The discussion revolves around the mechanics of rocket propulsion, specifically how hot gases propel rockets to escape velocity. Participants explore the underlying physics, including molecular interactions, conservation of momentum, and the potential for solar-powered propulsion systems. The conversation touches on both traditional chemical propulsion and electric propulsion concepts.
Participants express a mix of agreement and differing views on the mechanics of propulsion, particularly regarding the role of gas molecules and the necessity of expelling mass. The discussion remains unresolved on certain aspects, such as the feasibility of using heated gases for propulsion in space.
Some claims depend on specific definitions of propulsion and the conditions in space. The discussion includes assumptions about the effectiveness of various propulsion methods without resolving the complexities involved.
Individuals interested in rocket propulsion, space travel, and the physics of motion may find this discussion informative, particularly those exploring solar energy applications in propulsion systems.
jedishrfu said:At the microscopic level, I think you are right. In general though, it is explained as an application of Newtonian physics via the conservation of momentum where the exhaust from the rocket burn is mass ejected and so the rocket goes forward as a consequence. It you look at it microscopically, a chemical reaction occurs, energy is released, molecules move faster and temperature and pressure builds with some molecules escaping out the nozzle and others pushing against the rocket chamber pushing the rocket forward.
There are other forms of propulsion though as described in the wikipedia article:
http://en.wikipedia.org/wiki/Spacecraft_propulsion
Yes.So then if the propulsion is caused by the molecules of gas with high kinetic energy pushing the inside of the rocket, is it possible while in space to heat the gases inside the rocket and release them to cause further propulsion in space
Simon Bridge said:Yes.
Although just having a high speed (=high temperature) gas is not enough - you also have to let it out.
I take it you are thinking of using solar power to heat the gas?
This will work - and light-propulsion systems working on that principle have been developed.
Note: if you throw anything at all one way, you will move the other way (unless something stops you.)
This is how we'd normally think about how rockets work ... burning the fuel results in hot gasses, the rocket tube only has one exit - so the gasses escape that way very fast. The rocket goes the other way.
Siddharth Menon said:Yes Newtons law, but is this also possible in space where there are no particles present. I am thinking of a concept of an electric propulsion system which would obviously include the concepts of magnetism and such.
Like that physics prof 100 years ago who said that in the New York Times (that rockets in space couldn't work because there would be nothing for them to push against). This is so fundamentally wrong that I didn't think it was what he meant.Bandersnatch said:He's thinking of "molecule collision causing propulsion" but in the sense of molecules of the propellant pushing on the molecules in the air - a common misconception of how rocket propulsion works.
Alright i understand that, so it is possible to change direction etc. using hot gases. It may seem like i am asking stupid questions but i just want to be sure.phinds said:Like that physics prof 100 years ago who said that in the New York Times (that rockets in space couldn't work because there would be nothing for them to push against). This is so fundamentally wrong that I didn't think it was what he meant.