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

nature.com

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

#651

Post by rocqua »

kcorbitt wrote: post #47
e0m wrote: 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.

The rocket equation is the biggest block. Getting a constant thrust of 1g for 7.3 years is hard.

It takes an incredible amount of fuel, and an incredible specific velocity.

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

#652

Post by rocqua »

blueprint wrote: post #338
Balgair wrote: post #332

Earlier quoted context omitted.

The engineering issues are really tough, though surmountable. Currently, we just can't engineer the parts that will last that long in hard vacuum. Mostly because we can't test in that environment easily. Also, what do you do when all the light bulbs have burned out or gone haywire, what does that fault-tree look like for the billion and one parts on the craft? For a short journey of ~7 years, it's not a very big deal…

Yeah I'm to be honest just trying to awaken people to the priority being that we need to establish a self-sufficient colony somewhere other than Earth.

Honestly, as long as humans stay stuck to earth, losing all humanity on earth won't hurt anyone. As long as the extinction is instant. If we have colonies, those colonies need to suffer through the knowledge that we lost earth.

Establishing colonies is only imperative if the continuation of the human race is. I'd argue that humans have value only due to other humans. There is nothing inherently valuable about human life from a non-human perspective.

That is not to say I don't support space colonization, just that I don't think its a moral imperative.

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

#653

Post by rocqua »

BinaryIdiot wrote: post #336
neaden wrote: post #301

Earlier quoted context omitted.

Isn't part of the problem that any ship capable of interstellar travel is also capable of being turned into a WMD? I imagine a lot of people would get really nervous if someone for instance parked a bunch of radioactive material in low earth orbit, and even with fusion there would be the fear that someone could turn the ship around.

To be fair kinetic bombardment is stupid easy to do once you can put stuff into orbit. Put a few, 20 foot long tungsten rods into orbit and you can effectively nuke, without radiation, any location that you orbit over [1]. Sure this is a problem but it's one that already exists today, not necessarily only when we start building space craft in orbit. [1] https://en.wikipedia.org/wiki/Kinetic_bombardment

I always wondered how to de-orbit those rods. It's not like you can just 'drop' them as they are already in free-fall. You'd need to cancel quite a bit of orbital velocity to get the things to de-orbit. Aiming'd be even more of a bitch.

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

#654

Post by mmrezaie »

dcposch wrote: post #496
dmix wrote: 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…

> 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. this reminds me of one my favorite films ever. it is just four minutes long http://www.erikwernquist.com/wanderers/

I was very stressed and watching this calm me down. Thanks

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

#655

Post by rocqua »

JumpCrisscross wrote: post #86
e0m wrote: 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)

> about...2,000 Saturn V rockets Or about 670 BFRs [1]. It would take 6 cycles of tripling size and/or performance to get a single system with enough thrust to meet your 7/42 year schedule. The Saturn V first flew in 1967 [1]; SpaceX plans to launch its Interplanetary Transport System (ITS) in 2022 or 2024 [2]. That's an expected 60 years to triple performance. [1] http://waitbutwhy.com/2016/09/spacexs-big-fking-rock…

Don't forget about space debris. Hitting anything at the posted max speed is just gonna dril a hole straight through your ship. If it's big enough, it'll add some nice shockwaves to really mess up your ship.

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

#656

Post by pamparosendo »

dcposch wrote: post #496
dmix wrote: 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…

> 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. this reminds me of one my favorite films ever. it is just four minutes long http://www.erikwernquist.com/wanderers/

Great film!

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

#657

Post by bergoid »

scardine wrote: post #447
gydfi wrote: post #400

Earlier quoted context omitted.

Would they? I mean, we can see geological features on our moon, and our tides are orders of magnitude away from being rock-tearing events. I mean, the moon is small, but... how close do these planets approach, anyway?

The moon is not that small, it is 27% of earth's size. Any other satellite in the solar system is way smaller compared to the planet they orbit. I dare to say that earth and moon are twin planets instead of a planet and a satellite.

Unless you are excluding Pluto deliberately for not being "a planet", its moon Charon has half the diameter of Pluto. They are even both orbiting a common center of gravity outside Pluto.

https://en.wikipedia.org/wiki/Charon_(moon)

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

#658

Post by saalweachter »

mirimir wrote: post #590
saalweachter wrote: post #582

Earlier quoted context omitted.

One of my scale numbers is, everything between Jupiter and the Sun masses less than 2 Earths -- Venus, Mars, Mercury, the Moon, and all the asteroids mass less than the Earth. And only just barely! You get to around 99% of the Earth's mass with the rest of the inner solar system. All of the other rocky bodies in the solar system give you another 10% of Earth's mass out to Pluto and another 10% beyond.

You just blew my mind ;) What do we know about the gas giants' cores?

Gas giant cores are weird. Based on models of solar system formation, we're like, pretty sure they started with rocky (or icy) cores that were dozens of times bigger than Earth. But we're not sure they're still there.

Due to the intense conditions inside a gas giant, we're not sure if they still have a rocky core, or if the cores have liquified or even convected away to mix with the gasses.

So the answer could be "there are dozens of times the Earth's mass worth of rocky material inside gas giants" or "there is no rocky material inside gas giants", or anywhere in-between. We need more detailed study of the gas giants before we can answer that question.

Models of solar system formation also suggest the Kuiper belt started with dozens of times Earth's mass, but we only see about 10% there now, and we only have pretty good guesses about what happened. (I mean, it almost certainly got ejected, but the "why" is harder.)

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

#659

Post by Sembiance »

mjevans wrote: post #458
Balgair wrote: post #332

Earlier quoted context omitted.

The engineering issues are really tough, though surmountable. Currently, we just can't engineer the parts that will last that long in hard vacuum. Mostly because we can't test in that environment easily. Also, what do you do when all the light bulbs have burned out or gone haywire, what does that fault-tree look like for the billion and one parts on the craft? For a short journey of ~7 years, it's not a very big deal…

With a round trip parts delivery time OF a generation, and a communications delay of almost a decade (two for duplex), I don't see any reason not to classify such a mission as a short-range 'generation ship' / complete colony effort. Getting our 'eggs' out of a single cosmic basket is really important, however I think we need to at least take the baby-crawl to establishing an outpost in the asteroid belt. That would…

I feel that advancements in quantum mechanics will solve the communication problem.

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

#660

Post by mememachine »

echelon wrote: post #575

I imagine any intelligent life that evolves on a system with so many planets in such close proximity--many within the habitable zone, and each perhaps with atmospheres and organics--will have a much easier time than we do of pushing forward to becoming a multi-planetary species. We lucked out with Earth being as hospitable and resource rich as it is, but we're stuck in a deep gravity well with not much in our solar s…

> could have been

You write like its all over. Pretty odd.

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