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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

#691

Post by nradov »

BinaryIdiot wrote: post #634
nradov wrote: post #606

Earlier quoted context omitted.

Kinetic bombardment is silly and inefficient science fiction. Conventionally armed ballistic missiles can strike any point on Earth almost as quickly at a far lower cost and with greater survivability.

Well today sending a rocket up, putting these things in orbit and then dropping them would probably be a bit obvious and inefficient. But in the near future when we're mining asteroids? As long as they can be captured closed enough to Earth I would imagine kinetic bombardment would be pretty effective. They would be rather difficult to shoot out of the sky as ballistic missiles can be blown up prior to reaching targe…

Asteroid mining on any sort of commercial scale is far future, not near future. Even with fully reusable rockets, asteroid mining wouldn't be profitable; anything we need can be obtained cheaper on Earth.

Small asteroids are too irregularly shaped to be useful as precision-guided projectiles. As soon as they hit the atmosphere they're going to veer off course.

Kinetic bombardment satellites — whether fully artificial or asteroids guidance and propulsion strapped on — would be in known orbits with limited maneuvering capability and thus highly vulnerable to antisatellite weapons. It takes very little energy to kill a satellite; you don't have to vaporize it, just break any critical part in the communication, propulsion, or guidance systems. Satellites are generally easier targets to hit than ballistic missiles.

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

#692

Post by dTal »

noobermin wrote: post #121
chrisabrams wrote: post #36

Earlier quoted context omitted.

I was essentially thinking the same thing. I wonder if an elevator could be built between all of them?

One of the callers (a biologist, so not a crackpot) on TV suggested that given how close the planets were, he wondered if it were possible for there to be cross contamination between the planets given how close they are to each other. He referred to them being part of the same "ecosystem." I'm not sure how feasible that is as a non-astrobiologist, but it is an interesting idea.

Even if bacterial material were being transferred all the time, I think it'd be a stretch to call them the same "ecosystem" unless they were actually reliant on each other. But I'm not an biologist either.

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

#694

Post by neaden »

RugnirViking wrote: post #641
neaden wrote: post #557

Earlier quoted context omitted.

We've created a giant security apparatus based on Jet planes. They are not something we just let anyone buy or fly and if you deviate from your flight path these days you stand a good chance of getting shot down. People definitely get nervous about them.

Are you implying that rockets capable of transporting several hundred kg of tungsten to orbit are -not- tightly controlled? I imagine if you assembled anything close to this size without seeking extensive permissions you would be quite severely punished

No, I'm just addressed the analogy of jet airplanes and pointing out those are tightly controlled. I understand that current rocked are very tightly controlled, my point is just that any sort of interstellar rocket would be much more dangerous and thus have to be subject to much higher controls. A ship that was capable of reaching a significant fraction of light speed would be the most dangerous weapon ever created though, and existing controls might not be sufficient.

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

#695

Post by cgriswald »

Zardoz84 wrote: post #627
cgriswald wrote: post #571

Earlier quoted context omitted.

> Firefly's inhabited planets are still a heck of a lot closer, since the crew doesn't seem to noticeably age between the half dozen or so star systems that they visit The 'systems' in Firefly are really all one star system. The system includes a central star orbited by planets, four other stars, and a host of "protostars" (they really mean brown dwarves). I've tried, and can't imagine a scenario where, even if such…

Proxima Centauri have a earth mass planet : https://en.wikipedia.org/wiki/Proxima_Centauri_b

The Firefly system is one in which stars are orbiting stars are orbiting stars, and among these stars are many many planets and moons. Presumably the distances involved here can be traveled in a matter of days or weeks at some fraction of c. So, they're fairly close.

In contrast, Proxima Centauri orbits from a distance of about a quarter lightyear, and we've found a single planet orbiting very tightly. We've also found a single planet around Alpha Centauri B, also orbiting very closely. There may be more we haven't found, but probably not nearly as many as in the Firefly system. Firefly seems to use the idea that more stars mean more planets, but more stars and planets during formation means more chaos, more things to swallow up or rip apart planets, and more mass to throw them out of the system.

I don't think the Firefly system is necessarily impossible. You can even construct models such that the white star is at the focus of all other orbits (you know, if you're the Alliance and you need to do that for political reasons). (An Earth-centric model of our solar system needn't necessarily be wrong in terms of its ability to predict the position of bodies in the solar system - It's just needlessly difficult and convoluted.) I just think the Firefly system is highly improbable.

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

#696

Post by saiya-jin »

dekhn wrote: post #493
ConceptJunkie wrote: post #467

Earlier quoted context omitted.

It's not that improbable. They've found meteorites on Earth that have been identified as having come from Mars based on their mineral contents.

Sure, I was referring to the part where the microbe survives the initial blast, the passage through space, reentry, and landing, and happens to land in a spot where it can survive.

that passage through space could mean millions of years... can't imagine even spores surviving that, plus constant strong radiation

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

#697

Post by Arizhel »

bubersson wrote: post #613
Arizhel wrote: post #441

Earlier quoted context omitted.

It sounds like you're talking about the Bussard Ramjet. It collects interstellar hydrogen gas for use in fusion engines. The problem is that it's unlikely there's enough hydrogen floating around for it to really work.

Are there places that would have high concentrations of floating hydrogen? You would just need to "fly" through those.

Sure: stars. I don't think flying through those would work out well.

There's also nebulae. But that's only going to be useful when you're actually in a nebula, which isn't most of the time.

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

#698

Post by Arizhel »

misnome wrote: post #583
blueprint wrote: post #555

Earlier quoted context omitted.

When it comes to physics, it does in fact mean you can use the principle you discovered in engineering technology. That's kind of the whole point.

By the same 'argument', understanding the laws of thermodynamics (which prohibit perpetual motion) allows us to exploit perpetual motion?

No one's talking about perpetual motion here. Understanding the laws of thermodynamics allows us to build heat engines, which is how many of us got to work this morning. It also allows us to build nuclear reactors (or at least the steam-cycle part of it), which is how many of us get the power to write messages here.

What does our "understanding" of gravity allow us to do technologically? Nothing, because we have zero idea of how to manipulate it. The only thing we can do is understand how it works in the natural world so we can, for instance, navigate space probes accurately and get our GPS satellites to work. That's great and all, but it falls far short of the level of understanding that we have with thermodynamics and electromagnetism.

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

#699

Post by Arizhel »

maverick_iceman wrote: post #585
Arizhel wrote: post #539

Earlier quoted context omitted.

It does? Great; please point me to some instructions on how to build an anti-gravity device. I can easily build myself an electromagnet with some wire and a battery, so if our understanding of gravity is so great, I should be able to do the same with gravity, right?

What's your score?[1] [1] http://math.ucr.edu/home/baez/crackpot.html

What's your score? [1]

[1]https://www.buzzfeed.com/daves4/how-much-of-an-asshole-are-y...

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

#700

Post by dragonwriter »

bubersson wrote: post #613
Arizhel wrote: post #441

Earlier quoted context omitted.

It sounds like you're talking about the Bussard Ramjet. It collects interstellar hydrogen gas for use in fusion engines. The problem is that it's unlikely there's enough hydrogen floating around for it to really work.

Are there places that would have high concentrations of floating hydrogen? You would just need to "fly" through those.

> Are there places that would have high concentrations of floating hydrogen?

IIRC, a Bussard Ramjet is at least potentially viable at the typical density in the galaxy, but unfortunately for any use by humans to get away from our solar system, or local region of space (to a distance, IIRC, on the order of 1000 light years in any direction) is a pocket of relatively low density.

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