Space Travel Times

[Phil Masters]

A quick question for the de facto brains trust here, because my maths and astronomy are insanely rusty; what are the minimum and maximum travel times from Earth orbit to Mars orbit, for a spacecraft capable of 0.0125G acceleration for indefinite periods?

(Actually, is there a Web site that can answer this class of question? I'd have thought that someone would have created one, but Google hasn't found one for me yet.)

[Not another shrubbery]

Hey, Phil. Try this site, Space Travel Calculator. It's fairly easy to use (note that you don't need to fill out ALL the fields). That's just a point to point calculation, but does seem to assume acceleration to mid-point, then deceleration to the destination. 0.0125g acceleration with no limits leads to reasonable travel times within the solar system.

[Phil Masters]

Many thanks for that. Right, 15+ days...

[Humabout]

That low of an acceleration won't enable a Hohhman transfer, but you can take arbitrarily long to get there by just adjusting your tranfer orbit. As for the lower bound, the Pyramid article from Space Atlas entitled Halfway to Anywhere specifically addresses this concern with brachistochrone transfers. It also comes with a spreadsheet that does the calculations for you.

[Anthony]

The flat space point to point estimate won't be quite right because your thrust is lower than planetary gravity (it's higher than stellar gravity for most of your trip so that can fairly safely be ignored), but it only makes a difference of a day or two.