So just around the corner
C/10 (yeah right) would be a mere 40 years.
C/100 (unlikely) a snip at 400.
I doubt they'll be leaving a light on for us.
Astronomers who devised a technique to capture direct images of nearby potentially habitable exoplanets have found what could be a world orbiting a star a mere 4.3 light years away from Earth in the Alpha Centauri group. Details of the technique were published in Nature Communications on Wednesday, and it involves adding a …
There is a nice photo on a recent Astronomy Picture of the Day showing the lasers used for adaptive optics:
If you live in England, the CPRE is doing a sky survey this week. To participate, count the stars you can see with the naked eye in Orion, then go to the CPRE web site and complete the form (www.cpre.org.uk). This is to find out if the lockdown has had any effect on light pollution. Living in central Reading, I could just count 11 stars (Betelgeuse, Bellatrix, Rigel, Saiph, Alnitak, Alnilam, Mintaka, two at the end of the sword and two others just below the belt that I can only see by looking slightly away).
I stood at my bedroom window, against the toasty warm radiator for about 1 minute while I counted the stars I could see in Orion, then shut the window, and reported my result. I did not have to venture out at all really. Besides, if artists suffer for their art, why shouldn't we heroes and heroines of science suffer a bit for ours?
You'd need - roughly - the right gravity, the right magnetic field, the right level of insolation, the right order of rotational speed and orbit time, the right atmospheric composition, and probably a few other factors that don't immediately come to mind. Otherwise, although there could indeed be life it would probably be "not as we know it, Jim", and thus not best suited for humans. However some folks are contemplating living on Mars (apparently not for themselves though, just for others), and that planet is so unsuitable that we'd all have to be suited - permanently suited.
Many people glibly talk about "tera-forming" Mars. Which would mean pretty much manufacturing an entire atmosphere of the right composition and changing the climate completely. All started by using the extremely limited amount of machinery and materials that can be transported from Earth.
If that were even remotely possible to do within any practical period of time, then it should surely be absolutely trivial to adjust the CO2 content of Earth's atmosphere by a fraction of a percent, and alter our climate by less than a degree?
Changing the atmosphere of Mars would surely be trivial compared to creating a suitably powerful, planet protecting magnetic field to keep the new atmosphere from drifting off into space.
But don't panic, we've got lots of time to build one as the Great Oxidation event took hundreds of millions of years:
"the rise of atmospheric oxygen was not monotonic, but was instead characterized by oscillations, which together with climatic instabilities may have continued over the next ∼200 My"
Why would one need to protect the new, man-made air? Just replenish it every so often with falling icebergs from the outer fringes. One mile-wide comet would contain sufficient mass to compensate for decades, maybe millennia of air loss.
And they don't contain only water. Every infall would supply nice, juicy veggie-making fertilisers, too.
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" Which would mean pretty much manufacturing an entire atmosphere of the right composition and changing the climate completely."
A little while back, a milliard of years or so, little, teeny, tiny bugs managed to do this to the atmosphere of an utterly useless, uninhabitable rock we now call Earth.
Using mosses, lichens and other critters greening Mars shouldn't take more than a century. Maybe less if we dump tons of veggies and fungi all over the place.
Helping it along by dropping icy blobs onto the poles from the Martian skies would be fun, too.
Greening Venus would, however, be easier. Maybe even faster and Venus is *warm*.
It's a shame Man is never, ever, ever going to do any of those nice things.
The Alpha Centauri system is a triple star system comprising one red dwarf star, Proxima Centauri that already has a known planet or two circling around it, and two larger, Sun-like stars, Alpha Centauri A and Alpha Centauri B. This planet candidate is orbiting around Alpha Centauri A and this sighting now needs to be independently confirmed by other astronomers.
It would be great if it did exist because it again confirms that planets can arise in multiple-star systems. It would be even better if this planet turned out to be of roughly Earth mass and within Alpha Centauri A's habitable zone because that's when things really could start to get interesting.
The star system of Earth, the Solar System, has at least eight, sometimes ten or more prognosticatingly useful worlds and a dozen or so Zodiac signs. AlfaCent-A-One may only have a couple of planets and a second, quite tiny Sun-like object.
Proxima would be brighter to them than it is to us but not overly so. Almost certainly not bright enough to be seen as a "planet" and any planets of Alfa-Cent-B would be invisible from One's surface.
Astrological charts on One might be dead simple.
Which makes them quite generic and lacking in usefulness. The more pointers and markers and "houses" one has the more detailed and differentiated your predictions can be.
Gas-bags floating in the clouds of Jupiter or Saturn could have *incredibly* complex horoscopes tailored to their individualities quite precisely and tuned to very small temporal intervals as their moons have many, many short months.
What are you, a teenager? The odds of there being 1) life there and 2) developed enough to be hostile AND 3) developed enough to break the laws of physics by being able to reach us are, pun intended, astronomical.
You're wasting your time and your mind thinking about such guff. I doubt you - or any of us - have more than a couple decades left. Perhaps time to get your priorities in order?
Most exoplanets have been found by their transiting the star and dimming it. For this to happen, we have to get REALLY luck on alignment and it favours planets in close orbit to red dwarves. Look how rare transits of Venus are and we are in a similar orbital plane.
This is a useful new method for nearby stars as it can see planets in random planes
There are several ways of discovering exoplanets. See https://astronomy.com/news/2019/10/how-the-first-exoplanets-were-discovered for the first exoplanet discovery around a neutron star.
"A breakthrough in 1992 provided rock-solid evidence of planets. Astronomers Aleksander Wolszczan and Dale Frail tuned into the pulsar PSR B1257+12, 2300 light-years away. It should have pulsed every 0.006219 seconds, but every now and then, its pulses were a little off. Yet those off-beats came at regular intervals as well. After intensive study, Wolszczan and Frail came up with an explanation for why that was: it had two planets around it. One was three and the other four times the mass of Earth, and they rotated around every 67 and 98 days, rounded up."
Well, yes, but 'correct orbital plane' does not necessarily mean occulting the star. Several exoplanets have been found by the wobble induced in the star's true motion across the sky, meaning that the Earth has to be well outside the planets' orbital planes for the effect to be noticed.
I don't know what the orbital plane requirements are to periodically slow the periodicity of revolution of a neutron star are, but I don't think having the Earth in the same plane (i.e. occulting the star) is necessary. Astronomers please advise.
Given we currently can't, and actually never will, travel at the speed of light, it is a clear sign we should bin the idle fantasies of starting over elsewhere and simply solve earth's problems instead.
AC because I might be down voted into oblivion... But that's not the same as being refuted and proven wrong.
You don't have to travel at c to get places pretty quickly. A rocket which can sustain 1g can get anywhere in the galaxy in 30 years of time experienced by the people on it.
Of course the 'sustaining 1g' thing is just as impossible, so, well ,it doesn't make any difference.
It's not impossible, just not practical with our current engineering abilities. The technology for much more powerful and efficient engines is already known and has even been experimentally tested in some cases. All that's needed is to make it larger and more robust and to construct the infrastructure necessary to build it up there instead of down here, so that we don't have to spend inordinate quantities of resources launching fuel and materials from the earth's surface. It'll probably take about a century to reach that point.
>It's not impossible ...
I would be curious to know how much mass/energy it would take to maintain a 1G acceleration for galaxy spanning space travel. I suspect you might have to consume a few solar masses along the way and hope that any occupants don't get to upset about it.
It's all about specific impulse, or the efficiency of thrust to fuel expended. Our current engineering cannot match the requirements, but we have tested small-scale engines that are capable of a much higher specific impulse; they're just not capable of particularly high thrust. Not yet. There are also theoretical engine technologies that have yet to be tested, but which are more than merely hypothetical due to the fact that all of the components already exist in some form, though not yet in a form robust enough to be used for the purpose.
To say it can never be done because we're not able to do it now is a weird sort of arrogance, especially when all of the necessary components already exist.
they're just not capable of particularly high thrust. Not yet
Ack. I'd say the most efficient 'impulse' type of engine would be
* fusion reactor
* super-heated liquid/gas expelled at high velocity
* maximum impulse per gram of propellant
If the propellant is hydrogenous, it can also be "fusion fuel" even if only a small percentage (i.e. deuterium and tritium) are being used for that part of the engine's output.
Then you just need a LOT of it. Since hydrogenous material (methane, water, ammonia) is available on just about every planet in our solar system, in high abundance, shouldn't be a problem if you can make a big enough tank to hold it all.
* NOTE: to prevent melting engines, you inject raw fuel along the inside surface of the engine. The laminar boundary layer will allow turbulent flow, while protecting the layer itself, which will then evaporate and effectively cool the engine housing. Then you can have exhaust temps way above the melting point of the materials it's made of. Multiple injection points for 'raw fuel' will make sure that the engines run continuously without melting.
It's impossible with current physics. Have a bit of fun. Assume that you have a reaction mass which converts to energy with 100% efficiency. Assume that the energy is then converted to thrust with 100% efficiency. Next calculate how long it would take to decelerate at 1g from 0.25c back to 0. Don't forget relativity. (You don't want to be that guy.) I'm giving you the magic lasers & the power of the sun to get up to 0.25c. (And I DO mean magic. Do the math on creating lasers to drive the final mass calculated below at 1g.) Finally, use the rocket equation to compute how much reaction mass is required to drive a final payload of 500kg at 1g for that much time. Again, don't forget relativity.
Of course, we don't have to accelerate at 1g for the trip. A generation ship is almost certainly within current technology & probably engineering, just really freakingly expensive.
New physics, however, is new. Specifically, the idea of slipping past spacetime in some fashion rather than going through would conceivably eliminate the c barrier, but unless the tech to actually do so allows us to either bypass the rocket equation or throw a truly amazing constant at it, it won't do us any practical good.
"Assume that the energy is then converted to thrust with 100% efficiency."
hold-on: these are different units, energy is Joules (J) and thrust is a force (N) ? While energy and mass can be considered equivalent (E=mc2 and assuming we use anti-matter as energy source), how do you convert, even theoretically, energy into thrust at 100%.
It's a genuine question, not a trap
@ Claptrap314 "A generation ship is almost certainly within current technology & probably engineering, just really freakingly expensive."
Sorry, but I don't think so :o(
We have not yet discovered how to live sustainably on the resources of an entire planet orbiting a star yet, the idea that we could do so within the highly confined volume of a 'generation ship' is pushing it. Firstly you need a lot of people to provide a sufficiently diverse gene pool. The best minimum estimate I heard a long time ago was 500 people. Then you need to deal with keeping warm for tens of thousands of years. The only possible engine for that would be sustainable fusion power as it has the most efficient use of fuel, but even then, when you fuse the heavy hydrogen in heavy water, you only convert a small proportion of the mass into energy, so you will need a lot (and something to do with the Helium - of course fusing He would be good but I don't think anyone is even working on an He fusion reactor).
Then there is wear and tear. Check out the photo, 'Sea of Steps' by Frederick Evans:
Note, that is the wear of stone steps in less than 1000 years. Dealing with minute but cumulative erosion over the millennia on everything from computer screens and keyboards to living quarters, and everything has to be recyclable, and I mean everything: tooth fillings, people, animals, the atmosphere, because interstellar space is not expected to be overflowing with service stations for the passing spaceship. Then, of course you need shielding, not just form cosmic rays, but from heat loss (in space no one can hear you freeze).
And then, of course you need some way to accelerate your billion ton space vehicle towards your target star to some decent percentage of c.
So, sorry, I don't believe that we currently have anything like the technology to make a viable generation ship just yet. The best we could do is send lichens, tardigrades, cyanobacteria, and possibly a frozen wood frog (https://www.latimes.com/science/sciencenow/la-sci-sn-alaskan-frozen-frogs-20140723-story.html).
So I reckon we'll be staying put for a bit longer. A good job we're looking after our home planet so well really...
Yeah, I suppose I'm pushing it to consider H fusion "current tech".
As for the rest, I'm talking about hollowing out a mid-sized asteroid or three. I see no real technology problem there.
My idea of a generation ship is not "twenty years", but more like a thousand. YMMV.
Probably the biggest issue with a generation ship is the unexplored psychological effects, however. You need a stable society for the length of the trip.
What's our record on that?
While it's not possible to travel at or beyond the speed of light, there may be workarounds, such as proposed by Alcubierre. And who knows.. a lot of the tech we take for granted these days was 'impossible' less than a century ago. We've only even been meaningfully using electricity for less than 150 years.
Personally I'd love to live to see the development and implementation of a 'warp drive' or similar, but unfortunately I doubt we'll even have a manned mission to Mars before I die.
Came here to say pretty much the same thing.
It's a very self-defeating attitude to take, to say "We'll never achieve X based on our current understanding, so don't bother trying or even waste time thinking about it".
In the pioneering days of locomotive steam engines, many believed that it was unnatural for people to travel that fast, and that travelling faster than 30 or 40mph (not sure which, my memory fails me here) would impart significant damage to the human body. Now we routinely travel at 70mph (if you're being good) on the roads.
It was thought to be impossible to split the atom. That's literally what it's name means; un-cuttable. That was disproven rather thoroughly, and violently.
We don't understand everything about the universe. A lot of what we think we understand probably isn't right, or at least isn't entirely accurate. It's probably best to say that travelling at lightspeed isn't possible for now, and to keep an open mind for later.
Given we currently can't, and actually never will, travel at the speed of light
While you're absolutlely correct that we'll never reach, never mind exceed c when travelling through space, there's no proscription on moving bits of space/time containing a vessel around the universe faster than c, so it might well be possible one day to get from point A to point B faster than a photon. The only caveat is that the amounts of energy required would be enormous by today's standards.
Having said that, the 300+ HP my car produces today is an astronomical amount of power compared to what was available 300 years ago...
eh, fire up the "Jupiter 2" - let's colonize Alpha Centauri!
You don't have to go C to get there... just 1/2C will do. ~10-12 year trip, accelerate to 1/2C, coast, decelerate. It's been a Sci Fi staple since the 1950's I think...
Lots of water or methane or some other abundant mateial, a fusion reactor, and one big ass rocket engine that uses all that. Fusion energy would accelerate liquid to a point where you get peak impulse with minimal mass. CAN be done, but you need to accelerate to 1/2C over several months, then coast, then slow down again just before you arrive.
The hard part will be radio communications. Maybe this is where some kind of quantum resonance communication system would come in handy.
"Given we currently can't, and actually never will, travel at the speed of light,........"
That isn't how to do it.
The seeding of the Human Galaxies goes something like this:
In the early 1970's, SkyLabs are built, launched and joined together. An international effort uses this factory and science station to supply skilled labour to buil a city-farm in high orbit. Eventually, the burgeoning offworld economy sends factories to the Belt and the Trojans for metals and ices. Some of the mined stuff is dropped into H.E.O. to create and fuel many more habitats.
The city-farms supply refined metals and foods to the Earth. Mining and farming ends on the Earth. Some of the cities find HEO too restrictive so sprout engines to allow them to drift to Lunar or Martian orbits, some drift off into the Belt, the Trojans and - with enhanced protective shells - to Jovian orbits.
Meta-Law is written to protect the Rings. No exploitation is permitted there.
Some Cities find the inner System too crowded so slowly drift outwards, continuing to trade and communicate with the inner worlds as they go. Eventually, the cometary zone has a non-zero population.
The cometary zone of Sol isn't that much of a jump from the cometary zones of stars like Proxima, Wolf-359 and Barnard so falling away from Sol at glacial velocities becomes falling *towards* nearby stars. Time does not matter when ther is no real destination, when your entire civilisation comes with you and when re-supply and refuelling can be done from both your home-port and your destination by way of robots and trade.
It is not the flight of starships nor is it the falling of intergenerational arks, it is merely life going on as it always has but with the cosmos slowly swimming past your windows.
After many millennia, a refitting, refurbishment and refuelling pit-stop is made relatively near the targeted star and its debris clouds. There is, during the long fall, an opportunity to scan for suitable detritus to use as building materials, soil and other goodies.
The pit-stop may also be an opportunity for the City to breed, to make more of itself, to seed the new planetary system with descendants until some of those, too, drift out into the darkness.
After ten million years, perhaps fewer, Cities full of what once were Men appear at the other edge of this Galaxy.
After maybe two hundred million years, perhaps fewer depending on need, vision and technologies, the alien sons of long-lost Earth walk the worlds of nearby galaxies.
Once a species can build habitats that can be repaired for millennia, ubiquity and eternal existence is inevitable.
If only to get away from the blaring yammering of the home-worlds.
Of course, Humans aren't going to do any of this. Not ever.
Astronomers will have more opportunities to directly image new exoplanet candidates like C1 in the future.
Astronomers won't need to bother their little heads about any stars in the future, as they will be hidden by solid sheets of cheap telecom satellites, and the resulting flying junk clouds (We'll talk again when competing constellations of 3rd world countries start trying to elbow in). Adaptative optic that away if you can...
Telescopes are highly specialized tools, and are used for extremely different tasks: You won't need the same instrument configuration to check for exoplanets, to chart galaxy clusters or to calculate orbits of stellar bodies. Those tasks require very different instruments, sometimes even different optics, and as a result astronomers need many, many different telescopes. (If only so everybody gets to have some observation time during his lifetime!...)
Hubble is yet another specialist tool, excellent at some tasks, very bad at others. But its biggest problem, a real show stopper, is there is only one Hubble. Booking time on it is like meeting the president, it might take years for a mere minute.
Even with all the thousands of telescopes of all sizes strewn over the planet's surface, observation times are limited and waiting lists are long. And yes, even small and/or old telescopes can be just fine for some specific tasks which don't require as much definition as uninterrupted observation continuity over a longer period (impossible with Hubble).
Another problem of Hubble is there is no way to reconfigure it: Let's assume you need to install that new special occultation spectrograph you just devised. On a terrestrial telescope it would only require some hours/days of work, on Hubble, well, it's strictly and totally impossible...
Hubble is just one of the tools in an astronomer's toolbox. A nice tool, but not even the nicest of them, potentially even completely irrelevant depending on your field of studies and associated needs.
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