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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

#41

Post by akiselev »

ta1234567890 wrote: post #29
kadoban wrote: post #8

Earlier quoted context omitted.

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.?

Exactly From the reference article: > Travelling from the surface of Earth to Earth orbit is one of the most energy intensive steps of going anywhere else. This first step, about 400 kilometers away from Earth, requires half of the total energy needed to go to the surface of Mars. Which means that if we use something like a balloon/blimp in the first stage, it would be a lot more energy efficient. Anyone knows why it…

The Pegasus rocket used to launch satellites from a modified 747 for between 1990 and 2016 [1]. It just doesn't work out well in practice because the cost of the modified plane far exceeds the cost savings from a first stage unless you're doing half a dozen or more launches per year.

[1] https://en.wikipedia.org/wiki/Pegasus_(rocket)

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

#42

Post by kadoban »

yourbandsucks wrote: post #37
ta1234567890 wrote: post #29

Earlier quoted context omitted.

Exactly From the reference article: > Travelling from the surface of Earth to Earth orbit is one of the most energy intensive steps of going anywhere else. This first step, about 400 kilometers away from Earth, requires half of the total energy needed to go to the surface of Mars. Which means that if we use something like a balloon/blimp in the first stage, it would be a lot more energy efficient. Anyone knows why it…

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?

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

#43

Post by jerf »

cycop wrote: post #30
guelo wrote: post #21

Earlier quoted context omitted.

The fastest spacecraft humans have produced is the Parker Solar Probe which when it zips around the sun will reach 430,000 mph. At that speed it would take 173,000 years to reach this planet.

Great! , do that gravity assist a few more hundred times around the sun and we are there in 500 years.

You can't do a gravity assist around the sun once you've reached solar escape velocity, because you won't be visiting the sun again.

If we could pull that trick so easily, we already would have.

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

#44

Post by buboard »

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.?

Launching from a mountain is a possibility ( I think China does it)

Realistically, but not plausibly unless its an emergency, Thermonuclear bombs:

https://www.youtube.com/watch?v=EzZGPCyrpSU

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

#45

Post by tibyat2 »

tyri_kai_psomi wrote: post #10
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.

If it is depressing to think about it, then why think about it? Does it have any real implications for significant outcomes about your life or is it in a way some type of FOMO?

Congratulations! You are hereby awarded one “Useless Human!” badge. This is granted as thanks for being a know-nothing, like-button-coding-meta-chasing monkey who adds nothing to our race!!!

We hope to hear more from you, and will be following your career closely! Best of luck!

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

#46

Post by DidISayTooMuch »

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.

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

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

#47

Post by hinkley »

Miner49er wrote: post #11
kadoban wrote: post #8

Earlier quoted context omitted.

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.?

Solar sails might be able to beat it. https://en.wikipedia.org/wiki/Solar_sail

M2P2 was going to test out magnetic sails, but Wikipedia is telling me they generate less thrust per kilowatt hour than ion thrusters. Explains why I haven't heard anything further about it.

https://en.wikipedia.org/wiki/Magnetic_sail

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

#48

Post by jerf »

hinkley wrote: post #26
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 made it well into this decade before I was made aware of this fact. It's kind of a shock, still. At some point your planet is massive enough that you can't get into orbit with chemical rockets (even, I think, by flying them up like Burt Rutan?). The implications for the Drake equation are pretty big. Rockets without any promise of ever being able to break orbit are good for what, war? Would you keep developing them…

"At some point your planet is massive enough that you can't get into orbit with chemical rockets (even, I think, by flying them up like Burt Rutan?)."

Nuclear rockets don't seem to be very hard. They're somewhat dangerous if they explode, but they aren't very hard. Fairly solid prototypes were built decades ago and there's little to suggest they couldn't have been made production-grade [1]. We'd have them now if we didn't find the risk/reward to be too highly slanted to the "risk". Other species and other ecosystems may come to different conclusions, e.g., an ecosystem already more exposed to radiation and evolved to deal with much higher levels of it may judge it much less "risk" for some radionuclides to be scattered across the landscape in case of failure.

What can be more of a problem is being in a place where you have no obvious access to technology at all. However smart our cetacean buddies may be, it is not clear even at this point in the 21st century what path to technology they could possibly have from their starting point. "The literature", a.k.a. "science fiction" has hypothesized breeding programs to develop various tools, but it's still not entirely clear how they'd get from "breeding useful jellyfish" to, well, anything like technology as we know it. It's possible we're just not solving this problem because we don't have to, maybe there's some easy path with the right development path, but it's still not clear what that would be.

[1]: One of my markers for "the space age is truly here" is when we lift a nuclear rocket into space, sans fuel, and fuel it with space-sourced radionuclides. Earth-bound citizens will still complain, because "NUCLEAR BAD!", but their complaints will be ignorable at that point.

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

#49

Post by cthalupa »

DidISayTooMuch wrote: post #46
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.

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

It takes 111 light years from our reference point to travel that distance. If photons could perceive things, it would not take them 111 years by their perception.

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

#50

Post by jjtheblunt »

DidISayTooMuch wrote: post #46
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.

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

i'm pretty sure the assertions means that the 111 years needed would only age the traveler by 15 years
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