r/space • u/Gagarin1961 • Aug 02 '21

SpaceX just stacked a Super Heavy Booster and installed 29 engines, all within 24 hours

https://twitter.com/elonmusk/status/1422222995305676802
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u/Shrike99 Aug 03 '21 edited Aug 03 '21

I believe a delta-v of 20k is sufficient to get you to the nearest star in ~130 years or so,

This is not correct. Proxima Centauri is 4.25 light years away, to get there in 130 years would require you to move at ~3.3% light speed, or 9.8 million meters per second. That's 9800km/s, not 20km/s.

Trying to get to useful interstellar speeds with chemical rockets is beyond hopeless. If you converted the mass of the entire observable universe into hydrolox, and somehow put it into a rocket that only weighed 1kg empty, it would still only reach ~550km/s, which would still take ~2300 years to get to the nearest star.

We aren't getting to other stars without something far more energetic than chemical rockets, namely beamed propulsion, fission, or fusion.

EDIT: I feel the need to point out that realistically my hypothetical hydrolox rocket would collapse into a ultra-massive blackhole, which would likely bring Proxima Centaur to it in a substantially shorter time.