STEVE SANDFORD: Good morning.
AUDIENCE: Good morning.
STEVE: Welcome.
And welcome back to those of you
who have been here throughout
the series, if you have been
here throughout the series,
you had seen NASA's plans
for the next 30 years or so.
And the question is do
we have to kill you now?
The answer is no.
It is a civilian space
program and we work for you,
so you have seen the plan and
for the last two weeks you have
actually seen the program that
is underway today to build the
transportation system to
take people into deep space.
Today, and next week we are
going to concentrate on two
major problems that are between
us and being able to execute
that plan you saw the first week
of going to Mars with people and
Jeff Herath is here this morning
to tell you about the problem of
landing people on the surface
of Mars and how we go from
interplanetary speeds down to
zero miles per hour safely.
Last week we talked about
the rocket and how the rocket
accelerates the people, the
astronauts and their cargo out
of the gravity
world that we live in,
the steep energy well that
we live at the bottom of.
Now once the astronauts are in
space it is very easy to move
around, the only force you have
to overcome there is inertia but
the problem is when you get to
the next destination you have
got to take all that energy
that rocket put into you,
so now you are
speeding along at
25,000 miles per hour and
you got to slow down,
so now you are going down the
well and you got to go down that
energy slope safely, and that's
what you are going to
hear about today.
At this point in time we have
ideas about how to do that but
we can't say we have
got the solution in hand.
With that I am going to turn it
over to Jeff Herath who is the
product line lead at
Langley for Entry,
Descent, and Landing.
[Applause]
JEFF HERATH: Good
morning everybody.
I am Jeff Herath, I work
here locally at
NASA Langley Research Center.
And today I get to talk with you
about Mars and the challenges of
safely and affordably getting
humans to the surface of Mars.
So, first I want to
start with an image.
Does anybody see anything
there that you recognize?
AUDIENCE: Yeah.
JEFF: Yell it out.
AUDIENCE: The Moon.
JEFF: All right, so
you got the Moon.
And if you can see a little bit
further down there is this tiny
little red dot, that is what
Mars looks like in our night sky
from here at earth.
And in fact from the earliest
days when humans could first
look at the sky they noticed
this strange red light that
moved a little differently
than the other stars.
So, we have been looking at
Mars and wondering about
Mars for an awful long time.
And as we move forward we
developed new technology such as
telescopes, we are able
to look at and see
Mars in a lot more detail.
And in fact over time if you
look at the history of observing
Mars it has people in the 1600s
able to determine that Mars had
polar ice caps, we had also this
early observations they were
able to determine the
inclination of Mars or the tilt
of its rotation.
And then you get into
the 1800s, the late 1800s,
they could see more
surface features,
and they determined that these
were canals that were built by
an intelligent species
on a dying world.
That was in 1894, this was
the thinking at that time.
Now, of course, now that
is not actually the case.
But Mars really is a very
interesting place to study.
So, Mars is the fourth rock from
our sun and is named after the
Roman God of War.
Mars is half the diameter of
Earth but twice the diameter of
Earth's moon.
And in fact if you look
at the land mass of Earth,
took out all the oceans it is
about the same size as Mars.
Like Earth, Mars has seasons.
It has polar
icecaps, has volcanoes,
has canyons, has
deserts, and weather,
and some of the things, like I
mentioned the inclination in
that last side, Mars'
inclination on the rotational
axis is 25 degrees, very similar
to Earth's at 23 degrees.
The speed that it rotates,
at Earth we are 24 hours,
at Mars it is only 40
minutes longer at
24 hours and 40 minutes.
Now, the gravity on
Mars is lot less,
it is a smaller planet.
So if you weigh 100
pounds here on Earth,
you are going to weight 38
pounds on Mars which sounds
really good to people like me.
And the other thing is Mars
is further away from the Sun,
so only about 44% of the energy
that Sun and solar energy that
reaches Earth reaches
the surface of Mars.
And the next big thing
would be its atmosphere.
It has got very little
atmosphere compared to Earth,
it is about 1%.
And the composition of that
atmosphere is quite different,
about 95% of its
atmosphere is carbon dioxide,
where here on Earth that's
a very small percentage.
On earth we have a much higher
percentage of nitrogen and
oxygen that makes up our air.
Now the average temperature
of Mars is minus 64 degrees
Fahrenheit.
So it is kind of chilly.
And but the ranges are if you
go from night at negative 200
degrees Fahrenheit but then in
the hottest days at the equator
it can actually get
up to 80 degrees
Fahrenheit on the surface.
And as I mentioned Mars
atmosphere is really thin,
in fact it is too thin for
liquid water to survive on the
surface, it sublimates
directly to a gas.
But, however, several Mars
missions have found evidence of
past water in the Mars icy soil
and in its thin clouds and we
will talk a little
bit more about that.
So, why Mars?
Well, Mars is the most
Earth-like of the planets
in our solar system.
And so by studying these
different areas we are looking
at the history of
climate, looking at its geology,
we are looking at whether life
could have or ever did arise on
Mars and then also evaluating
it for the potential
for human exploration.
So these are some of the
key areas that we are really
interested in
looking at Mars for.
There is one thing that
ties all those together
and that is water.
Understanding the water on Mars.
And that is why when we, and
the Mars Exploration Program,
when we reinvigorated that in
1996 with the Mars Path Finder
Mission, the strategy has
been to follow the water,
and understand
the role of water.
And we have sent several
missions there and in fact I
will show you a couple of
highlights of those here in just
a minute, the Mars Exploration
Program is moving from follow
the water into looking for the
signs of life and looking for
the possibility of
human exploration of Mars.
So, few highlights of
our relatively
recent explorations of Mars.
So if we go back to the
Mars exploration rovers,
these were the rovers,
Spirit and Opportunity.
They were sent there, one of
their main questions was to
answer, was there water on Mars,
and they definitely answered
that, Mars was
once soaked in water.
In fact, in this slide when
I am showing here these are
perchlorate salt
that are found there,
can only form in the
presence of liquid water.
And in fact these particular
types were nicknamed Blue
Berries just
because of their shapes.
The Mars exploration rovers
found seven different types of
formations, types of minerals
that could only form in the
presence of
significant liquid water.
So, then we move on to our Mars
Reconnaissance Orbiter Mission.
This particular mission had a
ground penetrating radar as well
as a high
resolution camera on it.
So, what we are able to do with
that ground penetrating radar,
if you look at this, this is a
global map of Mars and we are
looking at the concentrations
of H2O or water within the
relatively, about
1 meter up to
2 meters within the
surface of Mars.
And as you go from the yellows
into the blues and indigos it is
more, it is higher and
higher water concentration.
So what we proved with the Mars
Reconnaissance Orbiter is that
there is
significant water on Mars,
particularly towards the
Polar Regions that there is
significant water.
What we didn't know is
how that exists on Mars.
Is it large chunks of
ice under the surface,
is it actually could be lakes
under the surface or is it just
loosely distributed all through
the soil or in different types
of minerals so from our remote
sensing we couldn't tell that.
We just knew that there is
a significant amount of H2O
underneath the surface.
And in fact the estimates are if
you brought all of that water to
the surface it would cover the
surface of Mars about 6 feet
deep, the entire surface.
So, that's a
significant amount of water.
So, what we did then is we
took the Phoenix Lander.
So, now we knew
there was water there,
but we didn't
know, as I mentioned,
what form it was in, so we
launched Phoenix and sent that
to Mars and landed it
in the Polar Region,
and one of the things
we noticed right away,
from one of the
first images back,
right after landing, this
is underneath the lander,
you will see that the landing
rocket sort of cleared away an
area and there is this nice
shiny smooth surface there.
So is that ice, what is that?
So, we took the arm which has a
shovel on the end of it outright
the side of the lander and
dug just a couple of inches in,
and what you see here this white
area is actually frozen carbon
dioxide or dry ice,
remember Mars has a
lot of carbon dioxide.
So there is an awful
lot of dry ice on Mars.
But what we also found, which is
hard to see in this bottom left
corner, its blown up there, are
these other little chunks and
then within a few hours of
that they actually disappeared,
so the water sublimated.
So we dug later, brought
those up into our ovens and our
sensors and we were able to
prove that that water ice,
very easy to get to
within the surface of Mars.
So there is
significant water on Mars.
It exists as ice within the soil
as well as potentially deeper
down it could be liquid
water, we don't know that yet,
but there is
significant water on Mars.
As I mentioned,
what's the next decade?
So we are moving from follow
the water to looking
for the signs of life.
And that's what our latest
mission that you may have heard
of the Mars Science Laboratory
is part of that transition.
With the Mars Science Laboratory
we landed the Curiosity Rover
there about two years ago, and
it is beginning this work of
looking for the signs of life.
Now the most important discovery
by Curiosity so far is that
ancient Mars did have
environment that could have
supported life.
If life had risen on Mars
their environments there,
life as we know it here on
Earth could have survived.
So, it looked at the
concentrations of carbon,
hydrogen, nitrogen,
oxygen, phosphorus,
and sulfur, they are all there
in the right concentrations.
They also found, looked at the
mineralogy and the clays that
were found in that area and
found that there was significant
fresh water actually, not
very salty water at all.
And in fact they believe if we
had been there we could have
dipped a cup in the water and
drank it without any issue.
So Mars did have
habitable environments.
We do not know to be clear, we
do not know if life ever arose
or currently may exist on Mars,
but we do we know that there
used to environments
where it could have.
So, Curiosity is the really
the monster truck of rovers.
If you look here these are the
other rovers that we have sent
to Mars, our very first one here
with path finder and then the
Mars exploration rovers and then
the Mars Science Laboratory at
about 1 metric ton.
And that 1 metric ton represents
the limits of our current entry,
descent, and
landing capabilities.
So, this rover is the biggest
thing that we know currently how
to put down on the
surface of Mars,
and that's based on significant
technology investments that were
made in the '60s and the
'70s leading up to the Viking
Missions, the Viking Program.
We humans have sent 40 missions
to the surface
of Mars from Earth.
Many of those have failed.
It is a very hard place to go.
In fact if you
are keeping score,
we have had 16 successful
missions versus
24 failures from Earth.
But since we are
talking about landers today,
we have had seven successful
landers and we have had eight
that have failed.
So, let's start talking about
what it takes first to how do we
get to Mars.
Now, you all had a presentation
on the Space Launch System,
I believe it was last week,
and so the first thing you need,
and won't go into detail because
you already know about that,
is a big rocket, and this is the
SLS and it begins with the 70
metric ton capability and will
grow to a 130 metric ton launch
capability.
So, let's talk little bit about
how the launch affects entry,
descent, and landing.
So, with your big rocket you
have to package your payload up
on the top of this
rocket inside of a ferring.
Now that ferring size is limited
by what the rocket can launch
and the aerodynamic loads
that are going to be on and it's
purpose is to protect your
payload whatever we are wanting
to send to Mars from the
atmosphere of Earth as we are
trying to push
through it really quickly.
But the size of that ferring
limits the size or the diameter
of the vehicle that
we can send to Mars.
And so what is that
important to entry,
descent, landing?
Well, the larger diameter
vehicle that we can get to Mars,
the more drag we can create
as we are trying to enter that
atmosphere and slow down and
therefore more mass we can get
to the surface of Mars.
But right now with our
current limitations,
as I mentioned before, we are
limited to about 1 metric ton to
the surface of Mars.
So, with that ferring up there
we have our vehicle packaged in
it, we launch, we accelerate,
after we get out of Earth's
atmosphere, we have
dropped the ferring,
we now get up into orbit.
We check our orbit and then
we ignite the engine again to
accelerate ourselves to escape
velocity and get us on the right
trajectory headed to Mars.
And that's when we move from
leaving Earth into what we call
the cruise phase, so we go from
the launch and departure to the
cruise phase, and cruise is
where we are traveling from the
Earth's vicinity to
the Mars' vicinity,
and I have a short video here
that describes how we do that.
 VO: How do you get to Mars?
 If you want to send a
spacecraft all the way to Mars,
 first you will need a fast
 rocket to escape the pull
 of Earth's gravity.
The heavier your spacecraft the
more powerful your rocket needs
 to be to liftoff.
 Next, make sure you
 launch at the right time.
Mars and Earth orbit the Sun at
different speeds and distances.
 Sometimes they are really far
apart and other times they come
 closer together.
 About ever two years the two
planets are in perfect positions
 to get to Mars with the
 least amount of rocket fuel,
 that's important.
 The total trip is
 over 300 million miles.
 Finally make sure
 your aim is right.
 You can't shoot for where
 Mars is at launch time.
 You have to aim for where it
 will be when you get there.
 It is a lot like how a
quarterback passes the football.
Also you may need to few thrust
to correct your direction along
the way so you don't miss Mars.
 If all goes well, you will get
to the red planet in about seven
 or eight months.
So, here we are.
We have gone from Earth to Mars.
We have arrived at Mars, and
this is what the planet looks
like as we get there and we
are getting ready for entry,
descent, and landing.
Now, one thing I
mentioned from the cruise,
lot of people, the analogy for
that is getting as accurately as
we need to, to Mars is like
making a basketball shot from
New York to Los Angeles.
Now, as it said in the video we
are able to cheat a little bit
because we can make small
corrections on the way there,
but we have to get very accurate
departure from Earth and we have
been able to do that very well
over the last several missions,
so that is working really well.
So, here we have
arrived at Mars.
This is what it looks like as we
are starting to get pulled into
Mars gravity well, it is
accelerating the vehicle towards
Mars, and so we are
ready to start entry,
descent, and landing.
But what really
is entry, descent,
and landing?
Entry, descent, and landing is
about the controlled flight of
the vehicle system through
all appreciable atmospheres
including the safe landing
where that is applicable.
So, we have to get from here
where in this case relative to
Mars we are going about
13,000 miles an hour down to the
surface and in this case,
the target was Gale Crater,
this was our
landing site for MSL,
and what it looked like
from--as we arrived in Mars.
And we have to
get from that 13,000
miles an hour down to through
atmosphere to the surface to
roughly 0 miles an hour
for a nice soft touchdown.
That's what you want.
Once you have committed the
EDL you are going to touchdown.
Now, hopefully we
don't make another crater,
but we want to
touchdown nice and softly.
So, let's talk about what the
key challenges
are for doing them.
The first is at Mars there is
too much atmosphere to land like
we do on the Moon.
So what that means is we are
traveling so fast and as we
start interacting with this
atmosphere that is there is an
awful lot of force
from the vehicle,
there is an awful lot of
heating on the vehicle and the
atmosphere itself
has different winds,
has density variations, so
all of these things conspire,
so that we can't just do a
propulsive descent
like we do at the Moon.
Actually have to
use the atmosphere.
The next is that there is too
little atmosphere to do it the
same way we do at Earth.
It is only about 1% of
Earth's atmosphere at Mars.
So that would be kind of like
landing the space shuttle at
100,000 feet here at Earth.
There is not just enough
atmosphere
to do it the same way.
Some of the other challenges
are there is a wide variety of
terrain elevations as well as
types of terrain to deal with
when we get to the surface.
And then we have this issue
of we design an EDL system,
entry, descent, landing system
here at Earth but we don't have
good ways to test that
end to end here at Earth,
to test the entire system
and it has to be done at Mars.
So that's a huge challenge for
getting a system that will be
reliable and actually
work when we get to Mars.
So, first, let's talk
about the atmosphere.
Like I said it is a very dynamic
atmosphere and it is poorly
characterized to date.
Now there are no large storm
systems like we have here at
Earth, but the seasonal and the
diurnal variations are actually
larger than what
we see on Earth.
And there are large sometimes
global dust storms and that has
huge changes on the density of
the atmosphere and changes how
we fly through it.
And actually on Mars
there are even dust devils.
So, in this case the Sun can
heat the Martian surface and
create winds, and sometimes
those winds create dust devils.
This particular one was captured
by the high rise camera on the
Mars reconnaissance
orbiter and then we created a
three-dimensional model of it so
that we can kind of fly around
like you are in a helicopter.
And you can see here on this
dark line on the surface is
actually the shadow of the
dust devil which allowed us to
recreate it height.
So, what you are
able to see from MRO,
we will go back to the original
image is that the dust devil is
about 100 feet wide on the
surface and about half a mile
tall, so it is
quite a large one.
But one of the things we didn't
know before sending the Mars
exploration rovers is how
prevalent or how common dust
devils are on the surface.
I don't know if
you all remember,
but those explorations rovers
when we sent them were only
designed for a 90-day life
because one of the main reasons
is we thought that dust would
collect on the solar cells and
they wouldn't be getting enough
energy to keep themselves warms
and their electronics will fail.
Turns out dust
devils are pretty common,
so you can watch their
battery life going down,
down, down, and then it gets hit
by a dust devil and cleans off
the solar cells, pops back up.
So we have had these exploration
rovers up there for many,
many years, like they had
their 10-year anniversary.
One of them is no longer
operating but the Opportunity is
actually still
operating on the surface.
So, the point is that the
vehicle system that we are
trying to get to the surface of
Mars has to contend with a lot
of atmospheric variability.
So, now let's talk about
the terrain elevations.
This is a global
map of Mars again,
and what we are showing here,
the black areas are the parts of
Mars that are above two and
half kilometers in altitude.
And so this is the type of
access that we would like to
have to Mars.
We would like to be able to
land anywhere
the colors are on this map.
And what you see here the red
Xs are where we have landed.
And so if we now look where
those actually are those have
actually been all
very low altitudes.
With our current technologies
and our current entry,
descent, and landing techniques,
we have to land at very low
altitude so we have as much
atmosphere as possible to work
with to slow the vehicle
down and get
it safely to the surface.
And so this is one of
our big challenges.
So, there are also different
types of terrain hazards,
you have got
mountains, craters, canyons,
rocks, but the point is we do
know a lot more
now than we used to.
So if you look here in the
Viking area at the same scale,
we really couldn't tell
anything about the surface.
And then the Mars
Global Surveyor came,
hey we can see there is actually
a crater there but can't tell
much more, and these days with
higher resolution camera on Mars
Reconnaissance Orbiter we start
being able to pick up features
and terrain types and understand
better where we are actually
sending these vehicle systems
and can better prepare them for
where they have to land.
I mentioned the EDL
system verification problem.
So, it is really because of the
complexity and the environments
that we are sending it to, the
EDL systems for Mars generally
can't be tested as
flown here at Earth,
as we intend to fly
them here at Earth.
So, we do component tests here
at Earth to build models of how
the different
pieces of the entry,
descent, landing system work.
And then we assemble those
models into an end-to-end
simulation.
And so all of the models of
the EDL component subsystems are
brought together into this
end-to-end system simulation.
So you have
models of the vehicle,
mass properties, you have models
of the atmosphere that we have
been talking about, you
have models of the parachute,
understand the
dynamics when that deploys.
Even get into the physics based
modeling of the radar system to
understand what kind of signals
you are going to get back,
from when and how much dust and
material is going to be kicked
up as you get close and how
the radar will react to that.
So, there are lots of
different models
that get pulled into this.
The simulation exercises
both the flight vehicle and the
algorithms that autonomously
fly the vehicle in the virtual
environment and that's one of
the things that actually the
simulations are very good at, we
can push the system beyond even
what we are
intending it to fly through,
we can find sensitivity.
So, we disperse different
variables such as how well we
know the vehicle's
center of gravity,
or how much wind
it might encounter,
and that way we can understand
better how this system will
perform when it
actually gets there.
Now we have run literally
hundreds of millions of these
entry, descent, landing runs
in computer simulations in the
development and the verification
of these EDL systems.
And actually now the systems
are so complex that the only
complete system performance
verification are these
end-to-end simulations.
So, let's take a quick
look at what the entry,
descent, and landing
sequence at Mars looks like.
All right, so we arrive at Mars
and we have had a crew stage
which is that little thing up on
the top there attached to us and
helping us get from
Earth to Mars accurately.
Well we Jettison that and then
we turn the vehicle to face the
Mars atmosphere, the angle that
we wanted to hit the atmosphere
and then in this case I am
showing the Mars Science
Laboratory sequence, we
Jettison a balance mass.
This is important because we now
have changed the balance of the
vehicle and we do that on
purpose so that when we start
flying through the atmosphere
the vehicle won't just fly
straight in like a bullet, it
will fly at an angle of attack.
It will fly a slight angle and
that gives us a lift vector.
And so we can use that lift
vector to then control and steer
the vehicle and
help us slow down.
I will talk about that
some more in a little bit.
So, we jetteson
that balance mass,
then we come slamming into
the atmosphere at about
13,000 miles an hour,
it starts heating,
so the rigid heat shield up
front is protecting us from
that, it gets up to about 3800
degrees and then we continue
going through that peak
heating and then we reach peak
deceleration which for
MSL was about 10 Gs,
so now think about
that in regard to humans.
We can't subject humans
particularly after being in
space for a long time to 10 Gs,
so we are going to have to for
humans slow down a
lot earlier and slower, right?
But for current state of the
art it is experiencing 10 Gs and
then we start maneuvering,
essentially doing S turns in the
atmosphere to help us slow down
and as we get down closer to
Mach 2 we can deploy the
supersonic parachute which helps
us slow down a lot more.
We drop the heat shield.
The radar system then is looking
for the surface to find out
exactly how high we are
and how fast we are moving,
and once it finds that
it drops the payload,
in this case for this mission it
was the Rover with a rocket pack
actually called the Powered
Descent Vehicle and it continues
slowing down relative to
the surface and touches down.
So, that is the current
state of the art for entry,
descent and landing at Mars.
And I will show you a little bit
more of that in a few minutes.
But while flying through the
EDL sequence the vehicle system
needs to be able to land
within a defined area.
Now, I showed you what Gale
Crater looked like from orbit
before, here is a
close up of it.
So, this was the landing area
for that Mars Science Laboratory
Mission, and we
targeted Gale Crater,
but that was impossible just a
few years ago because like when
we did the Path Finder Mission
it is landing uncertainty was
larger than the
crater itself, right?
But we have gotten a
lot better since then,
so here is the landing ellipse
or the landing uncertainty is
what we call it, for the Mars
Science Laboratory Mission.
So, after all the calculations
we do and understanding how this
EDL system will perform we
are very confident it will land
somewhere in that ellipse.
The target of
course is the center,
and in this case for MSL we
actually did pretty well,
we were only about 2 kilometers
away from the very center of
that ellipse, but the point is
for humans we need to be able to
land in an area that is 10
times smaller than that even.
So, within about 0.1 kilometers
of our targeted landing area.
So, let's take a quick look
at how sort of the history of
entry, descent, landing at Mars.
I mentioned the Viking Mission.
So, Viking sent
two probes to Mars,
they were landers, they entered
with a rigid 70-degree sphere
cone aeroshell and had a
supersonic parachute to
propulsive
descent on the surface.
Now, this was all possible, this
was the first landing at Mars,
so this was all possible because
of the significant technology
development activities we
had in the '60s and '70s.
Those activities made it
possible for us to understand
the 70-degree sphere cone
aeroshell and how
that was going to fly.
It qualified this disc gap band
supersonic parachute so that we
will be able to use that
as well as the
autonomous propulsive landing.
So, if we look at some of
the more recent missions,
Mars Path Finder, it
landed a small rover there,
used airbags and I will show
you that in just a second,
Mars Polar Lander was another
lander sort of like the Viking
era but we lost that one.
I don't know exactly why, but
through the mishap investigation
the most likely scenario was
that its computer was listening
to its touchdown
sensor too early,
so this touchdown sensor is
looking for a shock when it
touches on the surface to
turn off its landing engines.
And so what most likely happened
is it was listening to it too
early and then it deployed its
landing legs and shocked the
system and the sensor
thought it touched down,
it turned off the engine and
most likely fell the last 60
meters to the surface.
So, we then did the
Mars Exploration Rovers,
so let's take a look at
their EDL architecture.
So again we have 70-degree
sphere cone aeroshell separate
from the crew stage and we
are coming straight in to
ballistically into
the Mars atmosphere.
So that heat shield protecting
us from the air heating,
we are going through
peak heating and now peak
deceleration and as we get down
closer to Mach 2 we deploy that
supersonic parachute.
Now this we are still
flying relatively horizontally.
The parachute is actually
working on slowing us down and
sort of tipping us over and then
we can drop the heat shield and
then here is where it is
different from what we saw
before, it has the payload in
this tetrahedron
hanging down below.
And that tetrahedron has airbags
all around it which will inflate
as we get a little
closer to the surface.
So it is just like crashed the
airbags and as we get within
about 30 meters of the surface
these retrorockets fire bringing
the entire system close to zero
miles per hour relative to the
surface and then drops it.
And that system, that airbag
system hits the surface at about
54 miles an hour and then
bounces along until it stops.
Now, in the actual
missions, this is a simulation,
in actual missions they
bounced about
30 times before they stopped.
And then it deflates the airbags
and then opens the tetrahedron
and you have your payload
safely on the surface of Mars.
In that case it was one
of the exploration rovers.
AUDIENCE: What are you doing
to get the moment as the heat
shield protects...
JEFF: That's a
rigid heat shield.
The material, the actual thermal
protection system on the latest
ones is called PICA
and that's different,
for the Apollo ones
it was called AVCOAT,
so it is a different material
but the same type of idea with
that rigid aeroshell and
creating the shock
in front of the vehicle.
It ablates, it is an ablative,
burn off part of the heat shield
material, exactly.
Yes?
AUDIENCE: How do you avoid
landing at a very steep hill?
JEFF: The question was how do
you avoid landing on a steep
hill or incline?
So, one is we characterize how
well the system can do that,
like what type of
incline could it withstand.
And then we have used our
current orbital assets their to
create what are called digital
elevation maps of the area that
we are going to
land, a wide area,
so we understand where these
keep out zones are and so we
define our landing ellipse away
from all of those bad areas.
Yes?
AUDIENCE: What's the composition
of the balloons to keep them
from breaking on impact?
JEFF: So, the balloons
were a composite material.
It was based on Kevlar based and
then it had an essentially a gas
barrier inside to allow it to
inflate but they had a very
tough exterior that I
believe was Kevlar based.
So, we did an awful lot of
testing of those dropping them
on sharp rocks and throwing them
sideways at things to make sure
that they wouldn't rupture
within the parameters of how we
were landing, exactly.
AUDIENCE: What's the size of
the landing area that you are
looking at or dimensions
for humans?
JEFF: For humans to Mars we need
to be within about 100 meter
ellipse or 0.1 kilometers.
Right now we have got about,
depending on a lot of things
between 5 and 10 kilometer
ellipse that we can land in.
So we are over an order of
magnitude away from where we
need to be in our
landing accuracy.
So, then I mentioned the
Phoenix Mission before,
so this is now a more modern
lander but still in the same
type of architecture
that we did for Viking,
so 70-degree sphere cone,
getting through the heating,
same type of
supersonic parachute,
going to a propulsive
descent and landing,
which was successful.
So, now the most recent one
we have is the Mars Science
Laboratory which was landing the
Curiosity Rover
on the surface of Mars.
So this represents
the state of the art,
so we will watch how we
got to the surface with MSL.
[Video Presentation] So,
again same type but much larger,
same type of rigid aeroshell,
we drop the crew stage,
we now reorient this entry
vehicle towards the atmosphere
of Mars, we drop
that balance mass,
remember so we offset so we
will fly at an angle of attack.
So, now we will start to get
into the sensible atmosphere.
So the vehicle starts
to feel deceleration.
It uses rocket with reaction
control system to keep itself
oriented correctly, and then
here you can see we have done
the heating and it is starting
to steer back and forth and S
turns to slow down, get through
heat deceleration which again
for MSL was about 10 Gs.
So, now we are
continuing to slow down,
and as we get close we kick off
more mass to recenter ourselves.
We don't want to be offset
anymore so we can safely deploy
the parachute which there is
that supersonic parachute again,
the same style, just got bands
that we used for Viking
but much larger.
So now we have dropped the heat
shield and the radar is looking
for the surface and once it
finds the surface it is going to
drop the rover and the Power
Descent Vehicle which is the
Rover's rocket pack, they fire
and continue decelerating the
Rover relative to the surface.
One of the first things it does
though is a big left turn to get
away from the parachute,
so that's the
parachute avoidance maneuver.
So it has moved away
from the parachute,
now there is radar system
upfront there that is continuing
to look at the surface and
understand our altitude and our
velocity relative
to the surface.
As we get closer there is an
instrument called the MARDI
instrument, it's a
camera right here,
it is also looking at the
surface and comparing features
to understand how much we
are moving from side to side,
that's what it is doing there
and so now as we get closer to
the surface we lower the Rover
on the tether system below this
rocket pack and it continues
decelerating very slowly towards
the surface now and the
rover has set its wheels into a
landing configuration.
And right now everything is just
waiting for the touchdown sensor
and once it touches down it
cuts those tethers and the Power
Descent Vehicle flies away to
a safe distance and crashes,
but a safe distance
away from the Rover,
and one of the big benefits of
landing this way is you have now
got your Rover system on the
surface essentially ready to go.
All it has to do is stand up its
remote sensing mast and it is
essentially ready to go.
Relating that to is the Mars
Exploration Rovers that were
packed in that
airbag tetrahedron.
They were folded up like origami
and it actually I think was
almost three weeks of operations
to unfold everything and get
them setup and
actually ready to operate.
So, here we have landed
within our landing ellipse,
and there in the back is
that it is called Mount Sharp,
it is center of that Gale
Crater that we talked about,
and it has been operating for
just over two years and has just
now gotten over to the
base of Mount Sharp.
Now, it has done an awful lot
of science on the way there.
We have learned that there were
small rivers that even at least
knee deep in that
particular area.
And again I mentioned the big
discovery for the MSL is the
existence of ancient habitats
that could have supported life.
So, it's done a lot.
But the point is this is the
limit of what we can currently
do with our
current Entry, Descent,
and Landing technologies,
and so we have a
significant technology gap.
Look just along the bottom,
there are too many words on the
slide, where we are currently is
able to put 1 metric ton within
about a 10-kilometer
ellipse and access about
40% of Mars surface.
So where we need to be
potentially for human missions
is able to land 40 metric tons
within a 10th of a kilometer of
our target and have
nearly global access.
So it is a huge challenge.
It's why EDL at Mars is
considered one of the two
biggest challenges for
human exploration of Mars.
The other one being radiation
protection which you will hear
more about next week I believe.
But NASA has set the goal of
having humans at Mars in the
2030s and to accomplish that we
are going to have to leverage
activities all around.
It is a very successful, we
are going to be able
to do that in 20 years.
Most Entry, Descent, and Landing
capability roadmaps show you
have to have a consistent
effort over 20 years
for us to be able to get there.
And so we are going to be
leveraging our international
partners, commercial
partners to get there.
Other missions within NASA
that aren't just the human
exploration portion of
things like our science mission
directorate and the
missions that they send,
all of these things are going to
need to combine to help move us
stepwise closer
to humans on Mars.
AUDIENCE: During the heat shield
burn to Mars those mission
control lose radio
control completely?
JEFF: So, the question
is during the entry,
the very high heating portion of
entry does mission control lose
the radio contact
with the vehicle,
control is what you are saying.
So, first of all we are about,
communication time wise we are
about 14 minutes away.
So the vehicle is
actually working
autonomously that whole time.
There is not any active control.
So from the time we have
started entry at Mars,
when we get that signal, 14
minutes is gone by from the time
that it actually
started entering,
and so it is either safely on
the surface or crashed by the
point we get that
signal that it started.
But what does
happen, during entry
there is some radio blackout.
They are special radios we use
that have very small data pipes
that send us some small amounts
of data all during that time,
so it is all about the
health of the vehicle,
and if we have a bad day helping
us understand what happened.
AUDIENCE: What causes
the radio blackout?
JEFF: The question was what
causes the radio blackout.
The ionized flow.
So we are slamming into this
atmosphere and we are hitting it
so hard that we are
disassociating the species and
creating ions, heavy
ions and a plasma flow,
so that then surrounds the
vehicle and the radio waves
can't get through.
Yes?
AUDIENCE: Is the United States
the only terrestrial nation
which has landed on Mars?
JEFF: So, the question is,
is the United States the only
nation that has actually put
landers on the surface of Mars.
We are the only ones that
have done it successfully.
So, there have
been Russian landers,
the closest one they believe
they got a signal that it had
landed but they lost
contact immediately,
so we are not quite sure.
Most of the other failed during
launch or failed during EDL.
And there have been European
smart landers that also failed
during attempts.
So, the US so far is the only
one that has successfully landed
on Mars.
AUDIENCE: Are these coordinated
with other countries?
JEFF: So, are the
missions coordinated with other
countries?
Yes, in that even on like
MSL here as an example,
there are contributed mission on
the mission from other countries
like France and European
Union, yeah absolutely.
Thank you.
So, landing at Mars is not easy.
As we just said we have
landed a total of seven times
successfully on
the surface of Mars.
The point is all of these
successful landing systems have
landed at low elevations at
minus one kilometer or lower.
We have landed less than 1
metric ton and there have been
relatively large uncertainties
on our landing location.
And the EDL system, so critical
to the overall mission that it
generally drives the
mission architecture,
and as I have mentioned all of
the current Mars missions have
relied on the technology
investments in the '60s and
'70s, and we have essentially
gotten to the end of where we
can stretch those
technologies, where we can go.
So there is going to be need to
be systemic new investments and
new atmospheric flight systems
that are the basis for these
Entry, Descent,
and Landing systems,
because that
really the core of EDL,
is being able to fly these
vehicles through an atmosphere.
So the agency has started
working on some technologies.
Remember we mentioned in the
beginning that we don't have the
answer right now.
I will talk about some of the
things that we are working on.
So, we have developed new
thermal protection systems,
these are the materials on
the front of the vehicle that
protect you from all
that high heating.
We have got some new deployable
aeroshell concepts that we are
working on in developing.
There are mechanical
deployable and there
are inflatable aeroshells.
Now remember the
inflatable aeroshells,
I will talk about those in
more detail here in just a few
minutes, and then we have
what I call the mid L over D,
mid lift over drag vehicles,
these are more like flying
cylinders into the atmosphere,
and then we also developed new
parachutes, new
supersonic deceleration systems,
these systems actually inflate
inside the atmosphere and create
more drag and we are
also working on supersonic
retropropulsion and this
is essentially you are in a
supersonic flow and you are
going to fire a rocket into that
to help yourself slow down,
so that is another key one,
and of course the landing
systems from propulsive systems
to airbags to crushable
structures being able to
actually safely set
down on the surface.
So, how do we put these
technologies together for humans
to actually get to and
explore the surface of Mars?
So, NASA has done
lot of studies.
This I am not expecting to go
through in detail but this is
looking at different
combinations of these
technologies and we are running
simulations to understand how
those might work and which
ones are more effective,
and one of the key figures
of merit is the
arrival mass at Mars.
How much stuff do you have to
get from Earth to Mars for this
type of system to work, and this
study was done around getting a
40 metric ton
payload to the surface.
So in comparing this we end
up actually with architecture
number two winning out.
It had a very low mass at
Mars of around 84 metric tons,
but you will notice that
there is one over there,
number eight, that is a little
bit less in mass but its EDL
sequence has many
more critical events,
that's little more risky,
and so we ended up saying that
architecture two is
a better way to go.
So that's the thing.
If we were to pick today how we
are going to get humans to the
surface of Mars this is the
architecture we will take,
which is using an
inflatable aeroshell,
I will talk about
those in just a minute,
using an aerocapture approach,
again this is using the Martian
atmosphere to help
yourself get into orbit,
I will talk about that as
well, and then transitioning to
supersonic retropropulsion
and final autonomous propulsive
touchdown as well.
So, looking at this architecture
we don't see any clips,
we see that it can scale
to the human class mission.
Now there is a lot
of work to get there,
but there is nothing that
say that it can't be done.
So, let's talk about
some of those technologies,
I mentioned aerocapture.
So this is when the vehicle
system uses active control to
autonomously guide itself
into, in this case the Martian
atmosphere, flying through
the atmosphere taking a lot of
energy out and slowing down
but then fly back out of the
atmosphere into orbit.
So you didn't have to
carry a bunch of
rocket fuel to slow
yourself down.
You use the atmosphere, and this
allows you to use a smaller more
affordable launch vehicles to
get the system there and also
allows you to have a
higher payload fraction,
meaning, since you don't
have all that propulsion or the
propulsive capability
that you brought with you,
you can have more
payload, and the example here,
if you are really using
aerocapture you can have 80% of
your vehicle system to your
payload as opposed to if you are
doing propulsive
it is about 20%.
So it makes a big difference
in the architecture studies.
So, we need to slow
down more mass at
higher altitudes we
have talked about.
So the limit of
that ferring size,
the size of the aeroshell that
we can bring to Mars and help us
slowdown is a big limit.
Just have a small
image here on that,
but this is supposed to
represent the rocket ferring and
then that was the MSL shape and
it was as big as we can make it,
but if we used an
inflatable approach,
here it is stored and here it is
deployed we could carrying with
us, I mean we can store it and
launch it and everything and
then we are able to deploy it or
inflate it as we get to Mars and
it is a much larger drag area.
So, the anatomy of this, you
have an inflatable structure,
those are two main things, there
is an inflatable structure and
there is a flexible
thermal protection system.
The inflatable structure and
both of those by the way in this
case are packed very tightly in
forward of this so you have this
nice narrow vehicle.
So when it inflates, it
uses an inflatable taurus,
a stacked taurus approach and
there are straps that holds
together and carry
all of the loads,
and I don't want
you think inflatable,
I don't want you
to think balloon,
so lot of people think of these
balloons and they are squishy
and stuff like that, it is
actually quite a rigid structure
once it is inflated even
with just few PSI differential,
and the material
is very durable,
it is a Zylon based
material, kind of like Kevlar,
it has a gas barrier on the
inside and all of these are made
to be high temperature
material systems.
So we have that as the structure
but then you know when we come
slamming into that
atmosphere and we are at
13,000 miles an hour, it is
going to get really hot,
so we need this flexible,
because it is going to be folded
up, this flexible thermal
protection system to go on the
outside of it, and that's what,
I think here it is a pinkish
material along the outside, and
that's a material system that
can standup to those
really high temperatures.
And so if we are able to do
this it allows us to land,
if you remember these
images, that's a current access,
it allows us to be able to land
either more mass to the same
areas or the same mass to a much
higher altitudes and have much
more access to the
surface of Mars.
So, what I am going to show
now is a video of technology
demonstration of
this technology,
and it is from a mission called
IRVE-3 or the Inflatable Reentry
Vehicle 3 and it
shows the vehicle system,
you have the actual
video from the test here,
this was on the vehicle and this
is an animation showing kind of
what it is doing at the time.
So, we got to about 291
miles high, that is
higher than the
International Space Station,
we then release the heat
shield and start inflating it.
You can see it has come here,
this green line is its full
shape, you can see the
inflatable tauruses and the
straps and then it
reorients itself towards
the atmosphere of Earth.
So, as the Earth gravity wells
now accelerating and pulling us
back down into the atmosphere.
There are sensors on the front
here to indicate how high the
heating gets and things like
that because we are testing the
material system and we also have
a new way of creating a lift
vector, this instead of dropping
mass off we just shift our
payload mass within this,
does the same thing of sort of
unbalancing this so that when
we fly into the atmosphere
we can get a lift vector.
So, here we go into the
atmosphere at Mach 10,
decelerating and
heating, and look at this,
it is flying very steadily,
it is hard to even tell that's
what's happening over here.
It experienced 20 Gs of
deceleration because we were
trying to really push the system
to get as much heating as we
could, in a real mission
would never see actually 20 Gs,
but it was a very successful
test and it qualified this
particular material system
which we call the Gen-1 material
system to 30 to 40 watts
per centimeter squared,
what that means is it would
be relevant to the MSL class
missions that we are
working on right now.
But we want this type of system
to be able to work for human
class missions, that's the next
step that we are working on,
we have not done this test yet
but we have started working on,
it is called the THOR, the
Terrestrial HIAD Orbital Reentry
Test, so we are going to launch
on a much bigger rocket and go
up higher and faster, we are
actually catching our ride with
Orbital Sciences Antares Rocket.
So as they get up into orbit
we will drop off and they will
continue on to the
International Space Station,
but what they have done for us
in the partnership is they have
gotten our system up to really
high velocities and really high
energy and so then we
fire our deorbit motors,
inflate our new material system,
this is now called Gen-2 and we
are going to come in with five
times the heat rate and 50 times
the heat load that we
did in our previous test,
testing our new
material systems.
If these prove out then we are
talking about 60 to 80 watts per
centimeter squared, is
what we think this
material system can do.
Now, that starts to
become applicable
to the human class missions.
And that's what we
are working for here.
The one thing this test
doesn't get us is the scale.
So we are flying a
3.7 meter diameter,
that would be effective
for the MSL class missions,
but for human class missions
there are going to need to be 18
to 23 meters in diameter.
But we will have proven out the
load capability as well as the
heat rate capability
for the system.
So also mentioned
supersonic retropropulsion,
it is being one of
the key technologies.
So in this case we are coming in
at supersonic speeds and we need
to continue slowing down and
so we are going to fire rockets
into that flow and continue
slowing down the vehicle.
Now, we are partnering with
Space-X on this and so we have
computation flow dynamics to
understand how these jets are
going to interact
with this oncoming flow.
We have done wind tunnel tests
and now we are partnering with
Space-X who is wanting to use
supersonic retropropulsion to
return its first stage of
its rocket as part
of their business plan.
And so we have partnered with
them to get the data from those
tests and we actually
have at this point,
and so we are able to, we are
starting to use that data to
understand what the real next
step should be for developing
this technology, because one
of the keys is the particular
configuration is very important
for supersonic retropropulsion
to understand how you are going
to fire these jets to keep your
vehicle stable and
to slow it down.
But again this is something
that is being demonstrated with
Space-X and then NASA will
move it forward how we need to
develop that for human
class missions at Mars.
AUDIENCE: You are taking a
one-shot approach of this with
the biggest diameter vehicle
to accommodate your load,
could you stack loads within a
smaller cylinder and not have to
worry about the massive heat
load that you are going to put
on as it is entering
the Mars atmosphere?
JEFF: So, I am going to
try to repeat to make sure I
understand, so you are wondering
within the launch ferring of our
rocket if we can stack a greater
number of smaller loads within
that but using the
smaller diameters.
So what we have done is studies
based on at the different sizes
of vehicles that we need and
doing multiple launches or
multiple vehicles, looked at
in-space assembly of different
vehicle systems and the trades
always comes back that it is
more advantageous to have
that larger diameter aeroshell,
so that's why the
HIAD, in this case,
the Hypersonic Inflatable
Decelerator gives us
so much of an advantage.
Did that answer your question?
AUDIENCE: Oh it does.
The thing is if it
fails then you are done?
I mean one shot goes down and
you have a problem with that
heat shield then the
whole mission is at risk.
JEFF: Okay, so it is
a reliability issue.
So yeah, that's what the systems
are being designed to be highly
reliable, but then I think what
you might be getting at is like
with the Viking
missions we sent two landers,
even with the Mars Exploration
Rovers we sent two of those and
really in case one failed we
had another one
that was there and ready.
And so I can't say for certain
that will do that with the human
mission, but with the human
missions we make sure
the systems are reliable.
Most of the landings
are without humans,
they are going to be
pre-positioning resources and
getting things and everything
is there and turned on and ready
before those humans
ever leave earth.
So, if there is a failure then
we wouldn't be sending humans,
we would be sending
another mission to preposition.
Yes?
AUDIENCE: It is certain
that different materials,
different gas and different
elements are going to behave in
a different way in different
gravities and different
atmospheres, with
that inflatable system,
typically what gas you
design with to inflate?
JEFF: Yeah, so the question is
for the inflatable heat shield
structures what type of
gas do we use to inflate.
So in the tests that we
have done to date we have done
nitrogen, that's in there.
Now for this last
test I mentioned THOR,
we are actually going to use
Freon because we are limited in
our center body and Freon
is going to give us more
performance out of
our inflation system.
So we are going to use
the Freon gas there.
AUDIENCE: Wait a minute, isn't
that Freon releasing in the
atmosphere is a no, no
as far as a refrigerant?
JEFF: That's correct, it is a
relatively small amount and we
are using it
exo-atmospherically.
It is what's inflating
the structure
and it will come back in.
Yes?
AUDIENCE: Right now you are
talking about figuring out how
big the transportation system
has to be to get somebody on the
Mars or the payload can be, but
you have to consider that you
have to take extra
payload out to get it back on.
JEFF: Yes, exactly, and I am
going to get to that in about a
slide or two I think, exactly.
So, yeah, the question was, or
the statement was that we need
to take extra payload to mars
to be able to get them back home
and that is absolutely correct.
The last thing I want to mention
on EDL technology challenges is
being able to precisely
land, we mentioned that,
but also be able to avoid
hazards that we may not have
mapped or didn't know
about as it is landing.
So the first part is precision
landing and that has to do with
knowing very accurately where
you are and the vehicle being
able to know where it
is on a map and
accurately navigate to a point.
This is just representative of
our current knowledge of where
we are, so, that's
our aero-ellipse,
like a certain technology like
what's called Terrain Relative
Navigation, so a map in the
vehicle actually knows the area
very well and it is taking
pictures of surface and confined
itself on that map and redirect
itself to accurate point,
you then get this
tiny little circle of
knowledge area of your location.
So that's a potential
way of getting our
landings more accurate.
We also have hazard avoidance,
so this is using special sensors
such as LIDAR and other
instruments and cameras during
the descent to understand hey
there may be hazards where I am
trying to land and having the
ability to divert to a safe site
but still within the
requirements of your mission.
So, now we get to your
question about what do we
need to take along, right?
So if we are looking at
the 40 metric tons mission,
this would be two landers going
there for 40 metric ton mission
to Mars and so the first lander
has the very first thing is the
Mars Ascent Vehicle, so this is
how the astronauts will get back
off of Mars and also has the
multimission surface
exploration vehicle.
It has a fission
surface power unit,
has two fetch
rovers, it has a drill,
and then ISRU, In Situ
Resource Utilization,
so a unit that can actually
process the atmosphere and/or
the ice and water at Mars into
usable elements for the mission.
And then of course
there would be a
science instrument
package as well.
And the second lander bringing
the astronauts would also bring
the inflatable habitat as well
as the second surface fission
power unit and the second
Mars surface exploration unit.
So figuring out how to package
that and put that all together
and get it to Mars, and so here
is a current concept how we will
package that into a lander and
on the base of this lander is
you would have packed away the
inflatable aeroshell
that we talked about.
So the current studies are
looking at 40 metric ton
missions as well as 27 metric
ton missions and 18 metric ton
missions, and that gets to the
trades for how many launches you
want to make, if you could do it
with smaller launch vehicles but
a larger number of
launches, is that better,
those are the trades
that are going on now.
Yes?
AUDIENCE: How about the water on
the surface of Mars which is in
the form of ice and they
sublimate when you bring it to
the surface, if you
can't use it at all?
JEFF: It would, but it is
not immediate and we would be
storing the water
inside the container,
so it wouldn't
sublimate from there,
but if we just brought
liquid water to the surface,
yeah it would
evaporate, exactly right.
All right, this includes the
HIAD system and then if we are
looking at what an entry of Mars
would look like with the human
class system, we have the
inflatable aeroshell with our
lander system being
protected inside of that,
and this inflatable aeroshell
will be 18-23 meters across,
so much wider
than the barn here,
so it is a very large aeroshell.
So, the point is we have
seen what we are doing with
Exploration, so you have heard
about SLS and we are working
with our commercial partners to
have access to the ISS as well
as to low earth orbit and
creating that supply line,
whereas the SLS that NASA is
going to concentrate on is about
getting beyond Earth orbits or
beyond the earth gravity well
and we are developing that
from our initial 70 metric ton
capability to the 130 metric ton
capability that will carry the
space craft, the
crew, the cargo,
the equipment to deep space
destinations such as Mars and
really this is going to be the
platform to continue America's
tradition of human space flight.
In my mind I believe that we
humans can and will get to the
surface of Mars and in fact you
remember the picture I showed
you in the beginning, showed
what Mars looks like from Earth,
here is what Earth looks like
from Mars taken by one of the
rovers, that tiny
little spec right there,
I blew it up for you,
so that is everything,
everybody that we
know, every road,
every building, every city
on that tiny little spec.
For me it really puts
things into perspective.
So, these are some of the
challenges that we are working
on today and trying to get
humans to the surface of Mars
and I would like to think
about what's going to be real
tomorrow, so I have a
quick little video for you.
[Video presentation]
JEFF: I would be
happy to take any
questions you might have.
[Applause]
JEFF: Yeah, go ahead.
AUDIENCE: How can an astronaut
stay on the Moon before you have
to bring him back, and isn't it
more economical to have robots
doing the job without humans?
JEFF: So, the question is
to do on Mars or
the Moon?
AUDIENCE: On Mars.
JEFF: So, the question is how
long astronauts can stay on the
surface of Mars versus being
able to send robots that can
stay there longer.
So, actually with the
architecture for human
exploration of Mars they can
stay there for quite a long time
and the initial missions range
we are looking at short duration
first, so we get to the surface
and get back off successfully
but with the in situ resource
utilization they can actually
potentially stay there quite
long as long as we resupply them
with a couple of main things
but they will be able to produce
their own oxygen and several
other the key things that they
would need.
So we could have
long-term stay on Mars.
AUDIENCE: But that would be a
long time away from the first
mission where you bring people
up to stay for a long time.
JEFF: Most likely.
But yeah we are actually
trading those things now.
We actually don't know exactly
how and when we are going to put
humans on Mars and how
long we will have them stay.
Part of it does have to do
with the orbital mechanics.
So where Earth and Mars are in
relation to each other if we put
them on the surface and then
what it takes to get
them back to Earth.
So essentially when we go there
we are going to stay more than
just a few days they are
going to be there for almost two
years. They can be there for
two years.
AUDIENCE: Directly
on the first try?
JEFF: We won't do
that at the first try,
we will actually
do it most likely,
pretty quickly bring
it back the first time.
Go ahead.
AUDIENCE: I was surprised that
you have lift on that inflatable
heat shield, do you absolutely
need the lift or control?
JEFF: So, the question is
whether we actually need lift
with the inflatable
heat shields for control.
So this is one of the
ways that we are
looking at controlling it.
So we do want lift, in some form
we can generate it different
ways, but we do want lift so
that we can guide these vehicle
systems to get them to more
accurate landing locations,
that's the main reason,
so that we get a
lift vector that we can control.
AUDIENCE: Is Langlye, who is the
lead center on the EDL and what
is Langley's part of it?
JEFF: So the question is if
Langley is the lead center for
EDL and what is our
part in it right?
Did I get that right?
So, there are really four
NASA centers that work on Entry,
Descent, and Landing and
that's Langley and JPL and Ames
Research Center and the
Johnson Space Flight Center.
Now, different parts of Langley
I would think it is easy to say
we lead the
technology development of it.
So these new technologies and
developing how we are going to
put people on the
surface of Mars,
I think Langley is significantly
involved in all the activities
that are going on with
new EDL technologies.
Now there are some like
the mechanically deployable
aeroshell that is being led at
Ames but we are supporting them
and helping them with that.
So it really is a team
effort around the agency.
AUDIENCE: Cost
associated with mission,
in reality what
are we looking at?
JEFF: So, the question was cost
for making this dream a reality,
and actually I cannot
answer that for
the entire human mission.
So, we are looking at just the
technology demonstrations and
being able to get there and
then we are working with the
architecture folks which you saw
I think the very first week here
with the Evolvable Mars Campaign
and how it leverages activity
across the agency.
And so I don't know, Steve, do
you have a better answer for
that for what it will cost?
STEVE: We have looked at that a
lot and just so you know I think
today NASA gets about $17 to
18 billion a year and the human
exploration part of
that is $8 billion,
with the $8 billion we do
international space station,
all the work on the station and
we are developing the rocket and
the Orion, as well as
doing some technology work.
And of course we work for
the President at NASA and the
President says we
are getting enough.
However, depending on when you
want to get humans to Mars I
think it is safe to say that
we may need to spend more at,
may be we are getting about
75 cents on a dollar we need,
so we need a marginal increase
if we want to actually meet that
schedule goal of
getting there in the 30s.
JEFF: Right.
Yeah?
AUDIENCE: Seems like we are
littering the surface of Mars
with a large stack of junk.
Is there any
thought to that at all?
JEFF: So, there is
certainly thought given to it.
So we have been littering the
surface of Mars since the 70s.
But each vehicle system that we
send there goes through these
planetary protection and we make
sure that we are not sending
bugs from Earth and germs
from Earth and things like that.
But yes some of the vehicle
system parts and pieces and the
systems that are no longer
functional are just sitting
there on the
surface of Mars now.
AUDIENCE: Is any of it usable?
JEFF: Usable, well in the
sense of maybe some future human
mission absolutely could use
some of the material but that is
not in our plans at this point.
We wouldn't account on that.
AUDIENCE: Are the people who are
going to walk on the surface of
Mars alive today?
JEFF: So, the question is are
the people that are going to
walk on the surface
of Mars alive today?
So, we can get people to Mars by
the end of the 2030s but given
the way government works it is
most likely going to be 2040s,
yes so I would say they are.
AUDIENCE: Can you get any
transportation faster than
25,000 miles per hour?
JEFF: Yeah, that's one of
the technology areas
that is being worked on.
Different types of propulsion
to get us to Mars faster,
and I don't know if they
will talk about that next week,
but that's with radiation
protection and the exposure
during that crew's stage, one of
the ways we can mitigate that is
actually getting to Mars faster,
not taking the six to eight
months to get there, and so
there is direct propulsive,
there is some technology called
vasomer drive and some other
things like this that
could potentially
decrease that time to Mars.
And that's really potentially
a key for the humans.
It is not so much of an issue
for the prepositioning of the
cargo missions and
things like that,
so we can use more efficient
and slower methods like solar
electric propulsion that would
allow us to get there over a
longer period of time, but
we can also use that to slow
ourselves down as much as we
can getting close to Mars and
therefore the landing
systems could be more
capable when we get there.
AUDIENCE: The rotational
direction of Mars factored in?
JEFF: Absolutely it is, yeah, so
is the rotational direction of
Mars factored in to
the landing, yes.
AUDIENCE: Which
way would you go?
JEFF: Well, you
can go either way.
So retrograde or
prograde, but we
go with the rotation normally.
AUDIENCE: You are relying on
radio technology to communicate,
you can change the technology to
laser and get the landing point
site facing the Earth, the
device could be on the side of
the craft facing Earth, used to
communicate during that blackout
if you needed to.
JEFF: Exactly. So,
the question is
why aren't we using laser
communication
instead of just radio
communication to get information
back from Mars
from our vehicles.
So, now we have been using
the radio communication,
we actually have experiments
that are planned to go to Mars
to do laser comm.
Main thing is to
use it during entry,
descent, and landing, we have
this variable atmosphere to deal
with and so if it is real dusty
and issues like that we don't
know that we would be able to
get a good laser signal and in
those critical times.
So, we still want to have strong
radio signal to a satellite that
could then relive
through laser comm,
so that's why we are
looking at laser comm
in our orbital assets.
Another benefit of the
laser communication,
it can send a lot
more information.
I mean right now we have a few
assets there that communicate
through radios and
think of these pipes,
they are relatively narrow pipes
that we are sending data through
and there is this big backlog
of data and images waiting to go
through these pipes, whereas
if we get laser communication
working we will be able to
get a lot more data back.
STEVE: I am not sure if the
question was about the radio
blackout or whether it
was about the time delay.
If it is about the time delay
the laser and the radio wave
could travel at the same
speed, so even with
laser communication
it is 14 minutes.
JEFF: Right, it
will still be the
same time delay, exactly.
Thank you all very much.
[Applause]
STEVE: Thank you for
being here and we look forward
to seeing you next week
for the last lecture
on the radiation
protection problem.
macaroni
