Seeing the Closest Aliens Will Take Centuries

April 29, 2010 by Charles Q. Choi
This artist's conception shows a hypothetical twin Earth orbiting a Sun-like star. Credit: David A. Aguilar (CfA)

As telescopes become more advanced, we’ll be able to see more details about planets orbiting other stars - including indications that those planets have life. However, it would probably take many centuries before we could actually see the aliens.

Although our telescopes will likely become good enough to detect signs of life on exoplanets within the next 100 years, it would probably take many centuries before we could ever get a good look at the aliens.

"Unfortunately, we are perhaps as far away from seeing aliens with our own eyes as Epicurus was from seeing the first other worlds when, 23 centuries ago, he predicted the existence of these planets," said astrobiologist Jean Schneider at the Paris Observatory at Meudon. He and his colleagues discussed the difficulties of studying distant in the journal .

Schneider and his colleagues say that in the next 15 to 25 years, there will likely be two generations of space missions able to analyze exoplanets in greater detail. The first generation will feature 1.5-to-2.5-meter-wide coronagraphs to block out the direct light from a star to help search for giant planets and nearby super-Earths. The second generation will feature interferometers, coronagraphs and other equipment to better analyze the light reflected off these exoplanets. These missions could reveal what the planets might look like, and what they might have in their atmospheres or on their surfaces. At the same time, there will likely be coronagraphic cameras on extremely large ground-based telescopes.

After these projects, future missions could search for more potentially habitable planets either by peering at more distant stars more than 50 parsecs away or at rocky moons of seen in the habitable zones of nearby . The follow-up missions also could deeply investigate any exoplanets that display potential signs of life. Such missions will require much larger arrays in space — for instance, taking a 100-pixel image of a planet twice the width of Earth some 16.3 light years away would require the elements making up a space telescope array to be more than 43 miles apart.

Such pictures of exoplanets could make out details such as rings, clouds, oceans, continents, and perhaps even hints of forests or savannahs. Long-term monitoring could reveal seasonal shifts, volcanic events, and changes in cloud cover. One might even detect the presence of moons by shadows they project on the planets. More sensitive instruments could hunt for the wavelengths of infrared light associated with carbon dioxide, which could tell a lot about the atmosphere.

Beyond conventional signs of life as we know it, such as oxygen in atmospheres, another type of signal could be "technosignatures," features that cannot be explained simply by complex organic chemistry. Technosignatures could include laser light, chlorofluorocarbon gases, or even artificial constructions.

"Looking for aliens is philosophically important — it would tell us what is essential in the human condition," Schneider said.

Seeing the Closest Aliens Will Take Centuries
The closest star system to the Sun is the Alpha Centauri system. Alpha Centauri A, also known as Rigil Kentaurus, is the brightest star in the constellation of Centaurus and is the fourth brightest star in the night sky. Alpha Centauri A is the same type of star as our Sun, causing many to speculate that it might host planets that harbor life. Credit: STSci Digitized Sky Survey, Anglo-Australian Observatory

However, if scientists actually detect signs of life, it will frustratingly take many centuries before humanity can realize the hope of seeing what these aliens might actually look like, Schneider and his colleagues explained.

"It is very disappointing," Schneider said.

To begin imaging even giant organisms 30 feet long and wide on the closest putative , Alpha Centauri AB b, some 4.37 light years away, the elements making up a telescope array would have to cover a distance roughly 400,000 miles wide, or almost the Sun's radius. The area required to collect even one photon a year in light reflected off such a planet is some 60 miles wide. To determine if the lifeform is moving with a speed of even 2 feet per minute — and that the motion you’re seeing is not due to errors in observation — the area required to collect the needed photons would need to be some 1.8 million miles wide.

The only alternative would be to dispatch spacecraft out to the planet, but such a journey would be long and perilous. At speeds of 30 percent the speed of light, a 100-micron-thick interstellar grain roughly the width of a human hair would pack roughly as much kinetic energy as a 100-ton body traveling 60 miles per hour. No currently available technology could protect against such a threat without a spacecraft massing hundreds of tons, which in turn would be extraordinarily difficult to accelerate up to high speeds. One could instead travel more slowly and thus more safely, but at even 1 percent the speed of light (or about 1,860 miles per second) it would take millennia for the spacecraft to reach its target destination.

This artist's conception shows a hypothetical ringed super-Earth as viewed from one of its moons. Both super-Earth and moon are habitable and contain liquid water. Credit: David A. Aguilar, CfA

Regardless of the approach, it seems it will take centuries to get direct visual contact with any nearby aliens, at least in the framework of the science and technology we have now. What physics we might have in a millennium is not reasonable to anticipate, the researchers said.

"I hope that there will be an unpredictable revolution in physical concepts," Schneider quipped.

Not everyone found these prospects disappointing.

"We have always been planning on detecting life indirectly, by searching for atmospheric signatures of life, most likely of the single-cell variety," said astrobiologist Alan Boss at the Carnegie Institution of Washington, who did not take part in this study. "That is what we have been hoping for, and we are still a long way from being able to achieve even that modest goal. We will be overjoyed when we are able to accomplish that goal — it is a race with our planetary colleagues to see if they can find evidence for life on Mars before we find evidence for life outside the solar system!"

Of course, there’s always a chance we’ll get to study aliens close-up if they come seeking us, rather than the other way around. According to Boss, however, that is an unlikely event.

"We do not need to worry about aliens coming to Earth to enslave us — interstellar travel by living creatures is science fiction, not science fact," he said. "No one needs to worry at night about the interstellar air raid sirens going off."

Explore further: 3 Questions: Sara Seager on searching for Earth-like planets

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5 / 5 (2) Apr 29, 2010
All this article said to me is we need a game changer that hasn't been invented/discovered yet... i.e. what microlensing and transiting have done for planet hunting. Maybe we should focus on innovation as opposed to talking about building ridiculously huge telescopes with current technology...
5 / 5 (2) Apr 29, 2010
"Seeing the Closest Aliens Will Take Centuries" ... I disagree ... unless by "Centuries" he means two or three at the most. I think we'll see them a lot sooner than most people believe ... if they in fact exist.

I believe that technology will advance so quickly this century that we'll have the ability to explore the far parts of our galaxy easily within the next 150-200 years.
1 / 5 (1) Apr 29, 2010
@meeker I agree. With inventing and discovering of negative refractive index materials, one can assume there will be some other new method that would prevent the need for gigantic mirrors or lenses.
5 / 5 (1) Apr 29, 2010
With the advance of civilization one could expect an increase in efficiency. This means that civilizations even marginally more advanced than ours would be practically invisible as seen from other solar systems.

We still have cities that illuminate (needlessly) the sky at night.

A few decades ago we had radio antennas that broadcast TV/radio all over the place - including (needlessly) into space. Now we're doing it with directional beams to sattelites (which are invisible for anyone further out). I expect this trend to continue.

So I'm not sure whether we'd 'see' any aliens on other planets - even if our telescopes get a lot better.

I believe that technology will advance so quickly this century that we'll have the ability to explore the far parts of our galaxy easily within the next 150-200 years.

Unlikely unless we find a way to cheat light speed. So far nothing seems to be able to do that. If we're stuck to c then 100 years might be the trip time to our closest neighbor
3.7 / 5 (3) Apr 29, 2010
@meeker. What's your belief based on? Humans have so far traveled a maximum distance of ~230k miles. Alpha Centauri is ~ 25 trillion miles away.

That's a large jump, far too great to accomplish in a human lifespan with tech we can expect for a few thousand years (would require a minimum of .3c average travel speed, about 50% of the trip would be spent braking, very generous acceleration time, so it seems peak speed would be well over .5c).

So it would be a robotic probe, and we can expect that it would take about 100-130 years for a round trip, assuming we do this at .1c trip average. I'm going to go ahead an assume this century's space budget is devoted to get humans to Mars. Assuming we set out in 2100a.d we'd get news by 2200a.d. But first we need an inhabited planet to target! Which requires the right telescopes, which won't be available for a 100-200 years. That's in a perfect economic and political environment. If we make contact before 3000a.d it would be a miracle
not rated yet Apr 29, 2010

A few decades ago we had radio antennas that broadcast TV/radio all over the place - including (needlessly) into space. Now we're doing it with directional beams to sattelites (which are invisible for anyone further out). [p]

If we have been broadcasting to aliens sincethe 50s you supposethey might take: "Bang! Zoom to moon, Alice." as aggression?
5 / 5 (2) Apr 29, 2010
Assuming the law of accelerating returns is even mildly accurate, in my opinion it is ridiculous to argue what technology will be like in 200 or even 100 years because of sudden and new developments, which in turn accelerate further developments.

Many things may seem impossible now, but we are doing things now that were completely impossible from the point of view of someone living just 100 years ago.

No doubt in 100 years from now, things will be happening that will look like magic to us now.

And that's why science is so neat.
not rated yet Apr 30, 2010
What law of accelerating returns?
Apr 30, 2010
This comment has been removed by a moderator.
Apr 30, 2010
This comment has been removed by a moderator.
not rated yet Apr 30, 2010
The universe is obviously set up so that advanced aliens will never make it here to stick their proboscis into our affairs - just too far and too long of time away. It seems a universal law that the best evolving is done without interference - in the same way that nobody can hear every private thought of another. It's quiet for a reason. That being said, I'm all for these telescopes! But we might not like what we see in, say, a few thousand years from now when we can really peer down and watch some other sentient beings act out some hellish drama. If delusion and craziness is here, than it's sure to be found out there as well. We shouldn't think we're so special.
5 / 5 (1) Apr 30, 2010
If we are friendly I'm sure they will e-mail us a picture. ;-)
(if we are not friendly they may send us a virus)
5 / 5 (3) Apr 30, 2010
Game changer. v>c!

I think you really, REALLY don't want to go that fast (or even close to c). Every atom you encounter out there would be like a collision inside the hadron collider.

If you meet something as large as a grain of sand at those speeds you will be in a world of hurt (and evading it would mean being able to detect something that tiny from FAR away).

Not to mention that all radiation you meet coming your way will be blue shifted so much that you'll be bathed in a constant flow of ultra-hard gamma rays and that even cosmic gas molecules will create some serious radiation on impact with your craft.
not rated yet Apr 30, 2010
Over the billions of years and sitess it is
a: Quite possible for 'advanced' life to have arisen
b: That life could easily be a billion years ahead of us

If the laws of our current physics are inviolate we are never going to meet aliens.
If there is possible physics that we haven't discovered that allow crossing or communicating over serious distance in sensible time frames then it is possible other civilisations have the technology.

SO we should aim to 'go places' in 100 to 1000000000 years time and in the meantime wait and see if they arrive.
4 / 5 (1) Apr 30, 2010
The universe is obviously set up so that advanced aliens will never make it here to stick their proboscis into our affairs.

Obvious? Not only not obvious but probably wrong too. Just because our understanding of the laws of physics doesn't allow going faster than the speed of light doesn't mean that it's impossible, which means aliens could already have been here. There is no need to go FTL for humans or aliens to get to other stars anyway, heard of suspended animation? The comment about robots making a round trip is also wrong, there is no need for them to come back and when they get there the information they gather will come back at the speed of light. We are making advances with alternate propulsions like ion drives so gettin to Alpha Centauri will happen soon and the data will come back 4 years after a robot gets there.
4.8 / 5 (4) Apr 30, 2010
There apparently is one way around this lengthy time table that the article doesn't mention. Upon discovering the signature of life on an extra-solar planet, we could send a couple moderate to large-sized space telescopes (~1-10 meter diam.; used as an interferometer) out to the sun's gravitational focus (about 500 A.U. out) in a direction directly opposite of the target and get a factor of ~ 100 million increase in resolution, thereby giving us the ability to directly view the life on the planet.

Check out this link from Centauri Dreams website: http://www.centau...?p=11548

Supposedly such an observatory could "read the license plates on an extrasolar planet."
1 / 5 (1) Apr 30, 2010
Awesome, we no longer need AstroBiologists, fire this guy immediately
5 / 5 (2) Apr 30, 2010
Attempting to anticipate technological capabilities more than 10 to 25 years into the future is a waste of time for both the author and the readership, based on many examples from the history of sci/tech. There are too many unanticipated game changers. When I was a kid in the 60's we were taught that it would never be possible to image stellar surfaces other than the sun, let alone find (and analyze spectrographically) the composition of extrasolar planets.
5 / 5 (2) Apr 30, 2010
There is simple solution.
We need to construct device from photons only, and then send it to the nearest stars at speed of light.
When the device materialize near the stars, it starts send data to us.
What do you think?
1 / 5 (1) Apr 30, 2010
Strange story today on google news:
'aliens among us'. Not atypical as far as this type of story goes, but google doesn't usually list this sort of thing on it's news page. Alien captured by govt after abductions, is set free by pres Carter. Comments?
1 / 5 (3) Apr 30, 2010
Not to disrespect the story or those that are commenting upon it, but i would just like to be the one to not only introduce but passionately point out that "other life forms" let themselves be known to many people across this country and across this planet already, i do not judge if you don't believe it's true, please consider that I know those that have and frankly to think it's a big deal, is to deny the immense enormity of the manifestation of creation, which ever way you choose to believe or not even bother to think about it

It's obvious at this point in time that other life forms exst besides what we see or are fed to believe. They are all around us and soon enough something will happen where it will be more common among us, don't be too surprised is all i'm sayin' and don't think that it's the end of the world or let fear take over, it's life at it's greatest, the "good" side exists

therefore, let's not let the smokescreen of propaganda cloud us further in indoctrination
not rated yet May 01, 2010
Now we're doing it with directional beams to sattelites (which are invisible for anyone further out).

Even with a large dish and a narrow beamwidth, at geostationary orbit the beam will be several 100's of KM wide.
5 / 5 (2) May 01, 2010
Not to disrespect the story or those that are commenting upon it, but i would just like to be the one to not only introduce but passionately point out that "other life forms" let themselves be known to many people across this country and across this planet already
not rated yet May 01, 2010
He is after all the smartest man on the planet.
Was, perhaps. Getting too old to do good science so now he's doing propaganda, like Einstein. You see his nurse with the cleavage? He's turned into a media hog.
1 / 5 (2) May 01, 2010

I believe "Djinn" is the Islamic word for what Christians and Jews call "Demons".

It is odd that the Christian Bible has several records taken to be historical, in which "Angels" (some good, some evil,) visit the earth from "Heaven" at various times.

The oldest of such examples is when the "Sons of God" co-habitated with women, in Genesis chapter 6, which is spoken of later in Jude's epistle.

The second oldest of such examples are in the narratives of Abraham and Sarah, and Abraham and Lot in the Bible, in which God himself, accompanied by two angels(described as men,) appear in the form of men and talk to Abraham, and later Lot.

I am not saying that God is some "advanced alien". I believe God is omnipotent and transcends space and time.

However, "Angels" and "demons" are clearly described as finite, created beings. They seem to live forever, but they have finite locality.

So in a certain sense, angels could be said to be "spirit aliens".
not rated yet May 02, 2010

So in a certain sense, angels could be said to be "spirit aliens".

Does that mean they CAN dance on the head of a pin?
5 / 5 (2) May 02, 2010
I read somewhere that mainstream religionist scholars had pretty much abandoned the idea of angels and demons. I say why not go a little further and give up god himself? Then go home-

Two somewhat related questions- why would aliens come here themselves in ships when they could send nanobots or purpose-built probes? Why humanoids? Secondly, why would an omnipotent god need to act through intermediaries; why angels, prophets, clones, Fatima-type apparitions? His book says he talked directly to people sometimes, so-? My answer- sharlatans needed to corner the market on visions and priviledged communication with the almighty, for obvious reasons. From atop the mountain or within the holy of holies, you know? Sometimes cousin vinny played the part of Gabriel. Rubes love that stuff.
not rated yet May 02, 2010
I only read the title and here goes. Good luck with that. Not to get deep yet, but we haven't truly learned all of our colors of sight, sounds, or thought processes. We are still in the learning phase of science, so by the time we discover how to get to a really distant star without relying on propulsion will be decades and the resources are probably not on this planet.
not rated yet May 03, 2010
Yes, the dijin, along with the Christian angels & demons have been wandering around Earth for thousands of years, and are now making themselves apparent by flying in multi-colored aircraft, appearing in blurry photos on Ripley's, and running into poster "abram's" cohorts in the deep south. They live on Nibiru.

On a serious note I think that it's incredible that one can even hold a serious discussion about the specific time-frame humanity will contact other intelligent life. A few years ago Dirac's equation & SETI were fringe science, and today Stephen Hawking is commenting on the dangers of extra-sola communication. Whether it is 2200 A.D or 3000 A.D, the fact that we will surely find companions in the stars is fantastic enough.
not rated yet May 03, 2010
Drake's equation not Dirac's; became popular about 10 years ago.
not rated yet May 03, 2010
When they personally abduct me for investigative reporting of our species to their superiors... and they then let me remember if I ask nicely... then I'll let you guys know. I don't mind having a conversation with them about life on earth... especially if they let me take a trip in their lil' space ships so i can see out the portal at all the humans wandering the earth 8-)
1 / 5 (1) May 05, 2010
Now let me see - SETI was set up to search for extra-terrestrial intelligent life, based on some set criteria for distinguishing such intelligence.

Using those same criteria, the information content of DNA was analyzed and found to meet and exceed such requirements for intelligence.

So why do people still believe that the mind blasting, incredibly complex processes going on in the most basic cell is just the result of random physical events?

Makes the mind boggle. You might as well believe in fairy tales, and be better off.

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