The are 4 levels or types of space going vehicles, to the best of my knowledge as of 21/2/2016
Capable of lauching and travelling to Satelites, natural or artificial and returning to Earth. One way travel to other planets may also be possible.
An oxidising and reducing agent are mixed in the appropriate stoichiometric ratio and ignited examples include
2 moles of Hydrogen being mixed with one mole of Oxygen, ignition results in water. This was the process that powered the main rocket engines of the US Space shuttle, while its SRB (Solid Rocket Boosters) are powered by a reaction of ammonium perchlorate (oxidizer, 69.6 percent by weight), aluminum (fuel, 16 percent), iron oxide (a catalyst, 0.4 percent), a polymer (a binder that holds the mixture together, 12.04 percent), and an epoxy curing agent (1.96 percent). Many other examples exit, the bottom line is that all of these use a chemical reaction to generate heat and thrust. Typically this type of engine will run once for about 2 minutes.
Two way travel anywhere in the solar system, possibly one way trips to nearby stars.
These have been seen on earth in ancient times, however, modern man has not built one of these as yet. From my reading and thoughts about the chemistry involved, I have come to the conclusion that Mercury (quicksilver) is bombarded with a neutron source, producing an unstable isotope of Mercury which breaks down by radioactive decay releasing huge amounts of energy in the form of heat, this produces the thrust that drives the rocket motor.
Mercury has 7 stable and 31 unstable isotopes see wikipedia: https://en.wikipedia.org/wiki/Isotopes_of_mercury of the 31 unstable isotopes, 29 have half lives of less then a day, some as short as microseconds, so if we can add a neutron to a mercury atom, it well transform into an unstable isotope, which will decay into another element, often gold or platinum and will release a great deal of nuclear energy in the process. Mercury being a liquid allows itself to be pumped into a reactor vessel at a controlled rate, in the vessel the mercury could be exposed to neutron bombardment or a radioactive source, activating the mercury to decay and release neuclear energy in a controlled fashion. This type of engine would produce astronomical amounts of energy from a very limited amount of "fuel". Therefore vastly increasing the range and speed of travel of a ship powered by this type of engine.
Two way travel anywhere in the galaxy, possibly further, ships seem to be small, disc shaped
These to have visited the Earth, some scale models appear to have been built by John Searl in the late 20th century, videos of this type of technology can be found on youtube. Lenses Law is the scientific prinicipal that explains how this type of technology work, if fully understood, for an indepth explanation, click here lenz's law explained
In the book "secrets of antigravity propulsion" Paul Laviolette explains that high Voltage DC (150KV and higher) can produce an antigravity affect. In Thomas Townsend Brown's experiment with High Voltage DC he shows that gravity fields also contain an electrical component, as weight can be added or subtracted from a body through the application of HVDC. On Earth if the positive electrode at 150 KVDC is facing away from the Earth an object will get 1% lighter, if however, the polarity is reversed, and the negative electrode faces away from Earth, an object will become 1% heavier.
I like to think of gravity as a force acting between the moments of inertia of two or more bodies in space, where the moment of inertia of both bodies is in the same direction (parallel). If the moment of inertia of one body can be changed to the perpendicular plain of the other bodies moment of inertia , then no gravity will be felt by either body, and the body with the perpendicular moment of inertia will become weight less. A simple example of this can be observed when a frisby is "thrown" (spun) through the air, it will "fly" much further then a non spinning frysby. I was also amased that a gramophone record, or a similar flat disc with a hole in the middle can be thrown (spun) and will "fly" or hover further then any other type of frisby, clearly it is not an aerodynamic affect.
I believe that Albert Einstein spent many years of his life working on the unified field theory, officailly he did not crack the connections between Electricity, Magnatism and Gravity. However, I think that he did figure it all out, but that the details were classified top secret, as this knowledge has serious implicatiosn for the our world, the economy and potential weapons.
Can travel anywhere in the universe, at Faster then Light Speed. Ships can be large, usually cigar shaped.
It is thought that pure crystals can funnel energy. The TV series Stargate has space ships powered by this type of technology. Unfortunately, I cannot give a Scientific explanation of how this works or which materials the crystal need to be grown from.
The Atlantians were said to have utilised this type of technology to build their advanced civilisation. I read a book some time ago in which it was claimed that the atlantians managed to graft a large power crystal into the chest of a man, when he got angry, the crystal funneled that much energy that it exploded killing the man and leveling an entyre city similar to a small nuclear blast, ofcourse these are all just myths and legends these days.