Skip to playerSkip to main contentSkip to footer
Culture Express
  • yesterday

Category

📺
TV
Transcript
00:00All these rocks, these light-toned rocks that basically stood out against the rest of the environment inside this crater.
00:10Not only that, you could see that these rocks were layered.
00:14And moreover, just that picture, once you had it in close-up,
00:18was enough to suggest that these rocks were not lava flows, they were not volcanic rocks,
00:23which are characteristic of most of Mars and most of the other planets.
00:30Embedded in these layered rocks are little, sort of, roundish objects, like raisins in a muffin.
00:40These historic images of the Martian crust have now confirmed that water once existed on Mars.
00:47But they also point to a need for further exploration of the planet.
00:51Scientists studying Mars are now beginning to clamor for missions which would collect rock samples
00:57and bring them back to Earth to be studied more extensively in a controlled laboratory environment.
01:03We need to distinguish, you know, wishful thinking from reality.
01:09The importance is to know whether there was life on Mars.
01:12And that means whether or not we're alone in the solar system as a biology that developed on a planet.
01:22If no biology developed anywhere else in the solar system,
01:26then the big picture is that we're a rare thing.
01:31On the other hand, if it's the other way around,
01:34if there was life on Mars,
01:36then life on Earth is not some miracle.
01:40It's a statistical probability.
01:43If we look at planets elsewhere in the galaxy or in the universe,
01:48around other stars,
01:50then the prospect of there being life on those planets
01:52would, I think, be improved greatly
01:55if we knew that life had evolved and originated on Mars as well.
02:00Ultimately, the only way to know whether life exists on Mars
02:06or whether humans could live there
02:09is for humans to travel there and meet it.
02:16Fundamentally, the biggest challenge to getting humans to Mars is money
02:20because the technology is here.
02:23We can do it.
02:24Now, we went to the moon a long time ago,
02:28over 30 years ago, 34 years ago,
02:31and it's almost hard to imagine that it's been that long ago,
02:34but we did it.
02:35We can go to Mars, too.
02:37There are some issues that need to be worked out,
02:39but we know how to get there.
02:41We know what we need to build to get there.
02:43It can be done.
02:44What happens is that it costs a huge amount of money.
02:48It may cost $75 billion to $100 billion.
02:55It's primarily an issue of the human will,
02:59the political will,
03:00and the money being made available to do it.
03:03The key to spaceflight is cutting the weight of the rocket and spacecraft.
03:12Former astronaut John Connolly worked on the design of the Mars rover
03:16and the rocket that delivered the spacecraft into Mars orbit.
03:19In our business, mass equals cost.
03:22Every kilogram of mass we fly to Mars right now costs us approximately $1 million.
03:29If you can reduce the mass, you reduce the amount of fuel you have to push it,
03:33you reduce the size of the launch vehicle you need to lift it,
03:37and the cost of the whole mission comes down.
03:39So anytime you can reduce mass, you usually also reduce cost.
03:43The heaviest part of a spacecraft is its fuel.
03:49At liftoff, 90% of the shuttle's mass is fuel,
03:53stored in the orange silo-like object in the center of the shuttle.
04:01For any real cost-cutting,
04:03the amount of fuel the spacecraft carries must be reduced,
04:07seemingly a contradiction since without fuel,
04:10the spacecraft can't fly to Mars and back.
04:13So Dr. K.R. Sidra of the University of Arizona
04:18wants any manned Mars spaceflights
04:20to only carry enough fuel to reach Mars.
04:24And heater power is constantly monitored.
04:27Right.
04:28Once there, the astronauts would manufacture their own fuel to get back to Earth.
04:32When you can produce almost all the consumables that you need
04:36for Mars exploration,
04:38using materials that's locally available on Mars,
04:42with very little material that you carry from Earth,
04:45you suddenly open up the frontiers of exploration.
04:48Now you're able to breathe the air that you produce on Mars,
04:52you're able to drink the water that you produce on Mars,
04:55you're able to grow food out there,
04:57and for all your fuel needs, for all your electricity, heat needs,
05:02you're getting the local resources from Mars.
05:06The key is the high levels of carbon dioxide in the Martian atmosphere.
05:12Electricity generated by photovoltaic cells would act as a catalyst
05:16to combine the carbon dioxide with hydrogen extracted from water vapors on Mars.
05:24The result is methane gas.
05:28Light the flame on the Sabati area. Fantastic.
05:31The methane gas would be used as the propellant driving the spacecraft back to Earth.
05:38Whenever the explorers used what is available to them locally
05:43and lived off the land and conducted exploration that way, they succeeded.
05:48Mars is a new frontier,
05:49and we need to learn the lessons from history,
05:52and when we go to Mars,
05:54if we learn how to use the resources that are available there,
05:58we will succeed in our exploration of Mars.
06:02A more controversial and potentially dangerous approach
06:05would be to use an alternative energy source, such as nuclear power.
06:09If you have a more energetic propulsion means, like nuclear propulsion,
06:14then you can get to Mars in maybe 90 days,
06:17which is about half the time,
06:19and you can spend maybe 30 to 60 days on Mars,
06:23and then come back in about 90 days,
06:25so it really shortens the whole trip.
06:36It is unknown if nations and governments around the world
06:39will commit to spending the billions of dollars necessary
06:42to land humans on Mars.
06:47What you would say is thebrosia of Mars
06:48is a more energy source.
06:49They have three units of Mars,
06:50and therefore they have three units of Mars.
06:51Now, if they buy the Moon,
06:52it is more energy source.
06:53Let's get to ask your car in the US.
06:54What a really deep feeling is that
06:56of course the navigation is a co-op of Mars.
06:57The plane is the main event
06:58of Mars,
06:58and the Mars is the main event
06:59of Mars.
07:00One of those things that...
07:01it will be to theifi.
07:02The web is a great place to be aian.
07:06But if they do,
07:08the first astronauts on Mars
07:15up to Mars...
07:16Most astronauts on Mars will be faced with a blisteringly cold landscape, a seemingly
07:21never-ending expanse of barren rock and dry, reddish soil.
07:27Without their spacesuits, they would instantly perish in an environment devoid of oxygen,
07:32of vegetation, or protection against the howling dust storms that often fill the Martian sky
07:38for months at a time.
07:41Given this, the possibility of colonizing Mars for human habitation seems ludicrous.
07:47But the lure of the heavens and the adventure of exploring the stars has long been an almost
07:52irresistible motivation for many of Earth's inhabitants.
07:57And some dreamers want to go beyond space travel and advocate preparing Mars for human migration.
08:08Dr. Christopher McKay leads a team of scientists at NASA who examine the pros and cons of colonizing
08:14Mars.
08:15McKay is firmly in the wet and warm Mars camp, a true believer that Mars holds great potential
08:22for human exploration and exploitation.
08:24We have a lot of good evidence that early in its history, Mars had water, must have had
08:30a thicker atmosphere, had more active volcanism, was very much more like the Earth.
08:35In fact, three and a half, four billion years ago, we think Earth and Mars would have had
08:40all the same major ecological environments on both planets.
08:44If this theory is true, something must have happened over time.
08:49While Earth bloomed, Mars lost its magnetic field.
08:54The warm, wet atmosphere and the oceans that some believe once covered much of the Martian surface
09:00disappeared.
09:02The planet dried up and froze.
09:05Now McKay believes the very same noxious carbon dioxide emissions that threaten Earth with global
09:11warming could be used to thaw out Mars.
09:14The gases that we put into the atmosphere on Earth, which are pollution on Earth, would
09:19be medicine on Mars and it would make the planet warm again.
09:23The process is called terraforming, and the reality of whether or not terraforming will work
09:33is hotly debated.
09:36Terraforming research has focused on chlorofluorocarbons, largely blamed for creating holes in the Earth's
09:42ozone layer and contributing to global warming.
09:46These airborne chemicals are 10,000 times more powerful than carbon dioxide.
10:09McKay maintains that by releasing chlorofluorocarbons into the thin Martian atmosphere at a rate equal
10:15to Earth, the temperature on Mars could be pushed up 20 degrees Celsius, 68 degrees Fahrenheit.
10:22This warming effect would then encourage the planet to thaw out more on its own.
10:27The Martian south pole has a coating of dry ice, frozen carbon dioxide, covering frozen
10:34water.
10:35As the dry ice melts, carbon dioxide could be released into the atmosphere and
11:04further accelerate the warming process.
11:09McKay predicts this Martian warming would happen relatively quickly.
11:24And we could probably do this push from A to B in about 50 years, and then very quickly,
11:31in a few decades, it would go the rest of the way to the warm, thick atmosphere.
11:35As the planet warms, the hope is that there is ice frozen below the surface that will melt,
11:45furthering the terraforming process.
11:46We know there is water on Mars.
11:47We see it in the atmosphere, we see clouds, we see water vapor.
11:52We also see polar caps, which are very significant.
11:56The trouble is that we also expect to see a lot of water below the surface.
12:00Deep below, we don't have any information, and that ice may or may not be there, but certainly
12:05the models show that the near surface region of the planet is the coldest and has the greatest
12:09probability of being where the ice might be.
12:16On Earth, ice locked under the surface is called permafrost.
12:20But now, as a result of global warming, Earth's layer of permafrost is starting to melt, turning
12:26frozen tundra into swampland.
12:31On Mars, the ability to melt the permafrost will be essential to the terraforming process.
12:36It is hoped that as Martian permafrost begins to thaw, liquid water would make its way to
12:42the Martian surface.
12:47This abandoned subterranean military storage depot in Alaska shows what the Martian underground
12:52could look like.
12:54It was built right into the permafrost to hide tanks and other large weapons.
13:01Large lumps of ice cling to the walls.
13:11What is not known is how much ice exists beneath the Martian surface.
13:21Surface photos reveal large jagged lines called polygons.
13:28Earth's permafrost regions also are scarred by polygon cracks.
13:42Kenji Yoshikawa of the University of Alaska realized the polygons running through the permafrost
13:48in Point Barrow, Alaska, are roughly the same size as the polygons found on Mars.
14:02This is exactly like the Martian landscape.
14:04Well, of course, I've never been to Mars myself, but the images of Mars are strikingly similar
14:09to the view from here.
14:11At least, I can stand on these features.
14:13The distance between each polygon in Alaska is about 100 meters, about the same as on Mars.
14:21By studying the physical features of the permafrost and the polygons here, Dr. Yoshikawa thinks
14:28he can estimate the amount of ice beneath the Martian surface.
14:32Using a mobile radar device, he surveys the ground beneath the polygon structures.
14:38From the surface, polygons look like depressions in the Earth.
14:43But on radar, the ice, as seen in white, is significant.
14:49Starting one meter below the surface, an artery of ice runs 10 meters thick.
14:55The ice layers within the polygons are formed when the permafrost contracts during temperature
15:00changes.
15:02As temperature drops, the permafrost contracts and cracks appear.
15:24Measuring the Alaskan polygons, Dr. Yoshikawa realized that cracks of the same size held equal
15:31amounts of ice.
15:33Because the distances between polygons indicate how large the polygons will be, he also believes
15:40that Mars has polygons just as large as these in Alaska.
15:50This is a pretty big ice, sticking to rocks on both sides.
15:55When you go to Mars, I think you can find a similar structure from about 10 meters from
16:00the surface all the way down.
16:03So even though the surface looks like a desert with fine-grained sand, once you get down
16:07to a 10 meter depth, you will find these huge frozen structures.
16:11That means there's an enormous amount of ice in the Martian permafrost.
16:17If Martian astronauts are able to accelerate plant growth and raise the temperature of the Martian
16:30atmosphere with greenhouse gases, the theory is that buried ice will melt and seep up from
16:37the ground.
16:57As this water returns to the surface of Mars, some of it would vaporize and create clouds
17:02in the sky.
17:09Water vapor is actually a greenhouse gas more powerful than carbon dioxide, again possibly
17:15working to raise the planet's temperature.
17:18From these virgin clouds, rain would fall.
17:22And the hope is that soon enough, the reddish dust that has enveloped Mars for eons would
17:27be washed away.
17:29Earth-like blue skies would hopefully appear.
17:46Martian rivers and oceans could return.
17:51If the theory of terraforming became reality, the red planet of Mars would gradually turn blue
17:57and an Earth-like planet could be reborn.
18:00The amount of time it would take to go from beginning warming the planet to when there was
18:06life on the planet and maybe even trees could be very short.
18:09It could be between 50 and 100 years because it's just a problem of warming up a planet.
18:15Not everybody agrees.
18:17I'm sorry, I beg to differ.
18:19I respect these people very much.
18:21They're wonderful scientists and so on, but I think that the whole issue of terraforming
18:29Mars is pie in the sky for a long time to come.
18:34It's technically very difficult to do.
18:37It would take huge resources to put into effect and it would take a very, very long time to
18:42actually happen, to make the changes, to try to make Mars more livable.
18:47The other thing is that we don't know what will really happen.
18:52When you start some kind of a global change like that, there are always unintended consequences.
18:58My own opinion, and it's not everybody's opinion, is that it's probably not possible.
19:03And I say that for a couple of reasons.
19:05The first reason is that on Earth, we have a natural system which helps regulate the climate.
19:12And that involves things that are unique to the Earth.
19:15The geological nature of the Earth helps regulate the climate.
19:18It helps recycle gases back into the atmosphere.
19:23Now Mars doesn't have that.
19:25So in other words, you'd have to do that using human engineering.
19:29You'd have to simulate effectively what nature does for you on Earth.
19:35And I just think that as a project, that that just stretches me a bit too far.
19:41In my view, it would take, you know, tens of thousands of years even to get to the stage
19:46where you've warmed up Mars.
19:48McKay concedes that dealing with the lack of an atmosphere on Mars is the tricky part.
19:53The big difference, though, between that planet and Earth is that planet will not have oxygen.
19:58It will just have a thick CO2 atmosphere, carbon dioxide.
20:02And that carbon dioxide would be good for plants and microorganisms.
20:07But human beings would need a source of oxygen, like a mask, as they walked around on the surface.
20:12The atmosphere of Earth is about 20% oxygen.
20:14The atmosphere of Earth is about 20% oxygen.
20:19Oceans produce nearly one-third of that totem.
20:22The atmosphere of Earth is about 20% oxygen.
20:37Oceans produce nearly one-third of that total.
20:42The biological machinery making this oxygen is phytoplankton living in shallow ocean waters.
20:48These microscopic creatures photosynthesize much like plants do, absorbing carbon dioxide and expelling oxygen as a byproduct.
20:56Researchers at the Marine Biotechnology Institute in Japan are attempting to grow a species of phytoplankton that carry an enhanced ability to convert carbon dioxide into oxygen.
21:15Introducing this superproductive phytoplankton in Earth's seas might reverse the high levels of carbon dioxide associated with global warming.
21:34At this lab, the researchers are culturing a type of creature called cyanobacteria.
21:40These photosynthesizers have released oxygen into the Earth's atmosphere for nearly 3 billion years, long before plants ever grew on land.
21:50When Earth was still a young planet, the atmosphere was almost entirely made of carbon dioxide.
21:57But over eons, these microscopic creatures have slowly created levels of oxygen that most higher life forms require to survive.
22:07Results indicate that cyanobacteria can make oxygen nearly 10 times faster than ordinary land plants.
22:14So, after the Martian atmosphere is warmed with high concentrations of carbon dioxide, humans could stockpile the new Martian oceans with creatures like these.
22:21With time, Martian cyanobacteria could make oxygen that future generations of humans on Mars could breathe.
22:28So, after the Martian atmosphere is warmed with high concentrations of carbon dioxide, humans could stockpile the new Martian oceans with creatures like these.
22:42With time, Martian cyanobacteria could make oxygen that future generations of humans on Mars could breathe.
22:57But oxygen producing oceans would not be sufficient.
23:02On Earth, the majority of oxygen supply is formed by trees and plants.
23:07Tropical rainforests in the equatorial regions are often called the lungs of the Earth because they produce the greatest amount of oxygen humans breathe.
23:16So, Dr. McKay is scheming on how to grow forests on Mars in the shortest time possible.
23:32McKay has targeted Mars' equatorial regions where the climate could be very similar to the climate found in the mountain ranges of eastern Mexico.
23:43Towering high into the sky in the state of Veracruz is Mexico's tallest volcano, Pico de Orizaba.
23:50Its peak tops out at 5,700 meters, nearly 19,000 feet.
23:57At 4,100 meters, 13,000 feet, the mountain's year-round temperature hovers at 5 degrees Celsius, 41 degrees Fahrenheit.
24:08This is the temperature McKay expects a terraformed Mars would reach.
24:13Very old as the ones in the middle of the forest.
24:16So we would like to see how old are these and compare them with the ones below.
24:21What do you think about that?
24:22But McKay and Dr. Rafael Navarro of Mexico's Autonomous University have discovered another problem that will impinge on Mars' ability to grow trees.
24:31At 4,100 meters, where we are standing right now, is where we get the highest tree lines in the world.
24:41Below there we have a huge amount of trees, but above here we have very few trees, and even a little higher there are no trees.
24:50All these growth trees are related by the activity of bugs that are growing in the soil.
24:58What they do is that they convert the atmospheric nitrogen into a fixed form of nitrogen, specifically ammonia.
25:05And this ammonia can be absorbed by the roots of the trees, and then once they get it into their system,
25:12they can utilize it to make amino acids, purines, pyrimidines.
25:17These are building blocks to make DNA and also enzymes.
25:22Navarro's research compares soil samples taken from above the tree line with samples taken at a lower elevation.
25:37On the right is dissolved soil from above the tree line.
25:40Its faint color means low levels of ammonia, not enough for trees to thrive.
25:46Navarro believes ammonia-producing microbes in the soil are not active enough at this altitude.
25:52The culprit, the temperature.
25:55The drop in temperature at the tree line slows the microbes, inhibiting them from creating ammonia at a normal rate in the soil.
26:03We need to wait until the soil has some nutrients that will be provided by tiny bacteria,
26:14and then the trees will be able to use this nitrogen to grow.
26:18But Mars' atmosphere contains little nitrogen, so the microbes will have a difficult time producing ammonia
26:24unless considerable terraforming has already occurred and the atmosphere of Mars thickens to Earth-like conditions.
26:32Navarro acknowledges growing plants and trees will take time, moving in incremental steps.
26:38We need an interdependence and we need to begin from the lower level of the evolutionary tree.
26:44So the first step in this terraforming is these tiny microbes.
26:49They will play two significant roles.
26:51One is they will convert the atmosphere of Mars into oxygenic.
26:57And the second part is that they will fix nitrogen from the atmosphere into the soil for larger plants like grasses and moss to grow.
27:09And eventually, once the regolith has significant content of organic matter,
27:14then trees will be able to grow under this condition.
27:18So we need to go into steps.
27:20We cannot plant the trees immediately.
27:23Building a true functioning atmosphere on Mars will require developing a complex ecosystem rivaling the Earth's tropical rainforests in diversity.
27:33Once built, this Martian biosphere, created through human effort, would require sensitive biomanagement,
27:41something humans have been less than competent at here on Earth.
27:45And there are still huge doubts that without an Earth-like gravitational pull,
27:50Mars will not be able to sustain a working atmosphere.
27:54All the lighter elements and gases from the Martian atmosphere,
27:58most of them have basically gone off into space.
28:01Faster-moving molecules, which are lighter, like oxygen and nitrogen and water vapor,
28:08they tend to escape into space.
28:11So the question is, will we be able to hang on to the atmosphere?
28:15I think terraforming is an interesting concept, but as far as being practical,
28:21not any time in the near future, not any time even in the next couple of centuries.
28:27It's in the nature of life that when it moves into a new environment,
28:31that it changes that environment, but also the life then evolves,
28:35and then it becomes a co-evolution of environment and life.
28:39And I think this will happen on Mars as well.
28:42If we initially change the environment so that life from Earth can survive there,
28:46then what will happen over time is the environment will change,
28:49the life will change, and together they will go down a separate evolutionary track
28:54that will be different from the Earth.
28:56So we will really have two biospheres evolving in two different ways.
29:00It is impossible for humans to re-engineer the difference in gravity between Earth and Mars.
29:25The effects of low gravity on humans would be significant.
29:28Lower gravity creates a new form of human locomotion,
29:32as the Apollo astronauts found on the Moon.
29:35Hey, John, this is perfect with the limb and the rover and you and Stone Mountain and the old flag.
29:54Come on out here and give me a salute.
29:57Big Navy salute.
29:58Big Navy salute.
29:59Off the ground.
30:00Dr. John Charles is NASA's point man for studying human evolution in space.
30:14When you go onto the Moon, the gravity is different,
30:17and it turns out it's probably easier, instead of walking like we do,
30:21to actually sort of skip along and use both feet.
30:24You'll see the same kind of behavior, the same kind of two-foot behavior when a large animal,
30:27like a horse, runs or a dog runs.
30:29That's a typical, it's a very efficient way of moving given the gravity field that they're in.
30:34So we probably see that kind of movement on Mars as well.
30:41The longer humans spend on Mars, the more their bodies will probably change in shape and function.
30:47The effects of a long period of time on the surface of Mars or on the Moon are still questions to be answered.
30:57Essentially, we can assume that the changes in the human body will be either someplace in between the effects of normal gravity and weightlessness,
31:07or that they will actually mimic weightlessness in some regard.
31:14The Soviet studies on Mir documented how human muscles grow weaker and bones lose density and strength during extended periods of weightlessness.
31:24Now there is evidence that low gravity environments can damage the human heart.
31:29Well, our bed rest experiment is specifically designed to look at what happens to the heart itself in bed rest.
31:38Dr. Benjamin Levine heads up an experiment at Presbyterian Hospital in Dallas,
31:43where healthy volunteers spend days lying in bed doing nothing.
31:47In a vertical state, blood tends to pool in the lower extremities, forcing the heart to work harder to keep blood circulating.
31:56But lying down horizontally means the heart is less stressed.
32:01Lying down simulates a nearly weightless condition because gravity pulls at each part of the body equally.
32:07As the heart adapts to being in bed is that it gets smaller.
32:11It gets smaller and less distensible.
32:14That means when you try to fill it, it doesn't fill as much.
32:18After 18 days, the physical changes in the heart muscle are significant.
32:25On the left is a cross section of the heart before the experiment.
32:29To the right is the thinner, smaller heart after bed rest.
32:35The muscle itself is 5% lighter.
32:39In another bed rest test lasting 3 months, the heart dropped 16% of its muscle weight.
32:49So the more time a human spends on Mars, it is likely the more physical changes could occur.
32:56The next question is, that's only one generation.
32:59What about 10 generations or 20 generations or 100 generations?
33:04Well, that's evolution.
33:07That's relevant not for us, for you and I traveling to Mars, but for our children's children's children.
33:14And maybe they will develop new kinds of skills or new capabilities that we can't even imagine.
33:22And nobody will know that until we get there.
33:30Other evolutionary changes might occur as well.
33:34Scientists speculate that brain size could increase, our dietary patterns could alter, and sleeping habits could modify.
33:42Over time, maybe it will be more accurate to identify Martian humans as a different species than Earth humans.
33:52I think that the view of Earth from Mars, the view of the blue dot, the original blue dot,
33:58will be sort of like the view of a child looking at their parent.
34:03Always have love and respect, but realize that they must go their own way.
34:07So life on Mars must go its own way, and then maybe have to separate eventually from Earth in an evolutionary sense.
34:16And maybe that will be the first generation of many generations of life that leave and go beyond the Earth.
34:24And I think the fundamental question that I'm interested in is, what is the role for life?
34:30What is the future of life?
34:32And I see Mars as the first testing ground of the possibility that life has a future in space.
34:43Science has now established the case for life having begun in outer space.
34:49New discoveries inch us closer to determining whether life exists outside of our Earth.
34:55These discoveries only serve to renew human desire to travel into the unknown realms of the universe.
35:07And humans have developed the knowledge and the technology to take the next steps in a journey through the solar system.
35:16But at what cost?
35:21Earthlings have become more blasé, less enamored with the excitement and challenges space travel presents.
35:29Priorities have changed.
35:31With the misery of poverty and hunger and environmental ruin facing the Earth.
35:37Many question the wisdom of spending billions of dollars voyaging into the dark void of the sky, creating new planets for human habitation.
35:50Humans will soon need to decide how important it is to uncover the mystery of whether there is life beyond Earth.
35:59For more information on Exploring Space, The Quest for Life, visit pbs.org.
36:12Exploring Space, The Quest for Life is available on videocassette or DVD.
36:19To order, call PBS Home Video at 1-800-PLAY-PBS.
36:28Exploring Space Voz
36:30The Quest for Life Legends
36:38As a matter of Battlefield,たい-PBS are nominated you by a few знать minnis valueénerists,
36:43We hope can be able to speculate about the fact that people can score that the Sadly Tenoch Carnival is unasas.
36:48Definitely trust me to not be able to commit the тайrone for úpres to the future.
36:50So my second question, please assess the Frederick among our creators and astray.
36:53Please respect the opportunity to be clear online and aware that people can also get sealed!
36:56Exploring Space, The Quest for Life, is made possible by a grant from the estate of Sperry
37:19H. Goodman.
37:26And by contributions to your PBS station from viewers like you.