0:01

What does Mars's redish hue have

0:03

to do with its watery history?

0:06

We'll talk about it, this week,

0:08

on planetary radio. I'm Sarah Al

0:10

Ahmed of the Planetary Society, with

0:12

more of the Human Adventure

0:15

across our solar system and

0:17

beyond. Mars has been read

0:19

for billions of years, but

0:21

scientists may have finally cracked the

0:23

case on what iron compound actually

0:26

gives it that color. This week

0:28

I speak with planetary scientist Adomus

0:30

or Adam Valentinus from Brown University.

0:32

He's the lead author on a

0:34

new study that suggests that Mars's

0:36

surface dust is dominated not by

0:39

hematite as we long believed, but by

0:41

a different water-rich mineral, ferrihydrite. What

0:43

does that mean for Mars's watery

0:45

past? We'll get into the science,

0:47

the implications for future human explorers

0:49

on Mars, and what it tells

0:52

us about the red planet's timeline

0:54

for habitability. Then we'll revisit one of

0:56

the most iconic discoveries in Martian history.

0:58

The hematite blueberries found by the Opportunity

1:00

Rover in What's Up. If you love

1:03

Planetary Radio and want to stay

1:05

informed about the latest space discoveries, make

1:07

sure you hit that subscribe button on

1:09

your favorite podcasting platform. By subscribing, you'll

1:11

never miss an episode filled with new

1:14

and awe-inspiring Ways to Know The Cosmos

1:16

and Our Place Within It. For

1:20

decades scientists have studied the red

1:22

dust coating Mars and developed a

1:25

strong working hypothesis about what gives

1:27

the planet its distinctive color. The

1:29

leading idea was that iron in the

1:31

soil reacted with small amounts of water

1:34

and oxygen over long periods to form

1:36

hematite. It's a familiar form of iron

1:38

oxide or rust that we have here

1:40

on Earth. This fits well with our

1:42

broader understanding of Mars as a cold

1:44

dry planet that once held water but

1:46

lost it billions of years of years

1:49

ago. Earlier studies of iron oxide

1:51

and Martian dust, based primarily

1:53

on spacecraft observations, did not detect

1:55

any water bound within the

1:57

mineral structure. This led researchers to to

2:00

conclude that the dust must be

2:02

composed of an anhydrous hematite, anhydrous

2:04

meaning it doesn't contain any water.

2:07

The hypothesis was that hematite formed

2:09

under dry surface conditions through reactions

2:11

with the atmosphere long after Mars'

2:14

early wet period ended. But science

2:16

is constantly evolving, and new data

2:18

adds an important layer to the

2:20

story. Recent findings led by planetary

2:22

scientist Adam Valentinus, who's a postdoctoral

2:24

fellow at Brown University and formerly

2:27

at the University of Bern in

2:29

Switzerland, suggests that the red dust

2:31

might actually be dominated by a

2:33

different kind of iron oxide, ferrihydrite.

2:35

That's a mineral that holds water in

2:38

its structure. Adam's team combined orbital

2:40

and rover data with carefully

2:42

controlled lab experiments. By simulating

2:44

Martian dust and analyzing how

2:46

different iron-bearing minerals behave in

2:48

Mars-like conditions, he and his

2:50

colleagues discovered that ferrihydrite provides

2:52

a much better match to

2:54

what we actually see on the planet's

2:56

surface today. This discovery doesn't

2:59

overturn what we know. It deepens our

3:01

understanding. It suggests that Mars may have

3:03

rusted much earlier than we previously thought,

3:05

while liquid water was still present, and

3:07

that the red dust we see today

3:09

is a relic of a wet or

3:11

more complex climate history. Adam's team's

3:14

new paper called Detection of

3:16

Ferrohydrite and Martian Dust records

3:18

ancient cold and wet conditions

3:20

on Mars was published on

3:23

February 25th 2025 in nature

3:25

communications. Hi Adam, it's wonderful to have

3:27

you want to talk about this. Hi

3:29

Sarah, I'm very happy to be here.

3:31

Almost everybody knows that Mars is

3:34

red. Even children know that it's

3:36

the red planet, but trying to

3:38

figure out why Mars is red

3:40

turns out to be way more

3:42

complicated than we thought. When did

3:44

you first think to question this

3:46

long-standing idea that Mars has read

3:48

because of hematite? Yeah, so I was, you

3:51

know, thinking about this question during

3:53

my PhD thesis time. I was,

3:55

you know, I started my PhD

3:58

in the universe of burn-ins. Berlin

4:00

back in 2018 and perhaps

4:02

during, you know, midway towards

4:05

the completion of my PhD

4:07

thesis, I, you know, was

4:09

reading these papers and also

4:12

textbooks actually on the exploration

4:14

of Mars and what we

4:16

know about the surface, you

4:19

know, the surface composition, physical

4:21

properties and, You know, I was

4:23

kind of inspired by the

4:26

wealth of knowledge that has

4:28

been generated, you know, for

4:30

the last decades since the

4:32

age and the birth of

4:34

spacecraft observations and the exploration

4:36

of Mars since like 1960s.

4:39

And the question of why Mars

4:41

is read has been, you know,

4:43

tackled by several authors and several

4:45

scientists. And, you know, I, when

4:47

I was reading the literature, and

4:50

you know comparing what we know

4:52

now and what we knew before

4:54

I kind of noticed that there

4:56

are still you know unanswered questions

4:58

about the composition of Mars

5:00

and especially the composition of the

5:03

Martian dusts you know that the

5:05

dust is the carrier of the

5:07

color of these of this rust mineral

5:09

and then I decided to you

5:11

know reinvestigate and revisit this problem

5:13

that's been discussed since the 60s.

5:16

And yeah, and then, you know,

5:18

as I revisit it, I started

5:20

seeing something interesting, so we can

5:22

talk about this as well later,

5:25

yeah. Well, your paper suggests that

5:27

ferryhydrate is the reason why

5:29

Mars is red and not

5:31

hematite, as we originally thought.

5:33

Can you explain the differences

5:36

between these two compounds? Yes, so

5:38

both of them are iron oxides.

5:40

So, you know, as you, you

5:42

know, look at, for example, metallic

5:44

surfaces on Earth, they rust. So it's

5:46

a similar process that's happening

5:48

on Mars. You need the

5:50

material that has iron and this

5:53

iron is a certain kind of

5:55

specific chemical composition that

5:57

changes its properties when exposed.

5:59

to oxygen on water

6:01

and it's the siren forms

6:04

this iron compound known as

6:06

iron oxide and these two

6:08

minerals so ferrehydrate

6:10

and hematite they are

6:13

different because hematite does

6:15

not contain water in

6:17

this chemical structure so

6:19

that's why it's called ferrehydrite

6:22

meaning it hydrated water

6:24

containing and by looking

6:26

at you know and

6:29

by understanding which type of

6:31

iron oxide flavor there is on Mars

6:33

we can tell about the environmental

6:36

conditions and you know and and

6:38

the question of if there was

6:40

liquid water for example. What

6:42

conditions are necessary for

6:45

ferrohydrate to form versus hematite?

6:47

Yeah so hematite was thought

6:49

to form well hematite can

6:52

form actually in several different

6:54

environments but the environment that

6:56

was kind of canonically favored.

6:59

It was an environment that was water

7:01

poor. So there was people thought

7:03

there was no liquid water that

7:05

would could interact with this with

7:08

his iron minerals. So for example,

7:10

basalt, basalt is type of volcanic

7:12

rock that contains iron. And you

7:14

know, they thought that you can

7:16

form a hematite just by oxidizing

7:18

magma. So as magma reps on

7:21

the surface of Mars, maybe there's

7:23

some traces amounts of oxygen. and

7:25

that forms this hematite.

7:27

But ferrihydrate on the other

7:29

hand is formed, especially on earth,

7:31

in the environments that are water-rich.

7:33

You need liquid water and you

7:35

need also oxygen. So on earth you

7:38

need atmospheric oxygen for ferrihydrate to

7:40

form and water. And it can

7:42

be found in iron-rich streams, aquifiers,

7:44

it can be found on the

7:46

ocean floors, it can be found

7:48

in lakes, it can be found

7:50

in the ocean floors, it can

7:53

be found in lakes, in lakes,

7:55

in lakes, you know... even in,

7:57

you know, sewage waters of iron

7:59

mines. It's a widespread mineral,

8:01

but the thing is with

8:04

ferhydrate, it's a very young

8:06

mineral. Hematide, on the other hand,

8:08

it's found in old rocks. Ferhydrate,

8:10

in contrast, is a

8:12

young mineral. So we thought

8:15

that on Mars, the only

8:17

reason that ferhydrate could form

8:19

is to have brief interactions

8:21

between liquid water and rocks.

8:24

Or you need very low surface

8:26

temperatures and very low water

8:28

temperatures, so maybe near freezing.

8:31

And you could sustain that

8:33

perhaps when you have, imagine

8:35

you know these huge amounts

8:37

of ice, and maybe you

8:39

could have, you know, volcanic

8:41

eruptions that would melt this ice,

8:44

and then this ice would be maybe

8:46

very cold. So this water would

8:48

be very cold, and it would,

8:50

you know. form these flash floods

8:52

and these flash floods could maybe

8:55

chemically weather and interact with the

8:57

rocks and form ferret. I mean

8:59

there are so many different

9:01

repercussions of everything you just said

9:03

if this is the case. What

9:05

does this do to our understanding

9:07

of the timeline of water on

9:10

Mars? Yeah so this is also

9:12

you know kind of an

9:14

interesting question because there was

9:16

this mineralological model that tried

9:18

to... It's a great model.

9:20

A lot of the observations

9:23

that were made and concluded

9:25

based on this model are

9:27

correct. But you know, with

9:30

science, it is always, we have

9:32

to think of scientists

9:34

ever evolving and it's

9:37

never static. It's always

9:39

dynamic. You know, you have

9:41

to refine and improve

9:43

your theories. So what I'm saying

9:45

is that with this model, it's

9:47

called the Bibrin model, it's a

9:49

model that explains the

9:52

mineralogical evolution through time

9:54

on Mars, and you know, you

9:56

have the Noakian period, you have

9:58

the transparent Peter, the... period and

10:00

for each period of these

10:03

periods the observers and scientists

10:05

attributed a specific

10:07

mineral formation. So the

10:09

Amazonian period was thought

10:12

to produce hematite. So

10:14

three billion years of

10:16

Martian geological evolution the authors

10:18

proposed hematite. So they thought

10:20

that maybe hematite can form...

10:23

early on, as I said,

10:25

through magnetic and, you know,

10:27

oxidation of magma. But over

10:29

time, you can maybe oxidize

10:31

very thin layers of rocks on

10:33

Mars through, you know, these

10:36

traces amounts of oxygen. And

10:38

they thought that this process

10:40

continued for, you know, three

10:42

billion years. But what we

10:44

see is that If it's not

10:46

hematite and ferrohydrate you need liquid

10:49

water and we know that liquid

10:51

water on the surface of Mars

10:53

currently is not stable but there

10:55

was much more liquid water in the

10:57

past there are also other multiple lines

11:00

of evidence that also support this

11:02

so we're not the first to

11:04

say that you know there was

11:06

liquid water in the in the

11:08

deep Martian past but what we

11:10

are saying is that the dust

11:12

you know and this rust mineral

11:14

formed long ago and not and

11:16

it's not a contemporaneous recent geological

11:18

process that formed this this mineral.

11:20

So so basically we're pushing the

11:23

timeline back and saying that you

11:25

know in the past maybe three billion

11:27

years ago there was interaction between

11:29

liquid water and volcanic

11:32

rocks. It formed this rust mineral

11:34

and then over time you know

11:36

Mars lost its atmosphere it became

11:39

a hyperarid and once you have

11:41

a hyperarid arid environment You can

11:43

create dust because through erosion, wind

11:46

erosion, you know, you can erode

11:48

rocks and surface materials. And as you

11:50

erode, you make this dust. And you

11:52

know on earth, for example, we know

11:55

that's a higher desert or any

11:57

type of desert environment that is

11:59

very... arid and if there is

12:01

no rainfall, dust accumulates. And

12:03

as you know, there's no

12:05

liquid water, no precipitation, dust

12:07

can accumulate and on Mars

12:10

it is dust and gets

12:12

spread around by winds and

12:14

the global dust storms. So

12:16

and basically that's how this

12:18

characteristic red hue arises on Mars

12:20

is through erosion of these ferhydrate

12:22

rich rocks. That was kind of

12:25

the concept model that we proposed

12:27

in our study. That

12:29

is interesting because I was I was

12:31

going to ask you know if there

12:33

was water on Mars in large amounts

12:35

It would be in certain locations which

12:37

means that you would end up with

12:39

some places with way more of this

12:41

ferrahydrate versus other locations But if Martian

12:43

dust storms are actually the thing knocking

12:45

it around that would explain why the

12:47

entire planet ended up red instead of

12:49

it just being Congregated in areas which

12:51

is almost unfortunate because it would give

12:53

us an even more deep understanding of

12:55

where water was localized on Mars during

12:57

those times Yeah, this is a very

12:59

good point. You know, dust is

13:01

obscuring the signal. It's it's piling

13:03

a lot. You know, there are

13:05

source regions and there are also

13:07

regions where it accumulates and that

13:10

really makes it difficult for us

13:12

to understand where these free

13:14

hydrohydrated rocks are. But our

13:16

team is confident that there are

13:18

some tools and instruments that can

13:20

help us address this question. So

13:22

this is actually something we're thinking

13:25

about for the next project. Well,

13:27

this study combined spacecraft

13:29

data from Mars Express, the

13:32

trace gas orbiter, Mars Reconnaissance

13:34

Orbiter, and of course, the

13:36

Rovers as well, Curiosity, Opportunity,

13:38

Perseverance. How did you

13:41

bring together so many

13:43

different sources to make this

13:45

discovery? Yeah, so, you know, in science, if

13:47

you find something interesting, you

13:50

always need to provide

13:52

solid evidence. And the more

13:54

evidence you can provide that better,

13:56

because especially if you're finding something

13:58

that contradicts... a former theory,

14:00

you need to build confidence in

14:02

your result, in our conclusions.

14:04

So what I did is, you

14:06

know, I looked at other, not

14:09

only, well, I looked at multiple

14:11

data sources, as you just mentioned,

14:14

also, you know, not only I

14:16

used spacecraft observations and data, I

14:18

used also rober observations and

14:21

laboratory experiments. And the

14:23

exciting thing is that all of these

14:25

instruments and all of

14:27

these data, they supported the initial

14:29

observation and the initial conclusion that

14:32

ferhydrate is the dominance iron

14:34

oxide present in the Martian dust. What

14:36

would you say are some of the

14:38

biggest challenges of actually trying to

14:40

figure out the composition of this

14:42

dust using instruments in space or

14:44

even on the ground? Because we

14:46

can't, you know, obviously we don't

14:48

have Mars sampled return yet, so

14:51

that's a little challenging. That's

14:53

all I would say that the

14:55

biggest challenge is is probably you

14:57

know learning all these different instruments

14:59

and Understand the data because to

15:01

understand the day you need to

15:03

know how the instrument functions. What

15:06

are the caveats? What maybe the

15:08

likely artifacts? You know and difficulties

15:10

in working with the data. So

15:12

I think you know none of

15:14

these challenges cannot be you know

15:16

overcome with you know with the

15:18

work and it's just perseverance and

15:21

and motivation. So, you know, step

15:23

by step, as I started my

15:25

PhD thesis, I, you know, or

15:28

this project during my PhD thesis,

15:30

I continued working on this

15:32

during my postdoc time. So

15:34

at Brown University with Jack Mustard

15:37

as my supervisor, and, you know,

15:39

you just need time, you just

15:41

need work, and things, you know,

15:43

go your way if you just

15:45

persevere. So this project took me

15:47

about three years to complete, actually,

15:50

yeah. Oh wow. And clearly understanding how

15:52

these instruments work was really

15:54

pivotal to the way that you analyze

15:56

the samples in the lab. Because you didn't

15:58

just use, you know, our... normal methods

16:01

of analyzing these things in the

16:03

lab, you wanted to mimic the

16:05

way that spacecraft and rovers would

16:08

do this kind of measurement on

16:10

Mars to actually compare the two.

16:12

What was that process like? So

16:15

one of kind of the established

16:17

methods in Mars observation or

16:19

remote sensing observations of Mars

16:21

is to acquire a spectra

16:23

of the Martian surface, a

16:25

spectrum is basically, it tells

16:28

you how much of light

16:30

is reflected at different wavelengths.

16:32

And by, you know, these shape

16:34

and absorption features and the amount

16:36

of light, basically, that gets reflected,

16:38

you can, from the surface of

16:40

a planetary material, such as, you

16:43

know, a planetary surface, such as

16:45

Mars, you can tell something about

16:47

the composition of the surface. However,

16:49

if you compare these observations from

16:51

done by spacecraft and, you know,

16:53

rovers, you know, as you mentioned, you're

16:55

not there. You know, we don't have

16:58

the samples here on earth, so we

17:00

cannot compare directly. So we

17:02

have to make our own simulents.

17:04

So in the lab, you know,

17:07

we synthesized with the help of

17:09

one of my colleagues these different

17:11

iron oxides. And actually, I didn't

17:13

mention this, but on earth, there are

17:15

at least 10 or more iron oxides. So

17:17

these different flavors of iron oxides. So

17:20

I looked at all of them in

17:22

the lab. and I was mixing them

17:24

with the basalt and these mixtures, then

17:27

we analyzed them using reflective spectrometers.

17:29

So similar type of instruments that

17:31

are on the rovers and on

17:34

the spacecraft, and then that gives

17:36

us direct comparison in understanding, you

17:39

know, what is the actual composition

17:41

of the Martian dust, you know,

17:43

that helps us to really pin it

17:45

down and understand, you know, what

17:47

are the major mineralogical phases present

17:49

in the Martian dust. Martian

17:52

dust is really fine. How

17:54

did you go about getting

17:56

these tiny tiny tiny little

17:58

dust grains? Yeah. So that's

18:00

another thing that we did. Not

18:02

only we looked at different minerals,

18:05

but we also looked at physical

18:07

properties. So we know that the

18:09

Martian dust is extremely fine, just because

18:11

it's sticky, you know, you can

18:13

see it in the rover images,

18:15

you know, this redish hue, it

18:18

collects on solar panels, you

18:20

know, several rovers on Mars have

18:22

been really suffering because of this

18:24

dust, because it just, you know,

18:27

covers the solar panels and the

18:29

instruments. There's no energy generation and

18:31

these rovers just, you know, they

18:34

just stop functioning. So, so it's

18:36

everywhere and this small particle size

18:38

is also has an effect on

18:41

the spectral property. So it has

18:43

an effect on the way light

18:45

is reflected from the surface. So

18:47

basically to mimic these particle sizes,

18:49

we use this advanced machine in

18:52

collaboration with our colleagues at

18:54

University of Granoble in France.

18:57

we're grinding our powders, so we're

18:59

really, we really approached particle sizes

19:01

of close to, or even smaller

19:04

than a human hair, about 60

19:06

times more than a human hair.

19:09

And so these particles are really,

19:11

really fine. And we did see

19:13

that actually, after grinding, the

19:16

results were fitting much

19:18

better to the actual

19:20

Martian observations. Were there any

19:22

things that were actually mismatched

19:25

between this combination of ferrohydrate

19:27

and basalt with what we

19:29

actually see on Mars? You know,

19:32

science is, that's a beauty of

19:34

science. It's, you will, it's very

19:36

difficult or maybe even impossible to

19:38

always have a perfect match. So

19:40

we did see, for example, that

19:42

there are, you know, these effects

19:44

in the infrared range. So what

19:46

we focused on in our study

19:48

specifically with the visible range. but

19:50

we also looked at the near

19:53

and for edge range, so which

19:55

is basically longer wavelengths of

19:57

slides. We saw that there are these

19:59

effects. that may result from

20:01

the way how particles and powders

20:04

agglomerate and cement to

20:06

each other. And you may

20:08

see subtle differences in the

20:10

shape and the slope of

20:12

the continuum. So this is

20:14

basically a fancy term for

20:16

features as part of the

20:18

spectrum. And if it's inclined

20:20

or slightly, if there's a

20:23

downturn. So we saw that

20:25

between our data and the

20:27

observations, there's a slight difference.

20:29

This is quite minor. Well,

20:31

it's one thing for Ferrohydrate to form

20:33

on Mars, but as you said, it's

20:36

a totally other thing for it to

20:38

remain stable for that long period of

20:40

time. So how did you test to

20:43

see whether or not this would

20:45

break down in Martian conditions?

20:47

Yeah, so this was another set

20:49

of experiments that we conducted,

20:51

and this was in collaboration with

20:54

our colleagues at the University

20:56

of Winnipeg in Canada. So

20:58

as you see, as you have

21:01

noticed, this is quite a laboratory

21:03

led project. As I said, you

21:05

know, I work, I started working

21:08

in the University of Bern, then

21:10

University, and then University

21:12

of Winnipeg. So basically what we

21:15

did is we sent a few

21:17

samples to our colleagues at

21:19

University of Winnipeg, and they

21:22

have a Marsh Chamber. So

21:24

basically a Marsh Chamber is a

21:26

Marsh Chamber is a... It's basically a

21:28

kind of a closed system, a

21:30

closed container where you put the

21:33

samples in, you can

21:35

regulate the environmental conditions

21:37

such as temperature, relative

21:39

humidity, you know, you can also

21:41

shine the samples with the ultraviolet

21:44

light and, you know, simulate

21:46

the radiation environment that's present

21:48

on Mars. And then you

21:50

can test how all of

21:52

these parameters, how they affect

21:54

how they affect or how they change.

21:56

different properties of your

21:59

samples. interested in in

22:01

our case was to look at the

22:03

mineralogical structure of ferrohydrates, you

22:05

know, how the atomic structure

22:07

basically, how the atoms of ferrohydrates

22:11

and if the atoms and the

22:13

structure, the atomic structure and

22:15

ferrohydrate is affected by the

22:17

Martian conditions, similar to Martian conditions

22:20

because there was this idea that

22:22

ferrohydrate is not stable on a

22:24

Martian surface and that it would

22:26

change, you know, that it would

22:28

not be... present and it

22:31

would crystallize and change into, for

22:33

example, hematite. That was like one

22:35

of the prevailing ideas. So we,

22:38

you know, we decided to test

22:40

this hypothesis and what we saw

22:42

was that there was no change.

22:44

As you put this ferhydrate

22:46

in this chamber, you know,

22:48

you crammed down the humidity,

22:50

you fill it with carbon

22:53

dioxide, you know, you shine,

22:55

you know, ultraviolet radiation. Nothing

22:57

happened. We saw that ferhydrate

22:59

is... the crystal structure of ferhydrate

23:01

remains the same because we

23:04

also did another measurement just

23:06

after dehydration. So this experiment was,

23:08

it's kind of a, it's

23:10

dehydrating the sample. And then

23:13

we did extra diffraction measurements.

23:15

So we took an extra

23:17

diffraction pattern of ferhydrate before

23:19

the experiment and then we

23:21

took a second pattern after the

23:23

experiment. And then again, comparing

23:26

these these two. data sets we

23:28

saw no difference. So if their

23:30

hydrate is poorly crystalline, it's very

23:32

disordered mineral and there's no change

23:35

in ferhydrous structure. But we

23:37

are talking about timescales that are

23:39

like billions of years long. Can

23:41

we extend that out that far?

23:43

Very good question. This is actually one

23:45

of the questions that not only a

23:47

few of my co-authors asked, but also

23:50

their viewers asked during the review process.

23:52

So what I did is I looked

23:54

at the literature and at the theory.

23:57

So, at the theory. There's this law

23:59

or equation called Arrhenius equation and

24:01

it's quite widely used in

24:04

the in the chemistry in

24:06

the geochemistry communities and basically

24:08

it tells you that certain

24:11

kinetic reactions are very dependent

24:13

on temperature actually very

24:15

dependents so super sensitive

24:18

and as you so we have

24:20

to think you know about the

24:22

temperature regimes on Mars Mars is

24:24

very cold right now the average

24:26

surface temperature is minus 70 sea

24:28

So, Celsius, so very cold,

24:31

well below freezing temperatures.

24:33

And these actually surface

24:36

temperatures, they slow down a

24:38

lot of kinetic reactions, a

24:40

lot of these reactions that

24:42

would be happening on Earth,

24:44

but they don't happen or

24:47

are extremely slow down on

24:49

Mars. And basically I employed

24:51

these theoretical calculations,

24:54

which also suggested

24:56

that ferhydrates is... Basically, in

24:58

some sort of, it's in

25:00

a frozen state. It will

25:02

not crystallize and change into

25:05

other iron oxide, just because

25:07

it's very dry and also

25:09

very cold. And this was

25:11

great because these theoretical

25:14

calculations, they agreed

25:16

with our laboratory experiments.

25:19

And if we combine this with

25:21

the understanding of the conditions

25:23

under which these two different

25:25

iron compounds form, this could

25:28

potentially tell us a lot

25:30

about whether or not Mars

25:32

had this warm kind of wet

25:34

past or if it was mostly cold

25:36

and icy. Yes, so we discussed

25:38

this in the paper as well

25:40

because we know from, as I

25:42

mentioned before, from several past

25:45

studies that investigated the...

25:47

mineral of the Martian

25:49

surface, both from orbit and

25:51

from ground, you know, they

25:54

have identified various hydrated

25:56

minerals such as clays

25:58

and sulfates. And, you

26:00

know, this has been known since

26:03

maybe 2005. So now 20

26:05

years we have known that

26:07

there are these all

26:09

these other hydrated minerals.

26:11

So we discussed that

26:13

perhaps these clays and

26:15

sulfates, they perhaps formed

26:18

before ferrohydrate.

26:20

So you could have

26:22

had maybe warmer conditions

26:24

early on, but then the

26:27

surface... environment started to

26:29

become more cold and

26:31

dry and perhaps the

26:33

formation of ferret suggests

26:36

that it formed during the

26:38

latest gulps of water in

26:40

Mars history. Maybe it was

26:42

the last stage of these

26:44

mineral formations as water

26:47

was becoming colder, more

26:49

brief, maybe more episodic

26:52

and then at some

26:54

point completely dry. Both of

26:56

these iron compounds also require some

26:58

kind of oxidizing environment in order

27:00

to form. And we don't have

27:02

a lot of oxygen in the

27:04

Martian atmosphere today, but there is some

27:07

indication that there was more oxygen in

27:09

the past. I think there have been

27:11

some studies on manganese oxides and other

27:13

things found on Mars that suggests

27:15

that it did have a lot more

27:18

oxygen in the past, but what other

27:20

sources of oxygen could potentially lead to

27:22

the creation of these chemicals other

27:24

than that? Yeah, great great point.

27:26

This is also something that we

27:28

have discussed quite a lot in

27:30

the team, but also with several

27:33

scientists in the community. So

27:35

on Earth, as you mentioned,

27:37

you know, these iron oxides,

27:39

they form because of atmospheric,

27:41

well, they require atmospheric oxygen

27:43

and the Earth's atmosphere is

27:45

very oxygen rich, which is

27:47

not the case for present-day

27:49

Mars. However in the past,

27:51

they may have been a bit more

27:53

oxygen, but we... had to agree

27:55

that perhaps free oxygen,

27:58

free atmospheric oxygen... was

28:00

not required for fair hydrate formation.

28:02

And you know, there are alternative

28:04

chemical pathways that will result in

28:07

fair hydrate formation. So for example,

28:09

you can create oxidants in the

28:11

waters just by shining a UV

28:13

light. It's the process is called

28:16

photo oxidation. So as you shine

28:18

UV at the water, it creates

28:20

these OH radicals. So these compounds

28:22

that can react with iron and

28:25

oxidized iron just in, so you just

28:27

need the liquid water. You

28:29

can also. form some traces

28:31

of free oxygen by photolysis.

28:33

So if you're shining a

28:35

UV light at gas molecule,

28:37

water molecules in the vapor

28:39

form, it splits them up

28:42

into hydrogen and oxygen. And

28:44

perhaps, you know, some of

28:46

this oxygen free oxygen then

28:48

created by photolysis can react

28:50

with iron and oxidize it.

28:52

So what I'm trying to say

28:54

is that there are multiple pathways,

28:56

how you can oxidize. iron ox,

28:58

you know, iron minerals and manganese,

29:01

for example, manganese

29:03

rich materials, and perhaps

29:06

large amounts of oxygen

29:08

is not required. So, but

29:10

this is, again, this is something

29:12

that we are thinking about for

29:15

future work, and maybe, you

29:17

know, we find a way

29:19

how to distinguish between these

29:21

varying hypotheses. We luckily have

29:24

some really wonderful missions coming up that

29:26

could help us try to sort some

29:28

of this out. I'm really looking forward

29:30

to the European Space Agency's Rosalind Franklin

29:32

Rover, but also we're really pulling for

29:34

that Mars sample return mission over here

29:37

because getting those samples could potentially shed

29:39

light on a lot of these puzzles

29:41

that are going to be really

29:43

difficult to solve otherwise. Yes, definitely

29:45

for Mars exploration, you know. These

29:48

are exciting times and the Rose

29:50

and the Franklin rover includes a

29:52

drill so they can actually you

29:54

know drill into the subsurface for

29:57

up to I think two meters

29:59

depth so you could potentially

30:01

look at if there's a difference

30:03

in oxidation of the surface materials

30:05

as you go and drill

30:07

deeper into the Martian subsurface

30:09

and that could also actually

30:11

tell us about what kind

30:13

of oxidizing environment was present

30:15

on H& Mars but also

30:17

modern Mars because Mars is

30:20

although it has a very

30:22

thin atmosphere there's still processes

30:24

happening on the surface that

30:26

are interesting and we can

30:28

investigate. We'll be

30:30

right back with the rest of

30:32

my interview with Adam Valentinus after

30:34

the short break. Hi y'all LaVar

30:37

Burton here. Through my roles

30:39

on Star Trek and Reading

30:41

Rainbow, I have seen generations

30:43

of curious minds inspired by

30:45

the strange new worlds explored

30:47

in books and on television.

30:49

I know how important it is

30:51

to encourage that curiosity in a

30:53

young explorer's life. That's why

30:55

I'm excited to share with you

30:58

a new program from my friends

31:00

at the Planetary Society. It's called

31:02

The Planetary Academy, and anyone can

31:05

join. Designed for ages five through

31:07

nine by Bill Nye and

31:09

the curriculum experts at the

31:11

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31:14

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31:16

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31:18

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31:20

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31:22

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31:24

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31:27

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31:29

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31:31

factoids, hands-on activities,

31:33

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31:35

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31:37

passion for space, science,

31:40

and discovery starts when we're

31:42

young. Give the gift of the

31:44

cosmos to the explorer in your

31:46

life. It's funny that

31:48

after all this time all of this research on Mars

31:50

is so much that we still don't understand

31:52

Do you think that this finding

31:54

suggests that there's potentially other minerals

31:57

and processes on Mars that we

31:59

might have completely missed? understood? Well we

32:01

know a lot about Mars and I

32:03

think it's quite possible that there

32:05

are things that perhaps we have

32:07

not thought about and you know

32:09

they are just there in the

32:11

data which just there's you know

32:13

we need someone who looks and

32:15

revisits all these great data sets

32:17

that we have for Mars and

32:19

I think it's quite likely that

32:21

you know we could find something

32:23

that's not been thought about and

32:25

not discovered yeah. Well, it feels

32:27

weird to characterize it as completely

32:30

misunderstanding. I mean, even in this

32:32

case, we're literally just debating over

32:34

whether or not it's this flavor

32:36

of iron compound versus this flavor

32:38

of iron compound. Like, we understand a

32:40

good amount of the way that this

32:43

is falling out. It's just about which

32:45

one and what timing and what initial

32:47

conditions, which is going to take us

32:49

a bit to figure out, but I mean,

32:51

it's quite remarkable that we're at

32:54

this point. Sometimes, you know, we

32:56

find something new is because our

32:58

instruments and our data sets are

33:01

improving. So, you know, the early

33:03

Mars exploration was done using ground-based

33:05

telescopes, for example, and, you know,

33:08

we did not have spacecraft or

33:10

rovers there. And these scientific conclusions

33:12

and observations were quite limited in

33:15

the beginning. So as our instruments

33:17

are improving and as our data

33:19

sets are improving, we can actually

33:21

refine. a lot of these questions and

33:24

advance our knowledge of Mars's

33:26

geological history and evolution and

33:28

the environment that were present

33:30

not only on present daymark

33:32

but also ancient. If this

33:34

is the case then Mars would have

33:37

rested when it still had water present

33:39

on its surface and and that means

33:41

the red color is more of a

33:43

sign of a wetter past than this

33:46

slow oxidation process. What do you think

33:48

this suggests about the history of habitability

33:50

on Mars? So life as we know

33:53

it requires liquid water massive.

33:55

It has a mantra called

33:57

follow the water so for

33:59

a much exploration, tracing

34:01

the water and understanding

34:03

where the water was, is

34:06

quite important, especially for

34:08

habitability question. So

34:10

by identifying that the Martian

34:12

dust or this iron mineral

34:15

contains water, that tells us

34:17

that, you know, liquid water

34:20

was required and by this

34:22

inference, you can maybe argue

34:24

that that raises the habitability

34:27

potential of Mars because now,

34:29

you know, everywhere you look basically

34:31

because thus is everywhere you you

34:33

have some water that's trapped in this

34:36

mineral structure so perhaps we are

34:38

at this point where evidence for

34:40

liquid water in the ancient past

34:42

is can be observed right now

34:44

almost everywhere you know you have

34:46

ices in the poles you know

34:48

which are not on the carbon dioxide

34:50

but they're composed of water you

34:53

have these clay minerals and sulfates

34:55

that you know I talked about

34:57

which have been discovered in

34:59

the past. The dust is a

35:02

carrier also of hydration and you

35:04

know evidence for liquid water.

35:06

So I think I think all

35:08

of these lenses of evidence they

35:11

suggest that the conditions for

35:13

life may have been present

35:15

on Mars and now we

35:17

just need to basically find

35:20

the evidence which is I

35:22

guess the most difficult part

35:24

of Martian exploration.

35:26

However, we have perseverance rover

35:29

and also curiosity rover

35:31

who are investigating

35:33

these environments that contain

35:35

liquid water and perhaps they

35:37

can address these questions. You

35:40

know, I've been looking at

35:42

Mars images for most of my

35:44

career, but sometimes I still

35:46

get excited just by looking

35:48

at all these amazing images

35:51

that have been acquired by

35:53

perseverance rover, but also by

35:55

spacecraft data. But to note,

35:57

actually, you know, you mentioned

36:00

something. interesting about you know

36:02

human exploration of Mars. So

36:04

this kind of an observation

36:06

that you know we can make from

36:08

just the evidence of air hydrate

36:11

in the dust is that human

36:13

explorers when they once they land

36:15

on Mars you know suppose they

36:17

land somewhere where it's very dry

36:20

and there's no ice in a

36:22

subsurface they could potentially you

36:24

know use that Martian dust

36:27

and ferhydrate to to cultivate

36:29

this water because, you know,

36:31

ferrohydrate is hydrated. So there's

36:33

probably something maybe up to

36:35

an order of 10% by

36:37

weight of water in this mineral

36:40

structure. So you just need to

36:42

heat it up really strongly

36:44

and condense the vapor, the

36:46

gas released from ferrohydrate. And,

36:48

you know, you could use

36:50

this perhaps as a resource.

36:52

Mark Watney would have wanted to know

36:54

that during his, not real-time on Mark's.

36:56

No, but that's a great point. This does

36:59

have some implications there then. We're going to

37:01

need that if we're going to do it,

37:03

although we're also going to have to figure

37:05

out that whole perchlorate issue. There's a lot

37:07

there going on, but each and every clue

37:09

that we get takes us a step closer

37:12

to being able to put humans on another

37:14

world in our solar system, and that's

37:16

just amazing. But you touched on this

37:18

a little bit earlier, that you do

37:20

have some future plans for your research.

37:22

Do you want to talk a little bit

37:25

more about what you're going to

37:27

be doing next? The Discovery Fair

37:29

Hydrate on Mars opens several research

37:31

directions, and it raises

37:34

several interesting questions. So

37:36

one of the questions is constrain

37:38

the timing, so trying to understand

37:40

when the oxidation happens, because right

37:42

now we just use the... the

37:44

abundance of liquid water on ancient Mars

37:47

as perhaps the time when fair had

37:49

reformed and we you know we mentioned

37:51

something about three billion years ago but

37:53

we need to constrain this and understand

37:55

you know how long this could have

37:57

happened and then for that you need

37:59

to look at the geology and

38:02

this is one of the kind

38:04

of research directions that we will

38:06

take in the future. Another

38:09

thing is to understand how

38:11

ferohydrate forms so I mentioned

38:13

to you that you know

38:16

we on earth there are various

38:18

environments but

38:20

perhaps on Mars there

38:22

are geochemical pathways that

38:24

we have not thought about. So I

38:26

intend to look at ferhydrate formation

38:29

in the lab. So basically synthesize

38:31

this mineral in various different

38:33

ways, exposing it to Mars-like

38:36

conditions, you know, changing the

38:38

temperature, changing, you know, the

38:40

atmosphere composition, and seeing how

38:43

that affects ferhydrous formation, you

38:45

know, from these laboratory experiments,

38:48

we can maybe understand something

38:50

very fundamental and very interesting

38:53

about the... surface processes on

38:55

ancient Mars. So cool. Good luck with

38:57

all your future research and I'd

38:59

love to know more if you actually

39:02

do these experiments and find out something

39:04

cool because I'm just kind of mind

39:06

blown that we're still in the situation

39:08

where we're still finding out cool new

39:11

stuff from old data and combining it

39:13

with lab results the way that you

39:15

did. Really clever. That's awesome. Yeah. Thank

39:17

you so much. Yeah, it's exciting and

39:19

especially, you know, you know, I did

39:21

not mention that, but the Mars sample

39:24

return. mission hopefully will bring back

39:26

samples and in those samples you

39:28

will have dust because as I

39:30

mentioned dust is everywhere it's sticking

39:33

to every single you know objects

39:35

on the surface of Mars so

39:37

you'll have some contamination of dust

39:39

and if we study you know

39:41

these dust particles we can test this

39:44

hypothesis and really understand

39:46

you know if this fair hydrate is present

39:48

on the Martian surface although I

39:51

believe it is but you know

39:53

we always need to test. test

39:55

our hypothesis, but not only is

39:57

it important for testing the hypothesis.

39:59

But also just by studying the

40:02

chemical composition of this ferhydrate in

40:04

the return samples can tell us

40:07

a lot because you can look

40:09

at stable isotope measurement. So it's

40:11

basically it's a type of analysis

40:14

that looks at isotopic composition of

40:16

ferhydrate and that can tell us

40:19

about water temperature during the formation

40:21

of air hydrate. It can also tell

40:23

us about the source of the water.

40:26

So for example, it could tell us.

40:28

if it's meteoric or marine, so you

40:30

know if it's from precipitation or for

40:32

example if it will be formed in

40:35

oceans. And also it can

40:37

tell us also something about

40:39

habitability because we know that

40:41

on earth microbes interact with

40:43

a plethora of minerals and

40:46

iron oxide, namely ferhydrates for

40:48

example, is known to be

40:50

an important agent for these

40:52

microbial reactions. And you know that

40:54

there are... several different things we

40:56

can test by having the Mars

40:59

sample return happening and looking at

41:01

ferrohydrate present in

41:03

these samples. I cannot stress enough how

41:05

much I want those samples to actually

41:07

reach Earth. Where as an organization

41:09

trying to advocate as hard as

41:11

we can from our sample return,

41:13

it's going to take some time

41:15

and some work, but whether or

41:17

not these samples come home sometime

41:19

in the next 10 years or

41:21

some other time eventually. Eventually humanity

41:23

is going to get their hands

41:26

on something from Mars and we're

41:28

going to be able to figure

41:30

out these questions and I'm so excited.

41:32

I just I wanted to happen yesterday

41:34

instead of 40 years in the

41:36

future. Oh yes, definitely. I mean the

41:38

scientific community is also extremely excited about

41:41

the prospects of having the samples back

41:43

and You know, I hope that maybe

41:45

one day if the samples are brought

41:47

back, maybe you know, one of my

41:50

future students can look into it and,

41:52

you know, test these ideas. I love

41:54

that. And then they can use your

41:56

research and all the other people that

41:59

have come before. buying it all together and

42:01

oh the things we could learn it's going

42:03

to be a beautiful future when we get

42:05

all this back. Definitely I made my

42:07

research is you know based on you

42:09

know all the previous feature research from

42:12

the community so we're standing on on

42:14

the shoulders of giants and I mean

42:16

that's how that's a beauty of science

42:18

you're building and you know the future

42:21

future generations can also provide something very

42:23

interesting. Nice Isaac Newton reference. Thanks for

42:25

joining us Adam I really appreciate it

42:27

and good luck in your future research. Yeah,

42:30

thank you so much for having. I

42:32

enjoy this interview. If you'd like to get

42:34

deeper into this research, I've included

42:36

a link to Adam's full paper

42:38

in nature communications, along with a

42:40

great write-up from the European Space

42:43

Agency on this week's episode page

42:45

at planetary.org/ radio. Of course, Mars

42:47

has been surprising us for decades.

42:49

One of the most memorable early clues

42:52

to its watery past came

42:54

from the Opportunity Rover, which

42:56

discovered... tiny hematite-rich spherules scattered

42:59

across the surface nicknamed Blueberries.

43:02

They told a very different part

43:04

of the story, one shaped by groundwater

43:07

and chemistry. Here's our

43:09

two scientists, Dr. Bruce Betts,

43:12

for what's up. Hey Bruce! Hey there,

43:14

Sarah. I'm back from my big

43:16

whirlwind city adventure in DC

43:18

and also our beautiful gala.

43:21

It was nice to see you there.

43:23

That was actually my double.

43:25

Yeah, man, it wouldn't be

43:27

bad to have a clone,

43:30

just so she could do

43:32

some extra editing, maybe go

43:34

off to Mars, pop back

43:37

and tell me how it was.

43:39

Sarah too. I think. This research

43:41

paper is really interesting in that

43:43

we had a general concept of what was

43:45

going on with Martian dust, but even with

43:47

all of our data, there's still some wiggle

43:49

room in the chemistry there. So I think

43:51

getting those samples back will be honestly very

43:54

helpful. But even so, it's not like

43:56

we didn't understand what was going on

43:58

with Mars. We're just kind of refining.

44:00

understanding of which particular iron oxide.

44:02

So it's cool that we're in that

44:05

place. Hardcore mineralogy. Hardcore.

44:07

I wanted to bring this up with

44:09

you because I think even for me

44:11

one of the big things that

44:13

pointed to the fact that Mars

44:16

had liquid water in the past

44:18

was this discovery that blew up

44:20

in newspapers and on social media

44:23

about these so-called blueberries on Mars

44:25

that Opportunity found. They're not actual

44:27

blueberries. I've even heard little kids

44:29

ask me why there's blueberries on

44:32

Mars thinking that they're legit blueberries.

44:34

So I wanted to bring this

44:36

up and talk a little bit

44:38

about how that relates to hematite

44:41

and this broader discovery of what kind

44:43

of iron is on Mars. So could you tell

44:45

us a little bit about, you know,

44:47

what went down with opportunity and

44:50

why was that discovery so awesome?

44:52

Oh no, I know this. So

44:54

I'm going to back up a

44:56

little bit and take the picture

44:59

out to Spirit as well as

45:01

the Spirit Rover. So Spirit and

45:03

Opportunity were sent at the same

45:05

time and landing sites, obviously two

45:08

landing sites were picked and it

45:10

was interesting because Spirit's landing site

45:12

was based mostly on geomorphology. So

45:14

it was put into a location

45:17

at the end of a

45:19

big hundreds of kilometer long

45:21

valley channel that presumably water

45:24

liquid watered in and that's

45:26

how they picked where they

45:28

went. This is shortening a

45:31

story that took months and

45:33

years of scientists arguing about

45:35

it. But the opportunity site

45:38

was chosen based on spectroscopy

45:40

and perceived mineralogy. So using

45:42

the thermal emission spectrometer on

45:45

Mars Global Surveyor and complementary

45:47

data, they saw one of

45:49

the few places on Mars

45:51

that showed a spectra that

45:53

should have corresponded to coarse-grained

45:55

hematite. coarse-grained hematite being a

45:57

gray mineral that you may

45:59

have seen often made magnetic and

46:02

used in jewelry and things like

46:04

that. Well, it turns out that

46:06

is very exciting for those playing

46:08

the liquid water game, which people

46:10

play because liquid water is needed

46:12

by all life on earth. And

46:14

so finding a place that seemed

46:16

to have course green hematite was

46:18

a party when you're looking for

46:20

water, which might have something to

46:22

with life. So when it landed...

46:25

This was the this was the

46:27

era of airbag landings so you

46:29

inflate airbags around the entire spacecraft

46:32

it and when it lands it

46:34

bounces and they'd bounces and it

46:36

bounces and bounces and bounces bounce

46:39

bounce bounce. It's very tigger-like in

46:41

that respect. And in they referred

46:44

to opportunity as being a hole

46:46

in one because when it bounced

46:48

after bouncing a kilometer or two,

46:51

literally, it ended up in a

46:53

very small impact crater. And so

46:55

one of the first things that

46:57

saw was the miniature cliff side

46:59

of the impact crater that showed

47:02

exposed sedimentary layers and it showed

47:04

blueberries. which I'll get back to,

47:06

but course green hematite all over

47:08

the place. And this was very

47:10

exciting. But really though, the fact

47:12

that they managed to get a kind

47:14

of hole in one after practically bubble

47:16

wrapping a rover and dropping it

47:18

on Mars is kind of spectacular.

47:21

It was. And if you look

47:23

at those initial images, it was

47:25

very confusing, at least for those

47:27

of us not. truly in the

47:29

details of the imagery because it

47:31

looks like you've got like a

47:33

10 meter cliff that you're looking

47:36

at and it turns out it's

47:38

like 10 centimeters. But still showed

47:40

multiple sedimentary layers and there are

47:42

these things all over these these

47:44

little sphere walls so little spheres

47:46

that when you look at them particularly

47:48

in a false color they get they

47:50

look bluish. And in fact they are

47:53

bluer. They aren't really blue but they're

47:55

bluer than all the red stuff all

47:57

around and it turns out the stuff's

47:59

all over. where they landed when

48:01

they went out and they

48:03

drove on the planes. Why

48:05

is it important? Because it's

48:07

associated again with usually almost

48:09

always on Earth with liquid

48:11

water creation and things like

48:13

hydrothermal systems and the like.

48:15

So to get that instant

48:17

confirmation or practically instant. was

48:19

just a wonderful contrast. So

48:21

you take spirit, spirit, it

48:23

was the very end of

48:25

years into the mission work,

48:27

got its most powerful examples

48:29

of things that look like they're forming

48:31

liquid water in terms of seeing them

48:34

on the surface. Again, you've got this

48:36

huge channel flowing in anyway. It was

48:38

it was groovy and as soon as

48:40

they were called blueberries, the name was

48:43

was stuck. But this leads me to

48:45

another question, which is that

48:47

if course grain hematite is

48:49

this bluish color, then why

48:51

would people attribute the red dust

48:54

on Mars to this bluish iron

48:56

oxide? Well, it's more grayish

48:58

in reality and earth, but

49:01

still is a valid question.

49:03

I'll admit that I'm not

49:05

entirely sure, but I think

49:07

it is because there is

49:10

also fine-grained hematite and permutations

49:12

therein, and that tends to

49:14

be reddish. on Earth and is

49:16

also conforming aqueous water environments or

49:19

not as much. It would be

49:21

a different form of how you

49:23

arrange the, how you pile up

49:25

the molecules in a crystalline lattice.

49:28

Every time I learn more about

49:30

spirit and opportunity, I mean, I've heard

49:32

this story so many times, but

49:34

it still completely blows my mind

49:37

that that rover basically mission accomplished itself

49:39

on day one and then went on

49:41

to have. 14 years almost on Mars

49:43

so far beyond what we ever thought

49:46

it was going to be able to do. I don't

49:48

know. I just I'm really looking forward to the

49:50

day that we have these kinds of rovers

49:52

on every single terrestrial world because

49:54

just imagine what we could learn with one

49:56

of these going around on Mercury or even

49:59

the moons out there. That would be

50:01

so cool. Why don't we go

50:03

into our random space

50:05

factor the week? So

50:07

I'm going to talk

50:10

about ancient astronomers and

50:12

their accomplishments. So

50:14

the Mayans, we've got a

50:17

lot of bad rap for

50:19

their calendar and have other

50:21

reasons for bad raps. But

50:24

in terms of science and

50:26

astronomy, They were amazingly spot-on

50:29

for how little they had

50:31

in terms of equipment, essentially

50:33

none. They were able to

50:36

predict eclipses of solar and

50:38

lunar eclipses accurately. They have

50:41

their setups of, for example,

50:43

in Chechnitsa in... The Yucatan

50:45

Peninsula, you have things where

50:48

on the equinox, a shadow

50:50

appears, I don't know if

50:53

you've ever seen the picture

50:55

of the castle El Castillo,

50:57

the pyramid, and the shadow

50:59

appears looking like a feathered

51:01

serpent it was designed for,

51:03

but it's on the equinox

51:05

that it highlights that symbol.

51:07

And they also had an

51:09

observatory aligned to study Venus's

51:11

movements. Now an observatory didn't

51:14

have a telescope in it. that

51:16

we are aware of, but

51:18

was a isolated place that

51:21

is for astronomical observation. There

51:23

you go. Mine astronomers, well-played,

51:26

serves, well-played. Good stuff. I

51:28

mean, that's dedication

51:30

right there. learning enough about space that

51:32

you can track that kind of stuff

51:34

so you can build your buildings in

51:37

such a way that on one particular

51:39

day something happens. I was wowed by

51:41

that when I was a kid in

51:43

my hometown we had a building it

51:45

was an old California mission where the

51:48

sun at its peak when it hit that

51:50

meridian in the sky which shine right through

51:52

a hole in the wall on the winter

51:54

solstice. I mean just for that

51:56

one moment that is a really

51:59

beautiful dedication. And just a statement

52:01

about how deeply these things are

52:03

embedded in different people's cultures. And

52:05

there are, you know, civilizations, various

52:07

places that had this type of

52:10

thing. And of course, one of

52:12

the fundamental things was understanding the

52:14

calendar to understand, assuming you're at

52:16

the age of agriculture, to understand

52:18

when you should be planting crops

52:20

and what the sun's doing and

52:22

things like that. Right. And now people

52:24

can't even see the night sky because

52:26

we have too many lights. We have

52:29

professionals who are now far

52:31

more adept at those things.

52:33

That's fair. Because, you know,

52:35

satellites. So lights in the sky, I

52:38

can't see as well. satellites.

52:40

No, no, well, very

52:42

little atmosphere, depending where you

52:44

are. Now, what is this? I'm

52:47

trying to be the positive one.

52:49

Come on. Don't put me in

52:51

that position. Too late now, Bruce.

52:54

Now you're the positive one. Deal

52:56

with it. Oh, I would like

52:58

to. I think that's a very

53:01

great opportunity

53:03

for me going forward.

53:05

All right, everybody, go

53:08

out there, look up

53:10

the night sky and

53:13

think about the

53:15

most positive thing that

53:17

you have thought of when

53:20

looking up at the

53:22

night sky. Thank you,

53:24

and good night. Anytime

53:26

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53:28

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53:30

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