[Script Info]
Title: 
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:06.33,0:00:07.48,Default,,0000,0000,0000,,We've all seen movies
Dialogue: 0,0:00:07.48,0:00:09.73,Default,,0000,0000,0000,,about terrible insects from outer space
Dialogue: 0,0:00:09.73,0:00:12.29,Default,,0000,0000,0000,,or stories of abduction by little green men,
Dialogue: 0,0:00:12.29,0:00:14.32,Default,,0000,0000,0000,,but the study of life in the universe,
Dialogue: 0,0:00:14.32,0:00:16.100,Default,,0000,0000,0000,,including the possibility of extraterrestrial life,
Dialogue: 0,0:00:16.100,0:00:20.09,Default,,0000,0000,0000,,is also a serious, scientific pursuit.
Dialogue: 0,0:00:20.09,0:00:23.27,Default,,0000,0000,0000,,Astrobiology draws on diverse fields,
Dialogue: 0,0:00:23.27,0:00:24.16,Default,,0000,0000,0000,,such as physics,
Dialogue: 0,0:00:24.16,0:00:25.18,Default,,0000,0000,0000,,biology,
Dialogue: 0,0:00:25.18,0:00:26.17,Default,,0000,0000,0000,,astronomy,
Dialogue: 0,0:00:26.17,0:00:27.18,Default,,0000,0000,0000,,and geology,
Dialogue: 0,0:00:27.18,0:00:29.35,Default,,0000,0000,0000,,to study how life was formed on Earth,
Dialogue: 0,0:00:29.35,0:00:31.01,Default,,0000,0000,0000,,how it could form elsewhere,
Dialogue: 0,0:00:31.01,0:00:32.90,Default,,0000,0000,0000,,and how we might detect it.
Dialogue: 0,0:00:33.50,0:00:35.19,Default,,0000,0000,0000,,Many ancient religions described
Dialogue: 0,0:00:35.19,0:00:38.10,Default,,0000,0000,0000,,other worlds inhabited by known human beings,
Dialogue: 0,0:00:38.10,0:00:40.07,Default,,0000,0000,0000,,but these are more like mythical realms
Dialogue: 0,0:00:40.07,0:00:41.52,Default,,0000,0000,0000,,or parallel universes
Dialogue: 0,0:00:41.52,0:00:42.81,Default,,0000,0000,0000,,than other planets existing
Dialogue: 0,0:00:42.81,0:00:44.61,Default,,0000,0000,0000,,in the same physical world.
Dialogue: 0,0:00:44.61,0:00:46.43,Default,,0000,0000,0000,,It is only within the last century
Dialogue: 0,0:00:46.43,0:00:47.60,Default,,0000,0000,0000,,that scientists have been able
Dialogue: 0,0:00:47.60,0:00:49.18,Default,,0000,0000,0000,,to seriously undertake the search
Dialogue: 0,0:00:49.18,0:00:51.38,Default,,0000,0000,0000,,for extraterrestrial life.
Dialogue: 0,0:00:51.38,0:00:53.30,Default,,0000,0000,0000,,We know that at the most basic level
Dialogue: 0,0:00:53.30,0:00:55.45,Default,,0000,0000,0000,,organisms on Earth need three things:
Dialogue: 0,0:00:55.45,0:00:56.34,Default,,0000,0000,0000,,liquid water,
Dialogue: 0,0:00:56.34,0:00:57.55,Default,,0000,0000,0000,,a source of energy,
Dialogue: 0,0:00:57.55,0:01:00.00,Default,,0000,0000,0000,,and organic, carbon-based material.
Dialogue: 0,0:01:00.00,0:01:01.38,Default,,0000,0000,0000,,We also know that the Earth
Dialogue: 0,0:01:01.38,0:01:03.34,Default,,0000,0000,0000,,is just the right distance from the Sun,
Dialogue: 0,0:01:03.34,0:01:06.26,Default,,0000,0000,0000,,so as not to be either frozen or molten.
Dialogue: 0,0:01:06.26,0:01:08.39,Default,,0000,0000,0000,,So, planets within such a habitable range
Dialogue: 0,0:01:08.39,0:01:09.64,Default,,0000,0000,0000,,from their own stars
Dialogue: 0,0:01:09.64,0:01:11.88,Default,,0000,0000,0000,,may be able to support life.
Dialogue: 0,0:01:13.19,0:01:14.35,Default,,0000,0000,0000,,But while we used to think
Dialogue: 0,0:01:14.35,0:01:15.52,Default,,0000,0000,0000,,that life could only exist
Dialogue: 0,0:01:15.52,0:01:17.40,Default,,0000,0000,0000,,in such Earth-like environments,
Dialogue: 0,0:01:17.40,0:01:20.12,Default,,0000,0000,0000,,one of the most amazing discoveries of astrobiology
Dialogue: 0,0:01:20.12,0:01:22.53,Default,,0000,0000,0000,,has been just how versatile life is.
Dialogue: 0,0:01:22.53,0:01:24.43,Default,,0000,0000,0000,,We now know that life can thrive
Dialogue: 0,0:01:24.43,0:01:26.25,Default,,0000,0000,0000,,in some of the most extreme environments
Dialogue: 0,0:01:26.25,0:01:28.61,Default,,0000,0000,0000,,that'd be fatal for most known organisms.
Dialogue: 0,0:01:28.61,0:01:30.42,Default,,0000,0000,0000,,Life is found everywhere,
Dialogue: 0,0:01:30.42,0:01:32.55,Default,,0000,0000,0000,,from black smoke of hydrothermal vents
Dialogue: 0,0:01:32.55,0:01:34.60,Default,,0000,0000,0000,,in the dark depths of Earth's oceans,
Dialogue: 0,0:01:34.60,0:01:36.60,Default,,0000,0000,0000,,to bubbling, hot, acidic springs
Dialogue: 0,0:01:36.60,0:01:38.27,Default,,0000,0000,0000,,on the flanks of volcanoes,
Dialogue: 0,0:01:38.27,0:01:40.65,Default,,0000,0000,0000,,to high up in the atmosphere.
Dialogue: 0,0:01:40.65,0:01:43.13,Default,,0000,0000,0000,,Organisms that live in these challenging environments
Dialogue: 0,0:01:43.13,0:01:45.18,Default,,0000,0000,0000,,are called extremophiles,
Dialogue: 0,0:01:45.18,0:01:46.79,Default,,0000,0000,0000,,and they can survive at extremes
Dialogue: 0,0:01:46.79,0:01:47.64,Default,,0000,0000,0000,,of temperature,
Dialogue: 0,0:01:47.64,0:01:48.44,Default,,0000,0000,0000,,pressure,
Dialogue: 0,0:01:48.44,0:01:49.43,Default,,0000,0000,0000,,and radiation,
Dialogue: 0,0:01:49.43,0:01:50.47,Default,,0000,0000,0000,,as well as salinity,
Dialogue: 0,0:01:50.47,0:01:51.39,Default,,0000,0000,0000,,acidity,
Dialogue: 0,0:01:51.39,0:01:53.63,Default,,0000,0000,0000,,and limited availability of sunlight,
Dialogue: 0,0:01:53.63,0:01:54.50,Default,,0000,0000,0000,,water,
Dialogue: 0,0:01:54.50,0:01:55.88,Default,,0000,0000,0000,,or oxygen.
Dialogue: 0,0:01:56.99,0:01:59.34,Default,,0000,0000,0000,,What is most remarkable about these extremophiles
Dialogue: 0,0:01:59.34,0:02:01.40,Default,,0000,0000,0000,,is that they are found thriving in environments
Dialogue: 0,0:02:01.40,0:02:03.70,Default,,0000,0000,0000,,that mimic those on alien worlds.
Dialogue: 0,0:02:03.70,0:02:05.91,Default,,0000,0000,0000,,One of the most important of these worlds
Dialogue: 0,0:02:05.91,0:02:08.68,Default,,0000,0000,0000,,is our red and dusty neighbor, Mars.
Dialogue: 0,0:02:08.68,0:02:11.74,Default,,0000,0000,0000,,Today, astrobiologists are exploring places
Dialogue: 0,0:02:11.74,0:02:14.23,Default,,0000,0000,0000,,where life might once have existed on Mars
Dialogue: 0,0:02:14.23,0:02:16.53,Default,,0000,0000,0000,,using NASA's Curiosity rover.
Dialogue: 0,0:02:16.53,0:02:18.33,Default,,0000,0000,0000,,One of these is Gale Crater,
Dialogue: 0,0:02:18.33,0:02:20.06,Default,,0000,0000,0000,,an impact crater created
Dialogue: 0,0:02:20.06,0:02:21.59,Default,,0000,0000,0000,,when a meteor hit the surface of Mars
Dialogue: 0,0:02:21.59,0:02:24.27,Default,,0000,0000,0000,,nearly 3.8 billions years ago.
Dialogue: 0,0:02:24.27,0:02:27.67,Default,,0000,0000,0000,,Evidence from orbit suggest past traces of water,
Dialogue: 0,0:02:27.67,0:02:28.76,Default,,0000,0000,0000,,which means the crater
Dialogue: 0,0:02:28.76,0:02:31.18,Default,,0000,0000,0000,,might once have supported life.
Dialogue: 0,0:02:31.18,0:02:32.84,Default,,0000,0000,0000,,Planets are not the only places
Dialogue: 0,0:02:32.84,0:02:34.93,Default,,0000,0000,0000,,astrobiologists are looking at.
Dialogue: 0,0:02:34.93,0:02:37.52,Default,,0000,0000,0000,,For example, Europa, one of the moons of Jupiter,
Dialogue: 0,0:02:37.52,0:02:39.20,Default,,0000,0000,0000,,and Enceladus and Titan,
Dialogue: 0,0:02:39.20,0:02:40.35,Default,,0000,0000,0000,,two of Saturn's moons,
Dialogue: 0,0:02:40.35,0:02:42.60,Default,,0000,0000,0000,,are all exciting possibilities.
Dialogue: 0,0:02:42.60,0:02:45.02,Default,,0000,0000,0000,,Although these moons are extremely cold
Dialogue: 0,0:02:45.02,0:02:46.85,Default,,0000,0000,0000,,and two are covered in thick ice,
Dialogue: 0,0:02:46.85,0:02:50.03,Default,,0000,0000,0000,,there is evidence of liquid oceans beneath the shell.
Dialogue: 0,0:02:50.03,0:02:52.95,Default,,0000,0000,0000,,Could life be floating around in these oceans,
Dialogue: 0,0:02:52.95,0:02:54.88,Default,,0000,0000,0000,,or could it be living around black smoker
Dialogue: 0,0:02:54.88,0:02:56.84,Default,,0000,0000,0000,,vents at the bottom?
Dialogue: 0,0:02:57.50,0:02:59.32,Default,,0000,0000,0000,,Titan is particularly promising
Dialogue: 0,0:02:59.32,0:03:00.46,Default,,0000,0000,0000,,as it has an atmosphere
Dialogue: 0,0:03:00.46,0:03:02.74,Default,,0000,0000,0000,,and Earth-like lakes, seas, and rivers
Dialogue: 0,0:03:02.74,0:03:04.50,Default,,0000,0000,0000,,flowing across the surface.
Dialogue: 0,0:03:04.50,0:03:05.93,Default,,0000,0000,0000,,It is very cold, however,
Dialogue: 0,0:03:05.93,0:03:07.54,Default,,0000,0000,0000,,too cold for liquid water,
Dialogue: 0,0:03:07.54,0:03:09.38,Default,,0000,0000,0000,,so these rivers may instead be flowing
Dialogue: 0,0:03:09.38,0:03:10.66,Default,,0000,0000,0000,,with liquid hydrocarbons
Dialogue: 0,0:03:10.66,0:03:12.95,Default,,0000,0000,0000,,such as methane and ethane.
Dialogue: 0,0:03:12.95,0:03:14.92,Default,,0000,0000,0000,,These are composed of hydrogen,
Dialogue: 0,0:03:14.92,0:03:16.94,Default,,0000,0000,0000,,and, more importantly, carbon,
Dialogue: 0,0:03:16.94,0:03:18.48,Default,,0000,0000,0000,,which is the basic building block
Dialogue: 0,0:03:18.48,0:03:20.26,Default,,0000,0000,0000,,of all life as we know it.
Dialogue: 0,0:03:20.26,0:03:22.97,Default,,0000,0000,0000,,So, could life be found in these lakes?
Dialogue: 0,0:03:22.97,0:03:24.84,Default,,0000,0000,0000,,Although instruments are being designed
Dialogue: 0,0:03:24.84,0:03:26.51,Default,,0000,0000,0000,,to study these distant worlds,
Dialogue: 0,0:03:26.51,0:03:28.35,Default,,0000,0000,0000,,it takes many years to build them
Dialogue: 0,0:03:28.35,0:03:29.54,Default,,0000,0000,0000,,and even longer to get them
Dialogue: 0,0:03:29.54,0:03:31.13,Default,,0000,0000,0000,,where they need to be.
Dialogue: 0,0:03:31.13,0:03:33.19,Default,,0000,0000,0000,,In the meantime, astrobiologists work
Dialogue: 0,0:03:33.19,0:03:35.85,Default,,0000,0000,0000,,in our own natural laboratory, the Earth,
Dialogue: 0,0:03:35.85,0:03:37.11,Default,,0000,0000,0000,,to learn about all the weird
Dialogue: 0,0:03:37.11,0:03:39.38,Default,,0000,0000,0000,,and wonderful forms of life that can exist
Dialogue: 0,0:03:39.38,0:03:40.83,Default,,0000,0000,0000,,and to help us one day answer
Dialogue: 0,0:03:40.83,0:03:43.06,Default,,0000,0000,0000,,one of humanity's oldest questions:
Dialogue: 0,0:03:43.06,0:03:44.61,Default,,0000,0000,0000,,Are we alone?