solar system are, it would take one hell of an energy boost to kick the object out of the system. But if the layout of our solar system is any guide, in terms of numbers, but not mass, the vast majority of discrete objects that orbits the sun orbits in an very extended Oort cloud hundreds to thousands of times further from the sun than the farthest major planet. They are near the edge of the sun's gravity well to start with and are very loosely bound by the sun's gravity. The dekta V required to boost them into a hyperbolic trajectory could be just a few dozen meters per second. These objects require only a small influence on their orbital speed, say gravitational purtrbation of a star that passes with 1-2 light years, to get either sent them into the inner solar system, or ejecting completely out of the solar system.
As an order of magnitude estimate, you might say approximately for every comet that was sent into the inner solar system for us to see and catalogue, another was ejected from our solar system by the same event that sent the comet we catalogue in from the Oort cloud.
So even today, our solar system is probably still shedding objects similar to the one we detected into interstellar space In spurts with each relatively close encounter with nearby stsrs, or even rogue interstellar planets, which averages out to an long term average rate of at least several, possibly up to several hundred comets shed, a year.
There are probably still somewhere between a trillion and quadrillion meter sized object or above in the port cloud. So our sun won't run out of comets to shed into interstelar space during the remaining life of the sun.
