Narrator: Mars then and now -- 30 years after Viking.
I'm Jane Platt and you're listening to a podcast from JPL -- NASA's Jet Propulsion Laboratory in Pasadena, Calif.
Natural sound of control room: Nav is green for touchdown. ACS is green 1.5 degrees per second max. Point 2 g's. Touchdown, we have touchdown. (cheers and applause) We have touchdown.
Narrator: High drama, tension and excitement in the control room on July 20, 1976, when Viking 1 became the first spacecraft to land on Mars and beam back detailed images of its surface. An incredibly emotional day, remembered vividly by those who were there.
Gentry Lee: How do you possibly describe the first photograph that a human being has ever seen from the surface of another planet?
Narrator: Gentry Lee of JPL was mission planning director for Viking, including Viking 1 and its twin, Viking 2, which would land two months later. Bob Tolson of NASA Langley Research Center was the navigation manager.
Bob Tolson: These kind of things do change your life. You really, you appreciate a whole lot more the wonders of the heavens.
Narrator: Of course, since those historic Viking missions, there've been many more wonders, including the six spacecraft currently operating at Mars. JPL Chief Scientist Dr. Dan McCleese arrived at the lab during Viking. Let's get a quick roll call of what's up there on Mars.
McCleese: The Mars Global Surveyor, which is an orbiter that is characterizing the surface of Mars, its geology, its weather. We have the Mars Odyssey orbiter, which is looking at the elements on the surface of Mars, the two rovers -- Mars Exploration Rovers, Spirit and Opportunity. The Europeans placed an orbiter called Mars Express at the planet. The United States has one more orbiter, the Mars Reconnaissance Orbiter, that is just finishing its entry into its final mapping orbit.
Narrator: In fact, McCleese is principal investigator for an instrument on Mars Reconnaissance Orbiter. The entire fleet of current Mars spacecraft are, in a sense, offspring of the dramatic goals of Viking.
McCleese: What we began talking about with the Viking mission was a mission to land on the surface and begin the search for life on another planet. And from that perspective, the results that were coming back, even right from the very beginning, suggested that the surface of Mars was very, very sterile.
Narrator: No evidence of two essentials for life as we know it -- liquid water and organic material.
McCleese: There were channels that were seen from orbit but on the surface where we landed in both locations, the cold, dry rocky surface is what we saw around us, so these were all views of an alien world.
Narrator: No evidence of life on Mars? A big disappointment to many at that time.
McCleese: Well, ironically the success of Viking led us to close the doors to further exploration. In fact, it was over 20 years before the United States was to send back another mission. Nobody wanted to hear the life word associated with Mars. Therefore Mars was dead, cold, and low pressure and therefore boring.
Narrator: That next back-to-Mars mission, Mars Observer, failed shortly before arrival. And it wouldn't be the last disappointment over the years. In fact, the history of Mars exploration is a see-saw -- tremendous successes and some disheartening failures.
McCleese: Failure is part of the way in which one makes progress. We make progress as human beings by trying things that are sometimes too difficult. And that being too difficult, by luck, sometimes it works and sometimes it doesn't. And I think we learn. And so we apply what we learn to the next missions, and that's the way space exploration has been from the very beginning.
Narrator: After Mars Observer, NASA picked up and launched two hugely successful new missions - the orbiting Mars Global Surveyor, and Mars Pathfinder, which landed July 4th 1997. Its rover, Sojourner, was a predecessor of the current rovers, Spirit and Opportunity, which are still working after two-and-a half years. So three decades after Viking, with a fleet of spacecraft at Mars, what have we learned about the planet?
McCleeese: We've discovered that ancient Mars had regions which we call habitable, which means places where life might have begun. But even if it was never there, we believe that we have a second planet in the solar system, the first being Earth, where life might have developed. And I think that the fundamental new information about the planet is our conviction that it's a habitable planet.
Narrator: What's ahead in Mars exploration?
McCleese: One of our objectives was to bring rocks back from Mars to the Earth and make them available to researchers all over the world. And while that's still years in the future for us, because it's an expensive mission, it is one of our most important objectives. Another objective we have long-term is to get humans to the planet. Now I'm talking very far in the future. But each one of these robotic missions the rovers, the landers, the orbiters, all contribute to the preparation for humans, both in terms of their living there and in identifying what kind of science they should do when they're there.
Narrator: Before I give you a couple of urls for more information online, you might be interested to know that Mars Pathfinder in 1997 was the first Mars mission that the public could follow on their computers, watching as pictures came down.
McCleese: The event and the access to the images on the Internet made many of the members of the scientific community and the leadership recognize that the Internet was the future mode of communicating science to the public.
Narrator: More information on Viking, including other multimedia products, online at http://www.nasa.gov/viking . Info on NASA's Mars exploration program overall is at http://www.nasa.gov/mars . Thanks for joining us for this podcast from NASA's Jet Propulsion Laboratory.
For a full podcast, go to +http://www-stage.jpl.nasa.gov/multimedia/audioclips/viking-20060719/".
Visit the Viking mission page for more information about the mission.