Morning Introduction:

>> Good morning. We would like to welcome you here to a celebration, celebration for a little spacecraft which "Sky and Telescope" I think nicknamed this week on their line the Energizer Bunny of space because it just keeps on ticking. It has been out there 25 years and certainly has been a pioneer; and this is Pioneer 10 that we are talking about this morning. We would like to hope that you will enjoy today. We would like to present to you some of the people today that made this all possible, share with you some of the stories, some of the insight into Pioneer 10, and how it really came to be.

It's also kind of unique how life has its little twists. Because I remember I was there when Pioneer 10 was launched, and it was one of those launches that kept getting scrubbed, and the crowd that went out to see it kept getting smaller and smaller. I think by the time we finally launched, we were down to about 12 people. We started out with almost 100. And it was kind of late at night, so it's one of those things you really had to be there, you wanted to be there. And I wanted to be there because this was going to be the first spacecraft going to an outer planet. And also it was going to open up a brand new part of our solar system, which it really did.

So this morning we would like to start off by welcoming E. Julius Dasch, who is head of NASA's national space grant program and also the experimental program to stimulate competitive research, which is a mouthful there. But these are two of the largest of the higher education programs within NASA's education program. And these are concerned with teaching, research and public service. Dr. Dasch, who is a geologist by training, was telling me about his explorations to look for meteorites, some which included some of the Martian meteorites which we heard about recently. The Director, Frank Owens, could not be here, but Dr. Dasch has gratefully decided to come down to welcome us here to NASA headquarters. And we want to thank all the people here at headquarters for being so nice to us.

Welcome - E. Julius Dasch

>> JULIUS: Thank you very much, Bob. Teachers, members of The Planetary Society, NASA personnel and ladies and gentlemen. It's my pleasure to welcome you on behalf of the NASA headquarters education division. As Bob said, our director Frank Owens could not be here, and he asked me to welcome you for him and the division.

The division comprises initiatives in several areas, most of which will be represented by the activities here today. We do both precollege and university education initiatives, and we are divided into six areas of concentration: Teacher enhancement, student services, curriculum and dissemination, education technology, systemic or comprehensive programs, and mission related research projects. Our groups are all geared towards supporting the agency's four strategic enterprises: Space science, this activity, aeronautics, mission to planet earth and education and human development. We have gotten a lot of educational and scientific and technical values from the Pioneer 10 mission, and I look forward to sharing this history with you here today. Thank you very much for coming.

>> BOB: We have a rather unique audience today. While I was sitting here looking at our stage we suddenly realized that perhaps we need to introduce each other. We have a number of educators with us today. And if the educators would raise their hand so we can see who you are. Thank you very much for coming out in the weather that we are having. The 81 degree temperatures are gone. Shoot, just got here a day or two late.

We also have a large number of people from The Planetary Society. And if The Planetary Society members would raise their hands. That is very good. Nice even split it looks like today.

Also, I'd like to welcome the people on the Internet. Some of you in the audience have probably been wondering what is going on over here on this screen that is all the way to my left. Today we have a virtual conference going, for those people who couldn't be here personally. And we have with us I think almost 200 people in 11 different countries. And so what they are being able to do right now is hear what I'm saying. And also at the same time for those that couldn't get the audio, we also have their chat screen going out here, where you'll see that they are repeating what we say. And so people can see and hear what we are doing here in this room all over the world, which when we launched Pioneer 10, no one would have imagined that that would have been possible. So times change and things rapidly go forward.

Pioneer 10 - Larry Lasher

Well, my first honor is to introduce Dr. Larry Lasher, who is the project manager for Pioneer 10. And we have been working on this project for quite awhile. Larry is the person who started all this. So you have to give him a lot of credit for all the work that has gone into making this become a reality. And Larry is a person who is dedicated to education and to getting the word out about how well Pioneer 10 has done its job. He also is someone who, just to give you a little background, has been with various Pioneer or Pioneer programs, including a lot of those that dealt with the Pioneer Venus, dealing with the atmosphere. Also he was part of the program that we looked at to do a cosmic and lander return mission. So Larry has participated in a great number of different NASA projects.

So Larry will be here this morning to tell you a bit about the background of Pioneer 10. So Dr. Larry Lasher, who started all of this program.

>> LARRY: I see that I'm all plugged up here. Thank you for that fine introduction, Bob. I appreciate that. And it does my heart good to see this fine audience that we have here. I know you had to brave some inclement weather, but I'm glad that you were all able to make it.

Now I'd like to take you back 25 years ago to March 2, 1972, to Cape Kennedy, now called Cape Canaveral for the launch of Pioneer 10. Like a day like today, you could hear the sound of distant thunder and see lightning illuminate the Florida sky's; maybe not lightning today. Let's wait. And the launch had been delayed for several days because of high winds and other causes. Three launches were scrubbed already and we were facing launch interval restrictions. Really concerned. But wait?

The signal is given, it's a go. And at 8:43 p.m. there was ignition of the main booster engine and the Atlas Centaur launch vehicle lifts off the launch pad as shown here in the first slide. The grandeur of the night launch was enhanced by the lightning flashes and the brilliant light of the Atlas engine exhaust jets as it rose through the clouds. Then the second stage kicked in, thrusting Pioneer to space, the first space probe to the outer planets. And you could see, the white ball of bright white fire begin to disappear into a black void of the night sky as Pioneer was on its way to Jupiter and beyond.

The next slide -- I don't see the slide. I see. Remotely. Great. You can see a figure of the spacecraft with 11 instruments, and the details are coming on the slide. They are descriptively named. On the table in the front for the audience here in the auditorium I have a 1/12 scale model of the spacecraft. The actual dimensions are 3 meters in diameter by 3 meters in depth; 9 feet by 9 feet. The front is a disk shaped high gain antenna. And there is a medium gain antenna positioned on top of a tripod. There is a long boom overhanging the spacecraft. And positioned on that long boom is the magnetometer, which measures interplanetary magnetic fields. Extending from the body of the spacecraft are two trusses. At the end of those are positioned radioisotope generators, RTG power sources, that power this light for the transmitter and instruments.

Just hours into the flight, about 11 hours, we passed the orbit of the moon, and then three months into the flight the orbit of Mars. At four months, Pioneer was the first ever to enter the asteroid belt, that region of rocks and dust and debris that presented a barrier to interplanetary travel. We couldn't go over the belt because it was too thick without using prohibitively expensive launch vehicles. So all vehicles have to go through the belt.

Well, Pioneer 10 weathered a seven-month travel through the belt and emerged somewhat unharmed at all. Although there are minor hits and they were recorded, we discovered that future spacecraft could go through there without special protection provided. It turned out the spatial density of the dust and small rocks inside the asteroid belt was just about the same as the adjoining interplanetary space. So now, the path for all future spacecraft was opened. Voyager was able to go through and visit the outer planets. And Ulysses is currently drawing the second orbit. And then we have Galileo investigating Jupiter. Later this fall, we will go to -- the crafts going to Saturn and Titan will pass through the asteroid belts.

As Pioneer 10 emerged from the asteroid belt, signals were sent to the cape to prepare for Pioneer 11 to go on a similar trajectory. Pioneer 11 represented a backup in case something happened to Pioneer 10 as it went through the asteroid belt, or going through the intense radiation field of Jupiter.

Meanwhile, Pioneer 10 continued its journey towards Jupiter. And on December 4, less than two years, December 4, 1973, less than two years after launch, Pioneer 10 became the first ever spacecraft to make direct observations of Jupiter. It came within 130,000 kilometers or 80 million miles.

In the next slide we can see Jupiter with its great red spot and that dark thing is the shadow of Io, the innermost moon. The Pioneer took approximately 500 images of Jupiter and its satellites. It made -- the scientific instruments made measurements and charted the radiation field and located the magnetic field and also verified and confirmed that Jupiter was indeed a gas liquid giant. It also made the first accurate measurements of the Galilean fields. And the radiation fields were about 10 thousand sometimes stronger than anything we had ever measured here on earth.

Armed with that knowledge, we then retargeted Pioneer 11 mid- flight so that it could pass through the southern hemisphere of Jupiter and then get catapulted on its way to Saturn. So in the next slide we see the proof that Pioneer 11 was the first ever to visit Saturn. This picture that you are looking at is never seen on earth. The rings are back lighted. And so the bright rings in this Pioneer picture appear as a dark gap when viewed from earth. And the dark rings, from the Pioneer picture, appears as a bright ring on earth.

So, let's get back now to the odyssey of Pioneer 10. It continued the travel throughout space to a point about 11 years later from launch, June 13, 1983, it became the first earth made object ever to leave the solar system. My personal favorite. I think that's really a milestone.

And another notable thing is that Pioneer 10 used the gravitational catapulting effect of Jupiter. That was the first time that was ever done for interplanetary light. Pioneer 11 followed in its footsteps about seven years later to go out of the solar system.

Now Pioneer 10 finished really the initial mission, so we had another mission, and that is shown in the next viewgraph or slide. Excuse me. I missed this one. This is a painting of what Pioneer 10, how the solar system appeared to Pioneer 10 as it was out of the solar system. You can see the sun in the center and Milkyway Galaxy on the background. We used this painting for animation on the video that you have been seeing during the breaks and at the registration time.

Now if you go to the next slide, we see an Artist's rendition of the heliospheric boundary. This is the next mission, try to find out where they are. The heliopause in the center there is a meeting surface of the solar wind and that region outside the influences of the sun where interstellar space begins. The interstellar space is of unknown composition, really. But it does contain energyic flow and particles whose cosmic flow, as indicated here by the Galactic cosmic rays, have been detected as far inward as the earth and Venus. The solar wind is a flow of gases that, from the generation by the sun, it's a plasma subatomic particle, and it travels at the speed of 1,600,000 kilometers per hour or 1 million miles per hour. It undergoes a solar wind termination shock somewhere between originating and the heliopause, in which the flow goes from subsonic -- supersonic very abruptly to subsonic. And we see that the motion, in this picture right to left, there is a shock and it goes downstream.

There are a few other spacecraft doing the search, Voyager 1 and 2, but Pioneer 10 is unique as being the only spacecraft in the downstream direction. Unique also at this moment, because it's the farthest away.

Before we launched Pioneer 10, we felt that the extent of the solar wind was perhaps five times the effect -- fell off about at the distance five times the distance from the sun as the earth, or five AU, astronomical units, that is the distance between the sun and earth. 150 million kilometers or 193 million miles. The outermost planet is at about 40 AU. Pioneer 10 is now at 65 AU. And we have yet to find the heliospheric boundaries, but we feel we are getting close. Scientists now estimate that these boundaries are anywhere from 70 AU to 120 AU.

Now, Pioneer is traveling at the speed of about 45,000 kilometers per hour or 28,000 miles her hour, and it's continuing its lonely journey in outer space. The distance is about 6.2 billion miles or 10 billion kilometers. And we have what we call a two-way lifetime. That is the time that it takes a signal, radio signal, at the speed of light from the earth to go to the spacecraft and a confirmation signal being returned. It's now over 18 hours. That is how far 10 billion kilometers is. Sadly, in about a year from now, the RTGs that I mentioned before will be to the point where the power source is going to be low enough so that we will not be able to transmit any longer and we will lose radio contact with the earth. So what Pioneer 10, however, will do -- I should mention at that point it will be something like a ghost ship that has coasted silently into deep space.

In the next viewgraph or slide we note that in future years Pioneer 10 will pass by a number of star systems, and this is in ten years, there are some tick marks here on this line from the sun to where the Pioneer 10 will be in about a million years now. And those are five light years, the increment in that are the tick marks. 50 trillion kilometers or 30 trillion miles. In about 30,000 years it will have its closest encounter to a star system, red dwarf 248. In the vacuum of space, Pioneer 10 will probably last forever. And it -- undoubtedly it will outlast its home planet, because we all realize that in about 5 billion years the sun will expand and become a red giant and envelope the orbit of earth and consume us.

As our first emissary out of the solar system, Pioneer 10 carries with it a gold plated plaque, an aluminum plaque. And there is a message on it that was designed by Carl Sagan and Fred Drake. We see a man and woman. In the far right there are some bracketing bars, and that is the binary representation of the number 8, 1000, where 1 will be given on the top by a hyperfine radiation transition of a neutral hydrogen atom. And that has characteric wave length of about 21 centimeters, I believe, about 8 inches. And so this calculates the women's height to be about 5 foot, 6 inches.

Also to help identify the origin is in the center is an etched radio pattern of 14 nearby pulsars to the sun and a line directed towards the center of the galaxy.

You can also see that there is a lined silhouette of the spacecraft next to the people, who are there in scale.

On the bottom is a representation of the trajectory that the Pioneer 10 took, originated at the third planet of the sun and then being fixed gravitationally out of the solar system by the fifth planet. I think of this plaque as the cosmic equivalent of a message in a bottle cast into the sea and it's telling its finder, as Carl Sagan has said, where we are, what we are and who we are.

In the future, in the very distant future, probably, Pioneer may possibly pass by a planetary system like a remote stellar neighbor. One of those planets may have intelligent life. And if this life form has the technical capability and the curiosity, maybe it can find Pioneer 10, inspect it and find this plaque and then decipher it and find out the origins of this amazing spacecraft, Pioneer 10.

Thank you. And I now will take some questions if there are some questions.

>> I heard a report on the radio the other day that said that Pioneer 10 might be shut down fairly soon. How long do you expect (inaudible)

>> LARRY: The question is, there has been a report on radio and elsewhere, actually, there is one in Time Magazine, that at some time in the near future Pioneer 10 is not going to have communications with -- communications with Pioneer 10 might cease. March 31, and this is a response, March 31 missions operations for Pioneer 10 has been decided to be terminated, and the reason for that is that the scientific returns that we are getting from Pioneer, we can't justify it in terms of the expenditure. However, I expect Pioneer 10 to still remain to be a valuable space resource, because the DSN, the Deep Space Network, run by NASA actually makes use of Pioneer 10. They like it because it's the farthest one away. And it's in a unique direction. And so they can confirm their station tracking and the receiver performance with that.

In addition, the control room which we have been using for Pioneer 10 has been inherited by a new project, new mission at NASA, and the new mission, there are some new controllers that can use the real-time tracks of Pioneer 10 to actually train the new controllers in station protocol and data archiving.

Another question from the audience.

>> What are the odds that the message that is put on Pioneer 10 will be eroded by interplanetary particles, cosmic rays and the like?

>> LARRY: The question is, what is the possibility or probability that erosion will take place and obliterate that message. Dr. James Van Allen did calculations, not on the plaque per se, and he will be speaking this afternoon and could give a more definitive answer to this. Just to paraphrase or to summarize, we found that the erosion was not significant enough to do extensive damage. So I would say I feel that this message would be able to be read, it might be pitted somewhat, but we are -- of course most of that would have happened during the passage through the encounters. Interplanetary space is benign. So the answer is I think it will still be readable. Decipherable is another question. And the extraterrestrial, if they find it can they get the message? We think they can. If they are smart enough to get the plaque, they will be able to use it. It's logical. And we are using binary representation and the universal hydrogen atom. They should be familiar with this transmission.

How is the timing, Bob? Do we have time for another question? Okay.

>> Another question back there?

>> I think there is a microphone. Is there a microphone by the...

>> I'm just curious, do you ping the satellite as it goes out?

>> LARRY: I didn't understand the question.

>> In order to locate it, is it sending something back to us continuously or do you just have it on a map?

>> LARRY: Yes. We track it a number of hours per day. The transmitter is constantly on. So it's transmitting constantly, yes. When it's not sending scientific data, it represents radio signals, yes. But we have to be tracking it. We don't track it 24 hours a day. We have to share the tracking facility with other spacecraft that are used by VSM.

I didn't mean to go, not listen to your question up there. I'll try. Say it again. The question was, was there a similar plaque placed on Pioneer 11? Yes. Pioneer 11 was almost an identical spacecraft. And we had one on Pioneer 11 also, yes. The same plaque on Pioneer 11. Question back there.

>> What was the original expectation for how long Pioneer (inaudible)

>> LARRY: I believe the question is, correct me, is how long -- what was the original expectation for how long Pioneer 10 was going to transmit signal and data, is that correct? Is that the question? Okay. That is the question.

Well, there are a lot of ways -- the original might go was 21 months. It was to go to Jupiter. And so from one point of view, were we going to survive Jupiter? We did. But maybe more to the point of the question is the power sources that we are using, the RTG, how long could they last? Well, it went tremendously over the expected lifetime of those RTGs and the thermoelectric systems. Pioneer 11 RTGs failed two years ago, and that was launched a year later; so that would be like 22 years, and even that was fantastic. I would have guessed that anything we got over 10 years was wonderful, wonderfully more than we had expected.

As a matter of fact, it's kind of an interesting thing that happened is that we just did a maneuver in January, our maneuvers are to point the spacecraft back to earth so we can get a clean signal. And in order to do it, the power source has degraded, we needed to turn off the transmitter. The first time ever we did that. So we performed the maneuver in the blind. And the expectation was that the transmitter would not go back on again. We have a backup transmitter. There are two transmitters. So we expected to use the backup transmitter. After we did it blind, in five minutes that transmitter came back on. Just much more than we thought. Okay. I think my time is up. Thank you.

>> And incidentally, before I forget, we have an intermission coming up, and during that intermission we will be taking questions over the Internet. But if any of you would like to stick around and sit in here and participate in that, you are more than welcome to. We will have people available to answer questions at that time. Also for the intermission, just to kind of let you know, we will have some refreshments outside so you'll have a break there.

Well, it's my honor to welcome the next speaker, who is Richard Fimmel. And Richard, from what I gather, has been instrumental in the development of the Pioneer project. One of his interests was in the development of some of the science instruments that are onboard the Pioneer. Also he was the science chief for the Pioneer proposal. So, Richard knows a little bit about everything that went into the spacecraft and what we were looking for. He also was the project manager for Pioneer for awhile.

We will have a number of people here this morning who were project managers. A lot of you sit there and say gee, how did that work out? Keep in mind 25 years is a long time so we had people who came in and took over and watched the spacecraft on their tour of duty. So we have a lot of people that contributed to Pioneer 10's success.

Pioneer's Firsts - Richard Fimmel

I'd like to welcome Richard Fimmel who will tell us a bit this morning about some of the other aspects of the early Pioneer 10 days. RICHARD: Good morning. That was a great overview, Larry, of the mission. It takes me back through a lot of recollections, things that we had done over the years. Larry mentioned the asteroid belt. Just a comment on that yet. Today we don't think much of it and assume that this is a given that we will go through the asteroid belt. But I recall when we were almost paranoid about will we get through there? Is it a sea of gravel? What is the asteroid belt? And by targeting away from the known asteroids, the large ones, I would say luck was with us. But something was with us; we got through unscathed, and it seemed that other missions have and will. Nevertheless, going through the asteroid belt will still be an area of concern for future spacecraft.

There is a long list of first ever for mankind of Pioneer 10 and 11. I've been asked to enumerate some of these. You'll hear details about many of them this afternoon from the scientists who have devoted a significant part of their lifetime and their career to gathering these data and analyzing the data and studying the related phenomenon.

Pioneer was the first spacecraft to map the zodiacal light away from earth and to measure the integrated spar light from the galaxy free of this light. Now the so-called zodiacal light is a glow caused by the sunlight scattered from the small particles of interplanetary dust dispersed throughout the solar system. It's visible, if you look hard, as a glow along the ecliptic in the west, at the end of the evening and in the east before sunrise. By measuring the changing brightness of the light as the spacecraft travel outward, the spatial distribution of interplanetary dust could be mapped.

Once the spacecraft was beyond the asteroid belt or greater than 3 and a half AU from the sun, the zodiacal light brightness became greatly diminished and the background galaxy -- background star light from the galaxy could be measured free from interference of the zodiacal light. The background brightness is the total brightness of the stars too faint to be resolved as individual points of light.

Now, Pioneer also discovered that the counterglow is not associated with earth. It's a slight enhancement to the zodiacal light and directly opposite the sun in the sky. Originally we thought this was due to an enhanced cloud of particles trailing the earth. Also, the counterglow is not associated with earth, but is just due to the enhanced scattering in the backward direction of general interplanetary dust and is really a natural part of the zodiacal light.

Pioneer was the first spacecraft to bring back close-up images of the giant red spot, which is actually an anticyclone rotating in the opposite direction that they do on earth due to Jupiter's rotation.

Another measure of the size of earth and Jupiter is that the earth would fit into the red spot that you just saw three to five times just into the red spot, and that is just one spot on the surface of Jupiter. It also made the first and second measures of Jupiter's magnetic field.

This slide shows you images of a crescent Jupiter. From earth we always, because of our position and the sun's position, see Jupiter as a full moon. But as Pioneer 10 made the path around Jupiter and the so-called left turn, if you wish, moving away from Jupiter, we saw a crescent Jupiter for the first time.

Small digression here from the first. One doesn't normally think of an unmanned spacecraft of having excitement particularly past the trauma of launch. But on December 3, 1973, when the radio signal from the spacecraft disappeared as Jupiter got in the way, there was a lot of tension in our control room. Would the radio signal appear again? Would Pioneer still be functioning? Would the intense radiation destroy any of the spacecraft's electronics or the instruments? Would the scientific instruments work at all due to that intense radiation? Would we ever hear from Pioneer 10 again?

Well, the questions have all been answered. We did hear and it continued to function. However, the spacecraft suffered some damage. One sensor is one instrument that suffered damage. And some of the instruments switched modes as if inadvertent commands reached the spacecraft. And it was essential that we correction these as quickly as possible. Fortunately, the transmission time was only 15 minutes to get a close in measurement on this one unique chance. If the spacecraft disappeared further and further from Jupiter, we did not want to miss this unique opportunity.

Actually, I know many of the scientists and I were quoted as having said: This is the most exciting day of our lives. Indeed, I think in many ways it was, when you consider the years of preparation, the thousands of commands hand checked and the command sequences, the contingency plan and everything bearing fruition and working, was very gratifying.

Next slide, please.

These are Pioneer 10's images of the first of the large Jovian satellites. You see Io and Europa, Ganymede and Callisto. These are not photographs. These are images made by a simple fundamental spin scan technique using the photopolar end of a telescope as the -- spin stabilized, as opposed to the Voyager, which are free axis stabilized. So you get one swipe across the planet like the TV picture is generated, and then these have to be collected and put together to produce a photolike image.

There was also an ionosphere on Io. There is a Taurus around Jupiter. It discovered the rings of Saturn -- not discovered them. Excuse me. The first spacecraft to get images there. And we discovered that the rings sweep out the particles in Saturn's magnetosphere and discovered some additional rings and gaps.

One of the things here is what we at that time named the Pioneer division, which was not visible from earth. If you look up ahead you'll see that that is so faint from earth, and also a new satellite that we saw in that picture and a couple of other pictures.

Also made the first observations of the backlighted rings of Saturn that Larry mentioned earlier. Also discovered that there are particles in Saturn's ring gaps not visible from earth. Originally it had been our intention to go in quite a lot closer than the Pioneer did go through the rings. But headquarters, and one doesn't usually give a lot of credit to bureaucracy, but we were instructed to go with Voyager's going. The two Pioneers were in the 1 to $2 million class and the Voyager was in the over 800 million dollar class, and it was decided that it would be wise that we go where Voyager plans to go, just in case they should go further out. That was a wise decision.

After going by Saturn where we wanted to go, we could have seen that we could have destroyed the spacecraft and that would have been the end of the mission for Pioneer 11.

Next slide please.

This is the first image of showing some rough details, rather featureless, of the moon of Saturn. Pioneer also made the first polarization measurement of the atmosphere over a wide range of phase angles. Did the first mapping out of outer planet magnetospheres. Discovered Saturn's magnetic field and magnetosphere. It mapped the corotating streams of particles from the sun into the outer solar system, and identified an interplanetary acceleration processes.

Next slide please.

This is an artists concept of a warped current sheet. The two Pioneers mapped the solar field and discovered that there is a warp current sheet in space. You'll hear more about that this afternoon.

We made the first detection of helium atoms entering the solar system. Surveyed the galactic cosmic ray intensity to distances in the outer heliosphere. Pioneer was the first spacecraft, as Larry mentioned, to leave the known solar system.

May I have slide six, please?

On this slide, I can repeat. You can see where Pioneer 10 is on its own after going by Jupiter in the antisolar apex direction, that being the direction the sun moves in the Milkyway galaxy, and this is going in the opposite direction. It's the only spacecraft traveling in that direction. As far as I know in this lifetime it may be the only spacecraft ever to go in that direction, making the measurements of Pioneer 10 very unique in that aspect.

Pioneer 11 then went by Jupiter, came back by earth, and went on to Saturn. And here you also see the trajectories of Voyager 1 and 2. The Voyagers were launched with a higher velocity and travel faster than Pioneer and are moving ahead. At the moment, Pioneer 10 still remains NASA's or anybody's furthest out spacecraft.

The first spacecraft to carry a message intended for extraterrestrials. This was a concept borne in the mind of Eric Burgess and another journalist saying we are going out there, for hundreds of thousands of years, maybe millions, we ought to put some kind of a Rosetta stone or some message on the spacecraft. Larry described it and Carl Sagan agreed to put together the message that you saw and that is traveling on both Pioneers.

Each of these many firsts on its own that we have been talking about is just a piece of a massive jigsaw puzzle, so to speak. They help answer some of the where, the whys, hows, whens, et cetera, of the questioning mind that mankind has. As educators and others, you have a real challenge and I think a privilege of training and stimulating the minds of future generations of engineers and scientists to go out and find more answers and keep on putting this massive jigsaw puzzle together. For all you know, you could have a future Einstein or Thomas Edison or Shokley or James Allen or McDonald or Huntress or Smith who will devote their lifetime to bring us more of these answers. The challenge is great, no question about it. But so are the rewards.

Thank you.

I'll be glad to answer any questions, if I can field them. Good. I'll leave them for the scientists this afternoon. There is one? Sorry. Didn't see.

>> Can you tell us what instruments are still working on Pioneer, what data is being received?

>> RICHARD: Just about all of them are still working. However, the only one that is powered on at the present time is the Geiger 2 telescope, Dr. James Van Allen's instrument, and the University of Chicago -- I'm being corrected here by the present project manager. The ultraviolet instrument. And the reason for that is they are both low power and can still operate within the current that is currently available. We are not trying to say one is more or less important than the others. We do what we can with what is available.

Next? Yes, sir?

>> RICHARD: The question is, when will the distance from earth of Voyager 1 or 2 become larger than Pioneer 10's distance from earth? I don't know the date. Maybe Larry does.

>> LARRY: Yes. I've been keeping up on this. The date is February 1998 that we will be the farthest, that is Pioneer 10 will be the farthest away from the sun until February '98.

>> RICHARD: So Pioneer 10 will continue to communicate over that vast distance. I'd like to add that really some of the real magic in space research and exploration of unmanned spacecraft is the communications technology. Without that, without the Deep Space Network getting that data in for us, we wouldn't have anything. Another question?

>> RICHARD: The question is could I describe Pioneer's trajectory relative to the ecliptic at the present time. It's pretty much in the ecliptic. As much as I know, Pioneer 10 can. I don't know about Pioneer 11. I don't know if anyone else here knows. Basically, the -- of course the ecliptic is the plane in which all the planets rotate, and we have made no specific effort to get out of the ecliptic. I believe it's going out at a small angle. Sorry I can't answer you more specifically. Perhaps this afternoon, ask again.

Thank you.

>> Well, the time flies. Would you believe it's time for the first intermission? We do have some refreshments outside, and you are welcome to take a little break and go out there and kind of relax a little bit. If you'd like to stick around here, we will have some people that can answer your questions here as well. So I think according to our schedule, we should be back in here about 5 minutes to 11:00. So we will see you then.

Questions and Answers:

>> This is Fred Wirth. I'm one of the people from the project. I have a question here: Where is the trajectory headed in the future for Pioneer 10, towards or outward to the center of our galaxy?

Am I wrong to think that Pioneer will never be able to escape our galaxy?

Well, let me clarify that. Pioneer 10 is headed away from the galactic center.

And it is headed in the general direction of the constellation of Taurus.

So I'm not sure that I can answer the question whether it's going to escape our galaxy, but it's headed in the constellation of Taurus.

So I'm sorry, but I don't quite know the answer to the second half of the question.

This is from Sam. The question concerns is: How did you steer the Pioneer 10 through the asteroid belt without it getting hit?

The answer is we did not steer it. It was on a fixed path. It is the danger that was being addressed as being the asteroid belt representing some danger to the spacecraft, it was unknown how far the particles and asteroids themselves are spaced and we did not deliberately avoid the astronaut, it was just that the space in between the asteroid is very large and we did not get hit by any of them.

>> In an interview, well-known astronomer Carl Sagan spoke about the significance of Pioneer 10's Jupiter mission.

>> Jupiter has an atmosphere rich in hydrogen and its compounds, the same kind of atmosphere that the earth had at the time of the origin of life.

So we think that the building blocks of life are at least earthly life are being produced on Jupiter today raining down from the skies like manna from heaven. And Jupiter may be a vast planetary laboratory in the chemistry of life that's been working for about 5 million years.

If you use the solar system from afar, you can make an argument that life on Jupiter is like life anywhere else on the earth.

>> Pioneer 10 presented unique challenges to the project manager team at NASA's Ames Research Center.

>> Behind us this is the Mission Control room. Right now, there are -- merely to change the attitude of one of the instruments in the operating mode so we can look on Jupiter. The interesting feature here is that the round-trip light time, the time to get a message from here up to the spacecraft and then to get a return answer is an hour and a half.

So our people in there have to be used for this hour and a half delay when they start planning --

>> Since Pioneer's 10 encounter with Jupiter in 1973, communication with the 570-pound spacecraft experiences an ever increasing delay time.

Pioneer 10 is now so distant, at the speed of light, its radio signal takes 18 and a half hours to cover the 13 billion miles from earth to the spacecraft and back again.

>> Pioneer 10 was designed as a hearty spacecraft. Throughout its entire life time at the Ames Research Center.

>> I have a question here: How long does it take to build Pioneer 10?

Our teacher, Judy Jones, is in the audience. The contract which started in July of 1969, and the launch of Pioneer 10 was March of 1972. So with a little calculation, I guess you can come up with the number of months.

Then of course, at the same time that we were building Pioneer 10, we were building Pioneer 11 which was launched 13 months later.

Another question here is how many people did it take to build Pioneer 10.

I can only estimate that. The cost of Pioneer 10 and 11 including the cost of the hardware and all the data analysis was about $100 million and in those days the average salary was like $20 an hour, so you could figure that would be $20 into $100 million would be $25 or 2.5 million hours.

So that would give you some idea of how many people it took to build the spacecraft.

>> Thank you.

>> Okay, this is from Megan in Loma Vista. Her question is: How much did Pioneer 10 weigh on earth? The answer was 570 pounds. Of course, in space, we use mass rather than weight because we're looking at how much material is there.

But that would be its weight on earth, 570 pounds. That's what we can kind of relate to.

>> Hi, this is Mrs. Jones here in Washington, D.C., you're doing a good job, I'm really proud of you. Keep those questions going.

>> From Loma Vista, this is Larry Lasher, the Pioneer project manager.

I have a question for you. It said who made the design for Pioneer 10. Actually, the company that built Pioneer 10 spacecraft is TRW, and they're located in Redondo Beach, California. We gave them the basic design all those years and it was competitive and we chose the company that would do the best job. The question is how did you navigate Pioneer 10 through the asteroid belt without getting hit?

Well, we knew where the major asteroids were so we could point it so they weren't going to hit the major asteroids but it would be -- it was the smaller ones that we didn't know about which we didn't have any idea about and it turned out that the spatial density of those smaller asteroids were spaced out, it was cleaned out.

We didn't encounter any of them. And then there's a question from Josh from Loma Vista and question: How far is Pioneer 10 from earth?

Good question.

It's 5.2 billion, with a B, billion miles. If you want it in metric system. Just a second. It's 6.2 billion miles and 10 billion kilometers.

>> We have a question: What is the current velocity of the probe and how do you account for variation of acceleration and gravity?

What happens here is he current velocity of the probe is 28,000 miles per hour. That's 45,000 kilometers per hour.

And the acceleration is not due to the speed, the speed is fairly constant. If it changes direction, it has to go through the orbit in the galaxy. The speed is fairly constant. The speed barely changes.

Question from, I believe it's George from Louisville.

How does the slingshot effect add velocity to a probe? Larry Lasher, Pioneer project manager answering your question. What happens is that actually energy is stolen from the planet and given to the probe.

There's a transfer of energy and this is accomplished by a dynamical principle in which the velocity is going towards the planet changes and it goes away. The velocity changes direction and it changes magnitude and this relates to an increase in energy. And it takes it from the planet. Of course the planet has so much energy that it's so infinitesimal. It doesn't translate into a significant change in velocity for the probe.

Here's a question from anonymous, I can't see the name.

Question: What kind of result is Pioneer 10 getting currently from the GTT -- the results are we're getting cosmic ray intensity and cosmic count from the GTT. It's actually measuring the distribution of radiation, the ultraviolet, it's called the limen alpha radiation, it's a transition that happens in hydrogen.

Loma Vista again. Looks like it's a very active class.

They ask the question will Pioneer ever come back on earth? Sadly it will never come back to earth, it's in orbit in the Milky Way galaxy never to return. Okay, our next question, again coming to us from Lisette, this is Bob Hillenbrand.

How many planets has Pioneer 10 traveled by? Well, it traveled by only one planet and that was Jupiter and then it was slung by gravity out of the solar system. Part of the reason was the fact that Jupiter was the primary target for Pioneer 10 and after that, they decided that they could use Jupiter's gravity to take and guide Pioneer 11 towards Saturn and so that's the reason that on Pioneer 11 that they got both Jupiter and Saturn.

Okay, another, whoops, another -- that was slightly unplanned there.

Okay, this is from Gladys also of Loma Vista. Does Pioneer 11 look like Pioneer 10? And the answer is yes. The idea being was that back in 1970 when we launched the spacecraft, we weren't too terribly confident of our rockets and so there was a general plan that we would launch two that were identical with the hope that both of them would make it but also with the expectation that if one of them didn't make it, the second one would. And so under this plan, you'll notice that there were a lots of spacecraft that were launched in pairs during that particular period of time. So yes, Pioneer 11 does look like Pioneer 10. Okay.

Next one is from Philip also there in Loma Vista, is Pioneer 10's bigger than the sister ship and the answer is again, no, they were identical.

How are questions like this answered? Well, with difficulty sometimes, I guess. By return mail?

We're going to do it right here. What I'd like you to do is go to our Pioneer 10 Web site and on the Pioneer 10 Web site, there's a lab activity that we have under our education section which deals exactly with your question.

I'm going to be very honest with you. It's not the easiest thing to try and explain, so what I'd like you to do is to take down the Web site from that which you probably know if you're here, but that's http//quest.arc.gov.nasa./pioneer10 all as one word. The reason I got goofed up is people were waving at me because they thought I had it wrong, I'm sorry. But if you go there underneath the education programs section, there is a lab that deals with this and hopefully that will help you out. Http//quest.arc.gov.nasa.pioneer10.

>> How far do you think Pioneer 11 will be from the sun? Actually, we've stopped track being Pioneer 11 and I would have to go back and I'd have to find someone who could give you that information. So at this present time, I can't really answer that one. I don't know that anyone could get that one for you real quickly.

Who was the first person who see the Milky Way?

Well, you know the Milky Way and the stars and even ancient, prehistoric man were observing. We don't know who named it the milky way, we know there are a lot of different theories about how it came to be called that. One that comes to mind for me is the Greeks. There's a constellation known as Sagittarius which they called the milk pitcher, if you would watch it as it goes to the western part of the sky, it appears to tilt over and that's very, very close to the center of the Milky Way where it's fairly bright. So the Greeks came up in the idea that milk had gone out of milking pitcher and guess what, it got to be called the Milky Way. That's one theory as to where it got its name. But these are things which were known to prehistoric man. We know that from the cave drawings and things like that. And the fact that when written languages were put down, this was all really well developed. So we don't know who exactly that first person would have been. Couple of these other questions, what we are going to do is go back and find some of the people that were actually involved and we will try and get those answers for you a little bit later.

I think right now, we're going to take our lunch break and welcome you all to come back here at 1:30. Eastern time. An hour from now.