Revisiting the Viking Missions to Mars

The first Viking lander touched down on Mars 30 years ago this week. We look back at the Mars Viking missions with Joel Levine, senior research scientist at NASA's Langley Research Center.

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IRA FLATOW, host:

You're listening to TALK OF THE NATION: SCIENCE FRIDAY. I'm Ira Flatow.

Thirty years ago yesterday the first Martian lander set down on the face of the red planet. The lander was one of two twin Viking spacecraft, each one having two parts. There was an orbiter and a lander. And that set the stage for many other Mars missions to follow.

Joining me now is Joel Levine. He is senior research scientist at NASA's Langley Research Center and principal investigator on the Mars ARES mission. That's a proposed mission that would send a robotic airplane to Mars to fly over the surface looking for the chemical signs of life.

Dr. Levine joins us from NASA Langley in Hampton, Virginia. Welcome to the program.

Dr. JOEL LEVINE (Senior Research Scientist, Langley Research Center, NASA): Thank you, Ira. Pleasure to be here.

FLATOW: Could actually the ARES, could it actually find that lander if it were to fly in the right place?

Dr. LEVINE: Actually, we know where the lander is very accurately. And if we wanted to fly over the Viking lander, we could. Scientifically, though, I don't think it would be as exciting as the mission we have planned.

Our mission, as it's planned, is to fly over some of the oldest terrain on Mars, very highly magnetized crustal material that dates back to the beginning of Mars, 4.6 billion years ago.

FLATOW: Wow. Let's go back just not quite that far. Let's go back just about 30 years ago because I remember that mission. It was very exciting when that Viking touched down because we saw our first actual pictures of something sitting on the surface.

Dr. LEVINE: That's right. And we didn't know what we would find. When the Viking lander 1 landed on July 20, 1976, it sent back the first pictures from the surface of Mars.

As you remember, the photographs were constructed in a series of strips, vertical strips.

FLATOW: Right. I still have mine.

(Soundbite of laughter)

Dr. LEVINE: I was sitting - and I still have mine, too - and I was sitting there as it came in and I was wondering, would we see an ancient city? Would we see an elephant? Would we see something walking around?

Carl Sagan, a member of the Viking science team, said the best life detection experiment on Viking was the camera because we'd be able to see if, in fact, there were any form of life on Mars.

FLATOW: And it was those early Mars missions that put Carl Sagan on the map, did they not?

Dr. LEVINE: You're right. And he was a very important contributor to the early Mars missions and to the general interest in planetary exploration.

FLATOW: Let's talk about that mission. You say - you quote him as saying, the best experiment was the camera that showed the Viking sitting on the ground. But there were experiments on board to actually look for life in the soil, right?

Dr. LEVINE: Yes. There were three biology experiments on the Viking lander 1 and Viking lander 2. Let me say that I think Viking was perhaps the most sophisticated scientific experiment we've ever performed.

There were two dozen different experiments. There were instruments to measure the composition of the atmosphere of Mars as it entered the atmosphere. An important result of that measurement was the discovery of nitrogen on Mars.

Prior to that, we did not know nitrogen was there. Another important experiment was the measurement of nitrogen isotopes by Viking. And by looking at the difference in the ratio of isotopes it was concluded that Mars lost 99.99 percent of its atmosphere.

So, as Viking entered the atmosphere of Mars it made critical measurements. As it landed, it made measurements, meteorological measurements, measurements of the surface, and did some very sophisticated biology experiments.

FLATOW: What kind of life did it look for and how did it look for it? I mean, actual microbes, I remember, they were talking about on the surface.

Dr. LEVINE: Yes. It looked for life in the form of microbial life by looking at respiration products, by looking at how a microscopic form of life would ingest atmospheric gas and exhale gases.

And the measurements from Viking on the biology experiments did not suggest evidence of microbial life or any life on the surface of Mars.

What Viking did discover, a very important discovery, is that the surface of Mars is very highly reactive chemically. In fact Mars has a unique surface, and the surface of Mars is more chemically reactive than any surface we know about.

And it's believed that the high chemical reactivity of the surface is due to the deposition of chemically active gases from the atmosphere onto the surface, gases like hydrogen peroxide and ozone. So Viking discovered the surface of Mars to be a very strange place.

FLATOW: And did it not actually just sprinkle some ingredients on the surface to see if there were microbes, there would be the output the microbes would make?

Dr. LEVINE: Yes. Instead of sprinkling things on the surface, Viking had a shovel on an arm and brought samples of Mars' surface into a chamber. And in the chamber, the respiration and the metabolic properties of the surface sand material were measured and we added nutrients and measured the gases that were produced.

FLATOW: And of course every time there's something going on with Mars, from satellite pictures that show a face on Mars to this, even the first Viking mission, there was always some - there is always some sort of controversy. And there was actually controversy, if I remember, about that experiment of sprinkling the nutrients on the sample.

There was one person - I can't remember who it was - and it still is floating around, you know, in cyberspace, the idea that there was some life that was shown but we just didn't measure it correctly. There was a mistake done in the experiment.

Dr. LEVINE: Well...

FLATOW: And I'm sure you're familiar with that one.

Dr. LEVINE: Yes, the labeled-release experiment, the principal investigator was Gil Levin, and Gil to this day thinks that his experiment gave evidence of microbial life on the surface of mars.

I have to say that's a minority opinion. The general consensus is that the highly reactive chemical nature of the surface of Mars was responsible for the measurements he obtained.

FLATOW: 1-800-989-8255. We're talking with Joel Levine, senior research scientist at NASA's Langley Research Center.

You talked about Viking being the most complex laboratory experiment ever conducted. Why was it possible? Why was such a mission and - why was it possible that we could do that?

Dr. LEVINE: Well, I think the key aspect of Viking was a very strong, dedicated team of scientists and engineers and project managers that lived, 24 hours a day, the Viking mission.

They developed technologies, Ira, that are still being used today. Every landing we've had on Mars since Viking 30 years ago - Mars Pathfinder, even the Mars-exploration rovers Spirit and Opportunity - were based on Viking technology. A supersonic parachute that opened in the Mars atmosphere, the aeroshell design, is all based on Viking, and the thermal protection system.

And we had never landed - soft-landed an object on the surface of Mars, and there was no textbook. And as a result, Viking was highly tested both in laboratory facilities and in the Earth's atmosphere.

So we knew so little about the atmosphere of Mars, we knew so little about this technology, that we couldn't take anything for granted, and we are going back. Scientists and engineers at Jet Propulsion Laboratory had said very recently they are still going back to the database that Viking developed 30 years ago.

Let me point out that the Viking Project was developed and managed at the National Langley Research Center in Hampton, Virginia. The landers, which were the responsibility of Langley, were developed by a company called Martin Marietta. That company is now called Lockheed Martin.

And the orbiters were developed at the Jet Propulsion Laboratory. JPL also had responsibility for mission operations using the Deep Space Network. It was a first-class team of industry, government laboratories, and scientists at the leading universities in the country, and everything worked properly.

I think the reason everything worked properly is nothing was taken for granted. It was tested and re-tested and re-tested, and the organization, the management of the Viking Project - Jim Martin is a fabled project manager. He was the project manager of Lunar Orbiter. They had five out of five successes. They pinpointed the landing sites for the Apollo astronauts - high-resolution pictures of the surface of Mars.

Israel Taback was the chief engineer on Viking. Gerry Soffen was the chief scientist, the project scientist - a world-class scientist. Tom Young was the mission manager. There were some very, very dedicated people and it was a very dedicated team of about 500 scientists and engineers.

FLATOW: Dr. Levine, I don't want to put words in your mouth, and I want you to correct me if I'm misinterpreting what you're saying, but I'm almost hearing you saying those were the good old days at NASA and they're not here anymore.

Dr. LEVINE: I think they were the good old days. Well, I think that a project like Viking was a unique project. I think that we've gone to other approaches to planetary exploration - quicker, faster, cheaper to some extent. And Viking did not follow that philosophy.

FLATOW: Well, that brings us back to this, the ARES Mission, this proposed mission of your robotic airplane for 2012. Is that on the board? Or when you say proposed, does that mean it's not funded? Is it something you'd like to do or is it going to suffer from budget cuts to pay for missions to the moon and further to Mars?

Dr. LEVINE: Ira, every four years NASA solicits proposals for a program called the NASA Mars Scout Program. The proposals are due April 1 of this year, and the Langley Research Center in partnership with the Jet Propulsion Laboratory and with Lockheed Martin, with the Draper Lab and Aurora Flight Sciences, is proposing a robotic airplane to fly over the surface of Mars, about a mile above the surface.

It will fly for hundreds of miles. It will look for gases of biogenic origin. It will study chemically active gases. It will map out the distribution of water. It will study the surface of Mars and the interior of Mars. It will look for sub-surface water.

This is a new platform. As you know, we've never had an airplane fly through any atmosphere outside the Earth, and we believe that an airplane, an aerial vehicle, combines the best features of an orbiter and a rover. And we are proposing this NASA. The proposal is due April 1.

Four year ago, Ira, during the first Mars Scout competition, we were one of the four finalists, and eventually NASA selected Phoenix. Phoenix is a University of Arizona lander, stationary lander, that will land in the north pole of Mars; and it's scheduled to be launched next year.

Now NASA is soliciting new proposals for a launch in 2011, arrival at Mars in 2012, and we will re-submit the ARES mission.

FLATOW: Talking with Joel Levine, senior research scientist at NASA's Langley Research Center on TALK OF THE NATION: SCIENCE FRIDAY from NPR News. I'm Ira Flatow.

So this is a novel idea, and there is enough - how long would it stay up? Once it's flying and there's enough atmosphere to support it - that goes without saying, or else you wouldn't be talking about an airplane flying there - does it go up once? Does it never land or is it flying around until it runs out of fuel?

Dr. LEVINE: Well, Ira, it lands when it runs out of fuel. It's a rocket-powered airplane. It will fly for about 90 minutes before it runs out of fuel then it will make a graceful landing on the surface of Mars.

Now, Mars is a unique object to study I think for two main reasons - or at least I consider two main reasons. The first is of all the objects in the solar system, Mars is the most likely object for life, other than the Earth. So we're interested in the search for life outside the Earth. Mars is a good target.

The second reason we're interested in Mars is we believe that Mars has experienced catastrophic climate change over its history. We believe that in its early history - remember, Earth and Mars, the solar system, 4.6 billion years old. 4.6 billion years old the age of Earth and Mars and the solar system.

We believe when the Earth formed, when Mars formed, Mars was very different than it is today. We believe Mars had running water in the form of rivers. Mars had large lakes. And we also believe that Mars had planetary-scale oceans in the northern hemisphere.

Mars was very different. In order to have liquid water at the surface, the atmosphere of Mars had to be considerably thicker than it is today. Today, the surface pressure on Mars is 6 millibars. The surface pressure of the Earth is 1,000 millibars.

The atmosphere of Mars today is like the Earth's atmosphere is like at 100,000 feet. Yet in order to have liquid water on the surface, Mars had to have a much thicker atmosphere. And, in fact, Viking data 30 years ago gave us the first evidence that Mars may have lost 99.9 percent of its atmosphere.

FLATOW: This Viking data, you mentioned this a bit before, but I want to pursue it in the last minute we have here. Is anyone still using Viking data now...?

Dr. LEVINE: A very good question, Ira. We are still giving masters degrees and Ph.D.s at universities through the United States, in fact throughout the world, for analysis of Viking data.

Viking orbiters took over 50,000 images of the surface of Mars. The Viking landers took over 7,000 images of the surface of Mars. There just aren't that many geologists around to study all of those pictures.

I attended a briefing yesterday by a graduate student from Brown University who is completing his Ph.D. for using analysis of several dozen photographs that Viking took in 1976.

So there is a tremendous database about Mars that we're still exploring, we're still mining. And now that we have as a national commitment to send humans to Mars some time in the future, we are trying to find out as much about Mars as we can.

The Viking data set, which, true, is 30 years old, is one of the most exciting, one of the most productive data sets we have ever obtained.

FLATOW: Well, Dr. Levine, congratulations on this anniversary to you and yours at NASA and everybody else who took part in that mission. And good luck to you, and we'll be watching the future of your next mission, the ARES.

Joel Levine is senior research scientist at NASA's Langley Research Center and principal investigator on the Mars ARES mission proposed some time in the future. We'll hope to see it.

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