The Enemy of the Good (eideteker) wrote,
The Enemy of the Good
eideteker

Coming to rest.

Copied from facebook (sorry, but it's something).

One of the topics I was researching yesterday was sundive trajectories. It may be surprising, but it takes a fair amount of energy to travel to the Sun. You can't just fall in. Even if you leave Earth on an escape trajectory directly opposite the planet's revolution on the ecliptic, you still have a ridiculous amount of velocity just from being dragged around by the Earth's gravity. Which means you will keep falling at nearly the same speed as Earth (i.e. a near-Earth orbit, ~1 AU out from Sol). To stop and 'drop' into the Sun, you need to kill just about all of the orbital velocity you picked up just from starting on the Earth (or do something like slingshot around Jupiter, like the Ulysses probe*.

Which is a really long and overly-nerdy way of explaining how much energy it feels like it takes me to come to a stop and hold myself in stillness. It's not a question of just 'relaxing'; it is a very strenuous exercise.

* I later amended this post on facebook:
"a better example would've been the Helios satellites, which at their closest, barely got closer to the Sun than Mercury's orbit (0.29 AU / 43.432 million kilometers, still waaaay closer than you'd ever want to be). As an indication of the paradoxical nature of travel within the solar system: at perihelion, Helios-B was traveling at 252,792 km/h relative to the sun (aka 157,078 mph), making it possibly the fastest-moving manmade object ever?

The point is: It takes a SHIT-TON of energy just to "come to a stop" relative to the solar system."
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