Do all spacecraft need a propellant to change their speed or direction?

Question

Do all spacecraft need a propellant to change their speed or direction? (Please do not take into account the spacecraft using the gravity of other planets to do this). If not, what is used and how does it work?

Is solar wind made of the radiation from the Sun (photons) or is it matter, or something else? I always thought solar sails were just solar panels which converted light to electricity, is this wrong?

Answer 1

Yes. Conservation of momentum dictates that if the the spacecraft accelerates in one direction (ignoring gravity), there must be something else moving in the opposite direction (the propellant).

However, the propellant can take a wide variety of forms. You can vaporize teflon in a plasma thruster, you can eject nitrogen gas, you can shoot a beam of light from Earth (photons have momentum and can exert a force on the ship when they are reflected back), etc.

Answer 2

All spacecraft require some sort of propellant to change both their velocity and direction. Many also require an on-board propellant supply for adjusting their orientation in space as well. That is why spacecraft have a finite lifetime. When the fuel supply runs out, the spacecraft can't even keep it's antenna aimed at Earth. Propellants can take the form of various chemical fuels that can be stored for a long time in tanks, compressed gasses or even sunlight. Chemical fuels are usually something such as nitrogen tetroxide (N2O4) and various types of hydrazine, nitric acid, and various amine based propellants. They are not liquid oxygen, hydrogen, or kerosene, which will boil away or freeze up over time even when the tanks are well insulated. This is especially true of liquid hydrogen. A rocket can not be kept fueled with these proplellants for a long period of time, but a spacecraft may have to operate for many years. Therefore the fuel it carries must be storable for a long time. If just high pressure gases stored in tanks are used, they are typically nitrogen, argon or helium, which is also often used to pressure fuel and oxydizer tanks. Spacecraft that have a liquid fuel rocket aboard use what is called a "pressure feed" type of system to deliver the fuel and oxydizer to the engine or engines. A tank or tanks of high pressure nitrogen, helium or other inert gasses feeds gas into the tanks through a regulator. This pushes the fuel and oxidizer into the engine, where they mix, ignite and the hot gasses rush out of the nozzle producing thrust. Thusters are often a single propellant design that send hydrazine to a catalyst in the thuster that the propellant reacts with and the resulting hot gasses are expelled from a nozzle. Cold gas thrusters just vent gas into space without any combustion or catalytic reaction. It couls also be sent to an ion engine, which uses electricity and magnetism to turn the gas into a stream, of plasma that is expelled out of the engine, producing thrust. Sunlight simply pushes on a solar sail and changes it's speed slowly over time. The solar wind is not light from the Sun, it's a stream of plasma the star blows off into interplanetary space continously at an avererage speed of several hundred miles per second, or around 1.5 million mph.

Answer 3

Spacecraft obey Newtonian laws like everything else. For it to change direction something else must move in the opposite direction; a propellant. Spacecraft are affected by the solar wind and this needs to be taken into account on a long trip.

Answer 4

Normally yes.
Aside from employing the gravity force of other bodies (planets) the solar wind can be used as a propulsion technique. This has been studied for decades using "solar sails" for interplanetary travel.

Answer 5

Spacecraft can change their direction by torquing against internal gyroscopes. Over timescales of several days, they can use magnetic torques acting on external magnetic fields to change direction, or to spin down gyros that have gotten too fast.

Answer 6

sure, this concept might artwork in area... the problem is that by using fact the magnets push and pull the craft or practice or motor vehicle, they are additionally, in an equivalent-yet-opposite way pushing and pulling the gap station... quicker or later this technique is going to require propellants... whether the station is plenty extra super, it is going to nonetheless "drift" out of its sturdy orbit after each launch

Answer 7

Of course, "propellant" is involved. Newton's "action -- equal and opposite reaction" law.

Rockets, maneuvering jets (compressed gasses).

Think, and research. Your question is mighty broad.

Answer 8

i do not know what a propellent is.and the aircraft changes its direction with plates on the side of the wings it either moves up or down to make the air go through that way it will drop.u totally confused me i do not know who i am right now.