How could a helicopter enter and function in space? Could it enter the atmosphere and function, and if not what could be a suitable solution?
A normal, unmodified helicopter cannot exit earth's atmosphere. First the velocity needed to escape earth's atmosphere is about 11.2 km/s (25,300mph). The current world record for speed in a helicopter is 293 mph. A propeller on a helicopter can't exceed the speed of sound, 768 mph, which is far below the speed needed to exit earth's atmosphere. Even if a helicopter managed to get into space, propellers are used to push air down to fly and space is a vacuum.
The only possibility might be for a rocket engine used to enter/navigate in space and propellers used when within earth's atmosphere. There would probably be weight/size constraints of some sort, and stationary propellers might not survive reentry (also not very aerodynamic).
Another thing to note is the maximum ceiling for a rotary aircraft, which is below 25,000ft. Depending on what height you consider the edge of space, the height is much greater than that of a helicopter.
Ben, did you perhaps read/hear about the Rotary Rocket? While this is a space launch system with a rotor, it uses the rotor only for low altitude. A pure helicopter getting into space is totally impossible, as other posters have pointed out.
While not exactly the answer you are looking for, NASA did study the use of rotors for re entry into the Earth's atmosphere back in the Apollo program.
The idea in this case was to stow a set of rotor blades in the nose of the Apollo CM capsule and deploy them after passing through the plasma sheath of initial reentry. The rotors were unpowered and spun due to the aerodynamic forces of the airstream passing over them, essentially an autogyro. Once the rotor blades were deployed, the astronauts could control the descent and land the capsule virtually anywhere on land or at sea.
You can extend this idea by adding a propulsion system such as rotor tip ramjets so the astronauts have more control and the ability to climb, maintain level flight or even hover for a short period of time. The Hiller YH-32 Hornet used such a system. A more recent paper proposed using helicopter like blades deployed at supersonic or hypersonic speeds as a means of slowing down from reentry and making a powered landing, although this seems somewhat unlikely, with modern materials technology this may be possible: http://papers.sae.org/670391/
You could perhaps use it to fly through the interstellar medium.
In astronomy, the interstellar medium (ISM) is the matter that exists in the space between the star systems in a galaxy. This matter includes gas in ionic, atomic, and molecular form, as well as dust and cosmic rays.
Of course you would have to get there first and a helicopter wouldn't be much use for that.
Obviously rotors will not work in a vacuum. If your intention is to have a vehicle that can hover in the atmosphere as well as exit the atmosphere and escape orbit and dock with a mothership...
Perhaps it could use compressed air. Before it leaves the atmosphere it needs to store compressed air in canisters. While its in the atmosphere, it constantly takes in more air as it expends it. It could hover around like a helicopter by using a jet of compressed air, like a Harrier jump jet does.
Supposing this vehicle ran on fuel, it would not be very practical. It takes ALOT of fuel to escape orbit. Are you going to carry all of that fuel around with you while are you hover around the planet? It's air compressor would need to be powered by a portable fusion reactor or something. By the time you made this vehicle work, you could make just about any vehicle work. What exactly is the purpose of this vehicle?
Potentially, this "helicopter" could be made by utilizing plasma and electromagnets to create a plasma vortex to propel the craft. This could be used in combination with rotors, though that wouldn't be practical. In addition, for use of only rotors that wouldn't certainly be really practical in principle, as already stated above (it would be able to provide enough force for escape velocity).
So, obviously you're going to have issues with this in a hard sci-fi approach. You'll probably only get anywhere with a bit of hand-waving.
In that vein, you could imagine a rotor that is able to interact with "dark matter" that is ever present around the universe. Or neutrinos (implausible from physics standpoint due the orders of magnitude difference in forces) or photons (also implausible due to orders of magnitude difference in forces)
Thinking of this from the perspective of a vehicle that has the same pros/cons of a helicopter. A helicopter has to beat the air into submission 24/7 in order to stay in the air else it crashes and explodes. You could create a craft that is able to manipulate gravity/create unstable wormholes/interact with the fabric of space time so it can forcefully crawl towards its destination but if the reactor overheats everyone inside is gonna have a bad time.