Music and sound effects.
atomic clocks are central to
deep space navigation it's
just that those clocks are
on the ground. And so an
atomic clock generates a signal
and it is sent through the
antennae on the ground to a
spacecraft in deep space. And
that signal is turned around
and received back at the
transmitting. And with that
transmission of the signal
we can do measurements of that
signal. You know how the
doppler shift on the signal
is how we can know how fast
the spacecraft is moving and
how long that signal takes
is a measure of how far that
spacecraft is. So the deep
space atomic clock can change
that paradigm. It can originate
the signal at the earth
and it can end at the
spacecraft. Its good enough, that
small clock that we are
building is as stable and
accurate as the ground clock
that originated the signal. We
get to utilize some of the
efficiencies that the deep space
tracking network has to
offer today. The DSN supports
more downlink than it does
uplink and so at places
like Mars where we have a
number of spacecraft that are
competing for two-way tracking
time... you don't have to
do that anymore. What does
that do for us? well what we
have found with a 2 times
improvement in our tracking
data for a Mars orbiter, the
orbit information that we get
is improved upon by a factor
of five. One of the things
we are envisioning at Mars
is landing a pin-point lander,
one that can land to a
very precise location (beep
sounds) on the surface of Mars.
there's a lot of steps into
making that happen. One of
which is entering the top
of the atmosphere and taking
your entry state knowledge
and onboard flying a
trajectory with that entry state
knowledge. We way in which we
upload that navigation state
today is that we do all the
processing on the ground in about
six or so hours and before
entry we upload a final nav state
to the vehicle. Well you can
imagine after six hours of flight
that solutions is little stale
when you get to the top of the
atmosphere. Well with DSAC with
the measurement happening onboard
you don't have to suffer that six
hour delay. You can be computing
onboard in real time. And what
that does is where the six hour
solution is in error by a few
kilometers, this solution that's
onboard is only off by a handful
meters. that has a real benefit
to decreasing the amount of
propellant you have to carry to then
later fly out the errors you had
when you didn't know where you
were at when you originally were
at the top of the atmosphere.So
that's gonna open up new ways,
new science we are going to be
able to do. In fact it's going
to improve the gravity science
we are going to be able to do
at Mars today. An example of
gravity science improvement that
the clock enables further out is
NASA is envisioning going to
Europa; an moon around jupiter. And
to be able to do the measurement,
the gravity science measurement
that NASA is planning. They're
going to do it, one approach
is a flyby mission. So they will
fly by Europa with a four hour
tracking pass, and then have a
thirty day orbit around Europa,
and then come back again for
another flyby. And do a sequence
of thirty or so of these flybys.
Well if we have the atomic clock
on a downlink signal from that
flyby and it's received at the
earth we can do it at Ka band.
and the benefit of going to Ka
band isn't so much that it has
to deal with we can increase the
bandwidth but what it does do
is that it improves the accuracy
of the measurement that we are
taking, and it improves it by an
order of magnitude and that is
fundemental. Its that improvement
in the data quality that will
allow us to determine the gravity
well enough. If decisions need
to be made in real time, the
DSAC can enable that kind of
on-board navigation to occur.