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Water found on a potentially life-friendly alien planet

nationalgeographic.com

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Re: Water found on a potentially life-friendly alien planet

#61

Post by [deleted] »

TheOtherHobbes wrote: post #27
transreal wrote: post #2

With a planet this large, visiting it would be a one way trip due to the "The Tyranny of the Rocket Equation" [0]. I'm looking forward to the day we start finding exo-planets that are closer to Earth in size and which could potentially have space-faring races (and which we could leave if we were ever to visit them). [0] - https://www.nasa.gov/mission_pages/station/expeditions/exped...

Surface gravity will be around 2g, so even if it has a rocky surface it's not going to be a very comfortable home from home.

[deleted]

Re: Water found on a potentially life-friendly alien planet

#62

Post by mrmonkeyman »

archgoon wrote: post #4
transreal wrote: post #2

With a planet this large, visiting it would be a one way trip due to the "The Tyranny of the Rocket Equation" [0]. I'm looking forward to the day we start finding exo-planets that are closer to Earth in size and which could potentially have space-faring races (and which we could leave if we were ever to visit them). [0] - https://www.nasa.gov/mission_pages/station/expeditions/exped...

It's 111 light years away. For all intents and purposes, that's a one way trip right there; irregardless of the rocket equation. Even at relativistic speeds, you can't come home anymore.

Irregardless?

Re: Water found on a potentially life-friendly alien planet

#63

Post by jcims »

dkural wrote: post #52
DidISayTooMuch wrote: post #46

Earlier quoted context omitted.

Wait, is this correct? Doesn't 111 light-years mean even light takes 111 years to travel through? And light travels at 1c.

Light does not experience time at light speed - it is stuck in a static moment. So from our stationary perspective, light takes 111 years to come from a 111 light year distance, but from light's perspective it takes an instant.

>but from light's perspective it takes an instant.

And for that reason they don't experience distance either. So the term 'sun-kissed' isn't actually that far off...from the photon's perspective the sun IS giving you a kiss.

Re: Water found on a potentially life-friendly alien planet

#64

Post by brlewis »

typeformer wrote: post #25

I say let's go. Now, whether you believe it or not, it is a fact that the US government has acquired alien technology and yet continues to keep it hidden by being stuck in a cold war mindset of, "well, we can't let the Chinese or Russians get their hands on this". That is the ultimate expression of narrow thinking, especially when there is a whole universe out there! Bring on the downvotes but history will vindicate…

Historians please note: At the time this comment was made, the HN guidelines said, "Please don't comment about the voting on comments. It never does any good, and it makes boring reading."

Re: Water found on a potentially life-friendly alien planet

#65

Post by amelius »

ajconway wrote: post #18
archgoon wrote: post #4

Earlier quoted context omitted.

It's 111 light years away. For all intents and purposes, that's a one way trip right there; irregardless of the rocket equation. Even at relativistic speeds, you can't come home anymore.

Theoretically, you can. At 0.99c 111 light years take about 15 years of ship time to travel.

And how much time will it take a person to reach that speed at human-safe acceleration? And how much energy would it take?

Re: Water found on a potentially life-friendly alien planet

#67

Post by cryptoz »

Lots of discussion on the possibility of going or communicating, but for me the excitement is the narrowing of uncertainties in the Drake equation and the focusing of discovery of alien life, intelligent or otherwise.

Discoveries like this improve our understanding of likelihood of extraterrestrial life, which has direct Earthly implications. It also enables better estimates and searches for planets that are closer, say ~4 to 20 lightyears away, for those super interested in the traveling & communicating possibilities.

Re: Water found on a potentially life-friendly alien planet

#68

Post by usrusr »

kadoban wrote: post #42
yourbandsucks wrote: post #37

Earlier quoted context omitted.

Orbit isn't a height, it's a speed. 7 km/sec for low earth orbit. A balloon floating you higher while not making mach 20 isn't much of a shortcut.

How poor of a shortcut is it? I'm not really clear on what the math would look like. Would it just be better by approximately the ratio of gravity's strength at the surface vs the height of the balloon?

Better than the miniscule gain in potential energy (height x mass x gravity) because you also save a lot of aerodynamic drag not punching through the lower atmosphere at high speed and some "hovering losses" (rise time x mass x gravity, I'm sure there is a better term for that). But still not worthwhile due to the difficulty of floating a full size rocket. If you had a very very high mountain or tower, moving that full size rocket to the peak could be worthwhile. Theoretically, a civilisation trapped in a gravity well too deep for a solution to the rocket equation could dig themselves out by reshaping their planet from a roughly spherical geoid into a disc or rod (or into a torus for the really adventurous)

Re: Water found on a potentially life-friendly alien planet

#69

Post by markdown »

archgoon wrote: post #4
transreal wrote: post #2

With a planet this large, visiting it would be a one way trip due to the "The Tyranny of the Rocket Equation" [0]. I'm looking forward to the day we start finding exo-planets that are closer to Earth in size and which could potentially have space-faring races (and which we could leave if we were ever to visit them). [0] - https://www.nasa.gov/mission_pages/station/expeditions/exped...

It's 111 light years away. For all intents and purposes, that's a one way trip right there; irregardless of the rocket equation. Even at relativistic speeds, you can't come home anymore.

regardless

Re: Water found on a potentially life-friendly alien planet

#70

Post by cthalupa »

gdubs wrote: post #56
dkural wrote: post #52

Earlier quoted context omitted.

Light does not experience time at light speed - it is stuck in a static moment. So from our stationary perspective, light takes 111 years to come from a 111 light year distance, but from light's perspective it takes an instant.

Every time I think I’m closer to understanding matters of time and space...

Go watch a Carlo Rovelli lecture on time and loop quantum gravity.

Time might not even exist in and of itself.

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