T-Rex: Often we'll set up a ship or probe so they whip around the planets (including Earth), getting a sweet speed boost as they do so! This allows us to produce ultra-velocity spacecraft, effectively for free!
T-Rex: GREAT IDEA, RIGHT??
T-Rex: Except NOTHING IS FOR FREE (in physics anyway, THANKS REALITY). So where's this speed coming from? Oh, I'll tell you where it's coming from: every spacecraft we slingshot around a planet SLOWS DOWN THE ORBIT OF THAT PLANET. And it's not like we have the means to speed it up again!!
T-Rex: And guess what? We do gravitational assists with Earth ON THE REGULAR!
T-Rex: Plus, if we slow down Earth too much WE CRASH INTO THE SUN. Great work, SCIENTISTS! Way to invent a DOOMSDAY DEVICE / ORBITAL TECHNIQUE!
Utahraptor: Pfft.
Utahraptor: We'd stop before that happened. More likely: the year gets a day longer, and we make it a holiday to celebrate ALL THE FRANKLY AWESOME SPACEFLIGHT WE'VE BEEN DOING.
T-Rex: Hey! When you put it that way, I'm on board!!
Off panel: Also: we could slingshot a probe around Earth EVERY DAY for a million years and still not get that free holiday, so don't hold your breath.
T-Rex: Hey! When you put it that way, I'm sad and going back to bed!!
