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Seven earth-sized planets discovered circling a star 39 light years from Earth

nature.com

71–80 of 754 posts

Re: Seven earth-sized planets discovered circling a star 39 light years from Earth

#71

Uh oh. The "great filter" hypothesis is essentially that the rarity of intelligent life has to be explained by some parameter of the Drake equation, and that whatever the "small" parameter is is either in our past or in our future. If the "great filter" is the rarity of habitable worlds, then clearly we don't need to fear it, since we already found one. But if habitable worlds aren't rare, then it's more likely it li…

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Re: Seven earth-sized planets discovered circling a star 39 light years from Earth

#72
post #33

To get a spacecraft there it would take: Accelerating at 1g the 1st half, and decelerating at 1g the 2nd half, the traveler would experience 7.3 years of time. For observers it would take 41.8 years at a max speed of 0.998c If you had a near perfect hydrogen -> helium fusion engine, it'd take about 6 million tons of fuel (about the mass of the Pyramids of Egypt or 2,000 Saturn V rockets)

That actually sounds... more plausible than I would have expected. Like, doable with technology I can imagine being within reach in the next 50 years even if we don't achieve any currently-unforseen breakthroughs.

Which begs the question, why haven't we at least even tried to have done anything like this already?

Do we really need to repeatedly spend comparable amounts of money on yet another dramatic TV special about humans traveling to Mars, as narrated by a favored celebrity? We really are running out of time. And it almost seems like it's pre-determined to happen. :\

Re: Seven earth-sized planets discovered circling a star 39 light years from Earth

#73
post #38
post #33

To get a spacecraft there it would take: Accelerating at 1g the 1st half, and decelerating at 1g the 2nd half, the traveler would experience 7.3 years of time. For observers it would take 41.8 years at a max speed of 0.998c If you had a near perfect hydrogen -> helium fusion engine, it'd take about 6 million tons of fuel (about the mass of the Pyramids of Egypt or 2,000 Saturn V rockets)

What if we used engines powered by nuclear energy (fission or fusion)? Could we reduce the amount of fuel, since the energy density is so much higher?

You still need reaction mass.

Re: Seven earth-sized planets discovered circling a star 39 light years from Earth

#74
post #17

Earlier quoted context omitted.

Out of interest , although dimmer, are there any potential hazards simply due to the proximity of a dim star?

> are there...hazards simply due to the proximity of a dim star Tidal locking [1]. Similar to how our moon shines at us ass first all the time, the planets around TRAPIST-1 would be expected to have one face locked to their star. Instead of an equatorial belt bookended with loops of temperate zones, as we have on Earth, we should expect, climatically, an "equatorial" face and a "polar" face separated by a tropic-to-t…

Fascinating thank you

Re: Seven earth-sized planets discovered circling a star 39 light years from Earth

#75
post #39
post #33

To get a spacecraft there it would take: Accelerating at 1g the 1st half, and decelerating at 1g the 2nd half, the traveler would experience 7.3 years of time. For observers it would take 41.8 years at a max speed of 0.998c If you had a near perfect hydrogen -> helium fusion engine, it'd take about 6 million tons of fuel (about the mass of the Pyramids of Egypt or 2,000 Saturn V rockets)

We don't have any spacecraft that can go that fast, do we?

I've read about laser systems for sending unmanned crafts at high speed: http://www.space.com/29950-lasers-power-tiny-interstellar-sp...

Re: Seven earth-sized planets discovered circling a star 39 light years from Earth

#76
post #32

Wiki says "TRAPPIST-1 is an ultracool dwarf star that is approximately 8% the mass of and 11% the radius of the Sun. It has a temperature of 2550 K and is at least 500 million years old." https://en.wikipedia.org/wiki/TRAPPIST-1 Too young star for alien life hopes?

I think this is why there is no life on any of the planets. The star is just too young. However, the star could have a life span of 5 trillion years, it is safe to say that life could form on the planets and have plenty of time to develop.

Re: Seven earth-sized planets discovered circling a star 39 light years from Earth

#77
post #46
post #21

Earlier quoted context omitted.

At a constant 1g of acceleration, you could travel there, from the traveler's point of view, in ~2-3 years. (And in ~40 years from a stationary observer's point of view.) Mind you, a constant 1g acceleration (Or accelerating any human-carrying spaceship to relativistic speeds, really,) is about as plausible as a spaceship driven by pixie dust and unicorn farts.

Not according to public research on theoretical designs that have been about for decades . Unless you consider them unicorn farts! I'm only a coder though so I have no knowledge of this domain tho. I think the problem is simply it's too expensive to build space ships that probably won't work at all :( wasnt NASAs budget slashed ?

It's not money, it's the basic rocket equation: Newtonian acceleration requires fuel and the mass of fuel makes acceleration more costly.

Relativity makes things even worse.

Re: Seven earth-sized planets discovered circling a star 39 light years from Earth

#78
post #6

My favourite part of the press release: > The planets also are very close to each other. If a person was standing on one of the planet’s surface, they could gaze up and potentially see geological features or clouds of neighboring worlds, which would sometimes appear larger than the moon in Earth's sky. > In contrast to our sun, the TRAPPIST-1 star – classified as an ultra-cool dwarf – is so cool that liquid water cou…

So, basically, this is cooler than just about any world that's been depicted in sci-fi.

Check out "Rocheworld."

Re: Seven earth-sized planets discovered circling a star 39 light years from Earth

#79
post #33

To get a spacecraft there it would take: Accelerating at 1g the 1st half, and decelerating at 1g the 2nd half, the traveler would experience 7.3 years of time. For observers it would take 41.8 years at a max speed of 0.998c If you had a near perfect hydrogen -> helium fusion engine, it'd take about 6 million tons of fuel (about the mass of the Pyramids of Egypt or 2,000 Saturn V rockets)

Upvote for doing the math, but we're going to have to ditch traditional chemical rockets for this kind of trip. Fortunately, we're making progress on alternatives.

https://arstechnica.com/science/2017/02/nasas-longshot-bet-o...

Re: Seven earth-sized planets discovered circling a star 39 light years from Earth

#80
post #39
post #33

To get a spacecraft there it would take: Accelerating at 1g the 1st half, and decelerating at 1g the 2nd half, the traveler would experience 7.3 years of time. For observers it would take 41.8 years at a max speed of 0.998c If you had a near perfect hydrogen -> helium fusion engine, it'd take about 6 million tons of fuel (about the mass of the Pyramids of Egypt or 2,000 Saturn V rockets)

We don't have any spacecraft that can go that fast, do we?

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