How NASA Reinvented The Mars Rover

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Episode Transcript

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This is a real photograph of ahelicopter on the planet Mars. It was
built by humans on Earth and becamethe first machine to fly using aerodynamic lift
on an alien planet. NASA engineershave spent the past three decades working on
interplanetary exploration technology, going from avery small Mars rover up to a very

(00:24):
large Mars rover, and back downagain to the miniature Martian helicopter. We
are looking at the first steps ona journey that will unlock the secrets of
the universe. This is how NASAreinvented their Mars rover. Before we can
really talk about wings on Mars,we need to establish our foundation on wheels.

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Our upclose examination of Mars dates backto the mid nineteen seventies and the
Viking Landers. These were essentially scientificinstrument clusters that made an epic journey all
the way down to the surface ofthe red planet and delivered first hand information
about the composition of Martian soil.NASA launched both Viking one and Viking two
in the summer of nineteen seventy sixto take the most advantage of a close

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proximity window between Earth and Mars thatonly opens once every twenty six months.
By placing two landers in different areasof the planet, NASA was getting the
most diverse sample range possible, Butthese were still just two scoops of sand
in a planet sized desert. Theodds of finding an ancient fossilized Martian bacteria
using this method were not in ourfavor, so Mars landings were put on

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hold for two decades as NASA workedon developing their solution for exploring the Great
Unknown. In December nineteen ninety six, NASA was ready to send a new
payload to Mars, the Pathfinder again. This was a scientific instrument station that
unfurled itself on the Martian surface toreveal a collection of scopes, cameras,

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and meters. But Pathfinder also broughtalong with it a small prototype vehicle,
this little guy, Sojourner. Anyonewho is around in the late nineties remembers
the original Mars rover. This thingwas a pop culture icon. It was
incredible. We were driving around aremote controlled car on another planet. The

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twenty first century had arrived. Sojournerwas a technology demonstration. No one really
knew what was going to happen whenyou started to drive around a tiny car
millions of miles away on the surfaceof an alien planet, but there was
only one way to find out.The first Mars rover was about the size
and weight of a microwave oven.It had six wheels, each with their
own independent electric motor, and anexperimental new suspension system that was called the

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rocker Bogie. We know that thesurface of Mars is not smooth and sandy
like a desert. It's littered withsmall chunks of jagged rock, and the
last thing NASA wanted was for theirnew rover to travel millions of miles through
space just to get hung up ona rock before it could do any science.
With this high tech suspension system,the rover could safely overcome oppsticles up

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to one third of its own size. In this iconic photo taken by the
Pathfinder Landers camera, we can seethe rover conducting an up close examination of
a large boulder. Because this roverwas in such an early phase of development,
it didn't carry a whole lot ofscientific equipment that was still mostly handled

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by the Lander platform. But Sojournerwas equipped with a front facing instrument called
an alpha proton X ray spectrometer,and that allowed it to determine the chemical
composition of any rock that it coulddrive up to. The rover was even
equipped with an early form of autonomousdriving, not so different from what we
see in modern vehicles. It useda combination of camera vision and lasers to

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identify obstacles and maneuver around the Martianlandscape. Because the NASA team on Earth
could only communicate with the rover onceper day, they would essentially have to
set a waypoint location that the roverwould drive towards and then tune in the
next day to see where it endedup. So it was a pretty slow
process of exploration, with the rovercovering about one hundred meters of driving in
its three months of operation. Thatdoesn't sound like much, but it was

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significantly more performance than NASA scientists hadhoped for, and it gave the Space
Agency enough confidence to double down onthe Mars rover in a very big way.
If one little Mars rover was ableto captivate the world and write new
chapters in planetary science, then justimagine what two big Mars rovers might accomplish.
This was NASA's plan with the MarsExploration rovers, Spirit and Opportunity Both

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machines were launched on separate Delta tworockets in the summer of two thousand and
three, taking full advantage of thatfleeting Mars transfer window. This time,
instead of a lander that deployed aseparate rover, the lander was the rover.
After shedding its protective landing shell,each Exploration rover unfurled solar panels,
scientific instruments, and wheels, thenset off into the Martian desert. It's

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very difficult to get a sense forhow big these machines actually are because we
have no known reference points on Mars, so where the Sojourner Rover was about
the size of a microwave, Spiritand Opportunity were closer to the size of
golf carts. NASA had essentially justscaled up the six wheel drive Rocker Bogie
system to create these next generation rovers. The extra size and capability allowed the

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full collection of scientific instruments from thelander to now be fully mobile for the
first time. In the top ofa one point five meters tall mast.
Each rover had nine digital cameras.They were used for both navigation and to
create three dimensional panoramic images of theMartian landscape. The exploration rover also had
its main spectrometer placed on the endof a robotic arm that extended out from

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the front for closer examination of rocksand soil. With all of these upgrades
over their predecessor, the twin Roverswere able to accomplish orders of magnitude more
exploration and data collection than any previousMars mission. The Spirit Rover had a
lifespan of six years and drove fourpoint eight miles, while the Opportunity exceeded

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all expectations to last over fourteen yearsand cover twenty eight miles of the alien
landscape. This is the next generationof Mars rover. You're looking at a
self portrait taken by a robot onthe surface of the planet Mars. In
the year twenty twelve, this rover, named Curiosity, became the first of
a new breed of vehicle to roamthe Martian surface. Again, we have

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to establish a sense of scale here, because this machine is a lot bigger
than most people realize. So here'sour microwave sized Sojourner, and here is
our golf cart sized Opportunity. Andnow we bring in Curiosity. This is
around the size of a crossover suv. It's really big. You'll notice we

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have the same six wheel drive powertrainand a much bigger and beefier version of
the same rocker bogie suspension system.At this scale you can really see how
the wheels are linked to the mainbody of the rover. It's now a
tried and tested method for traversing thejagged, rocky surface. You'll also notice
that, unlike its predecessors, Curiositydoes not have solar panels. Instead,

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the rover is powered by a radioisotope thermo electric generator. Heat generated by
the radioactive decay of a plutonium isotopeis converted into electricity by thermo couples,
and any excess heat not turned intoelectricity is used to keep the systems warm
during the Martian night. With elevenpounds of plutonium two three eight on board,

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Curiosity's generator has a minimum lifespan offourteen years, and the rover is
still going strong to this day.In twenty twenty one, Curiosity was joined
on Mars by its own twin rover, Perseverance, part of the Mars twenty
twenty mission. Perseverance is mostly thesame car sized platform as its older sibling,
just with an upgraded collect of scientificinstruments and recording tools. It carries

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seven primary payload instruments, nineteen camerasand two microphones. It was the first
time that audio recording equipment had beensent to Mars, and that's how we
know that the wind on the Redplanet sounds like this. We can also
hear the sound of the rover itselfas the hollow metal wheels clang over the
Martian rocks, the gentle whirring ofthe electric motors, and the squeaking of

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the suspension system. And thanks toa very special payload delivered by Perseverance,
we have this. You are hearingthe sound of a helicopter flying on Mars
for the first time, and thisis the view from eighty feet above the
Martian surface, just like the Pathfinderback in nineteen ninety six, Mars twenty
twenty brought along one small piece ofexperimental technology, a helicopter drone named Ingenuity,

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hitched a ride in the belly ofthe rover and was deployed on April
third, twenty twenty one. We'veseen NASA make some pretty amazing progress with
their rover vehicles over the twenty fiveyear period that we just covered, but
there is still only so much thatcan be accomplished on wheels. This is
rugged and uneven terrain. Inevitably youwill reach a hill that is too steep

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to climb. If we want totake interplanetary exploration to the next level,
we have to learn how to fly. In many ways. Ingenuity was NASA's
biggest risk yet when it comes totech demonstrations on Mars, because we knew
without any doubt that wheels would workon Mars just as well as they do
on the Earth. But propellers area whole other story. This is a

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DJI Phantom drone. You've probably seenone before, maybe even own one yourself.
It's not so different from NASA's Marsdrone. The frame is a comparable
size to Ingenuity. The Dji isa bit smaller overall and about one pound
lighter. Using four tiny propellers,the Phantom can rise thousands of feet in

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to the air, while Ingenuity usestwo relatively giant propellers with a four foot
wingspan, and with this it achievesa maximum height of around eighty feet.
Ingenuity needs much larger flight hardware toaccomplish much less performance because it is flying
in an environment with less than onepercent the atmospheric density of the Earth at

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sea level. To find an equivalentair density on Earth, you would need
to go to an altitude of eightyseven thousand feet. The highest anyone has
ever flown a helicopter is just overforty thousand feet. In order to test
the helicopter's flight system on Earth,NASA had to use a vacuum chamber that
simulated the low density atmosphere of Mars. They also had to use a cable

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system that would pull up on thehelicopter at just the right tension to simulate
the reduced gravity effect as well.They even had fans blowing air across the
chamber to try and simulate wind onMars. Due to do all of these
factors, the propeller system on Ingenuityis very unique. Each blade is shaped
for maximum lift. They are constructedfrom am ultra lightweight foam with a carbon

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fiber reinforced shell. To achieve lifton Mars, the blades need to spin
at doubled rpm that would be requiredon Earth. The two propellers are counter
rotating to keep the drone stable inflight. A traditional helicopter uses a tail
rotor to do the same job.And a quad copter. Drone uses two
sets of counter rotating propellers on opposingcorners. Because of the small size and

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high energy requirements, Ingenuity is limitedto a maximum of ninety seconds flying time
before it has to stop and recharge. The internal systems of Ingenuity have a
lot in common with a modern smartphone. It uses two sony cameras, half
a dozen sony lithium ion battery cells, a cell phone grade inertial measurement unit,
and a Garmin ultimeter. The batteriesare charged by a solar panel mounted

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to the top of the drone.With d all of the technology built into
Ingenuity, there was still doubt thata helicopter would be able to perform on
Mars. Even within NASA, therewas opposition to the project, and some
top officials thought it was a wasteof resources to ship the drone along with
Perseverance. But just like the Sojournerrover before it, the first Mars helicopter

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has far exceeded expectations for its performanceand longevity. The initial technical demonstration had
only planned for five flights on Mars. Two and a half years later,
Ingenuity has completed sixty seven flights witha total of over two hours flying time.
The helicopter is currently being used asa scouting vehicle to help plan out

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the journey of the Perseverance Rover asit navigates the steep river deltas of the
Jezero Crater. The initial success hasalready begun to fuel new concept ideas at
NASA. The Mars Science Helicopter isa six propeller drone with a mass of
around thirty kilogram. The much largerhexaicopter would be able to fly up to

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ten kilometers in one mission and carryup to five kilograms of scientific payloads along
for the flight. If we remember, the Spirit Rover covered just under eight
kilometers in its entire six year lifespan, so to fly further in one day
with the Mars Science Helicopter would bea gigantic leap forward in our exploration of

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the Red planet. We know thatNASA is also envisioning a pair of Ingenuity
like helicopters for their Mars sample returnmission in twenty thirty. As the Perseverance
Rover explores the Jesero Crater, ithas been collecting samples from underneath the surface
regolith and leaving them behind in sealedtubes. The idea is that eventually NASA

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will follow up to collect the sampletubes and return them to the Earth for
study. The original idea was touse a fetch rover that would essentially retrace
the Perseverance journey and collect the tubes, but with the unexpected success of their
demonstration helicopter, NASA is thinking thatflying machines will be much faster and more
efficient for retrieving the samples. Andthis doesn't end on Mars either. Dragonfly

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is a quad copter drone that willfly on Saturn's moon Titan. This is
a surreal world where the frozen surfaceis covered by flowing rivers and seas of
liquid methane, so alien that itis almost incomprehensible, but the thick nitrogen
atmosphere on Titan makes an ideal locationto fly a drone. In many ways,

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we're lucky that Mars offers such achallenging environment to practice flying so relatively
close to home, because if wecan master the art of flight on Mars,
then the possibilities will be nearly endless.