JUDY WOODRUFF: If all goes according to plan, the U.S. will land its most advanced rover ever
on Mars by this time tomorrow night, nearly 300 million miles from where it lifted off last year.
It's a daunting task, one that will set up a more ambitious exploration of the Red Planet.
Miles O'Brien lays out the nerve-wracking challenges and goals of the mission.
MAN: And liftoff, as the countdown to Mars continues.
MILES O'BRIEN: It took seven months for the Perseverance rover to travel
between Earth and Mars and, once it arrives, seven
minutes to descend from the top of the atmosphere to the surface.
ALLEN CHEN, NASA Jet Propulsion Laboratory: Well, landing on
Mars is all about finding a way to stop and stop in the right place.
MILES O'BRIEN: When it comes to entry, descent, and landing, Al Chen is the man in the hot seat
at NASA Jet Propulsion Laboratory. It takes 11 minutes for radio signals to travel the speed of
light from Earth to Mars, too much lag time for Chen and his team to remotely pilot the rover.
So, Perseverance must land autonomously.
ALLEN CHEN: And that's kind of one of the central challenges, I think, of landing on Mars.
We can't participate. We can't guide it. We can't pilot it on its own.
We have to train Perseverance to do it on her own.
MILES O'BRIEN: It all culminates with what's called the Sky Crane. Retrorockets
fire on the descent stage, and the rover is winched down on the surface on tethers.
It all may seem a little harebrained, but the one
time NASA tried it with the Curiosity rover in 2012, it worked like a charm.
Perseverance is aiming for the Jezero crater, which may hold the answer to the big question:
Did life once exist on the planet next door?
Lori Glaze Heads Nasa's Planetary Science Division.
LORI GLAZE, Director, NASA Planetary Science Division: Jezero really stood out as
a potential landing site because, within that crater, we can see
absolute evidence that there was a lake that persisted there long enough that a river flowed
into that crater and deposited all of its sediments into a river delta.
MILES O'BRIEN: The crater has been bone-dry for 3.5 billion years,
but, in its wetter, warmer days, this place might have been a rich breeding ground for life,
perhaps something resembling bacteria or algae here on Earth.
LORI GLAZE: So, if those early microbes were present on Mars,
this is exactly the kind of deposit where they would be preserved.
KEN FARLEY, California Institute of Technology: What we are going to be
looking for are biosignatures, the leavings of microbial life.
MILES O'BRIEN: Geologist Ken Farley is the project scientist for the mission.
KEN FARLEY: Everybody is familiar with the idea that living things are made out of organic matter,
and some of that gets preserved. And the idea is that, using one of the instruments on the rover,
we can actually see how that organic matter is distributed.
MILES O'BRIEN: The science team prepped for the mission in Western Australia.
The rocks there are about the same age as those in the Jezero crater.
KEN FARLEY: When we look at these ancient terrestrial rocks
that have evidence of life in them, what we see is that microbes formed mats.
These are layers at the interface between a lake or a shallow sea and the mud at the bottom.
That held the sediment together and actually distorted it in very characteristic kind of
mushroom-shaped patterns called stromatolites. These are a really obvious kind of biosignature.
That will be something that we will be looking for very carefully with the rover.
MILES O'BRIEN: Perseverance will drill core samples out of rocks that might contain these
organic biosignatures. They will be sealed up in tubes and dropped off on the Martian surface
for a future rover to collect and send back to Earth. It's a concept called sample return.
LORI GLAZE: So, we are so excited about Mars
sample return. We are closer now than we have ever been before.
MILES O'BRIEN: But it's still a ways off. By the time the retriever rover launches to Mars
and a sample is sent to Earth, it will likely be the early 2030s.
Biosignatures are signs of possible life, but not smoking gun proof.
Teasing out that question will be a lot easier in a lab here on this planet.
LORI GLAZE: But when we get those samples back in the laboratory, that's what's going
to give us our best opportunity to be able to say whether or not some of those molecules that we're
finding were actually biologic molecules or whether they could form in other ways.
MILES O'BRIEN: But, for now, the star of this rover show
may turn out to be this little four-pound drone helicopter named Ingenuity.
MIMI AUNG, Mars Helicopter Project Manager: It's a game-changer. It's something that
will enhance space exploration, period, is the ability to fly around the planet.
MILES O'BRIEN: MiMi Aung is the project manager on this technology demonstration experiment.
They're planning five short test flights.
Mars changes the equation for flights with wings or rotors.
The gravity is about one third of Earth's. And the carbon dioxide atmosphere is much thinner.
MIMI AUNG: It's about 1 percent compared to
here, right, on Earth. Even though you're able to lift, right, you have to spin very
fast to lift. Because the atmosphere is so thin, you can't lift as much mass.
MILES O'BRIEN: If successful, Ingenuity could usher in a new era of mobile exploration on Mars,
a reconnaissance tool to find intriguing sites for science,
and it would be a historic first flight on another planet.
MIMI AUNG: It's been a long journey. I'm very goal-oriented. I want to get to
learn as much as we can about flight. Think of Wright brothers experiments,
right, the whole series of experiments. We -- at Mars, we just get to get one shot, right?
MILES O'BRIEN: And speaking of shots, Perseverance will aim its cameras at Ingenuity when it flies.
Another iconic image of a first flight awaits us.
For the "PBS NewsHour," I'm Miles O'Brien.
JUDY WOODRUFF: So exciting. Fingers crossed.
We will talk with Miles live tomorrow night to see if the mission to Mars is a success.