There seems to be some confusion about the meaning of "within the habitable zone".
From the paper (Introduction and Conclusions, respectively) [1]:
The habitability conditions of Proxima b, which orbits within
the HZ of the star, have been extensively studied (e.g. Barnes
et al. 2017; Ribas et al. 2016; Turbet et al. 2016; Meadows &
Barnes 2018). On the other hand, the candidate Proxima d orbits
much closer to the star and outside the HZ range.
In particular, the discovery of an Earth-mass planet orbiting Proxima Centauri (Anglada-Escudé et al. 2016), our closest stellar neighbour, was one of the most significant results in the field, in part because the planet orbits inside the habitable zone (HZ) of the star (e.g. Kopparapu et al. 2013).
So, Proxima d is too close to the star to be inside the HZ; it's within the HZ in the sense that the HZ is further out from the star.
The author of the Nature commentary, which claims that "it could have oceans of liquid water that can potentially harbour life", apparently didn't read the paper.
"Unlike the Sun, which will evolve into a red giant in 6.5 billion years and reach the end of its life at an age of about 10 billion years, Proxima will stay on the main sequence for another four trillion years due to its low mass and low energy production."
They laughed at me when I bought investment property on Proxima Centauri b, but who'll be the one laughing in 10.000000001 billion years?
Making an assumption here about Proxima Centauri's own Oort Cloud, but seems like if it's the same size as ours, they'd overlap? Seems like a potentially interesting way for "stuff" to get transferred from one solar system to another.
Thanks for that chart, that site is really worth checking out! There is a ton of cool stuff there, like the nearest starts, when we computed their distances, and other thing.
There's also the consideration of the host star to take into account.
I dislike the term "Earth-like" in these publications because it conjures images of a strange alien world able to support (human) life. Even assuming there were life capable of withstanding the constant flares from the host star, I suspect it would have to look very different in color and likely composition to the plant life here due to needing to capture a different part of the spectrum.
My education was in chemistry, I've wondered about this topic before. Visible light is actually special after removing the happenstance of DNA-based visual systems from the picture: IR tends to twist or translate bonds (warming) and UV tends to ionize.
Visible light being right in the middle is the trick which gives us photosynthesis, and sight, because in both cases a photon can be captured by a photosensitive bond. It's harder to come up with plausible photosensitive bonds for IR light, and most anything is photosensitive once you get far enough into UV.
Yes, "Earth-like" caught my attention too because red dwarfs are flare stars. I wanted to check my facts before commenting which led me down the rabbit hole of the history of Proximas flare activity, which is quite interesting.
Fun fact: Go outside on a clear night, and you can see 5-10,000 stars. There are 8 times that many red dwarfs in your field of view, and none of them are visible to the naked eye. But in 2016 Proxima was for a few minutes.
In March 2016 we saw a superflare: Proxima briefly became nearly a factor of 100 brighter, reaching a brightness just visible to the naked eye from dark sites.
Another point for anyone considering whether we should send a space-probe there...
The current fastest man-man object is the Helios 2 space-probe, reaching something like 25 000 kilometres per hour. Proxima Centauri is 1.3020 parsecs away from Earth.
So, just diving one by the other, we'd looking at something like 18 000 years as a rough order of magnitude for sending something from Earth to Proxima Centauri.
You'd be much better off waiting, well, even a thousand years for technology to improve rather than sending something now.
Note: this is a very dodgy line of reasoning. The Helios probe got a massive speed boost from a close encounter with the sun. But even if the speed is wrong by a factor of ten, we're still looking at somewhere between a thousand and a hundred-thousand years.
A probe based on nuclear pulse propulsion could do it in around 50 years, with today's technology. It's not that we can't do it fast (within one average human lifespan), it's that the project would be very expensive and something like Nasa has a relatively tight budget.
I mean we, as humanity, have to have an eccentric billionaire start a Martian fire (SpaceX Starship) under our lazy asses to even start to think about getting to Mars in a reasonable timeframe and in reasonable numbers (to start a colony). We are not funding making our species multiplanetary for the last few decades because we were too lazy, how can anyone expect us sending anything to the closest star (other than the sun)... You can't.
Going to Mars seems pretty useless to me at this time. It’s a super hostile environment and we don’t have the technology yet to have a self sustaining base there. Give it a few decades and progress in robotics will make a Mars base much easier. There is plenty of work to be done on Earth. We have to solve clean energy production and in general reduce pollution. These are massive technological challenges that deserve massive funding.
Maybe an unpopular opinion, but Musk is just plain wrong when he thinks there is any urgency to Mars exploration (or it's just vicarious arguments because rockets are cool).
Basically, the tech you need to make a Mars colony truly self sufficient is something like a compact fusion powerplant.
Before we have that, no point in worrying about using Mars as a "backup plan", because if Earth was screwed, Mars would have a couple of years to live at most.
And obviously it would be vastly better for humanity if Musk spent money on zero-emission large scale energy production, than on rockets.
Why is it weird that a private corporation is doing space exploration & technology? Most of the biggest sailing expeditions were undertaken by private individuals and companies (although often under the funding of a royal family). Locomotives and airplanes were also created and perfected by private individuals / companies.
The 1950s-2000s NASA model for space exploration was unusual in its centralized approach.
We do in fact have another billionaire, Yuri Millner, to push humanity towards the goal of reaching other stars with his "Breakthrough Starshot" initiative.
Yes, Parker breaks the 40+ year old record set by Helios. OP is using stale data.
The fastest crewed spaceship was Apollo 10 at 39,705km/h before reentry. After orbiting the moon they had lots of fuel left over so they just floored the engine on the way home. Not just falling back towards the planet but actively flying towards the ground for longer than any other Apollo mission.
This record can be broken with current technology, we just have to go back to the moon.
I find it enjoyable to think about the technologies that might just be in the cards further into the future.
If we ever figure out light-weight fusion drives, we could build light hugger space ships that accelerate to a decent fraction of the speed of light. At 1g acceleration it takes about one year to get to 0.9c, which would make the Proxima system accessible with a travel time of about 6 years. Or 8 years at 0.5g. Or 9 years if we 'only' get to 0.5c.
The same goes for laser-driven light sails if we just wanted to send a probe, although deceleration would be an issue. (There is currently an aspirational research project for this called Breakthrough Starshot)
The exciting thing about these technologies is that they don't require new physics in principle, just a lot of engineering. Of course, uploaded minds would probably always be better suited for space travel, but it's neat to know that even biological people could in theory make these trips.
IIRC, the limit with humans on-board is like .3c due to the red/blue shifting of the background radiation of the universe. At about .3c, it turns into microwaves/radar/x-rays and such, becoming quite bad for humans. There’s so much background radiation, there may be no way to adequately shield from it and/or travel may be limited only in the direction of less background radiation.
Maybe someone has a link to more information, that’s just what I remember from years ago.
> If we ever figure out light-weight fusion drives, we could build light hugger space ships that accelerate to a decent fraction of the speed of light. At 1g acceleration it takes about one year to get to 0.9c, which would make the Proxima system accessible with a travel time of about 6 years. Or 8 years at 0.5g. Or 9 years if we 'only' get to 0.5c.
No, we couldn't. The energy density of fusion isn't anywhere near close enough to make a lighthugger, you'd need insane mass ratios[1] and ramjets are probably unfeasible (as in, even-if-your-a-Kardeshev-II-civilization-unfeasible[2]).
This is exciting stuff indeed. Imagine a year-4,000 spaceship reaching Centauri before another spaceship dispatched 1,000 years before it?
For the cynical or pessimists: I'm not optimistic about humanity reaching year-4,000, I'm just possibilistic about it (as in the philosophical meaning [1]).
Thank you for your optimism, now let me balance that out a little.
Propulsion maybe the easier part of engineering. Afaik we are nowhere near to life support and environment control that could be considered stable for a time period of maybe 10 years or more.
The biggest biological advantage, adaptation is meaningless for large organism on such a timescale and maybe dangerous on a microbial level.
Whenever I read discussions about space travel and trying to approach the speed of light for human travel I have the feeling there's a lot of tunnel vision (excuse the pun). It always seems to assume travelling along a linear path through space.
In my mind, using the admittedly poor analogy of space-time as a membrane that is distorted by gravity, my thinking is we'll find some way to effectively bring two points in space-time adjacent to each other and 'step' between them. Wormholes, Warp, or whatever you want to call it.
Think of a flexible membrane 10 meters long and we are going to travel from one end to the other. We can either travel in a linear fashion over its surface for 10 meters or we can wrap the membrane so both ends are next to each other and travel 0.01m across the gap between them.
Yes, I know there are all sorts of obstacles and arguments against this simplistic visualisation but this is how I've always imagined the physics of any science fiction faster-than-light travel - worm-holes, warp drives, etc.
If you want an actual, real, possible-right-now analogy, think of our current situation where the fastest way to travel from London, UK to Sydney, Australia (1/2 way around the world) is through the atmosphere in an aeroplane travelling ~17000 kilometers and taking at best 19.5 hours.
SpaceX (Musk) Virgin Galactic (Branson), other companies [0], and space agencies [1] have talked about, and are actively working toward, stepping outside the atmosphere into space to reduce the time element to around an hour.
So just like with supposedly faster-than-light travel, by 'stepping outside' the linear/conventional thinking/physics we reduce the time of travel element dramatically. The start and end points don't move but the distance travelled by the transport vehicle itself changes in order to enable the reduction in time.
this is why we don't see any signs of life out there. there really isn't any point in trying to venture beyond your home. universe is just too big even at the speed of light when you start venturing beyond your local group.
That is assuming that the speed of light truly is the end-all-be-all. It is quite possible there are other ways of travel that we’ve yet to discover. I have no idea what they’d be but humans have really only been doing this space / astronomy thing for a few hundred years at most.
We have barely scratched the surface of what is truly going on out there. It would be incredibly “human centric” to think our current understanding of the universe is “it”, in my opinion.
If you get really close to the speed of light (which is not really practical from a materials engineering standpoint) your time of transit is significantly shorter.
Once these (extremely hard) engineering problems are solved, a trip to the next star can be a week-long affair from your point of view, but your friends back on Earth won't see you for about a decade.
I guess the assumption is their life span is similar to that on our planet. If the life span measured in thousand of years, it will be a different story.
with how small you can make a probe today there isn’t any barrier to making something 100x faster or more. throw up a small camera and transmitter with a huge ion thruster thank on top of a saturn v sized rocket of your choice and you will get going very fast
The other problem with sending a space probe is that the devs will have to actually deliver the Proxima Centauri mod on time and on budget, which, let's be honest, probably isn't going to happen for another few years. Think about it, you have to skin the whole planet, make sure the AI isn't weird, make sure it doesn't conflict with the existing storyline or retcon all the earth NPC memories. It's a HUGE project. Right now we just literally return a light curve from the function when someone looks at it.
And even if we could get the adversial networks to model all this garbage, etc it needs to line up with the plan of the rest of the Universe from the franchise and the managers can't even decide whether the photon is going to be a wave or a particle. Jeez. Vaporware like HL2.
Of course that doesn't necessarily preclude a nearby higher level Kardashev Civilization becoming interested in all the noise we're making and heading over.
As we put up systems beyond Webb, it may be possible to observe a hypothetical inbound craft / fleet some years off, which would have interesting effects on our current human society, once it became generally known..
My suspicion is that the social media generation would react a lot worse than the radio generation did to the 1938 broadcast of H. G. Wells' War of the Worlds:
All of the descriptions I've seen were "viable" in the sense of "we could hypothetically accomplish this in a few decades a for around $100 trillion". At least that was the estimate for Project Daedalus, which designed a nuclear pulse propulsion probe to do a 50-year flyby of Barnard's Star. Fun to think about but it's going to be a while before even the largest governments can afford to fund a project that most of its creators will never see completed.
Even if you get a very high specific impulse, you still need to pack a lot of reaction mass. You'll also need a lot of supplies (or a biome) because even if you get to 0.1 c, it's still 40 years to get there.
It orbits the star every 5 days; it's a quarter of the earth's mass. It's also a tenth the distance from its star that Mercury is from the Sun. It's earth-like only in that its temperature is consistent with there being liquid water.
IIRC from other publications, they expect something between .26 and 1.1 Earth masses, so it may well be a reasonably big rock. Surface gravity, composition and atmosphere are also big factors in being Earth like - Titan has a lower gravity, but a much thicker atmosphere than Earth.
Astronomers go to great lengths to name their stuff for good abbreviations. ESPRESSO is actually “Echelle Spectrograph for Rocky Exoplanet- and Stable Spectroscopic Observations”
That is pretty exciting. Some say life would be difficult because Proxima Centauri is a flare star, which has violent outbursts of radiation. Not more than the sun though, even if it is so much smaller. But the habitable zone would also be much closer to the star.
It has a significant life span of about 4 trillion years and could easily outlive the present universe several times.
Sweet let's crank up the generation ships. Of course picking a suitably inspiring name should be the first priority. Unity? Terra Nova? Gaia?
On a more serious note is this a good candidate for JWST, would it be able to infer chemical composition from the planet's spectrum or something?
Awesome though we went from (in my lifetime) learning at school that other planets have never been observed, to finding them sprinkled around basically every star just like our own. I feel like it won't be long before we detect the first potential chemical markers of alien life, if it's out there. Keep doing your thing space science folk!
Before anyone gets too excited I'd just point out that all they have found is a rocky world within Proxima's habitable zone. That doesn't mean that world necessarily has a breathable atmosphere, water, sufficient gravity, a geomagnetic field, rotation sufficient to distribute heat equitably across its surface (as opposed to it being tidally locked facing Proxima), or any of a dozen other features requisite to support life.
Oh... and did I mention that Proxima is a known flare star?
Wake me up when they find a terrestrial world in the habitable zone of Alpha Centauri instead.
Yeah I was being a little tongue in cheek with the excitement, still it's pretty crazy we're actually seeing and cataloguing exoplanets now which was still in the realms of science fiction less than half a century ago.
Anyway if Stellaris has taught me anything it's that the flares will add additional energy credits to the system... what's not to like?
Generation ships will take some time to get ready. We can railgun tardigrades and aphanizomenon flos-aquae there this year and let evolution do the rest. By the time we (or, more likely, the descendants of cockroaches) get there, it will be teeming with DNA-based life.
Readit News
From the paper (Introduction and Conclusions, respectively) [1]:
The habitability conditions of Proxima b, which orbits within the HZ of the star, have been extensively studied (e.g. Barnes et al. 2017; Ribas et al. 2016; Turbet et al. 2016; Meadows & Barnes 2018). On the other hand, the candidate Proxima d orbits much closer to the star and outside the HZ range.
In particular, the discovery of an Earth-mass planet orbiting Proxima Centauri (Anglada-Escudé et al. 2016), our closest stellar neighbour, was one of the most significant results in the field, in part because the planet orbits inside the habitable zone (HZ) of the star (e.g. Kopparapu et al. 2013).
So, Proxima d is too close to the star to be inside the HZ; it's within the HZ in the sense that the HZ is further out from the star.
The author of the Nature commentary, which claims that "it could have oceans of liquid water that can potentially harbour life", apparently didn't read the paper.
[1] https://www.eso.org/public/archives/releases/sciencepapers/e...
https://www.star-facts.com/proxima-centauri/
Also fascinating, a relative distance vs time graph of close stars. It turns out we'll have closer distances for 6 in the next 10,000 - 50,000 years.
https://www.star-facts.com/wp-content/uploads/2020/08/Neares...
Somehow I feel like Elon Musk has a print out of that graph on his office wall.
They laughed at me when I bought investment property on Proxima Centauri b, but who'll be the one laughing in 10.000000001 billion years?
"With the small stellar radius, Proxima d ... equilibrium temperature may reach 360K,"
NB: Earth's is 255K. Venus 260K, Mars 215K. So this doesn't tell the whole story, but is probably quite hot.
So it has a hot side, a cold side, and an intermediate ring at the terminator.
Probably not very comfortable.
I dislike the term "Earth-like" in these publications because it conjures images of a strange alien world able to support (human) life. Even assuming there were life capable of withstanding the constant flares from the host star, I suspect it would have to look very different in color and likely composition to the plant life here due to needing to capture a different part of the spectrum.
Visible light being right in the middle is the trick which gives us photosynthesis, and sight, because in both cases a photon can be captured by a photosensitive bond. It's harder to come up with plausible photosensitive bonds for IR light, and most anything is photosensitive once you get far enough into UV.
Fun fact: Go outside on a clear night, and you can see 5-10,000 stars. There are 8 times that many red dwarfs in your field of view, and none of them are visible to the naked eye. But in 2016 Proxima was for a few minutes.
In March 2016 we saw a superflare: Proxima briefly became nearly a factor of 100 brighter, reaching a brightness just visible to the naked eye from dark sites.
The current fastest man-man object is the Helios 2 space-probe, reaching something like 25 000 kilometres per hour. Proxima Centauri is 1.3020 parsecs away from Earth.
So, just diving one by the other, we'd looking at something like 18 000 years as a rough order of magnitude for sending something from Earth to Proxima Centauri.
You'd be much better off waiting, well, even a thousand years for technology to improve rather than sending something now.
Note: this is a very dodgy line of reasoning. The Helios probe got a massive speed boost from a close encounter with the sun. But even if the speed is wrong by a factor of ten, we're still looking at somewhere between a thousand and a hundred-thousand years.
I mean we, as humanity, have to have an eccentric billionaire start a Martian fire (SpaceX Starship) under our lazy asses to even start to think about getting to Mars in a reasonable timeframe and in reasonable numbers (to start a colony). We are not funding making our species multiplanetary for the last few decades because we were too lazy, how can anyone expect us sending anything to the closest star (other than the sun)... You can't.
Basically, the tech you need to make a Mars colony truly self sufficient is something like a compact fusion powerplant.
Before we have that, no point in worrying about using Mars as a "backup plan", because if Earth was screwed, Mars would have a couple of years to live at most.
And obviously it would be vastly better for humanity if Musk spent money on zero-emission large scale energy production, than on rockets.
The 1950s-2000s NASA model for space exploration was unusual in its centralized approach.
"A probe based on nuclear pulse propulsion could do it in around 50 years, with today's technology."
I was always under the impression that these vast distances were basically entire unreachable in several human lifetimes.
So we have the ability today to move 50K tons of parts into orbit, and come up with vast quantities of helium-3?
[1] https://en.wikipedia.org/wiki/Parker_Solar_Probe
The fastest crewed spaceship was Apollo 10 at 39,705km/h before reentry. After orbiting the moon they had lots of fuel left over so they just floored the engine on the way home. Not just falling back towards the planet but actively flying towards the ground for longer than any other Apollo mission.
This record can be broken with current technology, we just have to go back to the moon.
If we ever figure out light-weight fusion drives, we could build light hugger space ships that accelerate to a decent fraction of the speed of light. At 1g acceleration it takes about one year to get to 0.9c, which would make the Proxima system accessible with a travel time of about 6 years. Or 8 years at 0.5g. Or 9 years if we 'only' get to 0.5c.
The same goes for laser-driven light sails if we just wanted to send a probe, although deceleration would be an issue. (There is currently an aspirational research project for this called Breakthrough Starshot)
The exciting thing about these technologies is that they don't require new physics in principle, just a lot of engineering. Of course, uploaded minds would probably always be better suited for space travel, but it's neat to know that even biological people could in theory make these trips.
Maybe someone has a link to more information, that’s just what I remember from years ago.
No, we couldn't. The energy density of fusion isn't anywhere near close enough to make a lighthugger, you'd need insane mass ratios[1] and ramjets are probably unfeasible (as in, even-if-your-a-Kardeshev-II-civilization-unfeasible[2]).
[1]: http://www.projectrho.com/public_html/rocket/slowerlight3.ph...
[2]: https://www.sciencedirect.com/science/article/pii/S009457652...
For the cynical or pessimists: I'm not optimistic about humanity reaching year-4,000, I'm just possibilistic about it (as in the philosophical meaning [1]).
[1] https://en.wikipedia.org/wiki/Actualism#:~:text=possibilism,...
Propulsion maybe the easier part of engineering. Afaik we are nowhere near to life support and environment control that could be considered stable for a time period of maybe 10 years or more.
The biggest biological advantage, adaptation is meaningless for large organism on such a timescale and maybe dangerous on a microbial level.
In my mind, using the admittedly poor analogy of space-time as a membrane that is distorted by gravity, my thinking is we'll find some way to effectively bring two points in space-time adjacent to each other and 'step' between them. Wormholes, Warp, or whatever you want to call it.
Think of a flexible membrane 10 meters long and we are going to travel from one end to the other. We can either travel in a linear fashion over its surface for 10 meters or we can wrap the membrane so both ends are next to each other and travel 0.01m across the gap between them.
Yes, I know there are all sorts of obstacles and arguments against this simplistic visualisation but this is how I've always imagined the physics of any science fiction faster-than-light travel - worm-holes, warp drives, etc.
If you want an actual, real, possible-right-now analogy, think of our current situation where the fastest way to travel from London, UK to Sydney, Australia (1/2 way around the world) is through the atmosphere in an aeroplane travelling ~17000 kilometers and taking at best 19.5 hours.
SpaceX (Musk) Virgin Galactic (Branson), other companies [0], and space agencies [1] have talked about, and are actively working toward, stepping outside the atmosphere into space to reduce the time element to around an hour.
So just like with supposedly faster-than-light travel, by 'stepping outside' the linear/conventional thinking/physics we reduce the time of travel element dramatically. The start and end points don't move but the distance travelled by the transport vehicle itself changes in order to enable the reduction in time.
[0] https://www.telegraph.co.uk/travel/news/new-flights-space-lo...
[1] https://edition.cnn.com/travel/article/hypersonic-flight-air...
this is why we don't see any signs of life out there. there really isn't any point in trying to venture beyond your home. universe is just too big even at the speed of light when you start venturing beyond your local group.
We have barely scratched the surface of what is truly going on out there. It would be incredibly “human centric” to think our current understanding of the universe is “it”, in my opinion.
If you get really close to the speed of light (which is not really practical from a materials engineering standpoint) your time of transit is significantly shorter.
Once these (extremely hard) engineering problems are solved, a trip to the next star can be a week-long affair from your point of view, but your friends back on Earth won't see you for about a decade.
Deleted Comment
And even if we could get the adversial networks to model all this garbage, etc it needs to line up with the plan of the rest of the Universe from the franchise and the managers can't even decide whether the photon is going to be a wave or a particle. Jeez. Vaporware like HL2.
We should and do send probes anywhere that's practical. The question is more like when it will be practical to build star probes.
The current fastest man-man object is the...
The current fastest man-made object wasn't intended to reach the stars.
On the other hand, there are many challenges that make more sense to undertake as previous steps to develop the needed technology.
Deleted Comment
252 792 km/h
https://news.ycombinator.com/item?id=29638529
Of course that doesn't necessarily preclude a nearby higher level Kardashev Civilization becoming interested in all the noise we're making and heading over.
As we put up systems beyond Webb, it may be possible to observe a hypothetical inbound craft / fleet some years off, which would have interesting effects on our current human society, once it became generally known..
My suspicion is that the social media generation would react a lot worse than the radio generation did to the 1938 broadcast of H. G. Wells' War of the Worlds:
https://www.space.com/40435-finding-aliens-humanity-reaction...
It orbits the star every 5 days; it's a quarter of the earth's mass. It's also a tenth the distance from its star that Mercury is from the Sun. It's earth-like only in that its temperature is consistent with there being liquid water.
So even if the thing's tidelocked, and has no atmosphere because stellar flare-ups, it still counts as earth-like. TIL.
And suddenly i am imagining lots of very smart people drinking lots of caffeine.
"To find the wobble.."
this is not helping :)
"ESPRESSO is kept in a special room at the observatory, inside a tank "
oh come on ..
It has a significant life span of about 4 trillion years and could easily outlive the present universe several times.
https://en.wikipedia.org/wiki/BLC1
On a more serious note is this a good candidate for JWST, would it be able to infer chemical composition from the planet's spectrum or something?
Awesome though we went from (in my lifetime) learning at school that other planets have never been observed, to finding them sprinkled around basically every star just like our own. I feel like it won't be long before we detect the first potential chemical markers of alien life, if it's out there. Keep doing your thing space science folk!
Oh... and did I mention that Proxima is a known flare star?
Wake me up when they find a terrestrial world in the habitable zone of Alpha Centauri instead.
Anyway if Stellaris has taught me anything it's that the flares will add additional energy credits to the system... what's not to like?
Titanic. Moribund. Lethe. Purgatory I-X. etc.
It’ll be Spacey McSpaceface if we put it to a vote.