THE SEARCH FOR EXTRATERRESTRIAL LIFE

foreign ly possible that there's Life on Mars astronomers and scientists have for over 100 years speculated about the possibility of Life on Mars from what we know about the planet today and even in light of our Mariner photographs there's nothing that precludes the possibility of Life on that planet this is a Mars box a simulated section of the surface of Mars the temperature at one end the North Pole is 100 degrees below zero the temperature at the other end the equator varies from a comfortable 80 degrees during the day to a frigid 90 below at night yet there are forms of Light which can not only survive in this environment but if there is liquid water around they can even grow why scientists believe there may be life on planets such as Mars and how the search for such extraterrestrial life is being pursued is our story today on science reporter [Music] [Applause] [Music] [Applause] [Music] hello I'm John Fitch MIT science reporter today we're at the Ames Research Center South of San Francisco California to report on current efforts in the search for life on other planets the science of exobiology Ames has a long history of service in the field of Aeronautics but recently the National Aeronautics and Space Administration has constructed this brand new center for life sciences and is assigned Ames the responsibility for basic research in these Sciences as they're applicable to space missions to learn how scientists here are pursuing their search for extraterrestrial life we talked to Dr Richard young chief of the exobiology division well I'd say that as long as you're asking the questions whether there could be life on other planets I could almost unequivocally say yes there could be but as to whether there actually is life on other planets or not we simply don't know that's the object of much of what we're doing is to determine whether there is or is not now there are several problems of course in trying to detect life not only on another planet but in trying to detect life on the earth one is to find an acceptable definition of Life what what is life the things that move around or something like that yes all right but you haven't Defined Life you've given me an attribute of life and this actually is the way we do it for uh centuries scientists and philosophers have tried to Define life probably starting with Aristotle and even before and we find that interestingly enough that what Aristotle had to say about life and its definition is really no different from what we say about life today well how did he Define it well Aristotle pointed out that the difference between the living and the non-living is so subtle that we really can't put forth an ironclad definition of life it's it's futile we really can't I think that we can come up with a half a dozen different types of definitions that would be acceptable to individual scientists but certainly would not be acceptable to the scientific Community as a whole so we don't then attempt to Define life that's not that's not our purpose is there are there anything that you could really agree on yes I think so I think that life as we know it on Earth has certain attributes that is common or are common to all forms of life uh for example all life that we know of on Earth is composed of organic compounds carbon-based compounds uh proteins lipids carbohydrates are all the common building blocks of life and all life as far as we know and they all have carbon in them right DNA is a carbon-based large organic molecule that's the hereditary material of all cells on Earth now the question is of course can we extrapolate this knowledge what we know about life on Earth to potential life on the Planet X or Mars and the answer I think is yes we have to it's it's the only common starting point we could possibly have so we do attempt to make this extrapolation we assume first of all that life all life either on Earth or elsewhere in the universe is composed of organic matter and that these organic compounds will have a great deal in common we also assume that all life in the universe will metabolize in the same way but it's basically that life on Earth does this means that it that it life on Earth in order to perform its daily functions at the cellular level uses up certain materials let's say glucose sugar is one very common substrate for cellular metabolism and gives off waste products these waste products can be in the form of heat waste heat a gas or or even a fluid in some cases they have to have some kind of energy in order to stay alive exactly now this gives us something to look for we can look for either The Disappearance of a substrate if we know what the substrate is or we can look for the appearance of the end product of metabolism but the basic uh phenomenon the metabolic phenomenon should be common to all forms of life the third Criterion that we feel should be common is that of reproduction all life must reproduce itself in in order to survive as a function of time in order for evolution to proceed we must have reproduction either at the cellular level or at the level of the entire organism so that we would look for increases in size and increases in numbers of something as a function of time these three attributes we think then are about as fundamental as we could possibly get but just because things like work that way on the earth I mean that everything is based on carbon compounds and and these other characters characteristics that you man why should it be that way anywhere else yeah well this is a this is a hotly debated item of course but we use the following logic that in the universe there are many millions or billions of stars since we have that many stars there's no reason to think that some fraction of them at least wouldn't have planets around them in the same way that our own star the sun does some of these planets statistically at least should have environments on them that would be conducive to what we call chemical Evolution to the synthesis of organic compounds and sooner or later a living system should logically have Arisen on perhaps as many as several millions of these potential planets elsewhere in the universe these could be places all like the Earth some of them would be like the Earth some of them would be very different again you can only approach it statistically and and assume that some of them would be like the Earth the reason for making this assumption is that we know roughly what the abundance of the elements in the cosmos is we know that hydrogen for example is vastly more abundant than any of the other elements we know that carbon nitrogen and oxygen are also among the most abundant of the elements then as a planet was being formed from the Primitive nebula or gas cloud these elements should be there in their Cosmic abundance because of the great excess of hydrogen all of these elements would be in their reduced form maybe the best way to illustrate this is graphically foreign expenses would have started much the same way so that yes I think that in our own solar system I think that that's probably the case the planets on our own solar system presumably arose at about the same time uh Mars at about the same time as the Earth for example the atmosphere of Mars the Primitive atmosphere of Mars then should have been very much like that of the Earth carbon nitrogen oxygen in their reduced form it might have looked something like this ammonium methane water with perhaps an excessive hydrogen now in this primitive atmosphere there was certainly a great deal of energy available energy from the Sun for example in the form of ultraviolet radiation energy in the form of lightning in the Primitive atmosphere as is Illustrated here these sources of energy when imposed on an atmosphere of this type give us a situation that we can actually simulate in the laboratory and later I'll show you exactly how this sort of thing well works in the laboratory then we can we have found this and certainly other Laboratories have found that when one does irradiate this sort of an atmosphere with any of these kinds of energy even heat that organic compounds are synthesized and we can look at the Primitive Earth as having oceans which were essentially a dilute organic soup and all of the basic ingredients of living systems were there before a living system actually arose and of course there's a big gap in our knowledge as to what could have happened where did the first cell come from conceivably something like a coasterbating process or some condensation of polymers present in the Primitive ocean could have produced a very rudimentary counterpart of uh of a contemporary cell these things then would begin to metabolize producing new Gases such as oxygen free oxygen into the atmosphere which would form an ozone layer shielding out the ultraviolet light that was a responsible for many of the original syntheses but allowed then biological evolution to proceed by shielding out the ultraviolet light which would be lethal to many of our biological processes so some system like this may be a reasonable pathway along which life on Earth arose and perhaps and we have no reason to think that it would not have also happened on some other planet such as Mars and you can actually simulate this in the laboratory oh yes yes as a matter of fact I think probably the best thing to do now would be to take you into the laboratory and show you exactly how this sort of an experiment can be done to produce organic matter oh fine now in this particular laboratory we've put together a device with which we can actually simulate the the chemistry involved in this primitive atmosphere now what we've done here is simply taken a two-part flask in the upper part of the chamber we actually introduced A Primitive atmosphere methane ammonium water vapor hydrogen the bottom of the flask we have our primitive ocean in which we hope to ultimately collect our primordial soup the end products of the experiment the organic matter that's synthesized in the upper part of the flask we have four electrodes projecting into the flask and and these when they're turned on which we'll do here in a minute we'll create a spark which jumps the the Gap and simulates the lightning then as the reaction proceeds organic matter which is synthesized is carried down into the Primitive ocean as presumably was on the earth aliquotes can be drawn off for analysis okay can we try it yeah let's uh see if we can open the hood here and demonstrate this now we'll turn down the light a bit and turn on the oh yeah electrodes right and you can see uh lightning has done in the flask and then presumably these organic molecules are falling down into the ocean that's right that's right they fall into the ocean and accumulate there and this is probably the way it happened well how do you tell uh if they're there and if they are what they are well we have to take a sample and analyze it chemically now this can be done in a number of ways one technique that we use extensively here in Dr Pana peruma's laboratory is paper chromatography and here's a paper chromatogram in which we look for adenine which is one of the building blocks of DNA what we do is simply take a few drops of the end product of an experiment like this put it on a piece of the special paper which is similar to blotting paper but it's treated specially put a solvent front wet the paper with a solvent which will migrate down the face of the paper as a function of time now whatever material organic matter is present and is soluble in that solvent will also migrate down and it'll migrate at a rate which is uh is a characteristic of that particular molecule then we'll turn the paper over and do the same thing in another Direction so that we'll even further separate the components of this original spot see now we have a whole series of dark spots here on the paper Each of which is an organic compound the particular one that we were especially interested in in this experiment as I said was adenine and you can see it was the yield here was rather High there was a lot of adenine synthesized in this particular experience what is that and it is important because it is as I said one of the components of DNA and in fact ponoproma has now been able to synthesize practically all of the components of DNA or hereditary material not just adenine and my own personal feeling is that DNA will all itself ultimately be synthesizable in this in this fashion but just because you can build these building blocks and even the DNA does that mean eventually you can make a life in a test tube not necessarily I wouldn't say that's not a possibility but certainly wouldn't say that it necessarily is a possibility as a matter of fact it may not even be an objective of this type of experiment what we're interested in are the pathways along which life may have Arisen and we assume that life is the natural result of chemical Evolution and in understanding these Pathways we may at some later date be able to cast sunlight on this question of the origin of life but even if life could have gotten started on the in A Primitive atmosphere in the way you describe on Mars just as it may have on on Earth because they were similar as you pointed out from what we've seen of the Mariner photographs of Mars it looks like that planet is developed into a pretty inhospitable place is it possible that life could have survived there always yes well you're quite right Mars is undoubtedly an inhospitable Planet by Earthly standards what the biological significance of this is I don't know say something about that in a minute let's take a look at one of the Mariner photographs such as this one uh clearly from a photograph like this taken from 4 000 miles or more from the planet you can't tell much about life on Mars nor was this Photograph intended to tell us much about life on Mars I think that's the point to remember from a photograph that wasn't intended to tell us anything about life we should hardly expect to learn much in fact from photographs taken from our Nimbus satellite we can't tell much about the presence or absence of life on Earth in fact if we were just to look at a picture like this objectively we might be compelled to say there's no life on Earth we know better we don't really know much about the capabilities of life when we start talking about environmental extremes be it on Mars or on the earth the extremes of environment on the earth have been really very little studied we've studied samples from soil samples from the top of Mount Everest we find that surprisingly enough there are living organisms in their soils so that just based on what we know about the extremes of Earth I see no reason to rule out Life on Mars it seems entirely possible but still I noticed in this uh primitive or if you you did mention the importance of the of the ocean and in general we think of Life evolving out of the ocean there aren't any oceans on Mars is that necessary yeah you're right water is certainly a limiting factor we feel that based on what we know about the water content of the Martian atmosphere uh from my own point of view if we can't find ways in which more water than that can be available on Mars we can forget about life on Mars there probably isn't any in fact it might be of interest to you we've built a model in the laboratory in which we've attempted to show ways in which water might be available on Mars in spite of the fact that we see so little in the atmosphere and I'd like to show that to you now all right now I should start out by stating that you simply can't put a planet in a box but what we have constructed here is a chamber in which we can simulate many of the physical conditions that we know exist on the surface of Mars and particularly those that have biological significance we have a heavily insulated box inside of which we have a second chamber which is capable of withstanding the stresses of pressure and so forth the lid here is made of quartz so that we can contain the atmosphere and keep the pressure constant and also irradiating the ultraviolet the upper end of the chamber you can see we have a pole cap formed which simulates that that exists on the in polar latitudes on Mars you actually have Isa how do you make it so cold well this is controlled by the use of liquid nitrogen liquid nitrogen tanks outside the chamber we cycle nitrogen through the chamber and control the temperature at this end at about minus 100 degrees which is uh approximates that on Mars the high temperature the sun if you will is is done by using an infrared lamp bringing the temperatures at this end of the chamber to owe about 80 degrees during the daytime at night however it goes down to extremely cold temperatures perhaps as much as 80 or 90 degrees below zero so this is the equator and up there is we have a pole what are all these little aluminum houses or wires the wires we have in here are actually thermocouples that give us a temperature readout throughout the chamber so that we know what the temperature is as a function of latitude and as a function of depth in the soil this temperature then is actually read out for us on a strip chart uh giving us at any given time the temperature profile cold at this end this is at the polar end of the chamber then on up to something like 70 degrees Fahrenheit at this end the scale is in centigrade well that sounds rather Pleasant yes the only problem is that at night it's quite different at night it gets very cold and from the point of view of biology it's a tremendously rigorous environment now we've then taken this chamber pulled a dry Martian atmosphere through it assuming that moisture was present on the Primitive Planet pulled moisture out as it would have been lost to space because it left gravity there well a rarer atmosphere and less gravity right the the moisture then is controlled by these factors our objective was to see whether a permafrost layer whether ice would be tied up below the surface of the planet since the average temperatures are so much colder about 50 degrees colder than the earth in order to do that we started cycling through Martian day night and seasonal cycles and we found that this by the way is a longitudinal section of the chamber we simply cut it in half longitudinally we find that the temperatures at the polar end are minus 100 degrees at the equatorial end as high as plus 80 degrees but perhaps as low as minus 90 degrees cycled daily we found that a permafrost layer did form and then at a considerable amount of water was tied up below the surface of the planet this permafrost layer was actually continuous with the pole cap that you can see in the chamber a trace of water in the atmosphere carbon dioxide and nitrogen the primary components of the atmosphere if this analogy is a good one then all you need is a is a hot spot if you will a local hot spot on the surface of the planet melting the permafrost layer having water percolate to the surface and you have the Martian equivalent of a hot spring or an oasis where biological activity may be quite abundant let's say I suppose you did have some life starting there and surviving evolving how are you going to find out about it well needless to say we have to get to Mars which is a major problem once we get there we've designed a an array of Life detection devices and experiments which we'll look for these basic attributes of life that we discussed earlier we have here some models of of some of these devices which I'd like to show you I think they might serve to illustrate the point right now this first device that we see here is called Gulliver it's inventors Dr Gill Levin of Hazelton Laboratories in Virginia and this is one of several devices that are being designed and prototyped being built ultimately to be landed on Mars to send information back concerning uh life assuming there is life there now this one works very simply what we have here is essentially a bullet which is fired out onto the surface of the planet and you'll notice there's a string attached to the bullet this is a sticky string that unreals onto the surface the string is then reeled back into the chamber into a chamber containing a nutrient medium it could be sugar as the energy source uh the string then being sticky will pick up whatever adheres to it on the surface presumably dust or microorganisms or whatever happens to be there if they find themselves in an environment in this chamber that's hospitable in other words if they can utilize glucose they'll begin to grow in the top of the chamber we have a geiger counter a geiger tube a very simple common Geiger tube the glucose that's in there will be tagged isotopically it'll be radioactive because we'll be using c14 in the glucose if the organisms utilize glucose they'll evolve then c14 O2 carbon dioxide containing radioactive carbon and all we have to do is count the radioactive carbon as it's evolved as a gas as a waste product of biological activity what if these organisms don't like sugar well then unless we've chosen the right substrate we're out of luck the experiment simply won't work and that of course is one of the obvious limitations of this kind of an experiment you have to guess right about what the organisms are going to like and you have to guess right about what they're going to do what they're going to evolve if they do like the substrate you could use something else in there oh yes yes indeed now this chamber or this device is called The Wolf Trap it was designed by Dr Wolf fishniak and the University of Rochester and hence the name it has a sampler as well which is bounced out of the capsule itself onto the surface and these are both full-scale models by the way I see this then will aspirate a sample by creating a vacuum suck a sample of dust if you will into a chamber which might contain a growth medium very much like this one did uh the difference here is that we're monitoring a different end product in this case we're looking for changes in PH due to the assuming there are microorganisms they will grow they'll change the acidity or alkalinity of the medium this can be measured by pH electrode which is in the chamber so instead of looking for carbon dioxide Evolution we're looking for a change in the pH of the medium or also in this there's an optical device with which we can measure changes in the turbidity of the medium if there are bacteria for example and they start to grow they'll gradually Cloud the medium so that the beam of lightly attenuated and this information also can be telemetered and give us hopefully a direct evidence of biological activity now both of these as I said have limitations in that they can really only do one thing or a very limited number of things much further down the line when we have a capability of flying more sophisticated devices perhaps in the later Voyager program we would hope to land what amounts to an automated laboratory on the surface of a planet like Mars it might look something like this which was developed for us by the aeronutronic division of the Ford Motor Company is this uh full size this is a quarter scale model so that the ultimate device might be more like the size of this table this device has it is a laboratory it's a device that will do a multitude of analyzes as uh soil probes which can be used to loosen up the soil if it should be hard it has a sample collecting system which would actually take a core sample or it might aspirate a sample the way that one does it might have a sticky string array the sample then could be brought back into the laboratory start for future analysis treat it chemically with an array of solvents extracted we have a gas chromatograph in here a mass spectrometer an array of spectrophotometric equipment and it's a laboratory in in a modest sense of the word which we would hope to use on the surface of Mars to do to look for evidence of all of those basic attributes that we've been discussing chemistry metabolism and growth and it would take a fairly sophisticated device to do all of these things needless to say of course the fact that it is so sophisticated presents other problems engineering problems primarily the reliability of a device like this might be very difficult to compare to the reliability of a device like this so we're really talking about a future generation of experimental device here well Dr Young aside from the fact that we're naturally all very curious about how unique life is in the universe are there any other real reasons for trying to find out about extraterrestrial life well one of the the basic contentions or justifications if you will for this sort of work is that we really don't know much about the universality of biology the only life we know the only biology we know is here on Earth the only principles of biology that we're familiar with are here on Earth the physical sciences we have universal laws if you will the biological sciences we don't have them what we want to know is as you said is life indeed unique on Earth does it exist elsewhere if it does Exist Elsewhere does it follow the same laws that life on Earth does or is it made of the same things does it do the same things and does it have a common origin the origin of Life of course is one of the most fundamental questions we can be asked asking and I think it's really an underlying theme for this entire program well thank you very much Dr Young clearly exploring the heavens for signs of life is no simple matter years of research go into deciding just what questions to ask and how to go about asking them as we've seen scientists are already hard at work on payloads for a landing on Mars a landing which isn't even scheduled to take place until 1973. but when you're looking for something as Elusive and as ill-defined as life the payload has to be flexible and perhaps for conclusive evidence it will have to be the most flexible payload of all man himself today we visited the Ames Research Center near San Francisco California I'm John Fitch MIT science reporter [Music] [Applause] [Music] [Applause] [Music] [Applause] [Music] thank you foreign [Music] [Applause] [Music] foreign