Life on planet Gliese?

[PiTiFUL]

And then it goes onto how they need to do more research to be able to better refine their models.

Funding got axed.

... Extremophiles are only called extremophiles because the conditions are unusual on Earth. In unusual conditions, you're not going to have a lot of chances to develop, compared to usual conditions by definition.

Extremophiles are extremophiles because they survive outside of the optimum oxygen cycle of life. Titan is a prime example of an extremophile enviroment, it has weather, liquid on its surface, rain even, its the closest thing to earth in our solar system with the possibility of a truly alien life, evolved outside of the optimum oxygen environment and at best will produce microbes... wheres the link I asked for? There isnt one because there isnt a biologist who thinks a complex animal like life form can develope without oxygen.

And yet you completely ignored what I just said. Power consumption is not static. As in, we generate more power as time goes on. As in, those values relatively speaking will become smaller and smaller as time goes on.

I'm not arguing that the energy cost is going to decrease, but the percentage of energy relative to what we produce in a period of time is going to decrease.

In the first sentence you claim these values will become smaller and you follow up and say the energy cost isnt going to change!?! Make up your mind. I've stated nothing about how we will end up generating that kind of power, thats an entirely different set of problems, all I'm stating is the power required.

EDIT; ok I think I understand what your getting at, you are talking efficiency, correct? so what your saying is that as we increase efficiency we increase energy output? Problem is still power output, no matter how efficiently we can generate power, you are still not generating enough power even at 100% efficiency. On earth this isnt such a big deal because we just build more power plants, as many as we need, with a spaceship that is not possible. A correct analogy would be, can we supply the entire power consumption of the USA with one single power plant, no, and even that fantasy power source would still take 431 years to accelerate my ship to 1\10th the speed of light.

PS an atomic bomb is E=MC2 uncontrolled, in its purest form, we will not ever be able to generate power faster then the uncontrolled mass to energy conversion of a nuclear bomb. Once we apply control to the mass to energy conversion we slow it down, no matter how efficient it is, aka a nuclear reactor vs a nuclear bomb. So lets imagine a major scientific breakthru, we can create and utilize (as thrust) an atomic bombs total energy output in say one minute, thats far beyond even the theoretical fusion reactor. You can now accelerate my ship to 1\10th the speed of light in 1470 years.

And yet, the energy output of the sun in one millisecond is greater than that. And in terms of fuel it would be about 500 tons of antimatter, which could be easily carried by a 100000 ton ship (And you could probably build a spaceship much lighter than an aircraft carrier).

The energy output of an uncontrolled fusion reactor with a 4.4 million km circumference and a mass of 1.9891 x10 to 30 power kg is not relevant, read up on the energy used by plant life alone in one day, its mind boggling. Your antimatter calculation is off, antimatter could generate the power required with 10714 pounds or 5MT, thats using 1 pound of antimatter = 20 megatons as a base.

Creating antimatter requires a massive amounts of energy itself, here Bluemofia can your "Power consumption is not static." argument be applied. I heard creating one teaspoon of antimatter would bankrupt the USA... this was before the US went bankrupt

Actually I have grossly underestimated the mass of a generation ship. How many people do you need to have a viable genetic pool? then add some more as a safety factor multiply by 4 because they are going to breed during the trip and you can expect at least 4 generations to be alive at any point. So lets say 200 people to maintain a viable gene pool x 4, you need living quarters for 800 people plus all other nessesitys, hospital, school, recreation, mess halls, machine shops, storage ect, you need a greenhouse large enough to supply food and oxygen to 800 people, you need water to supply 800 people and the greenhouse for thousands of years, you need power source, engines, fuel... you need ships to land on the planet once you get there, equipment and supplies to get the colony going once you arrive, for safety you need double or more of everything you have for ship systems, because theres no home depots in intersteller space, and youll probably need a way to manufacture stuff from scratch, raw materials, forges mini factorys, in the end youre probably looking at millions of tons and just changed the power requirements by a factor of ten or more.

 

[uppi]

The energy output of an uncontrolled fusion reactor with a 4.4 million km circumference and a mass of 1.9891 x10 to 30 power kg is not relevant, read up on the energy used by plant life alone in one day, its mind boggling.

It is relevant, as it puts some upper limit on the amount of power that we could theoretically collect. Of course you would need huge solid angle coverage, but you could wait longer than a millisecond.

Your antimatter calculation is off, antimatter could generate the power required with 10714 pounds or 5MT, thats using 1 pound of antimatter = 20 megatons as a base.

No, it's not, assuming your figure of 12500 PWh is correct. Pro tip: Stick to SI units, makes the whole thing easier.

Creating antimatter requires a massive amounts of energy itself, here Bluemofia can your "Power consumption is not static." argument be applied. I heard creating one teaspoon of antimatter would bankrupt the USA... this was before the US went bankrupt

Anything involving antimatter is obviously only viable if we find some way to produce it more efficiently. The current antimatter production method is horribly inefficient, and there is no fundamental limit why it cannot be more efficient.

Actually I have grossly underestimated the mass of a generation ship. How many people do you need to have a viable genetic pool? then add some more as a safety factor multiply by 4 because they are going to breed during the trip and you can expect at least 4 generations to be alive at any point. So lets say 200 people to maintain a viable gene pool x 4, you need living quarters for 800 people plus all other nessesitys, hospital, school, recreation, mess halls, machine shops, storage ect, you need a greenhouse large enough to supply food and oxygen to 800 people, you need water to supply 800 people and the greenhouse for thousands of years, you need power source, engines, fuel... you need ships to land on the planet once you get there, equipment and supplies to get the colony going once you arrive, for safety you need double or more of everything you have for ship systems, because theres no home depots in intersteller space, and youll probably need a way to manufacture stuff from scratch, raw materials, forges mini factorys, in the end youre probably looking at millions of tons and just changed the power requirements by a factor of ten or more.

But you're assuming 50 years old technology. Building a spaceship from steel would be incredibly stupid. You would really have to optimize it for weight. If we could build huge carbon nanostructures that factor of 10 could be easily compensated by material science alone.

But its quite useless trying to make engineering estimates with current technology as we're not quite there yet. And to make engineering estimates with future technology is just wild guessing. But for your design the theoretical fuel/weight ratio is good enough that given enough technological advance it is just a matter of how much energy you sink in it.

 

[Perfection]

How many people do you need to have a viable genetic pool?

Just one (probably want a couple more in case she kicks it)

 

[PiTiFUL]

No, it's not, assuming your figure of 12500 PWh is correct. Pro tip: Stick to SI units, makes the whole thing easier.

Heh took me a bit to figure out what the heck I was looking at, then realized you plugged the information into E=MC2, so assuming 100% mass to energy conversion you get 500 metric ton, cool. The information I had then was bollocks and was out by a factor of 100. I got 12500 PWh based on this information... Accelerating one ton to one-tenth of the speed of light requires at least 125 billion kWh, and I assume this is at 100% efficiency.

Anything involving antimatter is obviously only viable if we find some way to produce it more efficiently. The current antimatter production method is horribly inefficient, and there is no fundamental limit why it cannot be more efficient.

No argument there, but just on the subject of getting a generation ship to a habitable star its not relevant, we just assume we have it. Of course in practice it is a big deal because we arent leaving until we do have it, assuming its even possible. Also theres the problem of not just creating it, but containing it, heh imagine the containment structure and power needed to keep 500t of antimatter away from matter... and would we even want that much antimatter on our planet, if something went wrong, Praxis seems to me we would have to be able to create it as we need it in the ship itself, so now youll need to add an antimatter factory to the ship too, with its power consumption, mass and whatever raw materials it needs.

But you're assuming 50 years old technology. Building a spaceship from steel would be incredibly stupid. You would really have to optimize it for weight. If we could build huge carbon nanostructures that factor of 10 could be easily compensated by material science alone.

Yup, scientific advancement in material is definatly one way we could help improve the possibility of star travel. But, its still going to have mass, and if we have to keep humans alive and safe and in sufficient quantity for a viable gene pool, a lot of mass, and thats the killer. The more you consider it, the more problems crop up, the more unlikely such an endeavor seems possible. Sure science can solve some issues but a lot of them are fundamental physical laws of nature, distance and time.

 

[uppi]

No argument there, but just on the subject of getting a generation ship to a habitable star its not relevant, we just assume we have it. Of course in practice it is a big deal because we arent leaving until we do have it, assuming its even possible. Also theres the problem of not just creating it, but containing it, heh imagine the containment structure and power needed to keep 500t of antimatter away from matter... and would we even want that much antimatter on our planet, if something went wrong, Praxis seems to me we would have to be able to create it as we need it in the ship itself, so now youll need to add an antimatter factory to the ship too, with its power consumption, mass and whatever raw materials it needs.

Making antimatter on the ship itself defeats its purpose, because we would need energy to do this and there is no energy source in interstellar space, so we would need fuel for that and that's why we wanted antimatter in the first place.

I think antimatter would best be produced in space, because space itself is already a good prepumping stage for the extreme high vacuum needed to store antimatter. I would imagine a lot of small producing facilities in space powered by solar radiation.

Trapping antimatter could in principle be done without any energy consumption in, say, a magnetic trap, as long as there is no heating of the antimatter. If there is heating, cooling is needed, which will require energy. I don't think it could be done at the moment (although I do wonder how well a giant magneto-optical trap would work in space...should actually be pretty good), but we're working on that.

Yup, scientific advancement in material is definatly one way we could help improve the possibility of star travel. But, its still going to have mass, and if we have to keep humans alive and safe and in sufficient quantity for a viable gene pool, a lot of mass, and thats the killer. The more you consider it, the more problems crop up, the more unlikely such an endeavor seems possible. Sure science can solve some issues but a lot of them are fundamental physical laws of nature, distance and time.

But these do not make it impossible, just very difficult. And you never know what scientist will come up with in the next 100 years. If you told a scientist from 100 years ago, what we are capable of at the moment he'd say you're crazy.

But I admit, there is the possibility that we will never get to another star, either because we find no way to do it, or because it would be so resource consuming that we're never going to do it.

 

[Perfection]

and if we have to keep humans alive and safe and in sufficient quantity for a viable gene pool, a lot of mass, and thats the killer

Not really, I already know a vehicle that can transport enough humans to form a viable gene pool. It's called a Geo Metro

 

[Bluemofia]

Extremophiles are extremophiles because they survive outside of the optimum oxygen cycle of life. Titan is a prime example of an extremophile enviroment, it has weather, liquid on its surface, rain even, its the closest thing to earth in our solar system with the possibility of a truly alien life, evolved outside of the optimum oxygen environment and at best will produce microbes... wheres the link I asked for? There isnt one because there isnt a biologist who thinks a complex animal like life form can develope without oxygen.

No, definition of extremophile is something that thrives, or even requires the extremes. This is not limited to oxygen, but includes high saline, high/low pH, high/low temperatures, etc.

You don't understand that absence of proof is not proof of absence, citing lack of complex organisms on Earth with alternative biochemistries to oxygen as proof of lack of complex organisms without alternative biochemistries. You haven't found a rigorous article saying it is impossible explicitly. The one article you dug up was one that reverse engineered current molecules to find that those molecules cannot be formed without oxygen, and thus blanket stating that life as we know it cannot have evolved without oxygen.

http://www.xenology.info/Xeno/8.0.htm

This is, however, an incredibly chauvinistic argument. The only rigorous conclusion that can be drawn from the lack of exotic biochemistries on Earth is that contemporary conditions do not favor those other systems. Since a rich diversity of habitats is possible in the Galaxy, peculiar life chemistries cannot be categorically ruled out.

http://www.xenology.info/Papers/Xenobiology.htm

For instance, there used to be the notion that oxygen (O2) is absolutely required for higher life. Many xenobiologists today categorically reject this proposition. Oxygen was largely absent during the first few billion years of evolution on Earth, and many organisms today still do not need this element to survive. Experiments have shown that plants grow better in air containing only about half the normal amount of oxygen, and the presence of O2 in the nuclear regions of contemporary living cells is usually fatal. Human scuba divers are poisoned by the gas at more than a few atmospheres pressure. Large creatures on any world may need some strong oxidant to power their bodies, but it may not have to be oxygen.

Biochemistries which utilize sulfur instead of oxygen are comparatively common on earth of the hypothetical biochemistries for complex living organisms. Another alternative suggested is chlorine, but that in itself runs into problems with the abundance problem, and therefore unlikely to exist in that regard (but not impossible).

EDIT; ok I think I understand what your getting at, you are talking efficiency, correct? so what your saying is that as we increase efficiency we increase energy output? Problem is still power output, no matter how efficiently we can generate power, you are still not generating enough power even at 100% efficiency. On earth this isnt such a big deal because we just build more power plants, as many as we need, with a spaceship that is not possible. A correct analogy would be, can we supply the entire power consumption of the USA with one single power plant, no, and even that fantasy power source would still take 431 years to accelerate my ship to 1\10th the speed of light.

Are you deliberately misinterpreting my statements? (NOT efficiency. NOT physical energy requirements. RAW power generation and consumption. The US power consumption was 9TWh in 1900. Now it is obviously far higher.) You say we require 12500 PWh. Then you state that the amount is 431 years worth of US energy, and therefore impossible.

The power consumption is not static. The US (and world) power consumption is projected to grow exponentially with time. It HAS grown exponentially with time. Eventually with the advancement of technology, 12500 PWh will be reduced to a smaller amount of time, say 400 years of energy, or 200 years, or even possibly 30 days worth long into the future. Power consumption is not static, and will grow over time. Eventually the 12500 PWh will become minuscule if trends continue, and that is when it will become feasible.

The 12500 PWh to accelerate the ship becomes trivial as time goes on and power generation technology improves.

PS an atomic bomb is E=MC2 uncontrolled, in its purest form, we will not ever be able to generate power faster then the uncontrolled mass to energy conversion of a nuclear bomb. Once we apply control to the mass to energy conversion we slow it down, no matter how efficient it is, aka a nuclear reactor vs a nuclear bomb. So lets imagine a major scientific breakthru, we can create and utilize (as thrust) an atomic bombs total energy output in say one minute, thats far beyond even the theoretical fusion reactor. You can now accelerate my ship to 1\10th the speed of light in 1470 years.

Problem with your statement is that uncontrolled explosions are usually one of the most inefficient methods of producing energy (lots wasted in useless things like vibrating atoms, making buildings blow up, etc.). Generating incredible amounts of energy fast is a rather inefficient way of doing things, as energy is wasted. Ion engines are incredibly energy efficient, yet they are also incredibly weak in power.

You also don't want all of that energy all at once, causing you to liquify under massive acceleration forces from all the energy released at once. The problem comes to controlling the reaction to run at an adequate rate. And a nice acceleration rate is at 1 g. Using safe accelerations, you can accomplish it in 35 days. How much energy you can generate to produce this becomes an engineering issue, rather than a physics issue.

 

[PiTiFUL]

http://www.xenology.info/Xeno/8.0.htm

So your backing up your view with a 30 year old book, which covers everything from alien sex to cosmic warfare, written by someone who has no education in biology and who frequently used SF authors as references? The picture of NCC-1701 on the cover is very apt because its mostly fiction. Heres some quotes from the author himself...

"Xenology was current as of 1979, but the field has made 30 years of progress since then. The reader will find numerous omissions of facts and valuable references that have been published in the intervening years, and probably even a fair number of outright errors which were unknown at the time of writing."

"The book contains some pretty speculative material in a few places, including material from speculative fact and science fiction writers when appropriate. But generally the text tries to stick to concepts and arguments that are grounded in some kind of precedent either in biology, technology, or the social sciences and the arts."

riiiight... here if you got some time to burn is something from an actual biologist who doesnt use Ray Bradbury as a reference.

http://www.stanford.edu/group/astrobiology/cgi-bin/?page_id=307

Trapping antimatter could in principle be done without any energy consumption in, say, a magnetic trap, as long as there is no heating of the antimatter. If there is heating, cooling is needed, which will require energy. I don't think it could be done at the moment (although I do wonder how well a giant magneto-optical trap would work in space...should actually be pretty good), but we're working on that.

Wouldnt the lasers in the magneto-optical trap be introducing matter (photons) into the antimatter? Heh was reading up on anti-matter, we have a long long way to go in that field and its still up in the air if its ever going to be feasible.

 

[Perfection]

Why the hell do you think it needs to be 1/10th the speed of light anyways? Why can't it be say, 1/100th?

 

[J-man]

The planet may not exist after all! A swiss astronomer can't find it....

http://www.wired.com/wiredscience/2010/10/gliese581g-may-not-exist/

Seems like this planet counts as unconfirmed...

 

[El_Machinae]

They can't yet rule it out as a statistical anomaly.

This story is SOoooo cool. I'm almost on pins with each new update.

Why the hell do you think it needs to be 1/10th the speed of light anyways? Why can't it be say, 1/100th?

Because if you leave at 1/100th c, then I'm going to wait x number of years for the economic and technological progress to advance, and then buy a faster starship than yours, and then get to 'your' planet first!

 

[El_Machinae]

It's just a numbers game, at that point, right? You're right, there's no reason for 1/10th to be the optimum. In fact, I expect that the optimum will be 90+% of c. Once you're going ~90% of c, it will be much tough for someone to scoop you.

My main point is that I'm scooping Perfie's homesteading efforts.

 

[Haseri]

How many people do you need to have a viable genetic pool?

Not sure, but I've seen the number 150 bounded around somewhere. Of course,t he more the merrier.

I think arguing that something will never be possible is an act of futility. We could be heading for another technological revolution, where technology and society afterwards is radically changed in such ways that we cannot even begin to predict them, much like the industrial and digital revolutions.

 

[uppi]

Wouldnt the lasers in the magneto-optical trap be introducing matter (photons) into the antimatter? Heh was reading up on anti-matter, we have a long long way to go in that field and its still up in the air if its ever going to be feasible.

No, photons are not matter in that sense. Annihilation happens, when a particle meets its antiparticle, so to annihilate an antiproton you need a proton. Photons have no antiparticle (there are no antiphotons), so they can interact with matter and antimatter compounds. Otherwise spectroscopy of antimatter would not be possible.

Fun fact: The current textbook value for the mass of the proton is made up from four measurements and one of these measurements is actually the mass of the antiproton. There are currently groups trying to spectroscopically measure the mass of the antiproton more accurately than the mass of the proton is known.

Yes, the field is very young (there is only one experiment in the world that can produce slow antiprotons and this one has only been running for ten years) and there is still much to discover. We will see in time whether this is ever going to be feasible.

 

[GhostWriter16]

Earth is not the only planet in our solar systems "habitable" zone, both Venus and Mars are in that region and yet we do not find any life on those planets.

Really? How the heck would Venus POSSIBLY be habitable?

Even Mars, how?

Now we just have to bring them democracy

There are about a thousand problems with Democracy. Let's teach them a Constitutional Republic

 

[SomethingWitty]

Really? How the heck would Venus POSSIBLY be habitable?

Even Mars, how?

I think that's the point of his quotation marks. Mars and Venus are within (arguably) the "Goldilocks region" but are obviously uninhabitable.

 

[Perfection]

Not sure, but I've seen the number 150 bounded around somewhere. Of course,t he more the merrier.

Nope it's one.

 

[El_Machinae]

You should source that.

edit: it doesn't really matter, since embryos are rather light, and we can carry millions of genetically diverse embryos rather cheaply

 

[Perfection]

Source: My Brain

 

[classical_hero]

Astronomers no longer sure about Gliese 581g

Last month, astronomers announced the discovery of the first potentially habitable extrasolar planet. But this week at an International Astronomical Union meeting, doubts were raised about the existence of this exciting new planet said to be orbiting the star Gliese 581.

Called Gliese 581g, the planet was determined to be about three times the mass of Earth, meaning it was a rocky world, not a gas giant like Jupiter.

Rocky extrasolar planets have been found before, but the unique trait about this planet was that it orbited within the red dwarf stars habitable zone, that region of space where temperatures are sufficient for water to remain as a liquid on a planetary surface.

Discovery of planet Gliese 581g
Astrobiologists were thrilled at the news, since liquid water is considered necessary for the origin and evolution of life. In fact, NASA has made it a primary aim to follow the water in the search for life elsewhere in the galaxy.

The star Gliese 581 is about 20 light-years away from Earth, located in the constellation Libra. [ Tour the planets around Gliese 581]

"The fact that we were able to detect this planet so quickly and so nearby tells us that planets like this must be really common," said Steven Vogt in a statement announcing the discovery.

Vogt is one of the lead astronomers of the Lick-Carnegie Exoplanet Survey, and lead author on the paper published in the Astrophysical Journal (and posted online at the arxiv.org web site). The paper also announced the discovery of planet 'f,' a 7-Earth mass planet with a 433-day orbit around Gliese 581.

Planet 'g' was calculated to have an orbital period of only 37 days. Although an extremely close orbit by the standards of our own solar system, because Gliese 581 is not as luminous as our sun its habitable zone must be much closer in.

Because the planet orbits so close to its star, astronomers said it must be tidally locked, with the same side of the planet always facing the star. This would mean that the star-side of the planet would be much hotter than the perpetually dark side, but a more temperate region could exist in the border zone between the dark and light sides.

To find the planet, the Lick-Carnegie team looked at 122 radial velocity measurements from the HIRES instrument on the Keck I telescope at the W.M. Keck Observatory in Hawaii. They also used 119 measurements from the HARPS instrument on the La Silla telescope at the European Southern Observatory in Chile. The HIRES measurements were taken over a period of 11 years, while the HARPS measurements were made over four years.

But planet's existence not confirmed
Francesco Pepe, an astronomer who works on HARPS data at the Geneva Observatory, said at the IAU meeting this week that his team could not confirm the existence of Gliese 581g.

In e-mail correspondence with Astrobiology Magazine, Pepe said that they could not confirm the existence of planet 'f' either.

The Geneva team, led by Michel Mayor, announced in 2009 the discovery of planet e in the Gliese 581 solar system. At approximately 1.9 Earth masses, this e planet is the lowest mass extrasolar planet yet found, and has a 3.15-day orbital period around the star.

"Since Mayor's announcement in 2009 of the lowest-mass planet Gliese 581e, we have gathered about 60 additional data points with the HARPS instrument for a total of 180 data points spanning 6.5 years of observations, said Pepe. "From these data, we easily recover the four previously announced planets b, c, d, and e."

However, he said they do not see any evidence for planet 'g,' the fifth planet in the system as announced by Vogt and his team.

"The reason for that is that, despite the extreme accuracy of the instrument and the many data points, the signal amplitude of this potential fifth planet is very low and basically at the level of the measurement noise, said Pepe.

Hunting alien solar systems
The planets in the Gliese 581 system were discovered using spectroscopic radial velocity measurements. Planets tug on the star they orbit, causing it to shift in position (stars and planets actually orbit a common center of mass). [ 500th Alien Planet May be Found Soon]

By measuring the stars movement in the sky, astronomers can figure out what sort of planets are orbiting it. Multi-planet systems create a complicated signal, and astronomers must tease out the spectral lines to figure out what represents a planet, and what is just "noise" shifts in the star light not caused by an orbiting planet.

Astronomers have developed various ways to reduce such noise in their telescopic observations, but it still creates a level of uncertainty in detecting extrasolar planets.

The Geneva team plugged the HARPS data on Gliese 581 into computer models to check on the odds the signal was the result of noise, rather than evidence of the habitable planet g as claimed by the Lick-Carnegie team.

"Simulations on the real data have shown that the probability that such a signal is just produced 'by chance' out of the noise is not negligible, of the order of several percents," Pepe said. "Under these conditions we cannot confirm the presence of the announced planet Gliese 581g."

Pepe noted that while he did not speak at the IAU meeting about Gliese 581 f, the other potential planet in this system announced by the Lick-Carnegie team, the HARPS data calls that planet into question as well.

"We haven't made a detailed analysis yet, but at first glance no statistically significant signal [for planet f] is emerging from our data set," he said.

Gliese 581 is already one of the most intriguing solar systems known, with four planets confirmed orbiting the star. The addition of the potentially habitable planet 'g' would make the system the go-to place in the search for alien life, but more work needs to be done to either confirm or refute the planets existence.

"I would say the detection was less than comfortably secure, even in the original Vogt et al. paper the paper was carefully worded, as opposed to what was in some media reports," said Ray Jayawardhana, a University of Toronto astronomer who was not involved in either study. "Of course, it's not easy to definitively rule out something, but the HARPS evidence is at least raising some doubts."