Just an FYI to add to the question. I wrote a program to calculate the travel time of a space journey, assuming that the starship accelerates at 1g to mid-point, turns over, and accelerates (decelerates) at 1g to the destination. The times I used are somewhat approximations, but should give the correct answer within an order of magnitude. The time will be as percieved by those on board, not as perceived by those at the origin or destination, as relativistic effects will need to be accounted for: PROGRAM SHIPTIME; VAR DEBUG: BOOLEAN; VAR LOOPING: BOOLEAN; VAR WAITING: BOOLEAN; VAR TEXT_INPUT: STRING [255]; VAR TEXT_OUTPUT: STRING [255]; VAR VAL_STATUS: INTEGER; VAR LIGHT_YEARS: REAL; VAR KILOMETERS: REAL; VAR METERS: REAL; VAR HALFWAY_METERS: REAL; VAR TEMP_REAL: REAL; VAR HALFWAY_SECONDS: REAL; VAR HALFWAY_MINUTES: REAL; VAR HALFWAY_HOURS: REAL; VAR HALFWAY_DAYS: REAL; VAR TOTAL_DAYS: REAL; VAR TOTAL_YEARS: REAL; BEGIN WRITELN ('BERNIE''S SHIP-TIME CALCULATOR'); DEBUG := FALSE; LOOPING := TRUE; WHILE (LOOPING) DO BEGIN WRITELN; WAITING := TRUE; WHILE (WAITING) DO BEGIN WRITE ('ENTER DISTANCE IN LIGHT YEARS, OR ZERO (0) TO END: '); TEXT_INPUT := ''; READ (TEXT_INPUT); WRITELN; IF (LENGTH (TEXT_INPUT) > 0) THEN BEGIN VAL (TEXT_INPUT, LIGHT_YEARS, VAL_STATUS); IF (VAL_STATUS = 0) THEN WAITING := FALSE; END; END; IF (LIGHT_YEARS <= 0) THEN LOOPING := FALSE ELSE BEGIN KILOMETERS := LIGHT_YEARS * 9460000000000.0; METERS := KILOMETERS * 1000.0; HALFWAY_METERS := METERS / 2.0; TEMP_REAL := HALFWAY_METERS * 2.0; TEMP_REAL := TEMP_REAL / 9.8; HALFWAY_SECONDS := SQRT (TEMP_REAL); HALFWAY_MINUTES := HALFWAY_SECONDS / 60.0; HALFWAY_HOURS := HALFWAY_MINUTES / 60.0; HALFWAY_DAYS := HALFWAY_HOURS / 24.0; TOTAL_DAYS := HALFWAY_DAYS * 2.0; TOTAL_YEARS := TOTAL_DAYS / 365.0; STR (TOTAL_YEARS:32:16, TEXT_OUTPUT); WRITELN ('TIME TO DESTINATION IS ', TEXT_OUTPUT, ' YEARS.'); END; END; END.

Between 3 and 6 months at current vehicle speeds. Why the difference. ? Well if we were to have a rocket engine with plenty of fuel we could just head (well almost) straight there (actually we would aim for the point in space that Mars would be in at arrival time). However we cant pack that much fuel, so we accellerate to break Earth orbit and slowly coast out to Mars orbit meeting up with the Red Planet in about 6 months. Also timing is important because every 2 years Mars' orbit brings it closer toward Earth's orbit. Packing less fuel we have room for more important things like air, water, food, and other essentials. Getting there is half the fun.....arriving with a live crew is the other half. Currently we can send probes to Mars but sending men is more difficult. We have to recycle air, water, and pack a whole lot of food just to get there and back or send the supplies ahead.