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. <i> VO: How do you get to Mars?</i> <i> If you want to send a
spacecraft all the way to Mars,</i> <i> first you will need a fast
rocket to escape the pull</i> <i> of Earth's gravity.</i> <i>The heavier your spacecraft the
more powerful your rocket needs</i> <i> to be to liftoff.</i> <i> Next, make sure you
launch at the right time.</i> <i>Mars and Earth orbit the Sun at
different speeds and distances.</i> <i> Sometimes they are really far
apart and other times they come</i> <i> closer together.</i> <i> About ever two years the two
planets are in perfect positions</i> <i> to get to Mars with the
least amount of rocket fuel,</i> <i> that's important.</i> <i> The total trip is
over 300 million miles.</i> <i> Finally make sure
your aim is right.</i> <i> You can't shoot for where
Mars is at launch time.</i> <i> You have to aim for where it
will be when you get there.</i> <i> It is a lot like how a
quarterback passes the football.</i> <i>Also you may need to few thrust
to correct your direction along</i> <i>the way so you don't miss Mars.</i> <i> If all goes well, you will get
to the red planet in about seven</i> <i> or eight months.</i> 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
