But this is where I am.
Another thing that you may have noticed is that I do actually own
more than one shirt.
This shirt would not be a very good shirt with the green screen.
I wear the same shirt all the time the green screen because it actually is
the best shirt that I have for the green screen.
If I did this when all the little spots would disappear,
it actually looks pretty funny.
The other thing you might have realized is I actually wear glasses.
I don't wear the glasses during the recording because again, the, it doesn't
work very well for the green screening because I'm sitting here with a big.
Window in front of me, and I sometimes get green reflected off of my glasses.
And when I try to green screen the glasses, I get little, weird sparkly
holes in my eyes and it makes me look like I'm possessed or something.
So for the rest of the time, you'll see me without glasses and with my fine,
fine blue shirt.
and you won't get to see my office behind me.
In any case, one of the really nice things about being here at Cal Tech in
the Planetary Science department is that there are people up and
down the halls who are the world's experts on so many different subjects.
Including the ones that we've been talking about.
And I can grab them as they're walking down the hall and
sit them down right here and make them record a lecture.
And so I've done that.
The next two sets of lectures are going to be from
Bethany Ehlmann who is a Professor of Planetary Science here.
And, she worked on the rover that went to that region with the hematite,
the, the opportunity that went to Meridiani Planum.
She's also done a lot of work with,
the orbiting spacecraft that take data looking at spectra.
We've talked about spectra some,
we've showed the spectrum of hematite, but since that time there has been much more
detailed spectroscopy to learn about the detailed minerology of what's.
Going on, in different regions on Mars.
And she's going to tell you all about that.
And use that to spin an entire story of the history of Mars.
After she's done with that, we're going to drag in John Grotzinger,
John Grotzinger was the chief scientist on the Curiosity Rover,
that one that's on Mars right this very minute.
And he's primarily a geologist, he looks at the.
The land forms on Mars and
tries to construct stories of what might be going on there.
It's interesting that you will, if you listen carefully,
you'll notice that Bethany Ehlmann whose mostly a mineralogist,
thinking about certain, the chemistry, and John Grotzinger, whose mostly a geologist,
thinking more about the landforms.
They actually come to some different conclusions about the history of Mars and
what might have been going on over the past four and a half billion years.
The story, the overall story is the same but the details are different.
See if you can pick out where they don't agree with each other.
And after they're all done, we'll come back, summarize everything that we
think we have learned about Mars, and how we're going to answer these.
Final questions that we'll still have, particularly after we see
the two different interpretations of what might have been going on.
Oh, hey, it's me again.
Before you watch the next set of lectures,
I just wanted to have a quick discussion about some terminology that's going to be
used, that we haven't used in class before.
You'll hear both Bethany Ehlmann and John Grotzinger use the term oxidizing or
reducing.
To describe environments, atmospheres, or subsurface environments.
These are words that are actually from a long time ago when
iron ore was first being smelted to form iron.
To form iron you take the iron, you put it inside of a kiln,
you heat it up very hot, and you reduce the amount of oxygen in the environment.
