# You Want This. You Need This.

Those of you who have bought and read a copy of The Core War and Other Stories may have noticed the reference to Kerbal Space Program in the acknowledgements…

(Those of you who haven’t – go buy a copy! Right now! Seriously – I’ll wait for you. Got it? Okay.)

…specifically “which taught me everything I know about orbital mechanics”.

Well, the beta is over and the first release version, 1.0, just shipped today. And so I’m here to suggest to you that you get a copy, too. It’s an invaluable resource for the SF writer, because it’s far easier to learn orbital mechanics from – specifically including developing an intuitive feel for them – than doing so from textbooks. And when you’re trying to do something complex enough that you need to go back to the textbooks, it makes it a lot easier to understand them. (And the fun needn’t stop there – it has a very active modding community whose add-ons let you simulate everything from life support to heat radiators, from exotic ISRU fuels to Orion drives…)

And it’s an invaluable resource for SF readers, too, at least if you like your SF relatively hard and want to have some idea how real spacecraft actually maneuver. (Fair warning: you may suffer somewhat from this if you have a problem with Science Ruining Everything, but, hey, knowledge has a price. Read better books!)

And best of all, it’s 25% off right now for launch day, so hie yourself over to the Kerbal Space Program web site and get yourself a copy. I personally guarantee that you won’t regret it.

# Hohmann Transfer Delta-V Approximator

Speaking of handy little Mathcad tools, this one is a generic delta-v approximator for planet-to-planet Hohmann transfers, based on the same mathematics as this Stack Overflow answer:

http://space.stackexchange.com/questions/1380/how-to-calculate-delta-v-required-for-a-planet-to-planet-hohmann-transfer

As mentioned there, it makes various assumptions, including that the bodies’ orbits around their sun are within delta of circular and coplanar (which works reasonably well for Sol), and that you aren’t using low-thrust drives and as such it can get away with treating burns as instantaneous. The further you wander away from these, the more approximate the approximation gets, belike. Caveat calculator!

Anyway, here it is:

https://onedrive.live.com/redir?resid=8B53BC30DA65DCAA!90356&authkey=!AAMfSsixhk7pGRI&ithint=file%2cmcdx

Enjoy!