When is the next mission to Saturn going to be and what would you want to find
out based on this mission that you don't
already know?
Don't know when the next mission is going to be
there are some studies being done in
the States at the moment and depending
on which scientist you talk to some
would like to focus on Titan and Enceledus
I'd like to focus on Saturn
but I'm still not quite sure what we
would want to do we need to get the best
out of our data you know one of the
things about about datasets is they're a treasure trove of information and
I think we're pushing the data as hard
as we can at the moment but there will
be scientists that come and look at it
in the future and find new and
interesting things so I'm partial to
Saturn at the moment but that's just
because the end of mission has been so
spectacular
Well I presume that it's only
every so often that the other
planets are aligned who can do this
slingshot out to Saturn
Yes you can you can do
really quick slingshots
The Voyager spacecraft, NASA was really fortunate because
all the planets were lined up
beautifully so it took it took Voyager
spacecraft rather a short amount of time
but you can always, you can
always get out there it's just whether
you want to take five years or ten years
Okay, questions, comments please wave wildly because I have
bright lights shining in my eyes
I was wondering, the visible surface
features of Saturn um I think that there
is a different rotation at the equator
than at the pole because it's a gas and I
would assume that in the metallic
hydrogen interior which is liquid
right because that that's how the dynamo
works that would also be rotating
differently and that's what's producing
the magnetic fields and all of these
things are moving at different speeds so
I guess to what extent can we say that
Saturn has one single day when the
period of the equator of the pole the
interior and the rock are all different?
Usually when you talk
about the rotation rate of a planet
you're talking about the interior
rotation rate but yes there are there
are lots of different rotation rates in
the atmosphere and Jupiter's the same
you've got different rotation rates in
different parts of the atmosphere
Can we infer the rocky rotation which isn't
part of the dynamo from
Can we infer the rotation of the rocky bit which is
not part of the dynamo from the
liquid part which is?
I think you're pushing it a little
I mean you can use models and
simulations to try and do that but you
can never be sure
Hello yes thank you for a wonderful talk that was splendid
Can I ask you a sort of romantic
question about Enceledus? You showed us a slide that said simple organics
and complex organics what does that mean
is that is that life or is that amino acids or what?
It's before amino acids so you would
need something else to happen to start
the the life process and that's where
the length of period of time comes in
having having ingredients is not enough
you need you need the process to be
stable enough over time that something
can happen.
Thanks for a great talk
you know that other open question as well as the rotation rate was the age of
the rings and can you say something as
to what you currently know about being able
to age the rings and knowing whether
they're something very recent or
something that's formed over a great deal of time and what physical
principles do you use to determine that
Oh now you're really pushing my knowledge
I think the only thing I
remember about well part of the the
F ring part of the ring grating orbit
that the science driving that was to try
and get an understanding of the
composition of the rings using gravity
to also try and get an understanding of
the age and my recollection is they're
younger than people think
what that means I don't know but if you
go to the Cassini JPL website
sure that there's a there's a write-up
about that it's it's not my field at all
so I don't know the details of it I'm afraid
but my understanding is they're
younger than ring scientists thought
they were going to be
But not recent
Okay someone in the gallery, is there a
microphone up there
Alright if I shout out?
Could you tell me please what would you say are the possibilities of life on Enceledus?
Do you think that is the mostly likely one, however you would rate that compared to Titan, to Mars?
What are your views on that? What sort of percentages can you think?
I knew I was going to get one of those
It's very difficult to tell
I would be very surprised if there
wasn't bacterial life of some kind
somewhere I think the outer moons in the solar system are a good possibility
because we know for example in in some
of the deep regions and our Earth's
oceans you can have you can have
bacteria forming and conditions where
you really think it's simply not
possible. I think for me the real step
change that's happened in the last 50
years or so which has really been
underpinned by the Cassini observations
of Enceladus and the desire and the new
missions that are going to Jupiter's
moons is the fact that you can have
liquid water at quite big distances from
the parent star. People have always
thought that you can only get liquid
water on the surfaces of bodies and so
that you know if you're looking at
exoplanets you need to look at planets
that are close to the parent star but
we've seen with the Jupiter moon
so Ganymede, Europa and Callisto, we think
they all have liquid water under the
surface and we seen with Enceladus as
well that you've got liquid water you
don't have to be close to the parent
star so I think for me that's been the
real change and I didn't answer your
question but
that's as far as I'm gonna go
Okay somebody else in the gallery could you shout please
Enceledus is tidally locked. Can you say whether the tiger stripes point towards Saturn or at an angle to it
They're at an angle to the north pole of Enceledus so I think
they're at an angle to Saturn but but
that's just based on looking at the
images but yes they sorry you mean the
side that's facing Saturn or the side
that's facing away from Saturn is that
what you meant?
- Apologies if my question wasn't very good but basically
if you're Saturn and I'm Enceledus and this is the south pole
are the tiger stripes pointing towards you or at a transverse angle to you?
It's at a transverse angle, yep
Over there please, just wait for the microphone
Thank you for a great talk,
also I was wondering for the tiger
stripes do you have any idea where they
came from like where they asteroids
colliding in or something like that
Don't think so, I think there was
something happening in the in the
interior so there was a huge amount of
pressure building and they had and the
liquid water and the the water vapor
that was being generated needed to
escape, yeah, we think something
similar happens at Europa one of
Jupiter's moons but there it's almost
you know when you see images of you Europa it's almost like you know when you
fly over Greenland I don't know if
you've ever flown to the States and you
fly over Greenland and you you look out of
the plane you see the bits of ice
breaking off from the edge of the ice
shelf that's what it looks like on Europa
It's different in Enceladus
but but we think we think it was driven
from internal processes
You know how you
showed the image of Enceladus the
expected heat map the actual
yeah what's it gets all the extra heat from?
That's the million-dollar question
It depends which scientist you talk to
everyone has their different ideas with
the easiest solution is that if if a
moon orbits around a planet if the orbit
is completely circular then the moon
will feel the same gravitational pull
all the way around but if the orbit is
not quite circular so in some parts of
the orbit it's closer to the planet than
in other parts the gravitational force
is strongest
and so that pulls the interior out of
shape and so it keeps it warm it stops
it from cooling down and so the easiest
solution is to have the heat source
being the orbit around Saturn
That's the easiest way. There are lots of other ways as well but
You mentioned how fantastic it was to work with such an international team, could you tell us
more about the design process how did
you coordinate the design of the
spacecraft in the very beginning?
I wasn't involved right in the beginning
I became involved after the instrument was
designed and it had just been delivered
but the way it's working on the Jupiter
mission where I am involved in the
design and it will be very similar is
that you write a proposal to build an
engine well first of all a space agency
decides to select a mission to go
somewhere and they then put out a call
for instrument ideas and you write a
proposal and you describe the instrument
that you would build and the signs that
you would do and you try and get the
best team around you so they've got no
choice but to choose you and you then
submit the proposal and you go through a
selection process and a selection team
will choose the different
instruments
and then you get together and you talk
to the space agencies and you say this
is what I want to do and they say okay
we've got 12 instruments where are we
going to put them we can't get
instruments getting in each other's way
How heavy can they be? How much data
do they need? And that's the processor
we're in at the moment for the Jupiter mission
And for me it's really
interesting because it's completely
different to planning the science which
we will do once the instrument's been built
[INAUDIBLE]
What we did is we knew on
Cassini that the 11 meter boom that we
had was perfect because we didn't see
changes taking place on the spacecraft I
hope no one from the European Space
Agency's here but when we first started
designing the Jupiter instrument we said
to the to the space agency that we
really wanted a long boom and they said
no you only need a 5 metre boom and so
what we did is we said to them that the
size of the field due to the spacecraft
that we can allow they can we can be
allowed to see at the end of the boom
was so small that the only way they
could do that was give us a 10 point 6
meter boom but don't tell them I said
that
Clearly Enceladus is losing a reasonable amount of mass so the whole phenomenon must be transient
Do you have any idea about what sort of magnitude of time it could last for?
No, we're almost certain it was
taking place in the early
Oh I should know this - in maybe the mid-1800s
because they were observations made from
the earth of something strange when you
looked at Saturn and they didn't know
what it wasn't it took a very long time
to work out that there was an E ring in
the first place so it's been happening
for a long time not not long in that in
the lifetime of the solar system but
yeah it can't go on forever but I'm not
going to put an answer to that I'm not
going to give you a number from that I
because I don't know it
Okay one last question over there
You mentioned that the initial plan once you arrived at Saturn was to hang around for four years
but clearly you managed a lot longer
so it would seem that somebody put more
fuel in this spaceship than was initially required
- You always do -
So to what extend do you build
flexibility into the design in the
mission and how politically difficult is it to get an in flight change?
You always put lots of flexibility
in, you always over design because it's
not as if if something goes wrong you
can't go and tweak something so you need
really robust instruments for example
and one of the things that surprises
people is that the type of instruments
we fly the they almost look quite old
compared to some of the new gadgets that
we have but the reason that you do that
is to be able to fly an instrument on a
spacecraft mission you need to show
there at a technology readiness level of
nine, so they need to have flown before
so you can't fly a mobile phone to take
pictures because it hasn't shown that it
can work before. So you always over
design you always have always have redundancy
For us we had two instruments
and on each of those instruments you had
extra power supplies and extra bits so
that if something went wrong you could
move to another bit but there's always
extra fuel but you also learn how to use
that fuel as well you get to know how
the instruments on the spacecraft work
But it went on a lot longer than than
anyone thought certainly and then the
political question I've forgotten what
it was? Oh you've got to persuade the
funding agencies to fund you because you
know to be able to operate the
spacecraft and the instruments and do
something useful with the data you need
to pay people to do that and so the way
that we did it on Cassini is a year
and a half before the nominal end of
mission we put a proposal into NASA
to say we wanted more funding and so you
need to almost make a new science case every time
Okay so with that I think I
will draw things to a conclusion and
just remains for me to thank Michelle
for sending is a super postcard from
Saturn so thank you so much
