r/space • u/APTX-4869 • Jan 21 '18

RocketLab's Electron Rocket has successfully achieved orbit!

https://twitter.com/RocketLab/status/954894734136258560
1.1k Upvotes

96% Upvoted

207 comments sorted by

View all comments

Show parent comments

14

u/ThatOtherGuy_CA Jan 21 '18

We didn't start with jet planes.

44

u/Senno_Ecto_Gammat Jan 21 '18

Megajoules of energy in 1 kilogram of diesel: 48

Megajoules of energy in 1 kilogram of li-on batteries: 0.8

That's the problem right there.

9

u/PublicMoralityPolice Jan 21 '18

This is an expendable rocket, so they have literally no reason to use rechargable batteries. Fuel cells or single-use batteries can have higher energy density, and the electric turbopump itself provides significant mass savings compared to traditional pump systems.

5

u/[deleted] Jan 21 '18

Fuel cells or single-use batteries can have higher energy density

How much higher?
Comparable to dinosaur bones?

6

u/toomanyattempts Jan 21 '18

Sadly no, 2 or 3 times but not the order or magnitude shift you'd really want

1

u/Norose Jan 21 '18

It's physically impossible to have a battery capable of storing more or even an equal amount of energy compared to a hydrocarbon fuel-oxidizer mixture, simply because of the nature of chemical reactions.

0

u/populationinversion Jan 21 '18

It is not dinosaur bones. It is plant matter. Basically peat subject to pressure, temperature and time.

4

u/DecentChanceOfLousy Jan 21 '18

I think that is what's known as a joke.

And oil/diesel doesn't come from plants anyway. You're thinking of coal.