**FTS-NASA-VOICE**

**Moderator: Trina Ray**

**January 30, 2007**

**1:00 pm CT**

Coordinator: Thank you for standing by.

Just a reminder that today\'s call is being recorded. If anyone has any
objections, you may disconnect at this time.

Ms. Jones, you may begin.

Jane Houston-Jones: Thank you very much.

Hello, everybody. This is Jane Houston-Jones. I\'m from Cassini Outreach
and I\'m going to be your host today because we are having our
semi-annual Project Science Review meeting where all of our Cassini
science people get together and talk. And right now what they\'re doing
is learning about the plans for our extended mission. And I think that
would actually make a pretty interesting talk in the future.

Our speaker today is Dave Doody. And Dave, besides being a good friend
of mine, leads the team of Cassini real-time mission controller
engineers. And these are the folks that work with the Deep Space Network
and send commands to the spacecraft. They check the various types of
data coming back from Saturn and initiate any needed responses to any
kind of problems.

Dave first published the Basics of Space Flight and that\'s the topic of
his talk today, as a tutorial for the JPL operations folks in 1993. This
was when he was working on the Magellan flight team. He makes updates to
it frequently and I actually have this link to our Saturn observation
campaign resources page because I think it\'s such a wonderful resource.
He is working on updating it as we speak.

And in his spare time, he teaches a public night course called Basics of
Interplanetary Flight at the Art Center College of Design in Pasadena,
California. He also can sometimes be found out of the sidewalk showing
Saturn through telescopes. So he\'s just an all-around great guy.

So with that introduction, I\'m going to remind everybody that if
you\'re on a speakerphone and you have some noise coming, you know, in
that bothers you, you can be guaranteed that it\'s going to be coming
across to all of us. So you can hit star-6 to mute your telephones.

Other than that, take it away, Dave.

Dave Doody: Okay, thanks, Jane. Thank you very much.

Hi, everybody. I think we\'ll be keeping this to under an hour although
there is more time available. And before it forget, I wanted to say
thanks to (Kirk Munsell) and crew for getting the PowerPoint and
materials available online.

A few mechanics for today\'s talk. If you can use the PowerPoint, please
do because there are a couple of animated images that will make sense
better if you can see them animating. And to do that, you should use the
PowerPoint file and then bring it up in the view slide show mode.
Otherwise, we can talk around them.

And in addition to that, there are - I wanted to keep the content of
movies in the PowerPoint show at minimum just to keep the file size
down. But there is one movie that it would be really good if you can
view while we\'re talking. And let me say in advance that that movie is
called out on Slide 10 of the PowerPoint or the - also the PDF
materials.

There\' a URL there that goes to the SOHO site and it\'s a movie taken
from the SOHO/LASCO instrument, we\'ll talk more about what all that is,
viewing the Sun. And that\'s the one movie that I will want to have
people look at in real-time if possible. Otherwise, we can still (arm
wave) over the phone.

Please interrupt; let\'s keep it a casual conversation, questions,
comments, boos, hisses. At any time, please just speak up and we\'ll
talk about your questions or comments.

So, the Basics of Space Flight, if you\'re on the PowerPoint or PDF,
let\'s go from Page 1 to Page 2, Slide 2 where I\'ve got the Basics of
Space Flight URL listed for future reference.

Have any of you seen it already? The URL, the Basics of Space Flight?

Jane Houston-Jones: I have, Dave. This is Jane.

Dave Doody: Well, I guess, it might take a little bit to mute and unmute
so I won\'t demand answers. But...

Jane Houston-Jones: I\'ll be sure to send it out to all the people who
attend this meeting so that they all can bookmark it.

Dave Doody: Okay. But it\'s spelled out here on Slide 2
www.jpl.nasa.gov/basics. And in this tutorial it\'s divided up into
three sections, Section 1 is the environment, Section 2 is flight
projects, different spacecraft, Section 3 is operations, launch crews
encounter and stuff.

For today\'s session, just in the interest of time, I think I want to
confine it to just two sections, our environment, where it is that we
fly interplanetary missions and a couple of different flight projects,
maybe heavily slanted to Cassini while not covering - (Julie Webster)
gave a CHARM talk a while back and so I\'m not going to duplicate hers.

But the tutorial online is broad in scope, it covers a lot of territory
but only at limited depths and the intent is that we want to show the
span of all the disciplines that are involved in interplanetary flight
and the relations among those disciplines.

Man: Excuse me a moment. I had called away and I don\'t see how you get
the PowerPoint presentation. All comes up for me is the PDF file.

Dave Doody: Oh, there is a password-protected site.

Jane, do you have the URL for that?

Jane Houston-Jones: I sure do.

Lets\' see, this is in the information that was sent out to announce
this meeting. But I will give it...

Dave Doody: The email, but I don\'t see it on the Web site either.

Man: It was not in the email actually.

Man: I have an email and it\'s not on the Web site.

Man: I sent an email to Trina about this but I didn\'t...

Jane Houston-Jones: She\'s been on vacation and...

Man: Okay.

Jane Houston-Jones: ...a meeting. Okay.

Dave Doody: Yeah, let\'s take a minute and resolve that.

Jane Houston-Jones: I\'m going to give everybody the URL,
http://jplis-ftor-cache02...

Man: Ca what please?

Jane Houston-Jones: Cache02...

Man: Okay.

Jane Houston-Jones: ....jpl.nasa.gov; it\'s long and that\'s why some of
you, I guess - I don\'t know why you\'re not getting it. I know I sent
it out to the Saturn Observation Campaign.

Are some of you getting it from the Solar System Ambassadors or the
museums?

Man: Solar System Ambassadors. It was not listed there.

Jane Houston-Jones: Okay.

Man: It usually is.

Jane Houston-Jones: Okay.

Man: And to make it easier on people, I eventually found it by going to
an old email.

Jane Houston-Jones: Okay, great.

Man: I was linking that way.

Jane Houston-Jones: I\'ll just remind (Kaye) to put that in her
announcements. But after jpl.nasa.gov, it\'s another slash and then
doclib/. So,\
http://jplis-stor-cache02.jpl.nasa.gov/doclib/.

Now, when everybody gets there, you\'ll have a page that says, \"Cassini
Document Library.\" And you click on the library name, CHARM documents,
and you may be asked for the password and the user name and the
password.

And if you are still with me, you type in, the user name is \-- all
lower case \-- the word Cassini...

Man: I came up NASA Space store, is that where I want to be? When I put
all that in.

Jane Houston-Jones: No.

Man: So NASA Space store is what came up with all that stuff. I have in
http:/jplis-store-cache02.jpl.nasa.gov and that\'s what came up.

Jane Houston-Jones: Okay. Then put in /doclib/ after nasa.gov/doclib,
document library, doclib/.

Man: I didn\'t like the - doc-lib?

Jane Houston-Jones: Doclib.

Man: Right. For some reason...

(Dan): So, Jane, this is (Dan) in North Carolina.

I think as I was overhearing, he might have typed out the word store in
the first...

Jane Houston-Jones: Stor...

(Dan): Right.

Jane Houston-Jones: ...not store.

Man: Thank you. I can\'t find it.

Jane Houston-Jones: If you want me to send it to you, I can email it to
you, however is the person who - tell me your email address and I\'ll be
happy to...

Man: (Arthur Ignelzi)...

Jane Houston-Jones: (Arthur)...

Man: Excuse me, I\'m starting over. Let\'s start over.

Jane Houston-Jones: Okay.

Man: Qualified@\...

Jane Houston-Jones: Could you start over again.

Man: Just start all over, the word qualified@san.rr.com. Thank you.

Jane Houston-Jones: Qualified@san.rr.com.

Man: Right.

Jane Houston-Jones: Okay. I\'ll send it right away.

Man: Here\'s another one for you, Jane.

Man: Thank you.

Jane Houston-Jones: Okay.

Man: Am I up now?

Jane Houston-Jones: No. Let me type this in.

Woman: Jane, could you send that out to all the - the group?

Jane Houston-Jones: I only have the Saturn Observation Campaign names
and I send it out every month. So the people who get their announcements
from the Solar System Ambassadors or the Museum Alliance, I don\'t have
those - I don\'t have - I don\'t know what the addresses to send that.

Woman: Okay, thanks.

Jane Houston-Jones: Okay, the next person.

Man: Rschmall@wi.rr.com.

Jane Houston-Jones: Okay.

Man: Thank you.

Man: And would you mind, you got to the user name but you never got the
password for that other site.

Jane Houston-Jones: Doc\$85.

Man: The D is the only capital, right?

Jane Houston-Jones: Capital D, lower case oc\$85.

Man: Thank you.

Man: Can I give you my email address?

Hello?

Jane Houston-Jones: Yes?

Man: Can I give you my email address please?

Jane Houston-Jones: And - can you tell me which list you didn\'t get it
on?

Man: No, I did not get it on the address that was given on the email
obviously.

Jane Houston-Jones: Okay, great. Tell me your email address.

Man: All right. It\'s (unintelligible) k4cg...

Jane Houston-Jones: K4c...

Man: Yes, that\'s correct, (Charlie), (gulf), (sierra).

Jane Houston-Jones: K4cgs@\...

Man: (Bellsound).net.

Jane Houston-Jones: Okay.

Man: Thank you very much.

Jane Houston-Jones: Okay, I\'m going to be sending this out.

And so, Dave, why don\'t you go ahead and then I\'ll see if I can find a
way to send an email while you\'re talking to the other people.

Dave Doody: Okay, that\'d be great.

Jane Houston-Jones: Take it away.

Dave Doody: Okay. Well, good. Thanks for doing the logistics. And this
reminds of flying missions before there was a worldwide Web and even
before email back on Magellan, we made the transition. Early part of the
Magellan mission, we had no email and the latter part of the mission, we
got again to use emails and then the worldwide Web came along in, what,
1992 or 1993, 1994, so - which is right when we put the Basics of Space
Flight up on the Web. Just one of the early Web sites.

So, regarding the solar system, it\'s been in the interest of study from
the beginning, pre-history actually. All our human ancestors have been
able to see the sky because Earth has periods at least and places where
you can see through the atmosphere up to the sky and you can see the
stars and a few of those lights in the sky moving as the stars didn\'t
move and they were termed wanderers of planets.

But for all of human history, up until very recently, all our
observations were based on visible light and then in about 1931 we\'d
began accidentally to observe in radio and then starting with the
emergence of space flight in 1957 and 1958 when the early Earth orbiters
started flying. Then we could get above the Earth\'s obscuring
atmosphere and take advantage of not only light and radio but the whole
rest of the spectrum.

And, you know, if you picture an electromagnetic spectrum, the visible
portion is just a tiny little slice. And so, opening up, observing solar
system in particular in all of the electromagnetic spectrums is what we
have available to us now. And then on top of all that, with
interplanetary travel, you can send instruments of course to many of the
solar system objects to measure their properties up close even directly
in some cases. And in one case now, we\'ve returned - two cases, that\'s
right; return material back to Earth from out in the solar system.

So let\'s go to Slide 3 and today\'s session will take a little bit
closer look at the interplanetary environment that we operate in and,
two, we\'ll see a little bit about some spacecraft and some instruments;
I think since there are a lot of amateur astronomers, we\'ll look at
some of the imaging instruments. And don\'t hesitate to come up with
questions or comments.

Page 4, Slide 4, I have a cartoon developed by our Spitzer friends.
Spitzer is the infrared space telescope facility which operates and
orbit about the Sun, trailing - as a trailing or leading? I think it\'s
trailing the Earth as the Earth and the telescope go around the Sun but
it has marvelous views and this is just an artist depiction from the
Spitzer people.

And it is in four quadrants here, A, B, C, and D, showing the typical
evolution of a star from the point where it\'s a cloud of interstellar
gas and dust, has flattened out into a disc. And from A to B to C is
probably about 10 million to maybe 100 million years where the disc
rotating of course because all the in-falling material didn\'t fall
straight in, it had some component of motion to that and that averaged
out to a rotating disc.

And of course formed a massive body in the center which in the case of a
star, begins using atomic nuclei together and producing energy from
nuclear fusion. And over the eons, the rotating disc and the force of
the star\'s radiation in the center clears out the disc. And by the time
you get to panel C and D, you\'ve got a disc that\'s mostly a star in
the middle, a bunch of big chunks or planets and a cloud and then in the
final panel, D, is what our solar system looks like today. You can\'t
even see the planets in the solar system in the nice prints that I made
but basically a star and a bunch of debris left over.

Now, in that D panel, if you imagine about a quarter of the way out from
the central star, our Sun, towards the outer ring and the outer ring is
representing what - in our solar system is the Kuiper Belt of
proto-comets, planetoids. About a quarter of the way out is about where
Saturn would be or where operating our spacecraft.

And I\'d like to pause and think about the distances in terms of light
time, first light going out from the Sun to Saturn since it\'s ten times
as far as the Earth is from the Sun; it takes ten times the length of
time for light or radio signals to get out to Saturn. If light takes
about eight-point-three minutes to get to the Earth from the Sun, it
takes 83 or so minutes to get out to the realm of Saturn.

In my night school class, last week we used a large room, 205 feet long,
gigantic meeting room, to deploy a scale model of the solar system. And
we had Saturn out at the edge of the room. The Sun was about 2.4 inches
in diameter at the other end of the room. And then I had a little
crawler that crawls along the floor from the Sun model at the scale
speed of light.

And, you know, you can say, \"Okay, it takes 83 minutes for light to get
out there.\" But when you\'re watching it go, when you\'re watching this
little battery-powered crawler moves at the scale speed of light, it
really hits you that that\'s a long, long way.

So by the time we finished walking around and discussing all the planets
and their moons and things, the hour was up and the little speed of
light indicator had only gotten half way out to the Saturn model.

Voyager, in this view, if we look at D as our solar system, Voyager 1
and Voyager 2 which we\'re still communicating with regularly are way
out there in our pass that outer disc. They\'re in the extreme far
reaches of the solar system and a signal at light speed to Voyager 1
these days takes 25 hours and change to get out to Voyager and back to
the results. So it\'s over 12-1/2 hour is one way, light time to where
Voyager is.

This Spitzer animation is available - I put a URL up there on Slide
Number 4 if you would like to see this animating and rotating as a
little movie. Now, of course the main motion from the proto-planetary
disc is still with us, the primordial motion of rotation around the
central star, we never got rid of, we\'re still living with that. And so
as we fly through the interplanetary medium, that\'s what we are under
the influence of.

Slide 4 shows an actual image taken by the Hubble Space Telescope,
looking on to a star in the Torus region in the sky, about 450
light-years distant from the Sun. And we happen to be looking nearly
edge on to the proto-planetary disc where the stars forming in the
middle, the disc is still thick and appears to us as a dark band and
above and below that dark band, you can see where the starlight is
illuminating the rest of the debris but there is that dark opaque band
where maybe planets are forming, maybe Kuiper Belts are forming, and
there are a couple of jets and they say that - I\'m not an expert in
this but from what I\'ve read, jets going out from the disc where gas
and dust are falling in to the embryonic star. The jets emanate and
carry energy and matter out many, many light-years away from the star.

Okay, I think if we go to Slide 6, here is the results. In our own solar
system we have the central star that contains most of the mass from that
cloud, 99.85% of the mass of that proto-planetary disc resulted in our
central star and since it's so massive, it has gravitation that just
dominates the whole solar system probably out to about a light-year
where comets like bodies in the outer Oort cloud way and way out in the
region near a light-year from here are moving so slowly that other stars
can influence them. In fact over the eon as other stars pass the Oort
cloud, they do disturb the orbits of bodies in the Oort cloud and as we
know some of them fall in with perturbed orbits towards the Sun.

So, mass and gravitation, Page 7, we have that primordial preexisting
dominating motion and I put a picture of the carousel and there are
horses on the carousel. If you use this analogy, if you're riding on a
horse on the carousel, you can wave your arms and you might even be
brave enough to get up off of the horse and move around to different
horses, but overall, you've got that primordial dominating motion going
around the center.

So, even though we send spacecraft out around the different planets, we
still deal with that primordial motion, everything is basically orbiting
the Sun. If you want it into the Sun, it would take a great deal of
energy to lose part of motion.

Okay, am I going to fast for people to chime in with any questions or
comments?

Jane Houston-Jones: You are going fine, Dave.

Dave Doody: On Slide 8, I've added to the results, of course, the
radiation from the central star, the Sun, keeps light, ultraviolet, in
fact throughout the whole spectrum from radio waves through infrared,
which we feel as heat through light red through violet light, more
energetic ultraviolet light.

And then x-rays and gamma rays do come from the Sun but they're mostly
confined to the flares that come as disturbances in the Sun\'s corona.
Those are energetic in x-ray and gamma rays.

So lots of radiation on Page 9 and there's more. The results of our
proto-planetary disc having collapsed into a star on extensive magnetic
field, Voyager 1 and Voyager 2 are still sensing the magnetic field out
where they are. And the solar wind and the occasional mass ejections
from the solar corona.

Now the solar wind pours out - it was discovered in 1958, I believe,
that the Sun pours out plasma that is protons and electrons, hydrogen
atoms that are electrically charged. The electrons stripped off of a
hydrogen atom and a few heavier atoms as well but mostly it's protons
and electrons streaming up a million miles an hour in the equatorial
region of the Sun.

And you may recall that a couple of decades ago, the Ulysses mission
went into orbit in the polar region - around that polar region of the
Sun and measured the solar wind not only in the equatorial but -
equatorial flame but also at the poles and Ulysses found that the solar
wind approximately doubles its speed up near the pole, the north and
south pole of the Sun.

So, here's this immense wind constantly streaming out of the Sun. And
there are occasional flares, storms probably caused when magnetic fields
do funny things in the corona to cause mass ejections.

Now, the large particles and bodies in our solar system, all to be
Newton and Kepler as far as following their paths or orbits around the
Sun. But these microscopic particles, protons and electrons, even some
dust particles that are charged, they don't care about Newton and
Kepler, they just follow the magnetic field lines of the Sun and also
planets that they encounter.

The - okay, let's look at the next slide - Page 10. This is the movie
that I invite you to have a look at in real-time. It doesn't play within
the PowerPoint show, but I did include the SOHO URL there. It's a long
complicated URL, but well worth it, I believe, as you wanted to copy and
paste into a Web browser. And you have probably seen me as before anyway
if you're as interested as I am in the solar system.

The SOHO spacecraft - SOHO stands for the Solar and Heliospheric
Observatory spacecraft. Since out at the L2 point, the Lagrange point
where it's in a stable position between the Earth and Sun, it's very
close to the Earth, but at the point where the Sun\'s gravitation
balance is balanced by the Earth\'s gravitation and so SOHO just sits
there staring at the Sun.

And this one instrument, LASCO, I forget what LASCO stands, for has an
occulting disc that's in - and it's visible in the image on Page 10 as
the dark blue circle in the center of the image, and you see a dark
strut going from the center down to the lower left in this image, that's
the strut that holds the occulting disc in front of the Sun.

So it's as though you're above the atmosphere - well, you are above the
atmosphere; that's as though you're watching a constant solar eclipse,
watching the corona, stream polar wind particles and mass ejections
outward from the Sun. If you have the movie available, please go ahead
and run it now.

The white circle in the center represents about the diameter of the
visible Sun and then you can see where the disc has blocked the glare of
the Sun. But if you run the movie, you'll see the evidence of the solar
wind streaming out, you'll see flares, coronal mass ejections coming off
of the Sun once in a while. This was taken, these series of images into
a movie, was taken in 2001 near the maximum of our solar activity
period.

About three seconds into the movie, you see a bunch of streaks snow in
the image. And that's where protons hit the camera or the imaging
device, the CCD in the camera. And it causes little white - short little
white streaks as though you're suddenly in a blizzard for a couple of
seconds.

These coronal mass ejections, large ones, can eject a billion tons of
matter at several millions miles an hour out from the Sun. So, when
you're flying in interplanetary space, you must have a spacecraft that
will not be ruined by getting run into by a billion tons of coronal mass
ejections, several million miles an hour.

And, of course, if you're a human traveling that distance out in
interplanetary space, you want to plan your flight to minimize your
chances of getting any exposure to CME's coronal mass ejections.

Okay, let's go to Page 11 where we show a cartoon of the Sun sending a
coronal mass ejection up towards the Earth. Fortunately, the Earth has
its own magnetic field that is strong enough to divert these charged
particles away from direct impact with the Earth and if that were not
the case, if the Earth did not have a magnetic field, life, if any,
would be very different on the Earth today.

But the magnetic field sets up a barrier and reach the particles around.
Some of the particles of course as you know fall in through the magnetic
field lines into the North and South Polar regions of the Earth and
other planets as well producing Aurora.

I've never seen an Aurora myself but of course I've seen pictures and
Aurora are caused when electrons and sometimes protons are diverted down
the magnetic field lines and where they impact molecules of air, they
cause them to glow.

Mercury and Venus have no magnetic field to speak off, no planetary
magnetic field like the Earth does. Mars does not have a planetary
magnetic field, does have patches on the surface that indicate there may
have been a magnetic field - a planetary magnetic field in the past but
Mars is only have this fragmented magnetic - local magnetic field.

Jupiter, Saturn, all the Jovian planets, of course have strong magnetic
fields and we can see Aurora on them as well especially if we look at
these planets in the ultraviolet.

Now, when a coronal mass ejection hits the Earth, the Earth's magnetic
field, it causes it to fluctuate and that can wreak havoc with the
electric grid even pipe lines down here on Earth.

Let\'s look at Page 12.

Man: Can I ask a question. This is Ken.

Dave Doody: Yes, you can.

Man: I would like to - it's a beautiful shot but what I'd like to know
is New Horizons is the first space craft that's going to actually travel
through one of these magneto tails, how is it that the Voyager
spacecraft didn't? I guess it's trajectory but I wonder if you could
talk a little bit about that.

Dave Doody: Oh, gee, you know, I wasn't aware of that.

Man: Yeah, that's a big point they're making.

Dave Doody: New Horizons will be flying through the magneto tail of
what, Jupiter?

Man: Jupiter, on this flight and it's coming up in a month.

Dave Doody: Oh, fortunate.

Man: Yes, and it extends, you know, all the way out to Saturn and I'm
just curious why the Voyagers for example did not pass through the
magneto tails of any of these...

Dave Doody: Yeah, but the Voyagers didn't because they were targeted
only to fly their gravity-assist trajectories and that held them right
in the ecliptic and got to a point and along trajectories that just
didn\'t happen to follow the field.

However, when Cassini past Saturn, we spent quite a bit of time going in
and out of the magnetic field because as Saturn, when it passed by
Jupiter.

Man: Jupiter, right.

Dave Doody: Yeah, passed by Jupiter on its way to Saturn, it dipped in
and out of the magnetic field of Jupiter while at the same time Galileo
was orbiting deep within the magnetic field. So that gave for days or
maybe several days or a week, I'm not sure what it was, Cassini did fly
along in the boundary of Jupiter but then of course Cassini's trajectory
wasn't designed to do that so it dropped off part of its opportunistic
investigation. So New Horizons will spend more time in Jupiter's
magnetic field; that'll be exciting for scientists who study magnetic
fields.

The - okay, the next slide on Page 12, it's not a very good image I
apologize but what we're looking at is Ed Stone\'s sink. Ed Stone is the
Voyager project scientist. He's been the Voyager project scientist for
many, many years since before launch of Voyager and I guess he must be
the happiest scientist in the world by now.

But he studies magnetic fields among other things and the solar wind and
this view of his sink shows where water is coming down from an unseen
faucet above and after the left of the image, hitting the sink and
spreading out. You know how a stream of water will hit a surface in a
sink and then stream outward but then it piles up and you can see where
the water is piling up here in this image.

Well, this is analogies and Ed Stone uses this as an analogy to the
solar wind; all those particles eventually slow down and bunch up and
they go subsonic at some point out there and it turns out that the point
is like where Voyager 1 is; in fact Voyager 1 is well beyond it now.
Voyager 2 will be approaching this termination shock as it's called very
soon probably within the year and should repeat the experience that
Voyager 1 did.

So Voyager 1 and Voyager 2 coming up investigating the region here where
the solar wind goes subsonic and bunches up and then pretty soon beyond
there and we don't know how far yet is where the Sun\'s magnetic field
ends and yields to the interstellar magnetic influences.

Now, there's an animation of this and I have the URL there in the Basics
tutorial where it merges into a view of animation that represents the
solar wind. So everything has that primordial motion orbiting Sun, under
of the proto-planetary disc and now the solar system.

Page 13, let's take a quick look at orbits. This is - a cartoon on Page
13 illustrates Isaac Newton's thought experiment that if Earth had a
ridiculously high mountain which should cannot and you put a cannon put
at the top of the mountain and fire the cannon, well, of course the
cannon ball would hit the Earth that it would follow an arc. And then
his thought experiment goes add more energy to the cannon and the cannon
ball will go further before it hits the Earth. And if you add still more
energy you can get your cannon ball to miss he Earth entirely.

Well, this thought experiment and the cartoon lends itself pretty well
to defining terms for orbits about Earth or obits about the Sun or about
anybody.

Let's see, Page 14 we have the term Apoapsis and we call that mountain
mount Apoapsis where Apo is - I guess it's from the great means the
farthest point in an orbit and imagine while you're at the high point in
your orbit adding more energy.

Well that takes you - let's look at Slide 15 and if you're Power Point
show is running this should show an animation and you'll see that cannon
ball missing the Earth and going all the way around the Earth. Well,
that completes Newton's thought experiment. But it also gives us the
chance to look at the word Periapsis, Apoapsis is the high point of an
orbit Periapsis is the low point of an orbit.

And I left out the intermediate stage where the cannon ball goes halfway
around the Earth and then impacts and then you can imagine packing more
energy into your cannon to lift that Periapsis altitude up so that it
misses the Earth entirely.

Okay, on Page 16 the animation should still be running and showing
Apoapsis and Periapsis but to summary them this is really a key to
interplanetary flight, as well as orbital flight around the Earth. You
added energy up there at Apoapsis and the effect was to increase the
altitude at Periapsis and so your cannon ball no longer hit the ground.

Well, on Page 17 the animation doesn't show this but the notes, the
opposite is also true and you can imagine that as your cannon ball is
flying past Periapsis, its closest approach, if you were to have energy
added say your cannon ball or space craft had a rocket engine where you
could momentarily add some energy, just a burst of energy tangent to
your orbital direction you could increase the altitude of Apoapsis and
avoid hitting that annoying mountain as you come around and that's
basically how you fly planets through - fly a spacecraft among the
planets in our solar system.

On Page 18 I blocked out the cartoon of the Earth with a cartoon of the
Sun illustrating that anything that orbits the Sun also has an Apoapsis
and a Periapsis; orbits are not exactly circular except in rare cases,
they're all ellipsis.

And on Page 19 then extrapolate that to a flight from Mars to Earth and
I'm not going to get into all the details because Nav \[Navigation
team\] is going to have one of these talk on.

But if you notice the blue circle representing the orbit of Earth around
the Sun and here the objects are going back around the other way,
reversed from the previous cartoons and there's no animation here this
is just a still.

You imagine a red orbit saying, \"Okay, this is the orbit that I would
like to fly to get up to another planet, say, Mars.\" So you realize
that here on Earth you are already a Periapsis of the intended orbit and
say you just add a burst of energy and that raises Apoapsis just like we
saw in the previous slide.

And if you raise it enough, had enough energy you get your Apoapsis out
to coincide with the orbit of Mars for example and if Mars happens to be
there when your spacecraft gets there then you can do stuff like slow
down, get into orbit or land there.

So that red part though is called a transfer orbit and I'm going to
briefly touch on Page 20 that orbit is called a Hohmann transfer and I
think believe that as it is and not to dwell on this.

Let's go to Page 21. Well, you don't need to use fuel to change your
orbit. Astronomers have known for a long time that comets traveling
through the solar system have their orbits changed when they fly by a
planet, for example Jupiter.

Spacecraft can do the same thing, this was proven in 1961 by a grad
student here at JPL; did all the computer runs to show that barely a
Voyager could use not just the gravity but the orbital momentum from the
planets Jupiter, Saturn and Uranus to fly without any increase in
propellant cost just about anywhere in the solar system.

The simulator is a gadget that I produced under a grant from the Art
Center College. On the Basic Space Flight Web site there are
instructions on how you can produce a crude version of one of these and
sometime in the near future I promise this year we'll have detailed
instructions on making a better simulator but it really drive's home how
the gravity assist works.

Let me spend a minute on the image on Page 21.

In the middle is an orange ball that represents the Sun and that sits on
a heavy wheel that's made of granite and on the wheel you can see on the
left - upper left part of the wheel is a little circular magnet that's
painted to look like Jupiter and do you have a mechanism that launches a
steal-bearing ball up across a glass surface.

And you get this Jupiter wheel turning so that you can simulate the
mass, the momentum of Jupiter going around the Sun and it's true that
the Sun has most of the mass of the solar system but the planets,
Jupiter mostly, has all of the angular momentum in the solar system.

I believe Jupiter and Saturn together contain about 90% of the angular
momentum from that proto-planetary disc; the Sun only has a small 2% or
so leftover.

So gravity assist uses the momentum - a huge store house of momentum by
flying by, say, Jupiter at a close enough distance so that you get
Jupiter's gravity to connect like an elastic connection just briefly and
you actually slow down Jupiter a little bit with your spacecraft just as
when you fly a bearing ball pass the rotating Jupiter magnet on the
simulator toy.

You store down the rotation of the massive wheel and that gives you a
kick your BB gets flung out across the solar system and if you\'re good
enough at it, you can hit the Saturn target out on the simulator. And in
the same way Jupiter loses momentum to give your spacecraft a boost.

Yes, question?

Jane Houston-Jones: I guess not.

Dave Doody: Okay.

Okay and then the simulator drives home the point that you don't notice
the momentum loss in the mass of wheel just as you don't notice the
momentum loss of Jupiter when you use that momentum to boost your
spacecraft.

Page 22 shows the URL for a movie where Jane is demonstrating this
thing; I'll leave that for you to browse if you like.

Page 23, well, maybe the most important result of the proto-planetary
disc is on Page 24, planets, where we live, and stuff, moons and
planets, comets, asteroids. If I were to pick a few of the moons of the
planets to really study, I would pick Jupiter's Io, which is volcanic.

Jupiter's Europa, which has a thin ice shell and a warm salt water
ocean. Saturn\'s Titan, of course, has a thick atmosphere, thicker than
Earth\'s and processes that are very similar to Earth\'s hydrologic
cycle. There are methane rains on Titan; this has been the subject of
previous telecons as well and Enceladus, Enceladus that Saturn has
constantly erupting geysers of water, water particles may or may not
have come from liquid water on tiny little moon, Enceladus, it's a real
surprise.

Page 25 is a nice back-lit image of Saturn where we realized that Saturn
also has a disc of rotating material that you can use to study things
like\
proto-planetary discs, galaxies as well as other ring systems. And of
course every particle and in Saturn's ring is a separate satellite
orbiting the planet interacting of course with one another and this
back-lit image was a subject of the previous talk on I'm not going to
get too much in detail but if you look at Page 26 I do have a lot of
detail available.

This is a draft that's online on the Basics tutorial Web site,
jpl.nasa.gov/basics. If you go to slant Saturn after Basics, you\'ll see
the page that I'm working on an it's not released yet, I don't have it
linked in to the rest of the Basics tutorial yet. I\'ll do that after
I'd have enough peer review and corrected some wording here and there
but it's there if you'd like to browse it.

The idea is that you go to that site and then you click on the image;
it's halfway down the page on that Web site. And if you're using the
right kind of Web browser it will let you see the whole image and you'll
have to scroll left and right and up and down to fly around in the
Saturn system as it were and read of the notes and the notes point out
all the various different effects of light and dark shadow and forward
scatter and back scatter, all these no back scatter here in this - yes,
there is.

But I invite you to have a look and send me comments too if you like;
I'm working on this.

There's also on that page Basics slant Saturn a very large image of
Saturn and the rings taken in forward scattered light, the normal
viewing angles and you can use your browser to fly around and look at
all the different annotations.

Let's look at Page 27. There is also a link from that Basics slant
Saturn site and experiment showing the difference between back scattered
light and forward scattered light where the particles that you're
looking at are close to the size of the wavelength of light. This is
true at Saturn particularly in the E ring, the F ring and also within
the Cassini division.

So when you're looking at particles on the order of a micron, 1 to 10
microns, say, in back scattered light; that is you are the observer on
the same side and the source of illumination and to show that in this
image on the left, back scatter, I've got a laser in my hand in the same
side as the camera shining a light through cloudy water and on the
right, the laser is behind the cloudy water shining towards the camera
and you can see that the cloudiness in the water which is about 1 micron
sized particles lights up like crazy and that's analogies to how you're
looking at the sunlight illuminating the tiny particles in Saturn system
and this applies throughout observations in the solar system.

I used a few drops of homogenized milk in a jar of water since the
globules of homogenized milk are about a micron in size.

Page 28.

Jane Houston-Jones: Hey, Dave this is Jane. Before you go on to Page 28
I just wanted to mention to people who go to this page and go to Dave's
images of the forward and back scatter. He has a link to the educational
activity that you all can do in you classrooms or your museums or your
event, recreating this activity so the link to that activity is on that
page.

Dave Doody: Well, good thanks.

Well, Page 28. My telescope is a 19-inch aperture, 7-3/4 inches; it's
Cassegrain and it has a 1 mega-pixel CCD but it's in orbited Saturn.
This is the narrow angel camera on the Cassini spacecraft, these pretty
close ups.

The CCD charged couple devise, you probably have your own if you're an
amateur astronomer, it's only 1 mega-pixel, 1,000 by 1,000 pixels; not
very impressive by Earth standard.

Page 29 shows the wide angel camera specs. Of course Cassini and many
other spacecraft replete with instruments like this telescope that view
in divisible and plus and minus a little bit and also instruments that
view ultraviolet infrared and far beyond so this is just a tiny sample.
And all those other instruments as well are described on the Basic\'s
Web site.

Page 30 is a crude illustration by analogy of how a CCD works. If you
were to picture a million aluminum cans with their tops open, all
bunched together tightly, you would have an analogy of a 1 mega-pixel
CCD and then picture it's raining over these aluminum cans and then you
have some way after the rainstorm of checking each of the cans for their
content and measuring how much water collected in each of the cans.

Well, the CCD uses tiny little solar cells, if you will, all bunched
together, a million of them on a chip in Cassini's case that collects
photons. In fact, it can register a single photon, CCD is pretty
sensitive and so if CCD then is charged a couple device. It\'s a means
for gathering and counting how many photons have hit your detector.

I'm going to cruise on up to Page 31.

If you go to the Basic\'s Web site slant Cassini, you will see an image
of Cassini with all of the instruments and major components called out
and if you click on the names, it'll bring up a page that explains and
gives specs for each of the instruments.

Moving right along on Page 32. If you're using the PowerPoint show you
should see this animated and it's a sine wave that represents the radio
wave coming back from a distant spacecraft.

The radio wave has the trace of a sine wave showing where the strength
of the field increases and decreases and increases and decreases. In the
case of, say, a Voyager that's happening at the rate of about 200,000,
3000,000 - million times a second, two or three gigahertz on Cassini.
It's in the neighborhood of 8,000 megahertz.

And in the animation I have the wave seem to flash forward and back
every once in awhile. If you're not seeing the animation of the picture,
if this standing wave in front of you were to jiggle 20% of the picture
size up to the right and then quickly jiggle back and that happens every
once in a while.

Well, that's how we send data from a spacecraft to the Earth in
Telemetry and Command. There are other forms of data, tracking data
which the navigators\' presentation were probably addressed later in the
up coming telecon but this for telemetry that is sending data back from
the spacecraft tele-meter measuring at a distance how is - how you send
its 1s and 0s once you've broken down your image or other science data
into 1s and 0s, you then stream them back to Earth.

And the symbols we use are jiggles in the phase of the wave; pretty much
like you see in the animation on this slide and it takes a number of
jiggles to be recognized as a bit, a binary digit, a 1 or a 0.

In the case of Cassini, the coding that we're using now, it takes six of
those little face wiggles to equate to 1 bit and the same scheme was
used - while Voyager, I mentioned, uses it and Voyager way out of the
edge of the solar system can still communicate at the rate of 1400 bits,
1s or 0s per second.

Spitzer Space Telescope nearer to Earth with great big antennas can
communicate up to 2.2 million bits per second. And Cassini when w have
the large aperture antennas scheduled on Earth, we use a (165,901) bits
per second, about 166K and to get that rate, the phase of the - the
radio signal has to wiggle about 10 million times per second.

Page 33 mentions our friends, the Deep Space Network, apertures on the
order of 70 meters in diameter, 34 meters in diameter, located at three
different places around the Earth, the GoldStone Complex in California,
the Madrid Complex in Spain, and the Canberra Complex in Australia. So
as the Earth turns, any one of those complexes can see any given
spacecraft.

The latest Deep Space Network antennas are a neat design where they've
got all the equipment down on the basement and they use a system of
mirrors and pipes to get the signal up and down between the big
reflector antenna and the equipment on the basement.

Then on Page 34 if you feel the need to spend a couple of rainy days
cutting and glowing and pasting, you can download all the parts for free
on the Internet; that\'s jpl.nasa.gov/scalemodels and build the Deep
Space Network antenna and see exactly how it articulates and moves the
signal from the antenna to the basement.

Please check back with the Basics, look in on it every once in awhile.
I'm upgrading it in the order of once a month and if you go to the
editorial page, it'll show what chapters have been upgraded and by all
means send me your questions. My email address in on Page 35 with which
I'll say, thanks a lot for joining us it's been a pleasure and we still
have time for anymore discussion I think.

Jane Houston-Jones: Thanks a lot, Dave.

So the great thing about Dave's talk here is that all the URLs and
everything is right here so that you can, at your leisure go in them, go
in-depth and visit some of these pages and some of these movies.

Does anybody have any questions?

(Ken Kramer): Yes, I have a question. This is Ken Kramer.

So I just want to understand your entire syllabus then pretty much is at
this Web site?

Dave Doody: Yes, that's right.

(Ken Kramer): Oh, excellent; that\'s all I wanted to know.

Dave Doody: And it's got a lot of links.

(Ken Kramer): Uh-huh. Very good. So we can look at that and learn and -
excellent, thank you.

Dave Doody: And comment please.

(Ken Kramer): And comment. Yeah, I definitely am going to comment on
your Saturn annotated slide there.

Why did you guys actually put...

Jane Houston-Jones: Could the speaker give his name please?

Ken (Kramer): Yes, Ken Kramer.

Jane Houston-Jones: Oh, sorry. Sorry I didn't recognize you, Ken

(Ken Kramer): Yeah sure.

Yes, in the picture on Slide 26 why have you guys put Saturn in forward
scattered light there?

Dave Doody: Page 26.

(Ken Kramer): Right. Saturn is actually in laid in the - amongst of the
rings.

Dave Doody: Oh, good I'll take that as a comment and adjust the wording.
Very good. Yeah, what we're seeing is the forward scattering around the
edge of the atmosphere to the right.

(Ken Kramer): Okay.

Dave Doody: The rings are shown in forward scattered definitely.

Good thanks for that.

(Kevin Cosby): Yeah, it's (Kevin Cosby). I got a question about the
Enceladus.

Dave Doody: Uh-huh.

(Kevin Cosby): Are you guessing on that or do you know that that could
be a salt water ocean underneath?

Dave Doody: Oh, Europa. That's...

(Kevin Cosby): Oh, I'm sorry yes, Europa.

Dave Doody: Yeah at Jupiter. Galileo studied Europa in-depth. There's
still a lot of interests to the possibility of sending a Europa orbiter
to learn for sure. But in the studies of Europa's gravity, Europa's
magnetic field, it does indicate that there's something creating a
magnetic field and the likely candidate is salt water, currents flowing
through salt water and the density and size measurements all strongly
suggest that there is a liquid water, salt water ocean.

Now, you\'ll never be sure until you bore through the ice and dip your
toes in it.

(Kevin Cosby): That's right.

Dave Doody: But it's a very, very strong several lines on evidence and
not only Europa but also Ganymede and Callisto have strong indications
of sub-surface water.

(Kevin Cosby): Okay. Thank you I didn't know that.

Less though with those ones, right?

Dave Doody: Yes.

(Kevin Cosby): I have a quick question for Jane.

Jane Houston-Jones: Sure.

(Kevin): You mentioned the - oh, your email, I wonder if you could send
us your email because I don't think it was included; if that's possible.

Jane Houston-Jones: It's everywhere all over the Saturn Observation
campaign Web site.

(Kevin Cosby): Okay.

Jane Houston-Jones: But I'll send it to you; I think most people already
have it and I'm just filling in for the CHARM talk this month.

(Kevin Cosby): Okay.

I want to ask about the Saturn Observation campaign.

Dave Doody: That's a good question.

Jane Houston-Jones: It's a great question. Okay, well these talks are
brought to you each month by the Cassini Mission to Saturn and from our
science - our science project team is actually sort of the sponsor of
these talks.

And the Saturn Observation campaign is - you're a member of the Solar
System Ambassadors?

(Kevin Cosby): Yes.

Jane Houston-Jones: It's similar to the Solar System Ambassadors except
that it's open to international participation and it's just sponsored by
the Cassini Mission.

(Kevin Cosby): Okay.

Jane Houston-Jones: So what we do in the Saturn Observation campaign is
encourage amateur and professional astronomers and non-astronomers such
as librarians or teachers or others who have an interest in observing
Saturn to do that to show the planet Saturn through their own telescopes
or a telescope of a local club to their communities and just like you,
Solar System Ambassadors, report your events to Kay, these members of
the Saturn Observation campaign report their events to the Cassini
Mission.

There's about 50 members of the Solar System Ambassadors who are
currently members of the Saturn Observation campaign; in fact that's the
model of the ambassadors was what was used about four years ago to start
the Saturn Observation campaign.

So it's very similar, it's a little less formal. We don't have the same
amount of like the ethics training and some of the - we'll have badges
or T-shirts or so forth like the Saturn - like that Ambassadors do.

But what we do is we all love Saturn and are wowed by the Cassini
Mission and we go out and do talks about Cassini and about for viewing
Saturn.

And to find out more information about it you can just go to the main
Cassini Web site and there's a link right on there to the Saturn
Observation campaign. And what I'll do when Kay gets back from Egypt is
I'll send out an email to all of the Solar System Ambassadors talking
about it because I have some really nice pages that people can use to
find Saturn and have a lot of resources.

(Kevin Cosby): Yeah, I'd like to definitely sign-up for this. I do a lot
of Saturn events and I wasn't aware of this.

Jane Houston-Jones: Yeah, I'll be happy to send you some information
about it.

(Kevin Cosby): Great. You got - you must have my email.

Jane Houston-Jones: I'll send it to all the Solar System Ambassadors.

(Kevin Cosby): Okay, very good. Thank you.

Jane Houston-Jones: Thanks for that great question.

(Kevin Cosby): Okay.

Jane Houston-Jones: That's the way to say, \"And now a word from our
sponsor, the Cassini Mission.\"

So with that, does anybody else have any questions? And if not, I think
we can end the talk. For those of you who want more information about
the Cassini Mission you know the URL it's saturn.jpl.nasa.gov and I
think with that I'll thank Dave very much for his talk and say goodbye.

Dave Doody: Thanks for participating.

Jane Houston-Jones: Yeah, thanks everybody.

Man: Bye-bye.

Man: Thanks, Jane.

Jane Houston-Jones: Okay. Bye-bye.

Man: Thank you, excellent.

END