8.3. Mars Flybys and Orbiters: Getting the Picture

Loading...

Del curso dictado por University of Illinois at Urbana-Champaign

Emergence of Life

57 calificaciones

University of Illinois at Urbana-Champaign

Emergence of Life

57 calificaciones

How did life emerge on Earth? How have life and Earth co-evolved through geological time? Is life elsewhere in the universe? Take a look through the 4-billion-year history of life on Earth through the lens of the modern Tree of Life! This course will evaluate the entire history of life on Earth within the context of our cutting-edge understanding of the Tree of Life. This includes the pioneering work of Professor Carl Woese on the University of Illinois Urbana-Champaign campus which revolutionized our understanding with a new "Tree of Life." Other themes include: -Reconnaissance of ancient primordial life before the first cell evolved -The entire ~4-billion-year development of single- and multi-celled life through the lens of the Tree of Life -The influence of Earth system processes (meteor impacts, volcanoes, ice sheets) on shaping and structuring the Tree of Life This synthesis emphasizes the universality of the emergence of life as a prelude for the search for extraterrestrial life.

De la lección

Week 8 - Astrobiology and the Search for Life in the Cosmos

No matter where you are or what you believe, sometime in your life you will look up into the sky and ask: What is out there? Where are we going? Is there life elsewhere in the universe? This course is dedicated to searching for answers to these questions. The fundamental concepts of life and habitable environments, established upon the modern synthesis of the Tree of Life, will direct us in recognizing biospheres that might be quite different from our own. In the last week of this course, we will look in detail at what the future has in store for space exploration and the search for life in the cosmos.

8.1. NASA Astrobiology: Roadmap to Life in the Universe11:44

8.2. NASA: A Platform for Inter-Disciplinary Science4:57

8.3. Mars Flybys and Orbiters: Getting the Picture8:37

8.4. Mars Rovers: Was the Red Planet Habitable?9:04

8.5. NASA Future Missions9:03

8.6. NASA Institute for Universal Biology8:59

8.7. Think and Wonder…Wonder and Think5:06

8.8. The Emergence of Life: Course Synthesis 6:33

Emergence of Life Outtakes3:58

Conoce a los instructores

Bruce W. Fouke, Ph.D.
Director of the Roy J. Carver Biotechnology Center
Department of Geology, Department of Microbiology, and Institute for Genomic Biology

[SOUND]

[MUSIC]

The US Space Program has invested decades of intensive and

expensive research to give us a fundamental understanding of what

the planets of our solar system are composed of.

Mars has been a logical target for that.

Its proximity, the possibility that it had habitable environments in the past, and

of course, the kind of the collective imagination of our society about Mars,

all lead to making Mars an important early target.

The first information that NASA retrieved was from

a group of what we call flyby satellites.

These are small robots, about a half a ton in size.

They don't go into orbit, but they brush through the outer portions of

the near proximity of the planet, and they take a group of pictures.

So, NASA launched the Mariner 3 and the Mariner 4.

Mariner 3, unfortunately exploded.

The top of it came off and it didn't reach Mars, but Mariner 4 was very successful.

It reached Mars and it took a whole series of black and white images.

Now, for modern day standards, these images are very coarse-grained.

They're crude.

They don't give us a whole lot of information that we really want at a high

resolution.

But for that time period they were remarkable, and they revolutionized our

idea of how the surface of Mars has been formed and what it's composed of.

Another thing that was really important about the Mariner spacecraft is that

Mariner 5, which followed the success of the photography of the Martian

surface by Mariner 4, Mariner 5, its target was actually Venus.

And as Mariner 5 was passing Mariner 4, they were able to negotiate and

interact in terms of communicating back with Earth.

And so, Mariner 4 also helped with exploration of other planets as well.

But that combination of the Mariner satellites also provided us not only with

black and white pictures of the surface of these planets, but

it also gave us fundamental understandings of what the solar system is composed of.

And one of the most important of those was solar wind.

The surface of the sun is constantly emitting high energy from its surface and

that propagates through the space away from it.

And it makes what we call solar wind.

It showers all the rest of the solar system with this energy.

And the thing that protects planet Earth is the fact that

we have a magnetic field, and

that magnetic field acts like an umbrella to shelter us from that solar wind.

Well, the next group of space craft that were really important for

advancing our knowledge of Mars, there were other flybys and

there were other orbiters, that's the idea of putting a satellite action into

a permanent orbit around the planet, was the 2001 Odyssey.

And the Odyssey satellite revolutionized again

our understanding of the surface of Mars.

That satellite had a suite of high resolution cameras that

gave us black and white and color images of the surface.

And it provided images that were extremely high resolution and

gave us the information about the topography, the surface features,

the surface structures that Mars was composed of.

And there, we got information about the magnitude of some of the features on Mars,

the geomorphology that had been formed through geological time.

And we'll talk about those in just a moment, about some of the drastic and

amazing features that we saw.

So, the Odyssey,

which is still operating, revolutionized our ability to understand the planet.

Now, there are many things that the Odyssey provided,

but one of the most striking was the idea of polar geysers.

And so, in black and white imagery, the Odyssey was

able to show that there are almost these spider-like dark veins that run and that

those veins connect together into central points that is shown on this image.

And [COUGH] the idea there was well, what can form that kind of a spider-like

network of line-like features that are connecting in the central points?

And our rendition is showing nicely that actually what has been proven is that

these are polar geysers.

These are where we have gases that are emitted from the polar ice sheets on Mars.

And they erupt like a geyser does.

And then, it spreads ejected material and sediments away from that.

It makes that kind of spider-like network of features.

So, polar geysers have been an important aspect of our understanding of Mars.

Another one is that we were, very, that NASA and

the US Space Program have been very focused on is there water on Mars?

The search for life includes the search for

water, the search for nutrients, and the search for

the chemical components that make up life, the fundamental building blocks of life.

And tracking the water has long been thought to be the way to track

the distribution of life.

Well, the Odyssey provided us with amazing photography of stratigraphic

sedimentological features on the planet, that could only have been formed by large,

vast reservoirs of water not so dissimilar from what we have on Earth itself.

So, in this imagery, we can see that this is at the lower

flank of one of the larger volcanoes that occur on Mars, and that volcano,

it erupted molten rock on the surface, and that lava formed what we call a dike.

It's a wall of lava that solidifies and becomes a solid wall of rock.

And that wall of rock was breached by water, and

we can see that from the water cutting a valley through that dike of molten rock.

Another thing that we see very commonly throughout many areas on Mars' surface

are flow-streams.

In other words, when flowing water is moving across a surface and

moving sediments and carving its way into the landscape, it leaves flow patterns.

And we can see from this image that there are very distinct flow-patterns.

So, the Odyssey really confirmed for

us the idea that there was very abundant amounts of water on Mars.

Another thing that the Odyssey prodded for

us was the absolutely remarkable magnitude of the scale and

the size of some of the geomorphic and geological features on the planet.

The largest canyon that occurs on Mars is actually as large

as the distance across all of North America, from San Francisco to New York.

And so, we know that in Arizona, in North America, we have the Grand Canyon and

that's an extremely large canyon.

It's a mile deep and it is very extensive, many miles in length.

But this would have been something on the order of thousands of miles in length.

And again, we don't have features like this on planet Earth.

And this imagery is so striking,

because also it shows very nicely that as the canyon was being carved

much of that had to have been carved by flowing water itself.

So, the combination of the flybys and the orbiter imagery

has given us the template of information that we've needed now, to move forward and

launch on the ground missions on Mars, as a preemptive strategy to prepare for

eventual human missions that occur on Mars.

In this image, we see this gigantic Arabian scale sand dunes that are marching

across the landscape to the lower

flank of one of the larger again volcanoes that occur on the surface of Mars.

And this kind of hybrid illusion imagery,

therefore gives us the base map that we need to move forward to plan missions,

to know what the distribution of elements and geological features are on the planet.

And with that combination of topography and geology and

geochemistry, then the decisions could be made to launch

the missions that we are now involved with, where we put rovers and landers on

the ground that are communicating with the orbiters themselves.

And the summary of all of this is that the flybys and

the orbiters have provided us with a comprehensive map of the surface of Mars.

And that map lays the groundwork then for the ongoing and

future missions of the US Space Program.

[MUSIC]

Explora nuestro catálogo

Inscríbete de manera gratuita y obtén recomendaciones personalizadas, actualizaciones y ofertas.

Coursera brinda acceso universal a la mejor educación del mundo, al asociarse con las mejores universidades y organizaciones, para ofrecer cursos en línea.

© 2018 Coursera Inc. Todos los derechos reservados.

Descargar en la App Store

Consíguelo en Google Play