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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

#291

Post by Balgair »

saganus wrote: post #191
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…

Very nice explanation. Thanks! 15 billion (as per a sibling comment) sounds like a lot, but relative to other, IMO not so important things like said plane, it's not that much. However I wonder if it would be worth it or if that money would be better spent creating a Hubble replacement for example.

Thanks! I just finished a 14 month class in Optics, so it's fresh for me. The alternative to putting something into space is much more preferable. No matter how big a ground based scope it is, you still have all of that air mucking up the data coming in and you just can't get as good of data. Space is just so much better, as you know, it is mostly empty of the matter we are trying to look at. Granted, for many EM frequencies, ground based is fine. But a lot of atoms we are trying to look at happen to be present in the air too, messing up the data. Space costs a lot more, but I think there is no comparison in the long run. The dark side of the moon would be a good combo of both advantages though. You could build and also maintain and modify a very very large telescope with out any air or other ground based interference. The flip side is that it would be even more remote than current space based telescopes and therefore more expensive to get things to, like people, air, water, food, and fuel. But, hey, it's the flipping Moon! Like, we have a semi-good reason to go back now! For science!

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

#292

Post by namlem »

spenczar5 wrote: post #129
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…

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…

Seems like the moon would be a good spot. We can build it much bigger than in orbit, and there's no atmosphere to cause interference.

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

#293

Post by mturmon »

ExactoKnight wrote: post #257
mturmon wrote: post #251

Earlier quoted context omitted.

The corresponding space telescope for exoplanet detection and spectral characterization is being planned for sooner than you may expect: https://www.jpl.nasa.gov/habex/ . This, or a similar concept, is hoped to be in the upcoming National Research Council decadal survey which recommends astronomical priorities for the 2020s. Current designs require as little as 4 meters. Stability is one advantage of space telescopes…

Promising developments, but christ, could they move any slower ?! We know what technology we need to build. Why must we wait a full two more years for a report to get finished before even beginning funding proposals on which path to pursue, before beginning any construction or engineering?! None of us are getting any younger. I know this is complicated technology to build, but contrast how fast technology moves in th…

I don't have time to reply to this with the level of detail required, but I'll just say that you underestimate the level of tech needed to deploy a mirror this good, and you overestimate how much we understand the instrument design issues. That is, we don't know what to build.

The trade studies are highly complex (how big the aperture is, how long the mission is, how much propellant is needed to slew the spacecraft, what the yield will be in terms of number of spectral characterizations, whether you need an external star shade). The star shade, if needed, would be a separate spacecraft.

General comparisons to "how fast technology moves in the valley" are not specific enough to benchmark what's needed for this rather unique mission.

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

#294

Post by tobmlt »

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…

In principle, I am right with ya. We need ways of beating (or at least coping with), the diffraction limit. It's fun to think of, say, stuff like this: https://arxiv.org/abs/1604.06351 (as far as big lenses go)

Using the sun as a gravitational lens would be pretty sweet. I have a feeling we will have some more tricks to play with E&M locally before we can go to space on that scale though.

edit: My own semi-blind musing has made me curious: metamaterials for super-lensing: https://arxiv.org/pdf/0905.0263.pdf

entanglment enhanced microscopes?!: https://arxiv.org/abs/1401.8075 (@shpx linked to this quantum stuff before me, by the way)

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

#295

Post by tobmlt »

shpx wrote: post #214
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…

Telescopes exploiting quantum effects would be able to be much smaller and have higher resolution. https://medium.com/the-physics-arxiv-blog/how-to-build-a-qua...

Nice! Thanks for making me aware of this research.

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

#296

Post by reindeerer »

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...

here is a telescope idea that is theoretically super scalable

http://www.pellegrino.caltech.edu/aarest1/

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

#297

Post by throwawayjaja1 »

2845197541 wrote: post #148
ExactoKnight wrote: post #131

Earlier quoted context omitted.

Finding the existence of life on another planet holds MAJOR implications for many organized and unorganized religions. It would tell us whether abiogenesis and life is common, or something truly unique. So while discovering life on another planet wouldn't answer exactly "why we are here", it would go a hell of a long way in shaping our answers to that question.

I apologize for being semantic, but I think that would answer the 'how' rather than the 'why.' I understand what you're saying though. As for the religious, well... I believe they will absolutely find a way for there not to be any major implications. New findings will be absorbed into the obfuscatory practice of apologetics.

Already been done, see CS Lewis

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

#298

Post by ExactoKnight »

Retra wrote: post #236
ExactoKnight wrote: post #195

Earlier quoted context omitted.

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.

If we discovered actual humans on a near-exact clone of earth, we'd still be about 50,000 years from something relevant here on Earth. Outer space is staggeringly expansive. Staggeringly . Like "your space probe is sad joke" expansive. We could develop our own alien life right on Earth within that timeframe.

You're thinking about this wrong. As long as we can send probes and/or communicate within compressed timeframes than physical transportation of humans doesn't matter.

E.g. Breakthrough Starshot can get us to many exoplanets within 20-30 years: https://en.wikipedia.org/wiki/Breakthrough_Starshot

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

#299

Post by ExactoKnight »

dredmorbius wrote: post #271
yoz-y wrote: post #270

Earlier quoted context omitted.

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?

The James Webb Space Telescope is an example of a segmented-mirror optical scope. The deployment video (simulation) is fascinating to watch: https://m.youtube.com/watch?v=v6ihVeEoUdo It has a 6.4m (21ft 4in) primary mirror. Which, from a pragmatics standpoint, answers your question. Though I suspect mission plans could be drafted for a larger scope yet. https://en.m.wikipedia.org/wiki/James_Webb_Space_Telescope

Fascinating video, but honestly the only thought that kept going through my head is: they've overcomplicated this.

Despite it's impressive number of steps, this does not look like good engineering.

Instead, it looks like a design by committee, with engineers going drunk on complex parts coming together rather than dumbing down the unfurling of this telescope down to its most basic possible mechanism, with the fewest moving parts possible (where failure is chronically always possible).

Seeing how overcomplicated this is, it's no surprise it cost $10 billion to build.

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

#300

Post by Retra »

ExactoKnight wrote: post #260
Retra wrote: post #176

Earlier quoted context omitted.

Do you realize how far away that star is? It would take 40,000 years just to reach the nearest star if we travelled at the speed of the fastest human created object in history. Why do you need to see a habitable planet soon? If you can't survive that trip, it means almost nothing.

Not at all. I don't care about traveling there, I want to know about what other life exists. Once we find a good target, the Breakthrough Starshot program is one example of a promising project that could get us results within our lifetime.

Breakthrough Starshot will get you to a negligible number of stars. Fewer than ten, probably. You think one in ten stars has life?
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