Dr. Jim Garvin: The next wave of discovery and beyond Mars was the outer planets.
Lindley Johnson: Pioneer 10 and pioneer 11 were, you know, the first two spacecraft to actually cross the asteroid belt.
Dr. James Green: Our first foray into the outer planets.
Dr. Jim Garvin: We were able to go and see these gas giant worlds for the first time by actually being there. What the mission did was not solve all the questions. What it did was, it raised the right ones to ask next.
Dr. Ralph McNutt: Voyager just blazed a trail of, you know, new knowledge throughout the entire solar system.
Dr. Daniel Glavin: The grand tour of the solar system, right? These planets only align, I think, every 176 years. So there was that one shot in 1977 to do it.
Dr. Lori Glaze: When voyager observed Io, the moon of Jupiter... -
Dr. Ralph McNutt: Was it a rotten orange or a pizza pie?
Dr. Stamatios Krimigis: And one of the graduate students noticed this protrusion at the edge of Io and said, "look at that!" he said, [gasps] "volcanoes!"
Dr. Jim Garvin: Hmm, not seen anything like this. Oh, gee, except on Earth when volcanoes erupt.
Dr. Lori Glaze: Io is the most volcanically active body in the entire solar system.
Dr. Jim Garvin: One of those "oh, my god" moments. We have something new.
Dr. James Green: Rather unexpected indeed.
Andrew Chaikin: It was this long odyssey from one world to another over decades.
Lindley Johnson: We had close-ups of all of Jupiter's large satellites. -
Dr. Jim Garvin: Voyager did that. It of course went to Saturn and saw the myriad of moons.
Dr. Ralph McNutt: And then of course, you know, Voyager 2 went on to Uranus and Neptune, and 99.9% of everything the human race knows about Uranus and Neptune was learned as a result of those two Voyager 2 flybys.
Dr. Nicky Fox: And then it's just kept going and going and going.
Dr. Ralph McNutt: Remember, these spacecraft are still working right now. They were lunched in august and September of 1977.
Dr. Nicky Fox: And going and going.
Andrew Chaikin: It's still sending back data from the very edge of what we would call the solar system.
Dr. Nicky Fox: And going and going.
Dr. Lori Glaze: To imagine that this little tiny spacecraft is just trudging along and then reaching the outer limits of our solar system.
Dr. Jim Garvin: Those missions begat the next phase of exploration of the outer solar system with, of course, Galileo and Jupiter.
Dr. James Green: We now knew we needed to get back to Jupiter and get into orbit.
Dr. Jim Garvin: Galileo had a problem with unfurling its giant, you know, 12-foot antenna.
Dr. Stamatios Krimigis: All of a sudden, instead of 100,000 bits per second, we could only transmit 10 or 20 bits per second.
Dr. Jim Garvin: We figured out a work-around to still capture the critical data even at a data rate that today would frustrate the kids of the world.
Dr. Stamatios Krimigis: And nevertheless, we learned a lot of things by virtue of the fact that we were in orbit around the planet. We stayed there for a long time. So that was a terrific mission.
Dr. Daniel Glavin: One of the missions that sticks out is actually a recent mission, the Cassini-Huygens mission.
Andrew Chaikin: Cassini is like the world series of planetary exploration.
Dr. Nicky Fox: Cassini gave us our first sort of close-up real images of the planet Saturn.
Lindley Johnson: You must think of Saturn and its satellites as a planetary system.
Jody Davis: You get this unprecedented look at Saturn's moon Titan.
Andrew Chaikin: And then it drops off this probe called Huygens that actually lands on Titan and sends back images from the surface with these little icy cobbles.
Lindley Johnson: I mean, Titan is another world with meteorology on it.
Dr. Jim Garvin: And it's raining methane in the southern hemisphere right now.
Andrew Chaikin: And we see lakes of liquid hydrocarbon on the surface of Titan.
Dr. Stamatios Krimigis: Nature seems to be far more imaginative than we are.
Dr. Ralph McNutt: The real sleeper on the Cassini mission is Enceladus.
Dr. Daniel Glavin: During the flyby, we found this plume of ices emanating from the south pole.
Dr. Stephanie Getty: These incredible geysers that are erupting ices and water and ammonia.
Dr. Daniel Glavin: But more importantly, the mass spectrometer on the mission found simple organic compounds: hydrocarbons.
Dr. Ralph McNutt: One of the things that you need for life is water, and you need organics, and it's interesting because these plumes that are coming from the south pole of Enceladus seem to have a little bit of both.
Dr. James Green: Many people ask NASA, "wow, what do you think, is Pluto a planet or not?"
Dr. Lori Glaze: Whether it's a planet or not and whether, you know, whether we grew up with Pluto being a planet.
Dr. James Green: Our opinion is: we don't care. It's an object worthy of study.
Dr. Lori Glaze: This is really kind of the last outpost in our solar system.
Dr. Jim Garvin: And new horizons is gonna fly by Pluto and all the other moons in July 2015.
Dr. Noah Petro: Being able to finally resolve the surface of Pluto and its number of moons-- its growing number of moons-- that's certainly gonna be really cool.
Dr. James Green: And that's really incredibly fascinating that even today we're finding new things about our solar system.
Dr. Ralph McNutt: It really is sort of the final voyage of discovery of looking at this first piece of what is really out there in the depths of the dark.
Page Editor: Tom Shortridge