"We've been doing astrobiology since 1984!"

Remarks of Prof. Jill Tarter from the SETI-Institute (California/Mountain View) concerning the serious scientific SETI work and its problems

The mission of the SETI Institute is to explore, understand and explain the origin, nature and prevalence of life in the universe. Founded in 1984, the SETI Institute in Mountain View, California today is a private, nonprofit organization dedicated to scientific research, education and public outreach and employs over 100 scientists, educators and support staff.

On September 15, 1997 the Board of Trustees of the SETI Institute appointed Dr. Jill Tarter to a new endowed position at the SETI Institute: the Bernard M. Oliver Chair for SETI. As a Principal Investigator for the non-profit SETI Institute in Mountain View, CA, Dr. Tarter served as Project Scientist for NASA's High Resolution Microwave Survey (HRMS, until its termination by Congress in October 1993. As such, she had the opportunity to melt together old and new engineering skills with a knowledge of the observable universe, in order to conduct and plan for thorough observations of the sky through a set of narrow band and pulse sensitive filters never before systematically employed by astronomers.

In September 1989 Dr. Tarter received the Lifetime Achievement Award for her contribution to the field of exobiology, and in particular to the search for extraterrestrial intelligence, by Women in Aerospace, a professional association in Washington, DC. In March 1993 she received two Public Service Medals from NASA and a Group Achievement Award for her contributions to NASA's HRMS Project. In February 1997 Dr. Tarter received the Chabot Observatory Person of the Year Award, and in November 1998 she received the Women of Achievement Award, Science and Technology category, presented by the Women's Fund and the San Jose Mercury News.

She has published scores of technical articles, has been elected to many professional societies, and has served on a number of scientific advisory committees. And she travels globally to present lectures and papers at numerous scientific symposia and colloquia. In April 2003 she did join the Heidelberger Toward Other Earths-Conference (DARWIN / TPF AND THE SEARCH FOR EXTRASOLAR TERRESTRIAL PLANETS) and gave a scientific lecture (SETI: Another way to find habitable worlds and public lecture in the conference centre as well ("SETI: Science Fact, not Fiction"). This event was open to the public and the conference participants. Despite the fact that Jill was very busy and stressed (jet lag) - she directly came from Puerto Rico (Arecibo) and did stay in Germany only for two days and than directly flew back - she was kind enough to join this interview. Thanks Jill - and may the ambitious scientific SETI-observations some day be successful...

The technical term brown dwarf was created by you. So why did you decide to specialize in radio astronomy and not became a planet hunter for example?

Jill Tarter: Actually I learnt how to do radio astronomy in order to do SETI. My undergraduate degree was in engineering physics. When I attended graduate school I did theoretical astrophysics, dealt with brown dwarf stars and what they might look like - and how you strip gas out of galaxies and clusters.

When I graduated from school someone gave me the Cyclops Report, which was the first engineering design study about how you might look at for signals from extraterrestrial intelligence. I was so impressed by the fact that I live in the very first generation of all human kind that could try to get an answer to this old question by conducting an experiment rather than asking the priests and philosophers. Somehow all the other questions became less interesting because here was something that could be practically done. So I just decided: That is what I want to do and so I learned how to do radio astronomy! On the other hand SETI is, as a matter of fact, a way of finding planets by looking for those planets which are inhabited. Therefore, actually, you could call me a planet searcher.

Last year the SETI institute did change their logo. Why didn't you take the chance to change the term SETI as well, for example into SETT (Search for extraterrestrial technology). Was it because you are looking as well for alien signals from higher developed extraterrestrial intelligent cultures with technology and not only for intelligent aliens?

Jill Tarter: We changed the logo for the very good reason that the SETI Institute actually does a lot more than just the radio search for extraterrestrial intelligence. In fact we've been doing astrobiology since 1984 when we founded the SETI Institute. We have over 100 scientists who are looking at ways to detect oceans under the ice in Europe [fourth largest moon of Jupiter], how you could get beneath the surface of Mars and look for relicts of life on Mars. So we have this much broader characteristic than the original logo, a radio telescope, expressed. The new logo which is representational is supposed to imply things like life, planets or signals and so on. That's why we changed the logo, it is more representative of what many of our people do. We didn't change the name for the same reason that JPL is still called JPL, although they really don't do anything related to jet propulsion anymore. But the name is branding. Since SETI's reputation has been growing, we hoped that the majority, and in particular the congressional community, could manage to learn to live with SETI rather than thinking about the option "Litte Green Man". So we kept the name, but it was widely discussed.

Since the beginning of recorded history humans of all cultures looked up at the sky and wondered if anyone else is out there looking back. Right now at the beginning of the 21st Century we are still asking the same question. If you look back at the short history of SETI - what was the most important paradigm shift?

Jill Tarter: There are a couple of paradigm shifts here that happened at the end of the 20th and the beginning of the 21st century and which are incredibly important. One is that we found planets around near-by-stars. We expected to find analogues of our own solar system. We haven't found those yet because we don't yet have the appropriate tools to find small earth-like-planets. In the coming decade we will know pretty definitively whether there are many other earths out there. Before we just had a theory which said they should be there - now we are getting the data.

The second thing is that we are getting a much broader view of life. I think we have a lot of chauvinism about defining life and thinking about big macroscopic human type life. But now we are experiencing that at least at the level of microbial life is far more sturdy. It can exist in extreme environments that we never even imagined That makes us aware of the fact that life elsewhere does not necessarily need a planet exactly like the earth in order to emerge. Digital electronics has replaced analog devices. That means we can benefit from this fantastic exponential increase in capability of our tools for observing in various ways either at radio part of the spectrum which we have observed since 1960 or at the optical part of the spectrum which is new. Both types of signals can not be produced by nature as far as we know. So we ended up looking at the radio for narrow-band-signals, which are very very compressed in frequency and continuous - or the pulse-duration is long. Nature doesn't seem to do that sort of thing.

In the optical field we're looking for signals that are very broad but very short in time, so that optical pulses last less than a Nanosecond for example. Now we have the technology to look for that type of thing and our technology is even getting better. So our tools are getting more compatible with the task. New technology is happening all the time. When the technology improves, when we get other, new tools we'll add them to what we're trying to do and take advantage of it. It doesn't mean that one is better than the other. When you really don't know what you are looking for - we have a saying that you shouldn't put all your eggs in one basket - you should try multiple things.

Although the TPF-Darwin-Meeting did not concern the SETI Program directly you did participate in this conference? Why?

Jill Tarter: Well, I'm here for two reasons. One is they were kind enough to ask me to give a public lecture about SETI because they understand that's is very popular. In addition, I presented a scientific paper because it turns out that SETI is a way of detecting a certain class of planets - planets which are not only habitable but planets which are inhabited by civilisation that have technology we can detect. Other searchers for planets or for life on planets around stars near our own Sun are concentrating on finding evidence of microbial life. It's possible to explore a larger region of the galaxy to look for planets which are far away and have technological inhabitants. So SETI is a different option for finding a certain type of planet. We don't know whether there are any such but indeed it is just one more option in the bag of tricks for trying to understand the prevalence and distribution of life in universe.

The likelihood of finding the first earth-like-planet is getting higher and higher because space telescopes getting better and better day by day. Do you think that TPF and Darwin will be successful?

Jill Tarter: Well actually before Darwin and TPF will start we have a small spacecraft called Kepler.

And COROT!

Jill Tarter: And COROT as well. And those will begin to tell us about what the frequency of small terrestrial planets actually is. They will be too far away to study individually. But we can say with some confidence that if we built a Darwin or TPF or a joint project to look realistically at a couple of handfuls of near-by-stars that there is some probability in fact that they will contain terrestrial planets.

It looks like Planet hunting seems to become a new Olympic discipline. It's very obvious that the scientist-crew who will discover the first real earth-like-planet will receive the gold medal. Is there a comparable situation among the different SETI-Teams? Is there any constructive competition?

Jill Tarter: Sure, we are all competing. We would all like to be the first to get a signal. There is no question that there is a motive there. But of course we are also cooperating. The SETI groups have been cooperating for a very long time. Indeed, the SETI Institute sponsored a series of workshops back in 1997. That gave SETI new perspectives in the current technologies. We really haven't done an engineering study since the Cyclops Report which got me started in this field. And technology changed hugely since then. So we sat down and brought in all the players and also we brought in a lot of technologists from Silicon Valley.

We said: "Okay what are our plans for the next twenty years?" One of the things that came out is that we should still continue with our radio-searches because they still make sense, but we should do it with our own telescopes! There are ways to build a radio telescope for SETI which are less expensive than traditional. It also turns out is that there is a new option: the optical technology that will allow us to look for very rapid broadband pulses.

For example, Charlie Townes came to that workshop. Back in the sixties, when the radio-searches got started, Charlie said: Why don't you look for lasers too? But the problem was that we really didn't have the fast photo-diodes that were necessary for the search. They were there, but not affordable to us at that time. But now we do have them. Although we still need to find a good way to search for transient signals. Almost all the searches require that the signal will be on when you're looking in the right direction. But there are many reasons that what might be out there is something that beams your way only occasionally. And everyone would miss that. So we are looking at ways to find transients in the radio and until now nobody has come up with a way to do it in the optical. So we're supporting these different technologies. I mean everyone hopes to be the first. But in the end we all want to know the answer of the question - and we will applaud very loudly any successful group.

It's a well-known fact that radio astronomers are very unhappy about the radio-pollution caused by satellites and other technology. The terrestrial interference is pretty bad here. Despite the very optimistic plan to build a radio telescope in outer space or on the dark side of the moon, what for realistic options do you have in fact to improve the situation?

Jill Tarter: We actually need to take advantage of the same technology that allows us to have all these satellites and mobile phone communication. We have to use that more aggressively ourselves to mitigate, to try and help to protect us from this interference. And so as we build this new telescope for SETI - the Allen Telescope Array (ATA) - we will make it out of small components that are only six meters and we use 350 of those and array them all together. Part of the reason for building it that way is to create an interferometer with so many elements that you have lots of different possibilities. So we can do in the radio field actually much better the same sort of thing that TPF and Darwin are trying to do with optical, which is null out the signals you don't want.

The interference which for the planet finders is the light from the star are for us the signals from satellites and other sources of interferences. We can actively spend as much effort computing in this field as we do for finding signals. We can aggressively use that type of construction of a large number of elements in an array to get rid of the worst of the satellite interference. Once we have developed these techniques we can stand up to the community around the world which controls the use of the spectrum and we can say: We're doing absolutely everything we can to mitigate against the effects of the interference. Now the other side also has to take responsibility and has to put an equal amount of effort into making their transmissions less dirty so that the interference does not spread across the spectrum.

Of course, as these technologies get more prevalent, they start to interfere with one another. We're looking forward - about the same time that TPF might actually be launched - to building another large telescope as a global project, not just as a SETI Institute and University of California project. A global cooperation to establish a radio telescope that is hundred times bigger than the ATA. And we will probably locate it on a place with very little population - maybe in the desert of Western-Australia or in some places in South-Africa or the Western United States with low population.

Furthermore we hope to find some agreement with the commercial transmitting industry that says: Alright, down here on the ground there are not many people, so you don't have any market, you are not selling any services. So as you go over why don't you change the direction your beams point in order to not directly radiate this one place on Earth where you not will make any money anyway. Hopefully, by demonstrating that we are doing absolutely everything that we can to protect ourselves we can get this kind of cooperation in the future. This option is less expensive than going and building a radio telescope on the far side of the moon.

By the way, the far side of the moon is not going to stay that way very long as NASA begins to use the L-2 as well as the L-5 vibration points as staging or parking orbits for their spacecraft with the idea of being able to service them in the future. We are already beginning to see that we might lose the far side and so we are thinking harder about what we can do on Earth. We have to do something different than we did in the past - and the first step is: Working hard to protect ourselves with everything that technology will provide.

SETI is still looking at the nearest 100 stars, among others. But is there no necessity to widen your horizon? Will there be a continuous intergalactic SETI-Observation some day?

Jill Tarter: Well, in fact there has been a number of searches of other galaxies. In order to detect a signal over intergalactic distances it has to be enormously much more powerful than a signal within our own galaxy. But we don't know what the luminosity function of transmitters is out there in the universe. It might be that there is a distribution which has a shape such that there are a lot of low-powered transmitters and there is a tiny, tiny tail with a few very powerful signals.

So the argument is like that: Suppose you pick a galaxy whose size is just equal to the size of your telescope beam, so all the stars fit in your beam at once and then you observe in that direction - now you will have in your beam all 400 billion stars from that galaxy. Possibly if there is just one or only a few very powerful transmitters you might pick them out. We don't know the answer because so far at least we have not detected anything. Galaxies or aggregates of stars that fit within your telescope-beam make sense to include in your search strategy.

How would the detection of an "intelligent" extraterrestrial radio signal change humankind?

Jill Tarter: Understanding our place in the cosmos is the next step in the Copernican revolution. We may eventually conclude that we are the only technological civilization in the Milky Way Galaxy, and so we have a right to hold onto our "top of the heap" view of ourselves. I personally doubt that this is so, and if we detect another civilization, its members will be so vastly different from us that the discovery will trivialize the distinctions among humans that today lead us to hatred and violence.

If you got the chance to participate in the first manned mission to Mars, would you join the expedition and fly to the red planet?

Jill Tarter: Absolutely. A lot of people call it the first people mission to Mars, not the first manned mission. In fact when I was an undergraduate student I was asked what I wanted to be and I said: I want to be the first woman on The Moon! Later I even did apply to be a payload specialist on the shuttle. Well, a women to the Moon or Mars - that is actually an option which is still open. We have not managed to put someone of my gender in those places yet.

Well, you're still young enough....!

Jill Tarter: I wish I were. But given a chance - absolutely: I would fly.

Is there any message you like to deliver to the millions of SETI@home users around the world?

Jill Tarter: I think that SETI@home as a distributed computer experiment has been successful beyond belief. I am very gratified that so many people are so interested in SETI that they will in fact donate their computing time to do this. And that is a message which fortunately is not being lost on the politicians at least in the United States. I think it's part of the reason that the climate is changing in Washington D.C.; we can now look in the near future at forming a public-private partnership between the philanthropic private funds that have funded all the SETI work for the past ten years and federal funds.

I don't think anybody in the SETI community ever wants to be totally funded by federal funds again, because it was very dramatic when all the funding was terminated in 1993. SETI was in a terrible state. We have managed to find private support and that helped us to do some very innovative things. But indeed the technologies that we want to use are getting more expensive because we have already exhausted all the simple things. That means that the scale of funding that SETI requires is getting to be larger than probably we can sustain with philanthropic funding only. One of the things that SETI@home has done in a very visible way is to show the political leaders that indeed the public really is interested in SETI.

Are Senator William Proxmire and Senator O'Bryan, who terminated the SETI-Program in 1993, of the same opinion?

Jill Tarter: Senator Proxmire retired in 1989, and Senator O'Bryan, who terminated the funding for SETI in the United States, has also retired. Now we have a new generation of supporters. And I think SETI@home is playing a big part in that.

Some people claim (even Frank Drake) that the WOW-Signal so far was the most serious suspicious signal which ever was detected. What is your personal opinion about the Jerry-Ehman-Signal? Is it still a mysterious one?

Jill Tarter: The Ohio State University Radio Observatory operates with a dual beam feed horn system. Knowing that terrestrial technology of various sorts would cause interference, the builders of the telescope installed dual East-West feeds as a filter to exclude emissions that were not coming from small sources moving on the sky at sideral rate. An extraterrestrial signal should appear first in the west beam and then in the east beam, as the Earth rotates with the telescope pointed at a fixed declination.

More recently, Paul Horowitz improved on this scheme for his BETA search by adding a third, omni-directional antenna, with the requirement that sources that appear to transit through the two beams must also not be seen in the omni-beam. Why this improvement? Side lobe structure and temporal variability can combine to mimic the expected dual-beam pattern. So possible signals that pass the first discriminant, and exhibit the desired dual-beam profile, are subjected to an additional test.

Never is a signal that appears in only one beam accepted as a candidate. Yet in 1977, that was exactly what happened with the WOW! signal. That signal failed to pass the test intended to discriminate against interference, and yet it has become part of the SETI folklore, generating a small cottage industry for over twenty years. In my opinion, this has not helped the credibility of the SETI endeavor.