Are There Rules For How To Avoid Contaminating Other Planets? (Or Our Own?)

Is there an internationally-agreed protocol to avoid compromising the detection of life beyond Earth with living matter of earthly origin, and for quarantining any organisms crossing that boundary either way? If there isn’t such a protocol, should there be one?
The fascinating surface of Jupiter’s icy moon Europa looms large in this newly-reprocessed color view, made from images taken by NASA’s Galileo spacecraft in the late 1990s. This is the color view of Europa from Galileo that shows the largest portion of the moon’s surface at the highest resolution. Credits: NASA/JPL-Caltech/SETI Institute

The fascinating surface of Jupiter’s icy moon Europa looms large in this newly-reprocessed color view, made from images taken by NASA’s Galileo spacecraft in the late 1990s. This is the color view of Europa from Galileo that shows the largest portion of the moon’s surface at the highest resolution. Credits: NASA/JPL-Caltech/SETI Institute

Originally posted at Forbes!

There certainly is a protocol to avoid contaminating other worlds which might host life, and it is broadly described by the phrase “planetary protection.” Planetary protection boils down to not sending any spacecraft to places which might host life without pushing the spacecraft through our absolute best, most ridiculous sterilization process, to avoid even potentially contaminating that world with Earth microbes. It also means protecting our own planet from any microbes which might live over there, and carelessly letting them roam free on our home.

Any country which has signed on to the Outer Space Treaty, overseen by the United Nations (which is most of them at this point) is legally bound to try their best to avoid contaminating any world. Generally, we want to avoid bringing too many Earth contaminants along in any case, because it will muddle our measurements of the other world. The last thing you want to do when taking a very precise measurement of a moon of Jupiter is to accidentally also measure Leftover Earth Bits.

The current guardian of the planetary protection guidelines is a committee named COSPAR (Committee on Space Research), and they’ve got five tiers of “how much does your spacecraft need to be super sterile.” The first is for objects like the Sun or Mercury, where there’s no hope of life on that world. The second is for objects like the Moon or Venus, where there’s interesting chemistry but it’s pretty unlikely that you’re going to contaminate any life there. The third is for flyby missions, where you’re going past a world which could have life, like Europa or Mars.

One of the Viking landers being prepared for dry heat sterilization. Image credit: NASA

One of the Viking landers being prepared for dry heat sterilization. Image credit: NASA

The fourth category is also for worlds which might have life (in our solar system, this usually includes all worlds with water by default) but is for landers and rovers, where you’re getting much closer to the place that life might be. A flyby mission, in principle, should not get that close to the planet -- but a rover is going to be right there in the dust. All of our Mars rovers are in this category, and have to undergo really strenuous sterilization. If your rover is not searching for life, and is not in an area that might have any (a really dry part of Mars, for instance), you can get away with only having 300 bacteria per square meter of your spacecraft’s surface. (This is still very, very clean.)

If, on the other hand, you’d like to look for life, or would like to go near where there appears to be liquid, your spacecraft has to be 10,000 times cleaner. The only way to do this is to bake your spacecraft in a dry heat oven, which was done for the Viking landers, whose purpose was to search for life on Mars.

For stuff coming back from other worlds, there’s a similar “is there life?” divide for what needs to be done with the material. For something coming back from an asteroid (like the Osiris Rex mission, and Hayabusa 2) where we really don’t expect there to be any life, you just want to not contaminate your precious sample -- it’s a standard level of scientific caution, like with not wanting to measure the Earth when you’re intending to measure Io.

Recent Cassini images of Saturn's moon Enceladus backlit by the sun show the fountain-like sources of the fine spray of material that towers over the south polar region. The image was taken looking more or less broadside at the "tiger stripe" fractures observed in earlier Enceladus images. It shows discrete plumes of a variety of apparent sizes above the limb of the moon. The greatly enhanced and colorized image shows the enormous extent of the fainter, larger-scale component of the plume. Imaging scientists, as reported in the journal Science on March 10, 2006, believe that the jets are geysers erupting from pressurized subsurface reservoirs of liquid water above 273 degrees Kelvin (0 degrees Celsius). Credit: NASA/JPL/Space Science Institute

Recent Cassini images of Saturn's moon Enceladus backlit by the sun show the fountain-like sources of the fine spray of material that towers over the south polar region. The image was taken looking more or less broadside at the "tiger stripe" fractures observed in earlier Enceladus images. It shows discrete plumes of a variety of apparent sizes above the limb of the moon. The greatly enhanced and colorized image shows the enormous extent of the fainter, larger-scale component of the plume. Imaging scientists, as reported in the journal Science on March 10, 2006, believe that the jets are geysers erupting from pressurized subsurface reservoirs of liquid water above 273 degrees Kelvin (0 degrees Celsius). Credit: NASA/JPL/Space Science Institute

But if we’re not sure if there should be life, or we’re suspicious that there might possibly be life in our little sample, and we want to bring it back to Earth, you have a whole lot of quarantining to do before you even get back. First you have to make sure that your spacecraft is clean enough to safely go there and not contaminate, say, Enceladus. Then we have to make sure that Enceladus doesn’t contaminate us, and the suggested path there is to take your entire spacecraft, and put it inside a box, and then send that box back to Earth. Since the box didn't go to Enceladus, it should be safe to land the box on Earth, and then you can take the box to the cleanest clean room of all time to crack it open and retrieve your sample. Hopefully, with those precautions in place, both the Earth and Enceladus are uncontaminated, and scientists will be very happy.

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Could Life Exist In A Star's Atmosphere?

Could life exist in stellar atmospheres, even if it wasn’t life as we know it?
On June 5 2012, SDO collected images of the rarest predictable solar event—the transit of Venus across the face of the sun. This event lasted approximately 6 hours and happens in pairs eight years apart, which are separated from each other by 105 or 121 years. The last transit was in 2004 and the next will not happen until 2117. Image credit: NASA/SDO

On June 5 2012, SDO collected images of the rarest predictable solar event—the transit of Venus across the face of the sun. This event lasted approximately 6 hours and happens in pairs eight years apart, which are separated from each other by 105 or 121 years. The last transit was in 2004 and the next will not happen until 2117. Image credit: NASA/SDO

Originally posted at Forbes.

Alas, life is pretty much guaranteed a quick trip to vaporization if it tried to live in the atmosphere of a star like our own. Stars like our sun have a surface temperature of about 10,000 degrees Fahrenheit (or about 5800 Kelvin), which is hot enough to keep iron suspended in a plasma, and to melt even the hardiest known compounds and alloys. This is way, way too hot for any kind of biological structure; any kind of complex molecule would immediately burn. The surface of the sun is the coldest part of the entire star; if you go deeper into the star, it only gets hotter. Bizarrely, a short distance above the surface, it also gets hotter for reasons that we still haven’t quite worked out. So if molecules aren’t going to survive at the surface, there’s no chance for life anywhere else in the star, either.

That's not to say that there’s no hope for atmospheric living, so long as we're willing to look at a slightly cooler place. We recently discovered that our own atmosphere seems to be rather full of living things suspended surprisingly far up in our atmosphere. A hurricane scouting plane took samples of the air, a little over six miles (10 kilometers) above the surface, and found a phenomenal density of bacteria and fungi apparently thriving up there! At the very least, the bacteria they found were not all dead, which is a good start.

This was a bit of a surprise, as the higher you go up in the atmosphere, the less protection you have from the high-energy ultraviolet (UV) radiation from our sun. UV radiation is generally dangerous to life, which is why everyone should wear sunscreen. Ultraviolet radiation is high enough in energy to ionize atoms and molecules, kicking electrons out of their otherwise stable orbits; this can damage cells, causing them to mutate or die, depending on the severity of the damage. In humans this damage can lead to skin cells reproducing much faster than they should – it’s one of the triggers for skin cancer. The atmosphere does a fairly good job of blocking most UV light, but the further up in the atmosphere you go, the less protection there is. At 6.8 miles above the surface, 75% of the mass of the atmosphere is below you, so this really is a very extreme, unprotected place for bacteria to survive. To find a large volume of bacteria, live, seemingly unaffected by the UV dosage 6 miles up really was unexpected. Currently, we think that storms are responsible for flinging so many bacteria nearly to the stratosphere, but it’s the tiny mass of the bacteria which allows them to stay suspended up there for a while, along with dust and water vapor, which can eventually form into clouds.

The interesting piece of the puzzle from an astronomical perspective is this; finding not-dead bacteria in our own atmosphere means that it’s not entirely crazy to suggest that the same thing might happen in other atmospheres. Suspicions immediately turn to Venus, everyone’s favorite 860F degree, runaway greenhouse, volcano-ridden, battery-acid raining planet. Now that description, while not inaccurate, does not paint a picture of a particularly habitable planet. On the other hand, we don’t particularly expect to find life at the surface, where we have lost each and every one of our probes to a combination of crushing and melting after a couple of hours, max.

However, if you stay away from the surface, there’s a layer in Venus’s extraordinarily dense clouds which is positively balmy in temperature. It sits about 65 kilometers above the surface with a pressure about equal to the pressure at the surface of the Earth, and is about standard room temperature. Unfortunately for humans, this is also the part of the atmosphere of Venus which rains sulfuric acid. This toxic acid rain evaporates before it hits the surface, leaving a catastrophic layer in the atmosphere where no humans would dare to pass.

For bacteria, however, this may not spell immediate demise, because there are also extremophiles on Earth which are fine with sulfuric acid. There’s a class of bacteria which live in caves, form stringy mats, eat sulfur compounds, and produce sulfuric acid as a byproduct. They hang from the ceiling of the caves and are called snottites, or, if you prefer, snoticles. These caves are seriously unhealthy places for humans (generally explorers need to be wearing heavy-duty protective gear and gas masks) both because of the general lack of oxygen and because of the sulfuric acid dripping from the ceiling. But if a similar class of bacteria were present in the reasonable temperature, reasonable pressure cloud layer of Venus, they might be able to survive fairly well without worrying too much about the omnipresent sulfuric acid.

This sort of thinking isn’t limited to just Venus, though it’s the closest, we have the most information on it, and probably is the easiest to explore; Jupiter has also been subjected to the same thought experiments. There’s a long line of science fiction authors exploring the ideas of Jovians, with many of them working off of creatures living in the clouds. Though it’s unlikely that there are airborne jellyfish or cloud whales on Jupiter, it’s certainly possible that microscopic life could be suspended in the more charitable cloud layers.

To stretch back to the original question about stellar atmospheres, the very lowest mass end of the spectrum of stars is composed of brown dwarfs – stars which missed the amount of mass you need in order to start fusion burning in their cores. The coldest of them are really quite cold; the most extreme surface temperature is somewhere between -54 and 9 degrees Fahrenheit, which is right about the limit of coldest survivable conditions for extremophiles on Earth. Not all brown dwarfs would be suitable; we need them to be as Jupiter-like as possible, which happens only with the smallest of them, where the boundary between a Jupiter-like planet and a failed star is the fuzziest. But given what we know about stellar atmospheres today, if life can thrive in the high atmosphere of gas giants, then the lowest-mass stars, which may yet outnumber stars like our own, could be the home of starborne life.

Of course, all of this, though logically laid out, is purely a thought experiment until we can go exploring and see for ourselves. There are missions that have been designed with present technology to look for exactly this, and that may yet give rise to our first indications of life on a planet other than our own.


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Does life exist in other planets?

We can’t think of a single good reason why it shouldn’t, if the conditions are right!

The hardest part is getting the right conditions. On Earth, the biggest requirement for life is water. Our planet is very good at growing things in every possible location, so long as it’s near or in liquid water. Life arose extremely quickly after the formation of the earth, which seems to indicate that if once the Earth had a surface with liquid water on it, there were not a lot of other stumbling blocks to overcome before life could spring forth.

Having liquid water usually means that the planet has to be in a relatively narrow distance window away from its star, and have a surface upon which the water can rest. Effectively, we need rocky planets at exactly the right distance from the sun such that all the water doesn’t freeze solid or evaporate away. Outside of that distance band in a solar system which allows for liquid water, there are precious few opportunities for liquid water to exist, except in unusual cases like Enceladus, a moon of Saturn, and Europa, a moon of Jupiter. Both of these moons are thought to have an ocean of liquid water under their icy surfaces. These small moons can maintain liquid water because the tidal forces from the massive planets they orbit are constantly stretching the rock at the cores of the moons. This stretching heats up the rock, and that heating provides the energy required to maintain liquid water, even though these moons are far too distant from the sun to keep liquid water on their surfaces. As a result, planetary scientists are very excited about the prospect of being able to find life on Europa and Enceladus, but in order to go check, we’ll have to send a craft to those moons to look directly.

Also within our solar system, we are currently looking for evidence that life once existed on Mars. The information coming back from our Mars rovers tells us that Mars was once warmer and wetter than it is now, which means that it should have been a good place for life, back when it was able to hold liquid water. However, since Mars has become very cold over the years, we don’t expect to find evidence of life currently thriving there.

Looking for planets outside our solar system becomes much more difficult than looking within it; for starters, it’s much more difficult to find the planets to start with. We then need to filter out only the ones that fall within this magic range of distances from their star where liquid water can exist. The technology to find rocky planets in the liquid water zone has only recently been developed. These planets are extremely hard to detect, and push the boundaries of the sensitivity of our telescopes. The Kepler satellite has begun to push into this realm of extrasolar planets, and the massive amount of data it took before the end of its mission is still being analyzed. It seems, from the data that’s been studied so far, that about 20% of all stars like our sun have a planet around it like the Earth - a rocky planet near enough to the star to have liquid water.

Proving that liquid water does in fact exist on those planets is more difficult still - you have to detect the signature of water in the atmosphere of a planet that is light years away. Proving the existence of life will be an even more difficult task, but once we begin to find lots of planets with liquid water on their surfaces, the odds are pretty good that one of them will contain life of some form. It will be much easier to search for life within our own solar system, since we can actually go to these places and see what’s there directly.

No matter where it might be - the search is on.

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Where are the aliens?

Where are the aliens? Do they exist?
Source

Source

They’re out there! They’re just really, really, really far away.

Think about it this way; we’re one planet around a relatively average star at no special location in our galaxy, at no special location in the universe. What makes us believe we’re the only form of intelligent life in this vast universe? The trouble lies in the vastness.

Astronomers traditionally tackle this question by means of the Drake Equation, which takes all the pieces we think need to align for life to evolve, and multiplies together all the probabilities that they’ll occur in the same place at the same time within our galaxy. In a simple form, it asks the following series of questions: From the number of stars in our galaxy, what fraction of those stars will have planets? On average, how many planets are at just the right distance from their star, when liquid water can exist at the surface? Of the planets with liquid water hanging around, how many of those should we expect to have any form of life, no matter how simple? What fraction of those planets with life will also have intelligent life? And what fraction of those intelligent life forms are still around now and potentially able to communicate with us?

There are at least 100 billion stars in our galaxy, and hundreds of billions of galaxies in the universe.  Pretty much every star we’ve looked at in our galaxy has at least one planet, which means we’re dealing with an overwhelmingly large number of planets in the universe.  Our Earth went from ‘liquid surface water’ to 'life’ in a cosmic blink of an eye - that doesn’t seem to be the hard part.The tricky part is getting from bacteria to a species that contemplates the skies above.  Even if you’re extremely pessimistic about the fraction of planets that have any form of life, and pessimistic about the fraction of planets with intelligent life, the sheer number of planets out there dominates these calculations.  There simply has to be other life out there, and if not in our galaxy, in another. 

Here’s the sticking point: the galaxy is huge. It takes light 50,000 years to travel from the centre to the edge of the galaxy: 100,000 years to make it all the way across. And the distances between galaxies are even more extreme. Light from the Andromeda galaxy takes two and a half million years to reach us, and that’s our nearest neighbor. Two and a half million years ago, humans were only at homo habilis. We don’t have any record of modern humans from earlier than 200,000 years ago. Our first radio telescope was built all of 80 years ago.

We can do a few more rough calculations to figure out how bad the problem is. Let’s assume that you do your calculation and work out that by optimistic numbers, there should be 1,000 intelligent, communicable civilizations just in our galaxy. If those civilizations are randomly scattered around the galaxy, on average they’ll be separated by 2,800 light years. But maybe 1,000 is a little too optimistic. Say there are only 15 civilizations in our galaxy; now they’re separated by about 23,000 light years. If there’s only one civilization per galaxy, you’re back to separations of millions of light years. Communication between civilizations (even in the most optimistic of cases) would be effectively impossible.

No matter what, whatever forms of life exist out there will be as uniquely suited to their home planet and home star as we are to our own, and will assuredly look nothing like Hollywood’s favorite “little green men”.

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