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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

#171

Post by mabbo »

kadoban wrote: post #8
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...

So that's purely for a chemical rocket, right? Is there any combination of tricks that can realistically push the envelope there? For example can we use a space elevator to start higher/faster (or, I don't know, balloons? a catapult or railgun or something?), laser power delivery from the ground, so we don't have to carry all the fuel, and an orbiting way-station for refueling, etc.?

> For example can we use a space elevator to start higher/faster (or, I don't know, balloons? a catapult or railgun or something?), laser power delivery from the ground, so we don't have to carry all the fuel, and an orbiting way-station for refueling, etc.?

These methods will all help with the first 1% of your problem, getting off of the earth.

But you need so many orders of magnitude more energy to reach the kinds of velocity needed to get to another star in less than a million years. It's just an unfathomable amount of energy per kg. Put simply: if you can get to another star, getting off the planet is nothing.

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

#172

Post by chr1 »

chenning wrote: post #115

A very quick search suggests that earth will become uninhabitable somewhere between 500 million and 2 billion years from now. If we shot a probe to this life-friendly alien planet with some sort of primordial soup, even traveling at the speed of light it would take 4 billion earth years to get there. Do I have that right? Basically we'll never even come close to being around when it finally arrives, if it ever arrive…

The threat in 500 mln years is that all CO2 will be used in shells of see creatures. But considering how good we are at freeing more carbon this issue should be easy to fix.

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

#173

Post by nothis »

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...

> 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).

I just realized I have no real concept of how many stars there even are within, say, a 100 light year radius of our sun (I guess that's a more realistic thing to find out than the number of planets).

A quick search provided some estimates and they're kinda... disappointingly low, at around 20000 stars. That's a number where some "1% of 1% of 1%" kinda filter quickly ends up in a scenario where a planet fitting all our criteria might simply never be in reach. For something more "realistic" (I know, heh!) like 20 light years, there are only 150 solar systems. I've seen different numbers and have no idea how they're calculated but for the usual astronomic scales which quickly go into "billions" territory, it seems we're kinda stuck with a comparably small list of candidates.

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

#174

Post by stjohnswarts »

methodover wrote: post #169
gdubs wrote: post #56

Earlier quoted context omitted.

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

So, actually, like, it's actually really intuitive I feel like: From the perspective of an object accelerating, newtonian physics works totally intuitively. If you had a rocket that could accelerate at 1g indefinitely, you just go faster and faster and faster and you get to any destination you want (even far away!) pretty quickly. And it would be a rather comfortable trip! You'd have Earth-like gravity the whole way.…

There is nothing intuitive about relativity unless you understand the physics and math behind it. Intuition can only be as good as your knowledge and experience.

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

#175

Post by chr1 »

Miner49er wrote: post #6

It's depressing to think that if there is intelligent life on that planet, we won't be able to communicate with them in any way in our lifetime, yet it's so close. Unless they started sending communications our way over a century ago.

It is more depressing that our lifetime is not even 100 years long. Hopefully Aubrey de Gray's predictions about longevity escape velocity would turn out to be true and we or our children would be able to wait for communications spanning multiple centuries.

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

#177

Post by PorterDuff »

bena wrote: post #71
ajconway wrote: post #18

Earlier quoted context omitted.

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

Which would put you in your 50s to 60s if all you did was go there and back.

Heck, I managed that without interstellar travel.

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

#178

Post by mabbo »

manicdee wrote: post #134

Some caveats per Marina Koren https://twitter.com/marinakoren/status/1171873631808438273 1. This planet probably doesn’t have a solid surface 2. Being in the “habitable zone” doesn’t mean a planet is habitable 3. The detection is of water molecules, chances are the water only exists as vapour in the atmosphere of this small gas giant. 4. If you ask 10 astronomers about this you will get 11 opinions

Years ago as a second year computer science student, I mentioned to a grad student I knew how disappointed I was about a certain algorithm. "It's O(n), but the constant is enormous! There's no point unless you have billions of elements"!

She said to me "Yeah sure, but who cares? What it really tells us it's that it's possible to do this in linear time at all. That might not have been true, and now we know we might find a faster linear algorithm."

(All of this is paraphrased because it's been over a decade).

The point is: we have found another planet with water. We now know this is possible! We know that it's probably not super uncommon (or else we wouldn't have found one so soon). That's what's amazing about this.

So what if it's not perfect, it's a great discovery!

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

#179

Post by mrkstu »

0xffff2 wrote: post #109
mrkstu wrote: post #75

Earlier quoted context omitted.

Isn’t that orthogonal to interplanetary travel though? If you go straight up far enough you’ll be out of Earth’s gravity well. You’ll still need acceleration to escape the solar gravity well, but you’ll never need horizontal acceleration necessary for Earth orbit.

>If you go straight up far enough you’ll be out of Earth’s gravity well. While you could theoretically do this by accelerating directly up, You still have to accelerate somehow.

Understood, but somehow the discussion ended up around achieving orbital velocity instead of escape velocity (the one relevant to the original sub-thread topic), two very different numbers (though escape velocity is ultimately a higher number.)

https://physicsabout.com/orbital-escape-velocity/

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

#180

Post by peteretep »

Swizec wrote: post #22
ajconway wrote: post #18

Earlier quoted context omitted.

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

So you can survive the trip but even if you come back home, it’s not home anymore? Imagine leaving 222 years ago and coming back now ...

I mean that sounds pretty awesome if you invested your funds well. I'd definitely be willing to be the first person who did that.
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