By: Minahil, Anam and Mawra
Immense momentum flows in the atmosphere occur due to the continuously bombarding of space dust. This fact transfers energy and moving particles around into this world or onto other planetary systems.
On the scale of approximately 10 raised to power 5 of dust enters space including varying size particles. The particles present in thermosphere can be displaced by colliding with other particles. This increases momentum to a greater extent. Such collisions can give particles in the atmosphere the necessary escape velocity and upward trajectory to escape Earth’s gravity. Two types of particles that will be considered are either light elements/molecules that form Earth’s atmosphere or bigger particles capable of harboring life or life essential molecules. The former possibility implies an exchange mechanism of atmospheric constituents amongst widely separated planetary bodies. As for larger particles capable of harboring biological constituents, the most likely scenario for thrusting them into space would require a double stage approach, whereby they are first hurled into the lower thermosphere region or higher by some mechanism and then given an even stronger kick by fast space dust collision, which eventually leads to escape velocity and an exit from the Earth’s gravity.
Space dust is bombarding the Earth from all directions. Although much of this dust will get pulled down by Earth’s gravity and fall to the ground, given the high entry speeds of this dust in the order of and even much bigger than escape velocity levels, some of the dust that enters the Earth’s atmosphere will then graze through it. For larger sized meteorites, such phenomenon is well known and is visible in spectacular fireballs that streak through the sky, sometimes accompanied also with meteor showers. Some fraction of the lighter space dust will also simply pass through the Earth’s atmosphere.
For a space dust particle that is grazing past the Earth, just beyond the point where it moves exactly parallel to the ground beneath it, this space dust will be moving with an increasing upward incline relative to the ground immediately below it. It is beyond this point that if it collides with particles in the atmosphere it will give those an upward force, accelerating them to higher altitudes. At very high altitudes around 150km and higher, we observed from the above estimates that at escape velocity level, drag and heating effects are not significant. Above this altitude, fast moving space dust will not heat up significantly and will continue to move fast. Anticipating that the chances of space dust hitting small particles in the atmosphere is a rare event, which will be verified below; it will be assumed that a given atmospheric particle may have at most one or two collision with space dust. If this is to provide adequate momentum to the particle, the fast space dust needs to be at least the same or greater mass than the particle it hits. In such collisions, by momentum conservation, a considerable portion of debris after collision will then leave with about the same speed and direction as the incoming fast particle that initially hit it.
If such a collision by a fast moving space dust particle with some upward velocity happened at high enough altitude, then the struck particle, whether attaching itself to the incoming space dust particle or scattering elastically/semi-elastically, could be accelerated to escape velocity level. If that small particle contained any biological constituents, these would be thrust out into space, free of the Earth’s gravity.
Thermophiles are known to survive in temperatures reaching up to 400K. Thus for microbes that manage the hypervelocity escape from the Earth, it seems some would be hardy enough to also survive in the region of space nearby Earth. If these microbes continued to journey further out in the Solar System, radiation levels would decrease but temperatures would get much colder down to 40K at the outer part of the Solar System. Collisions of huge meteorites with the Earth are a well-known mechanism for raising large amounts of material from the Earth out into space, some of it possibly containing microbial life Gladman, Melos. Although this is a potential mechanism for throwing microbial life into space, it occurs very rarely, on geological time scales.
This microbial life once in the harsh space environment would have the best chances of survival if around the time of the impact other near Earth objects, like asteroids, comets etc., in the Solar System were also sweeping past the Earth and collected the microbial debris, thus helping to protect this life and facilitate its transfer to larger planetary bodies. So this question needs further study and examination to prove that life travels through space dust.