if a ship say the U.S.S Enterprise were to travel to Mars for a mission or something how long would it take? Minutes?Hours?.is there an estimate as to how long space voyages usually take in Star Trek?
The Enterprise D's maximum speed is warp 9.8. This is equivalent to around 1,015,313,576,887mph
Given that Mars is typically around 249,000,000 miles from the Earth, that means that the Enterprise could (if they were monumentally stupid enough to do an in-system warp jump) reach Mars in substantially less than one second.
That all being said, the fastest we ever see a ship traveling at sublight speeds is half-impulse (half the speed of light). That means that a realistic journey would be around 10 minutes, depending on the amount of time it takes to get your luggage through security.
Due to revisions to the warp speed scale over the decades of Star Trek production, this would vary at maximum speeds. There is, however, a general agreement that Warp 1 is equal to the speed of light, and for our purposes, that is fast enough.
At their closest, Earth and Mars are 225 million kilometers apart, which is equal to 12.5 light minutes, making the journey from Earth to Mars, if a straight line course was possible, twelve and a half minutes at Warp 1. At their furthest, they are 22.3 light minutes apart, leading to a journey something in excess of 23 minutes apart; a direct course is impossible at that point, as the sun lies along a straight line between Earth and Mars at that point.
Complicating factors include: limitations (inconsistently expressed on screen) to use of Warp Drive within a solar system, likelihood of traffic throughout the solar system, the need to avoid collision en route, and the fact that no on-screen version of The Enterprise has been limited to Warp 1. As Richard points out, at maximum warp, the journey would be nearly instantaneous.