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

nature.com

141–150 of 754 posts

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

#141
post #106

I was reading up about earth alternatives recently, and upon realizing the distance was always going to limit us, no matter how perfect the planet, I realized we need to travel at the speed of light. I think our "best shot" at that right now, is to digitize humans. If we could store consciousness in binary, we could then transmit it at the speed of light (like we do with data every day!). You'd need a receiver on the…

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

#142
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…

Though that kind of performance is probably not going to come about from improvements to chemical rockets but moving to fusion. There are some promising developments on fusion reactors (see Breakthrough in Nuclear Fusion? - Prof. Dennis Whyte https://www.youtube.com/watch?v=KkpqA8yG9T4)

Guess something like that with the 100 million C gas doing the propulsion maybe?

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

#143
post #39

Earlier quoted context omitted.

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

I think we do if you look at it in terms of acceleration. As I understand it, In space there is almost 0 friction so "fast" is more about acceleration than "top speed". In this view, 1g isn't that fast.

Doesn't energy required to accelerate keep exponentially increasing, though? ke = mv^2

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

#144
post #4

Earlier quoted context omitted.

Well, it's estimated that it will still be around in 4-5 trillion years, so, if we can get there, and it's habitable, that gives humanity a little longer lease in the universe.

Source on the 'trillions of years' number?

I got you -- The accompanying Nature paper gives a 10 trillion year figure.

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

#145
post #17
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…

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

Michael Okuda has raised the question on his Twitter feed of whether the planets would be close enough to the star that tidal force could be an issue---hard to say at this point (in the sense that they're not loose clouds of rocks, so tidal forces haven't sheared them apart, but I'd assume it's unclear whether they might have interesting geological activity, such as frequent earthquakes or unexpected extra heat due to internal friction).

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

#146
post #102

Based on Voyagers current speed it would take approximately 18000 years to reach this system, the referance of a jet airplane taking millions of years seemed a bit misleading, with current technology and using gravitational boosting I would think that the time could be much less. Maybe it would be worth sending a probe? Granted I will never see it in my lifetime but it might be a project I could get behind.

18k years is a very long time, though. There is a project looking at the feasibility of getting very small probes somewhere 10 times closer in perhaps decades rather than millennia: https://www.nytimes.com/2016/04/13/science/alpha-centauri-br...

That is exactly what I meant, thank you for the link. I defiantly would support projects like that.

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

#147
post #62
post #39

Earlier quoted context omitted.

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

No, but we probably could with enough fuel. The bigger issue is space dust. Hitting it at relativistic speeds would be like flying into a cosmic shotgun for the entire journey.

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

#148

Close orbit around a relatively cold star. Interesting. I wonder what their 'day' vs 'year' looks like. Also their atmosphere and surface pressure. They could be 7 copies of Venus for all we know.

If they are tidally locked as reported, then there will be no day, not really. Just as there is no day on the moon.

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

#149
I'm having a hard time finding more data on the density of matter in interstellar space.

Wikipedia says

> The density of matter in the interstellar medium can vary considerably: the average is around 10^6 particles per m3 but cold molecular clouds can hold 10^8–10^12 per m3 [1]

But I imagine that interstellar gas would be easier to fly through than interstellar sand. Do we know the composition of matter in interstellar space?

[1] https://en.wikipedia.org/wiki/Outer_space#Interstellar_space

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

#150
post #17
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…

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

Like others have pointed out, the combination of the planets being tidally locked so only one side gets sunlight and the strong X-ray radiation and flaring from the host star make it considerably un-Earth-like, and harder for life as we know it to develop.
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