Why not? It's not just a tech for negating the pull of nearby planets - it's a tech that pulls crewmen towards the decks on which they stand, thus clearly providing pull where there originally was none. Such tech could obviously pull a ship forward in empty space if properly applied. Or then turn conventional rockets super-efficient!
Interestingly, while we sometimes hear of warp signatures, evidence on impulse trails is hard to come by. Wouldn't those be commonplace if ships indeed needed tailpipes? Or is there so little exhaust that it can't be told from natural deep space particles except with very special equipment in very special circumstances?
What i meant was, gravity is quite a weak force so not much use to attaining high speeds quickly unless, like the Romulans you have an artificial black hole for power.
I suppose anything travelling at impulse is likely to be within sensor range and if it's not, it must have set off so long ago that the trail is cold? More likely, being able to detect a ships' trail negates cloaks and a lot of story tropes. Likely it was never bought up as it would spoil the narrative.
It appears that rocket-style steering is a backup option available in dire emergencies ("Booby Trap"), but too primitive and low-performance for routine use. It's too bad that ST:TMP introduced this rather silly 20th century style technology to the Trek universe at all - but then again, that movie dumbed down Trek in so many other ways it's difficult to believe in the "upgrades" or "maturing" the movie insists on introducing... Luckily, the TNG era spinoffs forget most about that stuff and return to the magic of TOS (at least when it comes to technology).
Yes, thrusters are used in spacedock, which suggests they are used for slow, careful manoeuvres. The bang from impulse engines is a bit too strong I suppose.
Did TMP dumb down the tech though? Do you mean they started to ignore real world physics or that they started to wind back the clock to real world physics to make it less magical? The less magical and more rooted in real world physics it is, the more I like it.
Ion propulsion is definitely a thing in Trek and would involve using ionised gas to move forward, using as suggested above, projected force fields to redirect the thrust force forward to reverse but it looks like Wikipedia and the Technical Manuals have done the work for us:
"The impulse engines are nuclear fusion engines in which the plasma from the fusion reactor powers a massive magnetic coil to propel the ship. It is a form of magnetodynamic or magnetoplasmadynamic thruster. This is used in conjunction with the ship's warp drive's alteration of the ship's relativistic mass, to achieve mid-to-high sub-light speeds. Thrusters, on the other hand, are closer to the designs of a high-efficiency reactant propellant (i.e. a sophisticated rocket engine) and are usually used for high-precision maneuvers.
Magnetohydrodynamics (
MHD) (
magneto fluid dynamics or
hydromagnetics) is the study of the magnetic properties of electrically conducting fluids. Examples of such
magneto-fluids include plasmas, liquid metals, and salt water or electrolytes.
A
magnetoplasmadynamic (MPD) thruster (MPDT) is a form of electrically powered spacecraft which uses the Lorentz force (the force on a charged particle by an electromagnetic field) to generate thrust. It is sometimes referred to as Lorentz Force Accelerator (LFA) or (mostly in Japan) MPD arcjet. Generally, a gaseous material is ionised and fed into an acceleration chamber, where the magnetic and electrical fields are created using a power source. The particles are then propelled by the Lorentz force resulting from the interaction between the current flowing through the plasma and the magnetic field (which is either externally applied, or induced by the current) out through the exhaust chamber. Unlike chemical propulsion, there is no combustion of fuel."
So what this would indicate is that the ships should have a tail pipe, that thrusters would be needed to fine tune the ship's direction, that an active warp field is needed to change the relative mass of the ship at higher speeds.
Does this mean that the NuEnterprise should not really be able to perform hairpin turns in an atmosphere without either creating a warp field (bad for life outside the bubble), a massive thrust of super-hot gas (bad for life in its path), hydrogen thrusters, or using a tractor beam as a repulsor (bad for life in its path). I'm still not clear why they needed the warp engines online in STiD unless impulse and thrusters and emergency batteries were all offline and if they were then the ship is once again going to warp to change direction and it does not seem to be doing that? I don't get it.
