Space travel: distance & time

[Allan]

Hello again!

I have completed my first novel (speculative fiction) and it will soon be published via Amazon. I have not forgotten the help I received from this community and will definitely have this site in my acknowledgements.

I've begun a second book. This one is less speculative and more sci-fi. Naturally this author is going to need a bit of help understanding certain aspects of physics and space. As always I do appreciate your ability to actually understand and explain (evenif I don't get it) the concepts I can only write about.

The scenario : an unmanned rocket leaves from Earth and is on a one way trip to a star 100 light years away.

The assumption: Unmanned rockets can travel approximately 157,000 miles per hour, resulting in 1 light year taking consuming about 4,250 years.

The question : How long would it take the rocket to travel the 100 light years?

As always, any help or insight you can provide to help me accurately portray this aspect of my book will be sincerely appreciated (and presented in my acknowledgements).

Thank you in advance

 

[PeriapsisPrograde]

157,000 mph ~= 70,200 m/s, or 0.02% of the speed of light. Relativistic effects would be low. Simply taking 100ly/157000mph gives ~= 427,000 years, or 1.348e13 seconds.

 

[Allan]

Thanks. Is 157,000 mph a realistic speed for an unmanned rocket?

 

[Hielor]

Thanks. Is 157,000 mph a realistic speed for an unmanned rocket?

"Speed" is not a particularly realistic concept in space. Rockets don't have a speed, they have an acceleration--their speed is only limited by relativistic effects, and 157,000mph is too low for that to be much of a factor.

More important than "how fast the rocket goes" is "how quickly does the rocket accelerate." Starting from a (relative) standstill, how long does it take the rocket to get to a given speed?

In a science fiction setting, this may be relevant: [ame]http://en.wikipedia.org/wiki/Space_Travel_Using_Constant_Acceleration[/ame]

 

[Hlynkacg]

This site has been invaluable to me both in Math and Creative Writing.

Hit it up.

 

[Allan]

Thank you. The mental realignment was necessary and Im sure it will help. Unlike my first book this one actually uses the massive distances of space to incubate my plot. Each of you has helped me more than I can thank you.