Crazy Eddie wrote:
Actually, let's reflect on that for a moment. Every space ship ever made in history has had some capability to operate in an atmosphere; at a bare minimum, they've been equipped with parachutes and float devices. More advanced concepts have had wings and landing gear for glide landings, and SpaceX is developing capsules capable of propulsive landings at a prearranged landing site. Is it really all that strange to think that that same basic capability wouldn't be preserved and enhanced over two hundred years?
Every spaceship in history has been tiny compared to the Enterprise and if you look at how much energy it takes to get them up and out of the atmosphere and scale that up to the size of the JJprise and other starships it must be obvious where I'm coming from. I realise that you can invent magical technology that overcomes the energy needed to lift something that heavy but that isn't the science on which impulse power is based. They are actually trying to build one too:
"This engine, currently under development at the University of Hunstville by a team working in collaboration with Boeing, NASA and the Oak Ridge National Laboratory, would by comparison be about twice as fast as the best current technology.
According to Txchnologist, General Electric’s online tech magazine, this fusion reactor would be fueled by “a few tonnes” of deuterium (a heavy isotope of hydrogen) and lithium-6 (a stable molecule of lithium) in a crystalline structure — hence the “dilithium crystal” claim. Technically, dilithium is a molecule with two covalently bonded lithium atoms, while lithium-6 features six bonded atoms, but we can forgive them for the temptation of using a little poetic license. When the deuterium and the lithium-6 are forced together under high pressure they undergo a fusion reaction — a process which they’re still trying to turn into a net producer of energy. While fusion isn’t yet a viable fuel source, recent developments in the field seem to indicate that we can’t be far away.
The engine, dubbed the “Charger-1 Pulsed Power Generator”, would be constructed in space along with the rest of the spaceship to avoid the tricky engineering difficulties of getting all that delicate fusion equipment up through the atmosphere — just like the International Space Station.
Once ready, the reactor would be engaged, and millions of amps are passed through super-thin lithium wires in 100 nanosecond pulses — this could generate up to three terrawatts of power. Those wires vaporise into plasma, which is collapsed onto the core of deuterium and lithium-6, inducing a fusion reaction.
The energy from that would be forced out the back of the ship in a so-called “z-pinch” using a “magnetic nozzle”, a component which the team are also developing. The engine’s potential top speed? Over 100,000km/h. That’s roughly the same speed at which the Earth orbits the Sun."
"The fusion fuel we're focusing on is deuterium [a stable isotope of hydrogen] and Li6 [a stable isotope of the metal lithium] in a crystal structure," Txchnologist quotes team member and aerospace engineering Ph.D. candidate Ross Cortez saying. "That's basically dilithium crystals we're using." Let's pause and savor that for a moment. Dilithium crystals. Awesome.
Plenty of obstacles will need to be overcome during the development process. The issue of harnessing fusion is prominent, but there is also the question of turning the power generated by fusion into thrust for an engine. The craft using the impulse drive would also need to be assembled in space, much like the International Space Station.
"Imagine using a 1-ton TNT equivalent explosive and putting it out the back end of a rocket.
That's what we're doing here," Cortez says in a press release about the project. Now we can all practice saying "full impulse power" to our imaginary starship navigators."
I'd pity the Iowa farms caught in that backwash.
Oooh - and I found this in-universe theory too which looks fun. Once again though, the backwash would be pretty devastating on a planet's surface:
Impulse drives come from the Star Trek Universe, and like most Star Trek tech it is based on fairly exotic physics concepts. Source material from Star Trek, which now spans over 35 years, is sometimes notoriously inconsistent, and the exact nature of the Impulse Drive often changes on a scriptwriter’s whim. However, I’ve run across two "official" (i.e., approved by owning company Paramount) explanations, listed below.
GRAVITY WAVE IMPULSE DRIVE
Tech Level: 19
The gravity wave scheme is probably the neatest (in every sense of the word) explanation for how the Impulse Drive works. It seems likely that it was created by the show’s science advisors and then promptly ignored and/or dumbed down by numerous scriptwriters. It is, however, the best fit in describing the capabilities of the drive as seen on the various shows through the years.
First of all, an impulse drive is NOT a conventional fusion or ion reaction drive as many people (and even some older source material) assume; those are reserved for a Federation ship’s "maneuvering thrusters." In fact, its proper name is the Inertial Magnetronic Pulse Drive--or more simply the I.M.Pulse, or impulse, Drive.
The drive works as follows: a pellet of deuterium-deuterium fusion fuel is fused in a high-energy reaction (perhaps by a Daedalus-like system with crossed high-energy particle beams) that is contained and modulated in a "magnetronic" field. What exactly a magnetronic field is, and how it differs from a plain ol’ magnetic field, is not explained. Judging from how its used, though, it may be a magnetic containment field merged with a strong nuclear force or gravitic force field. (Not a "force field" in the Star Trek sense, but a small region of space where the strong nuclear force or the gravitic force is enhanced on a quantum level.)
Basically, the magnetronic field contains and focuses the fusion implosion to such a degree that it generates a substantial amount of gravitic as well as electromagnetic energy. These powerful but short-lived gravity waves are used to push or pull the ship in various directions. By "pulsing" the drive thousands or even millions of times a second, a Federation ship can achieve the insane accelerations we often see on the show.
The "focusing" of a high-energy fusion reaction to produce gravity waves may sound odd, but it is actually based on solid theory. Certain types of black holes called kugelblitzes (German for "ball lightning") can be created solely by extreme energy densities, just as conventional singularities can be created by extremes of matter density. Kugelblitzes are thought to have been formed in the wake of the Big Bang. The impulse drive may, in fact, be constantly creating extremely short-lived, or "virtual," microscopic kugelblitzes that evaporate after a few microseconds, living just long enough for the ship to use their gravitational influence.
According to Star Trek’s canon, Impulse Drives operating all-out at peak efficiency ("full impulse") can achieve 25% of lightspeed, often within a few seconds. It is possible to go even faster, but at an ever-increasing cost to engine efficiency. Ninety percent lightspeed or so is supposedly the theoretical maximum, and the ship would have to be pouring all its power for hours into the drive to sustain ever-tinier increases in acceleration.
Needless to say, a gravity wave Impulse Drive is an extremely powerful and versatile form of sublight propulsion. Since the gravity waves produced can be either attractive or repulsive (like anti-matter, anti-gravity --theoretically-- exists, but is not generally found in nature) a ship equipped with an impulse drive can accelerate or decelerate without changing it orientation.
The Impulse Drive exhaust ports shown on the Enterprise are not used in the same way conventional rockets exhausts are; they are used solely to vent the plasma the fusion pulses generate, and only add relatively small amounts of acceleration to the ship compared to that generated by the Impulse Drive proper. It should be noted, however, that even this ‘waste’ exhaust would still be dozens of times more powerful than any conventional rocket that exists today.