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Four Earth-sized planets detected orbiting the nearest sun-like star

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Re: Four Earth-sized planets detected orbiting the nearest sun-like star

#281

Post by tim333 »

yoz-y wrote: post #270
spenczar5 wrote: post #129

Earlier quoted context omitted.

Very large telescopes can achieve great resolving power, but they run up against atmospheric turbulence, particularly in many of the spectral regions we care about for checking out exoplanets. Radio light passes right through the atmosphere for the most part, which is why you see very large radio telescopes, but they're not very practical for infrared or visible light scopes. Space-based telescopes are a better avenu…

What is the practical limit for a size and weight of an object that we can realistically put into space now? I imagine that a, for example, 10meter wide lens would be extremely heavy and can not be really split into pieces for shipping. How much smaller space telescopes are for the same performance?

Space X's Falcon Heavy is supposed to launch in november with a 57 ton payload. I'm not sure how big the payload can be.

I wonder if you could make one with a few bits of lens that fold out? They'd have to be positioned more accurately that one wavelength of light (to ~100nm say or a 10,000th of a mm) which is tricky on earth but might be doable in space where you don't have gravity making things flop?

Re: Four Earth-sized planets detected orbiting the nearest sun-like star

#282

Post by jerf »

ExactoKnight wrote: post #195
jerf wrote: post #109

Earlier quoted context omitted.

And the answer is if you accomplished a miracle and cut military spending in half and freed up 8% of the federal budget, there would be a rioting mob charging towards the money... no... that doesn't really capture how much we're talking here... there would be a rioting mob charging the suddenly-available huge pile of MONEY MONEY MONEY MONEY MONEY and there's very little reason to believe space exploration would be an…

Having near certain evidence of life existing on another planet, due to seeing oxygen present in the emission spectra of an atmosphere of another planet, would be a true game changer for space probe and exploration funding. Astronomy funding stagnates when its about rocks and geology. Bring real evidence of aliens into the mix and you've defined humanities focus for the next century.

I'm not the one who downvoted your message because you can't downvote replies to your own post, but I suspect you got downvoted because you crossed threads. If you follow the "parent" up from my post, you'll see that it didn't involve the discussion about finding oxygen.

I agree with the text of your message; it just isn't an appropriate reply to what I said. In fact if such a thing was discovered I'd say all bets are off in terms of the response.

Re: Four Earth-sized planets detected orbiting the nearest sun-like star

#283

Post by pault »

awiesenhofer wrote: post #75
baron816 wrote: post #37

Ok, let's assume we find a warm, watery planet like Earth's within ~20 light years, and we figure out a way to travel >= 50% the speed of light, making it somewhat reasonable to get there. If the planet's gravity is greater than 10% different from Earth's, or its Day/Night cycle is much different from Earth's, wouldn't it still be a nightmare to live on. Anatomically modern humans have lived on Earth for 200,000 year…

Thats why I enjoy the Culture series so much - why search endlessly for a habitable planet when you can just build yourself a nice, perfectly tailored orbital?

And in doing so tidy up the system of wandering debris (a trade-off whose conservatory elegance is almost blissfully appealing to the average Mind).

Re: Four Earth-sized planets detected orbiting the nearest sun-like star

#284

Post by saiya-jin »

bachaco wrote: post #139
lmm wrote: post #18

Earlier quoted context omitted.

If we wanted it badly enough, we could get to tau Ceti with current technology. The Orion designs are sound, and could carry a population capable of sustaining itself for the 100-odd years it would take to get there.

I wouldn't mind dying of old age inside a space ship. As long as I have internet connection / computer / private room, I am all good.

internet connection to where? earth's internet? yeah, with ping of 1-20 years?

Re: Four Earth-sized planets detected orbiting the nearest sun-like star

#285

Post by narrator »

ExactoKnight wrote: post #101

I am flabbergasted that as a society we aren't rushing to build a 100 metre wide telescope mirror large enough for us to directly image the spectra of the potentially habitable exoplanets around us. A telescope this large could tell us whether any of these potentially habitable planets contain oxygen, and thus, biological processes. Yet thanks to funding cuts in science the biggest telescope we have in the pipeline r…

Anything further than a 100th of a light year past the edge of the solar system we aren't going to be able to send a probe to so why bother except to provide subject matter for sci-fi. Even if we see that there is intelligent life on that planet there's nothing we can really do about it.

If they are a few hundred years ahead of us technologically they know about us and don't care. If they are a few hundred years behind they won't be able to receive our transmissions. I know science nerds need a wondergasm, but until we get some decent deep space propulsion technology it doesn't freaking matter. Seriously, except for some cool TV shows what tangible benefit had deep space cosmology brought us in the last 40 years?

Re: Four Earth-sized planets detected orbiting the nearest sun-like star

#286

Post by Symmetry »

vinchuco wrote: post #88
baron816 wrote: post #37

Ok, let's assume we find a warm, watery planet like Earth's within ~20 light years, and we figure out a way to travel >= 50% the speed of light, making it somewhat reasonable to get there. If the planet's gravity is greater than 10% different from Earth's, or its Day/Night cycle is much different from Earth's, wouldn't it still be a nightmare to live on. Anatomically modern humans have lived on Earth for 200,000 year…

Weird question. Can we make Earth a spaceship by somehow manipulating the orbit of the moon?

Well, we'd need to apply 40 km/s of delta-v. The moon weighs 1/80th as much as the Earth. By the rocket equation, we'd have to throw the material of the Moon away from Earth at 3219 km/s or 1/100 of the speed of light in order to accelerate Earth enough.

Re: Four Earth-sized planets detected orbiting the nearest sun-like star

#287

Post by gammarator »

BurningFrog wrote: post #146
spenczar5 wrote: post #129

Earlier quoted context omitted.

Very large telescopes can achieve great resolving power, but they run up against atmospheric turbulence, particularly in many of the spectral regions we care about for checking out exoplanets. Radio light passes right through the atmosphere for the most part, which is why you see very large radio telescopes, but they're not very practical for infrared or visible light scopes. Space-based telescopes are a better avenu…

Aside from turbulence, gigantic earth bound telescopes struggle with weight and fragility of the giant mirrors. That aspect is also much easier in space. Once you get it out there, which is hard...

Extremely large telescopes use segmented mirrors to avoid this problem.

Re: Four Earth-sized planets detected orbiting the nearest sun-like star

#288

Post by Symmetry »

1812Overture wrote: post #30
lmm wrote: post #18

Earlier quoted context omitted.

If we wanted it badly enough, we could get to tau Ceti with current technology. The Orion designs are sound, and could carry a population capable of sustaining itself for the 100-odd years it would take to get there.

Orion designs really only work if you're evacuating the planet. Massive fallout and radiation would be caused by each launch.

Well, some fallout. Orion is designed to to use small, single stage atomic bombs even if it does use lots of them to get out of the atmosphere. Those individually produce much, much less fallout than the huge fission-fusion-fission bombs that are mounted on ICBMs. Getting Orion to space would produce less fallout than the Bikini Atoll test. But then again there was a reason the various nuclear powers agreed to stop testing atomic weapons in the open air.

Re: Four Earth-sized planets detected orbiting the nearest sun-like star

#289

Post by sqeaky »

dmix wrote: post #242
sqeaky wrote: post #104

Earlier quoted context omitted.

I think a slim profile and large ablative shield are two good ideas. that largely solve both of these issues. Build something like the TransAmerica Pyramid (without the two white flanges) and put the motor(s) where the foundation would be as to make the building fly like a rocket. Put the motors on at one G and you get artificial gravity, a slim profile and damage equally distributed along the bulk of the ship and mo…

TIL about Ablative Armour, thanks for the interesting read. Isn't turning the ship at those speeds nearly impossible? You'd either have to slow the entire ship down first (the whole idea) or burn a ton of fuel to turn it while accelerating at a percentage of light speed, while avoiding debis and the spaceships engines explosions. I believe this is why scientists researching this prefer magnetic sails as a means to sl…

The reason an arrow, airplane or a rocket in atmosphere stays in one orientation during flight is unequal drag.

The feathers/fletching on an arrow produce more drag and the the arrowhead is dense and moves the center of mass really far forward. As air passes over it the center of mass is pushed back least and the part with more drag are pulled back more.

In space there is no air so rotating the ship is trivial. Consider comets or planets that are constantly revolving. Also, don't confuse turning with changing velocity and direction or travel.

In my previous example the ship would stay in constant motion even though it is turning a 180 degrees. The actual turn could be done with rockets or reaction wheels and by spending very little force to do it.

Re: Four Earth-sized planets detected orbiting the nearest sun-like star

#290

Post by Balgair »

ExactoKnight wrote: post #190
Balgair wrote: post #132

Earlier quoted context omitted.

Noise is noise. If you put gain on the signal in general, you'll put gain on the noise too. That's why James Webb is in space and the 30 Meter Telescope (TMT) is in Hawaii, less atmosphere and clear air means less noise inputted. Still, the TMT is pretty darn good. So yes, you are correct, bigger telescope means more noise (in gestalt) while in atmosphere. THe reason bigger is better is because you can resolve smalle…

> If the TMT costs X, then the 100-MT should cost about 11X, and with the 15% doubling factor, its ~15X for only a 3X increase in radius. The Thirty Meter Telescope cost $1 billion. So the 100 Metre Overwhelmingly Large Telescope would cost ~$15 billion using your ~15x multiplier. That's large, but for perspective: The F-35 fighter jet program cost $168 billion. Like with the Large Hadron Collider, if the extra cost…

As would I! Unfortunately, it seems the Realist sect of International Relations seems to be en vouge these last few decades. That said, there is an existential threat to 'science' in general with these large and impossible to replicate engineering experiments. They kinda get subsumed into the 'Big Science' camp where the budgets mean more than anything else and then incentives get muddied. In the physics field, there is still enough animosity and ego between the researchers to keep it all in 'science' and the results don't get massaged like in bio where it's all 'Big Science' now and the results get tweaked.

https://en.wikipedia.org/wiki/Realism_(international_relatio...

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