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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

#371

Post by Symmetry »

mkaziz wrote: post #99
rm_-rf_slash wrote: post #30

Earlier quoted context omitted.

Actually they are fewer. A dim star has less high energy radiation and a lower probability of harmful solar flares.

More radiation = more mutations = healthier/faster evolution!

Life is more than capable of evolving mechanisms to increase or decrease it's mutation rate. On Earth Eurkaryotic cells with large genomes have developed nuclei to reduce their mutation rate and bacteria are more of a mixed bag with some even deliberately uping their mutation rate above what would be cause by radiation, etc. So in the long run eukaryotic life would just have to waste more resources on mechanisms to resist the effects of the radiation.

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

#372

Post by literallycancer »

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

Contract SpaceX to bring the rods into orbit, then bill per strike. KBaaS, disrupting warfare since 2017.

Back of the envelope calculation: rods with length of 6m and radius of 5cm weight little over 900kg. Falcon 9 can bring 22.8 tons to LEO. So we can get up about 24 of these in one go. If we want to use the USAF dimensions of 6.1m and radius of 0.15m, then it's only 2 of them, maybe 3 with some adjustments to the rocket.

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

#374

Post by blueprint »

semi-extrinsic wrote: post #344
blueprint wrote: post #326

Physicists have got blinders on. Once we solve the gravity problem everything changes. I've been searching for a decade for scientists who can confirm my info but tbh most everyone seems to have abandoned themselves already.

> Once we solve the gravity problem I have a feeling I'm going to regret asking, but here we go: what "gravity problem"?

You're familiar with the fact that there is no proper, substantial, accepted model or principle of both gravity and EM that unify them, correct? And we don't knowingly have the ability to build technology that manipulates gravity (trivial interpretations aside). And we also don't know how our actions actually affect the dynamic field that is gravity. Cause the stress-energy tensor says it is dynamic. Or perhaps I'm just completely bonkers. Life certainly would be a lot easier if I were.

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

#375

Post by raarts »

fsloth wrote: post #309
MrZongle2 wrote: post #133

Earlier quoted context omitted.

Most likely several hundred quatloos' worth, I'm guessing. :D Edit: Oh, HN, you are so humor impaired sometimes.

Voting is a mechanism to signal whether the comment adds anything to the discussion. Star Trek references really don't add anything to an actual scientific discovery. I would much rather read actual engineering rather than entertainment driven thought.

I think you've just proven his point.

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

#376

Post by ars »

jerf wrote: post #167
noobermin wrote: post #88

Earlier quoted context omitted.

Of course, #askNasa didn't win me a question, but could any astrobiologists comment on this question: Tidal locking means the planets would always have a side facing the star, leading to very different thermodynamics in terms of climate and weather on the planet, not to mention radiation. Doesn't that very much hurt the chances for life on those planets?

The debate rages. The problem is that one side of the planet is essentially exposed to space and thus tends to be at cosmic background temperature, and the other side exposed to the star. It is thought by a lot of people that anything volatile enough to be a gas, ever (so, including water), would rapidly end up migrating over to the frozen side, so even if the planet started with the right mix of water and whatever o…

I think one idea is large mountains on the dark side and the water slides back down as a glacier that melts, and eventually vaporizes, and back in a circle.

You have to watch out though - make your mountains too high, and you shift your center of gravity, and now your mountains are no longer elevated.

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

#377

Post by gech »

CoolGuySteve wrote: post #214
dexwiz wrote: post #62

Earlier quoted context omitted.

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.

According to this paper, you can travel around 0.5 c before the radiation caused by colliding with interstellar hydrogen kills you: http://www.scirp.org/journal/PaperInformation.aspx?paperID=2... "Going slow to avoid severe H irradiation sets an upper speed limit of v ~ 0.5 c. This velocity only gives a time dilation factor of about 15%, which would not substantially assist galaxy-scale voyages. Diffuse interstellar…

Couldn't you put some kind of "snowplow" on the front so it pushes the oncoming detritus away to the sides?

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

#378

Post by Spare_account »

blueprint wrote: post #368
Spare_account wrote: post #367

Earlier quoted context omitted.

Elon Musk is working on that. http://www.spacex.com/mars

And you're certain enough that he's going to be able to do it in time and that he's doing it properly enough that you don't have to do anything about it. And you'll continue to go about doing the exact same things. Got it.

In no way attempting to deflect from my own regrettable inaction, I'm curious to know what you're doing about it?

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

#379

Post by bradyd »

hackuser wrote: post #357
flexie wrote: post #194

Earlier quoted context omitted.

Fascinating! Would vira or bacteria beable to survive travelling from Earth to Mars in or on a rock or vice versa?

IIRC, that is a serious hypothesis for how life began on earth, seeded from elsewhere (maybe not Mars). But certainly someone here knows more than I do about it ...

The theory is called Panspermia

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

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

#380

Post by narag »

josho wrote: post #98
jdormit wrote: post #39

Earlier quoted context omitted.

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

If I understand our capabilities correctly we can't even escape the solar system without using gravity assist boosts from other planets, let alone sustaining thrust for a long period. http://solarsystem.nasa.gov/basics/chapter4-1

"Capabilities" seems a little ambiguous to me. Is it what we have done or what we could do? Using those boosts is a way to achieve the same results, only cheaper. Yes, it's slower than building a big ass rocket, but it seems people that sign the checks are in no hurry.

Also if I'm not mistaken, Voyager probes were not even intended to live so long or leave the system.

If there were a reason to send a probe to another star as soon as possible and no matter the cost, there would be a way, maybe not fast, maybe very expensive, maybe something weird, but it would be done.

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