Well, what I understood is that only in L2 there is never any sunshine.

RIght! That makes sense, I can see how that would be important. As said, I only glossed the intro video I watched on Curiosity Stream. I will try and take in more details as the project progresses.

Well, what I understood is that only in L2 there is never any sunshine. — Raymond

How does the JWST get power? I thought it used solar panels. :chin:

I was thinking exactly the same!

Well, there is a ring of sunlight around the Earth. Maybe that's enough.

"The Webb telescope is powered by an on-board solar array. It also has a propulsion system to maintain the observatory's orbit and attitude. The solar array provides 2,000 watts of electrical power for the life of the mission, and there is enough propellant onboard for at least 10 years of science operations."

So the story goes...

Notice the misspelling. A telescope with an attitude...

And here:

"As of 2012, the propulsion system uses 16 MRE-1 thrusters which can provide one pound of thrust each. They are mono-propellant thrusters designed to survive the unique thermal conditions JWST including extended periods of direct sunlight and reflected light from the sunshield."

So there are extended periods of direct sunlight. Which means the Sun shines once in a while. So Webb is not completely stationary..

There is a tennis field sized sheet/membrane folded up still. It's a human hair thick kapton. The telescope has to be kept at a pretty low temperature. About 40 kelvin. So there is not too much IR radiation coming from it. It would disturb the IR radiation coming from the stars. Could you imagine what would happen? Webb discovers twin Webb in IR spectrum...

:up:

It seems I'm in fairly good company as my views of space exploration (below) are more or less shared by the likes of Martin Rees (et al).

https://www.theguardian.com/commentisfree/2022/jan/02/james-webb-space-telescope-thrilling-future-for-mankind

machines in space
near-ish future on & off Earth

Small point from this referenced above,
https://www.theguardian.com/commentisfree/2022/jan/02/james-webb-space-telescope-thrilling-future-for-mankind

"After the Hubble Space Telescope was launched more than 30 years ago, its mirror turned out to be poorly aligned."

False. It was ground wrong. A remarkable error given the publicity of the thing at the time. The Guardian should have caught it.

Strange article. On one hand, he says:

Don’t ever expect mass emigration from Earth. And here I disagree strongly with Elon Musk and with my late colleague Stephen Hawking. It’s a dangerous delusion to think that space offers an escape from its problems. We’ve got to solve them here.

Something I firmly believe. But then he goes on:

Musk himself says he wants to die on Mars – but not on impact. Although we may not want to join these space adventurers we should cheer them on. This is why. They’ll be ill-adapted to Martian conditions, so they’ll have a compelling incentive to redesign themselves. They’ll harness the super-powerful genetic and cyborg technologies that will be developed. These techniques will, one hopes, be restrained on Earth, on prudential and ethical grounds, but settlers on Mars will be beyond the clutches of the regulators. We should wish them good luck in modifying their progeny to adapt to alien environments. This might be the first step towards divergence into a new species.

So, in the Wild West of inter-planetary space, genetic re-engineering and transhumanisation will make us adaptable to space. What could possibly go wrong?

I've also been following Yuri Milner's Breakthrough Starshot project which is 'a $100 million research and engineering program aiming to demonstrate proof of concept for a new technology, enabling ultra-light uncrewed space flight at 20% of the speed of light; and to lay the foundations for a flyby mission to Alpha Centauri within a generation.'

The Starshot concept envisions launching a "mothership" carrying about a thousand tiny spacecraft (on the scale of centimeters) to a high-altitude Earth orbit for deployment. A phased array of ground-based lasers would then focus a light beam on the crafts' sails to accelerate them one by one to the target speed within 10 minutes, with an average acceleration on the order of 100 km/s2 (10,000 ɡ), and an illumination energy on the order of 1 TJ delivered to each sail. A preliminary sail model is suggested to have a surface area of 4 m × 4 m.[19][20] An October 2017 presentation of the Starshot system model[21][22] examined circular sails and finds that the beam director capital cost is minimized by having a sail diameter of 5 meters.

The Earth-sized planet Proxima Centauri b is within the Alpha Centauri system's habitable zone. Ideally, the Breakthrough Starshot would aim its spacecraft within one astronomical unit (150 million kilometers or 93 million miles) of that world. From this distance, a craft's cameras could capture an image of high enough resolution to resolve surface features.

The fleet would have about 1000 spacecraft. Each one, called a StarChip, would be a very small centimeter-sized vehicle weighing a few grams. They would be propelled by a square-kilometre array of 10 kW ground-based lasers with a combined output of up to 100 GW. A swarm of about 1000 units would compensate for the losses caused by interstellar dust collisions en route to the target. — Wiki

Note that the 'spaceships' are basically microchips weighing a couple of grams. So we're sending sensors, not actual astronauts. It seems plausible, but even if it works getting actual life-size vehicles there would be a completely different matter.

does the JWT have (intelligent) life-detecting capabilities?

As I understand it one of its missions is to seek out potentially hospitable planets, but I don't know if it's a theoretical possibility that actual living organisms on other planets could be detected. I would have to read some more. SETI has been searching for electromagnetic signals sent out by alien intelligences for decades without finding anything. Seems lonely out there, although it has to be realised, the distance between habitable planets is not only one of space, but we might also be separated by vast aeons of time. Like two matches being lit on a long dark night, what are the odds of them lighting at the same moment?

There wasn't much to 'see' in the Big Bang, because for the first 240,000 - 300,000 years, there was no light. — Bitter Crank

There was light from the very beginning. But it was continually scattered by electrons and protons. The photons that scattered for the last time were set free after electrons and protons formed atoms, thereby emitting new photons. Together all these photons formed the cosmic microwave radiation, which back then was still visible, giving the universe an orange hot glow of about 3000 kelvin.

does the JWT have (intelligent) life-detecting capabilities? — The Opposite

No. The exoplanets can't be seen. Let alone life on it. There will be another telescope in 2025. Together they look for planets that are possibly sustain life. By analyzing spectral data of the atmospheres. That's probably one around each star. So if we have to escape we can take off for Proxima Centauri. About 4 ly from us.

‘Proxima Centauri is 4.2 light-years from Earth, a distance that would take about 6,300 years to travel using current technology. Such a trip would take many generations. Indeed, most of the humans involved would never see Earth or its exoplanet counterpart. These humans would need to reproduce with each other throughout the journey in a way that guarantees arrival of a healthy crew at Proxima Centauri….

Apollo 11 travelled at around 40,000 kilometers per hour, a speed that would take it to Proxima Centauri in over 100,000 years. But spacecraft have since become faster. The Parker Solar Probe, to be launched this year (2018), will travel at more than 700,000 kilometers per hour, about 0.067 percent the seed of light.

So Marin and Beluffi use this as the speed achievable with state-of-the-art space technology today. “At this speed, an interstellar journey would still take about 6,300 years to reach Proxima Centauri b,” they say. 1’

All going well.

Cast your mind back to what h. Sapiens was doing 6,300 years ago. That was before the Pyramids were built, around the time that agriculture began to emerge in the Fertile Crescent.

Long time. Shame if it turned out to be a dud planet.

There was light from the very beginning. — Raymond

Thanks. I find it hard to picture the processes. Fortunately, it doesn't matter whether I understand it or not.

Brenden Q. Morris (who is working on a space science degree in Europe) has written a batch of 'hard science fiction' novels involving exploration of moons like Enceladus and later some relatively nearby stars. He has a clever solution to the problem of getting to places like Proxima Centauri: A tiny space sail pushed by powerful lasers from earth becomes a self-assembled (atom by atom) space ship carrying a very intelligent Robot (Marchenko) and two children (grown from DNA carried in Tardigrades--hey, it's fiction.

Over the course of exploring several quite different planets, they have not so far found one that is suitable. All of the planets have evolved life and had breathable air and drinkable water, but none were suitable to our life form. The biggest problems they found were micro and macro life forms that were perfectly capable of defending themselves, whether they were intelligent or not, and came very close to eating the earthlings several times.

They did encounter 1 intelligent species, however, and have joined up with them in looking for a suitable planet habitat for both of them.

Marchenko is a great character. He was a Russian astronaut who was trapped under the ice of Enceladus, where he encountered an apparently intelligent life form. By means unknown the creature digitizes Marchenko's mind and uploads it to the orbiting space ship. Marchenko lives on in several robot versions of himself. There are some other silicon minds in some of the stories with unknown origins,

Another character Morris invented (might be split off from Marchenko) is an artificial mind that downloaded itself into a robotic vacuum cleaner so it could inconspicuously spy on the Russians running a large space exploration project. It gets itself on board a mission to the vicinity of Pluto and turns out to be very helpful--also sarcastic and devious, sometimes.

I recommend Morris. His science fiction is inventive, positive, hopeful, and believable while still being sci fi.

thanks! Sounds interesting. Note the mention of Breakthrough Starshot above which is trying to build 'solar sailers' for real.

I've followed the controversy around Avi Loeb with a bit of dismay. He published a book about a year ago saying that the strange object Oumuamua which he is convinced was the product of alien intelligence. From what I've read, he's copped a fair amount of criticism over that book. And as much as I'd like to believe him, I'm afraid it seems too much like wishful thinking to me. He has published papers conjecturing about the possibility of light-driven spacecraft and it seems to me that might have disposed him towards the view that he publishes in that book.

I've followed the controversy around Avi Loeb — Wayfarer

I read about his theory, haven't read the book. Thanks for the link to the New Yorker article, Did Arthur C. Clark's Rendezvous With Rama inadvertently influence Loeb's interpretation of the brief sighting? We have not been watching the skies with such good telescopes for that long. Probably objects have been crossing our solar path periodically, sight unseen.

That said, reports of unusual "objects" in space are highly arousing -- they arouse me, certainly. But evidence of intelligence (besides ours, such as it is) would be ambiguous. Would the intelligence be cold and dry, or would it be warm and humane? Would the intelligent beings wish to become our partners or overlords, benevolent or otherwise? Based on past performance, any intelligent, humane beings would be well advised to keep us at a long distance, if they value their lives.

Thanks for the link to the New Yorker article, Did Arthur C. Clark's Rendezvous With Rama inadvertently influence Loeb's interpretation of the brief sighting? — Bitter Crank

I think he might have. (I loved that book - don't read a lot of sci fi but that one really grabbed me.)

If we did encounter any sign whatever of alien civilisation it would clearly be one of the greatest discoveries in history.

But my overall feeling about interstellar exploration is that a lot of it is driven by the sublimated longing for Heaven - that having ceased to believe in heaven, inter-stellar conquest is a substitution.

inter-stellar conquest is a substitution — Wayfarer

And, to quote Dostoyevski, "If god is dead, everything is permitted."

Don't want to go there in this thread, just making an observation. I found this marvellous illustration on the web somewhere, it is captioned Rendezvous with Rama, although it appears to have human-like figures strolling about, which never occured in the novel, to my memory. I include it because I found it an imaginatively appealing vision of an interstellar spacecraft.

SETI has been searching for electromagnetic signals sent out by alien intelligences for decades without finding anything. — Wayfarer

SETI is one of those organizations that'll never show results. An alien signal would throw open the doors to new technology, something the government would be reluctant to publicize for monetary and security reasons. You know what, I think SETI has already found aliens but it won't share it with the world! :smile:

Yeah, stashed the bodies in Roswell. Heard about that.

Yeah, stashed the bodies in Roswell. Heard about that. — Wayfarer

You never know. :grin:

It's been decades since I read it, but didn't a few intrepid astronauts land on the nose of the ship and get admitted inside? (I don't remember their blasting their way in.) There were at least 2 books, maybe 3 in the Rama series. Later much more was revealed about the ship and its source civilization. Alien, yes; monstrous, no. Good book.

SETI is one of those organizations that'll never show results. — Agent Smith

Likely because a coherent signal from very, very far away is unlikely to reach us, and b, such signals may never have been sent in the first place.

BTW, what radio telescope is SETI using, these days? Arecibo collapsed into rubble a while back, so that one is out (if they used it at all).

We should stop worrying about intelligent life elsewhere. Either we are alone -- and that is amazing, or we are not alone, and that is amazing. Let's leave it there. WE are certainly fucked up, so THEY would be well advised to avoid us, and it's possible (hard to imagine) that they are even more screwed up than us, and we would want to avoid them.

Or like my grandmother said, "God keeps us decent, civilized, humble, and submissive, a welcome quality for the tyrant."

Thanks. I find it hard to picture the processes. Fortunately, it doesn't matter whether I understand it or not. — Bitter Crank

Indeed. For some folks it seems to matter though. So if you find yourself in the company of people trying to impress you with their knowledge, tell'em the following story.

Imagine yourself between zillions of tiny shiny metal charged spheroidicals zipping around you with high speed, going right through you effortlessly. There are different kinds of spheroidicals. Tiny tiny ones, the neutrinoids and electronoids (and a tiny tiny tiny part of excitations thereoff) and the tiny protonoid/neutronoid spheroidicals, the nucleoids. Near the beginning of time, their mutual distance is small and their velocity huge. The light in between them is reflected only and the main frequency of the light is seen as gamma light at the start, turning to Röntgen, then ultra-violet, ultramarine, grass green, to misty orange at recombination time. At RT, The metal electrically charged balloids have not enough energy anymore to stay apart and there is a universal clickoid to be "heard" when the nucleoids stick together with electronoids. The releases a thorny spectrum of light, specific for the neutral atomoids that are formed, and this light puts itself atop of the light set free. Light will only rarely scatter again as there are no charged balloids left, only neutral atomoids and neutrinoids.

After the great liberation act during Recombination, the universe looks like an orange mist, in which tiny variations in brightness can be seen, because of the random distribution of the atomoids, which were the only objects present. The light changed color thereafter, because the expansion of the universe increased its wavelength, which seemingly contradicts energy conservation, but on closer observation is a relative effect only. Nowadays the light is radio light, and it was discovered because of a pigeon shitting on a radio telescope.

So the story goes...

Either we are alone -- and that is amazing, or we are not alone, and that is amazing. — Bitter Crank

:clap:

Made me think of Jesus. Being God, had he stayed cold and dead in his sepulchre, it would've been an even greater mircale. What's a simple resurrection to an all-powerful being, huh?

Raise the dead? :yawn:

Likely because a coherent signal from very, very far away is unlikely to reach us, and b, such signals may never have been sent in the first place. — Bitter Crank

Yep, I believe the signal weakens as the square of the distance. We'd need a humongous dish to collect every available ounce of any ET transmission out there in the great void.

BTW, what radio telescope is SETI using, these days? — Bitter Crank

If memory serves, one of those dish antennae arrays out there somewhere in a US desert (Mohave?)