In space travel there is a saying that the first 50 miles and the last 50 miles are the most dangerous. See how a single spark inside a spacecraft or a micrometeoroid less than an inch wide hitting a space station can turn a routine mission into a lethal nightmare. As the missions become longer, venturing to Mars and beyond, the potential disasters will only become bigger. What would happen if a spacecraft ventured too close to a black hole or was hit by a gamma ray burst?

According to the laws of physics we can never travel faster than the speed of light...or can we? Light speed allows us to see things instantly here on Earth, and shows us the entire history of the universe going back nearly 14 billion years. Learn all about light speed, the ultimate constant in the universe and discover ways scientists envision breaking the "light barrier" which may be the only way the star travel of our imaginations ever comes to reality.

As man moves to colonize the cosmos, the realities of sexual relationships and reproduction need to be addressed. Probe the physiological, psychological and cultural challenges of sex in space. From the sex act through birth, look at how the extreme environments of space exploration might effect copulation, conception and developing human tissues, as well as how issues around sex might impact the emotional lives of astronauts. Get to the bottom of the rumors to find out if space sex has already happened, and look at how the burgeoning space tourism business may soon lead to a boom in space sex.

They soar through the heavens, fly through the oceans and glide along land. But these are not creatures found on a wildlife safari. These are life forms from another planet. Armed with scientific fact and a little imagination, experts come together to take you on an unprecedented journey to the edges of our imagination. Scientists, astrobiologists and astronomers create five lines of extraterrestrial evolution, and explain how creatures on the surface of Earth offer a helping hand to understanding life in The Universe.

Asteroids and comets have left their imprint on planet Earth, literally. Since the turbulent formation of the solar system, these space rocks have continued to impact earth. Some have been so violent that they've led to mass extinctions. What's more, radical new theories suggest that asteroid and comet dust harbor deadly viruses that may have triggered some of our worst pandemics. The possibility of future cosmic collisions remains a legitimate threat. Yet, despite their dangers, asteroids and comets may hold vital natural resources, which could actually preserve mankind.

When mankind eventually leaves the cradle of Earth and ventures forth into the uncharted territories of the cosmos, where, and what form, will our new homes take? Will they be cities under glass, entrenched in distant alien soils? Will they be gleaming metropolises hanging in orbit above our heads, or in the lonely void of space? Will they be hollowed out asteroids, strip-mined for the valuables they horde? How will we grow food? What will the new era of spacesuits be like? The rovers that carry us around? Will robonauts, advanced robotic machines, perform the most dangerous tasks for us? How will we live... in space?

It sounds like a Hollywood blockbuster: a deadly asteroid is on a collision course with Earth. But in reality, it's only a matter of time before a giant space rock threatens to wipe out civilization. An asteroid took out the dinosaurs sixty-five million years ago. Are we next? This episode analyzes the threat and explores the many ways--from a nuclear bomb to ingenious new technology--that experts are proposing to stop Armageddon.

Could we be unique in the universe or is there another planet similar to earth somewhere in the cosmos? Is it possible that Alpha Centauri, our nearest star, is home to another earth-like planet? Earth sized planets have been hard to find, but indirect methods are coming on line to give scientists a good survey of how many such bodies may be in the universe. How rare would it be to find life on another earth-like planet?

An exploration of mysterious phenomenon, including alcohol clouds in space, pulsar planets, the possibility of a planet beyond Neptune, and dark matter.

There have been both helpful and harmful effects on life on Earth from cosmic effects. Cosmic Phenomena includes the beauty of the Aurora Borealis and rainbows to the dangers of UV radiation and cosmic rays, from the miracle of photosynthesis to the thrill of a meteor shower as we explore the effects caused by the sun and other extra-solar sources, which can get under our skin and scramble man's technology, make life possible and be a threat to our existence all at once.

The majority of space exploration has occurred in Low Earth Orbit, around 120 miles above sea level. For a cool $20 million, any person can take a ride on the International Space Station, around the 1,100 mile band around Earth. Commercial prospects for LEO are huge, there are big dangers lurking for anyone interested in traveling this way, such as radiation, , cosmic rays, and space debris numbering in the thousands threaten any spacecraft traveling in orbit. It's a new frontier and maybe the final frontier, and the possibilities are endless if you are willing to travel to the edge of space exploration.

The planets of our solar system have experienced epic catastrophes throughout their long history, both raining down from outside and bubbling up from within. We'll voyage back in time to investigate the violent events that profoundly shaped the planets, including earth itself. We'll witness stunning revelations about what transformed Mars into a barren, hostile desert...The disaster that changed Venus from temperate to hellish...The impact that blew away Mercury's mantle, turning it into a planetary core...A colossal disturbance that rearranged the orbits of the gas giants...Titanic impacts on Jupiter...And how a lost moon may finally explain Saturn's rings.

Could there be a monstrous, undiscovered star orbiting our own Sun? Could it be scattering killer comets throughout our Solar System like clockwork every 26 million years? New scientific surveys are probing the edges of our Solar System--a realm populated by giant worlds and mysterious planetoid--hunting for Nemesis, the Sun's purported evil twin. We may be on the verge of discovering this ultimate death star, suspected of causing every mass extinction in Earth's history. We employ everyday experiences to explain what Nemesis is and why it's been so hard to find. Experts start a wildfire on a dry California hillside, race a NASCAR around an oval track, and juggle fire, all in the effort to present how Nemesis works, and why life on Earth may depend on its discovery.

At 4.6 billion years old, the Solar System is our solid, secure home in the Universe. But how did it come to be? In this episode we trace the system's birth from a thin cloud of dust and gas. Shocked by a nearby supernova, the pull of gravity and natural rotation spun it into a flat disc from which the Sun and planets coalesced. It all happened in the space of 700 million years, during which the planets jockeyed for position, dodging the brutal bombardment of deadly asteroids and setting into the neat, stable system that we now realize might be a rarity in the universe.

What might happen if the first manned mission to Mars crashes hundreds of miles from the rocket that would take them back home? Could they survive the crash, and travel across the brutal Martian surface to their home ship? We'll show what the astronauts would have to do to survive dust storms and space radiation, while extracting vital resources like water from the Martian soil itself. It's a dramatic vision of the very near future, where survival can depend on pre-industrial technology and human ingenuity.

Earth may seem like the most hospitable planet in the solar system. But look again. Startling new discoveries reveal the blue planet has been plagued by more chaos and destruction than scientists once imagined. Stand on the Earth billions of years ago as a primitive planet slams into it. Shiver as our entire globe is frozen over like a gigantic snowball. Feel the heat as mammoth volcanoes scorch the landscape and darken the sky. From a cosmic gamma ray burst frying away the ozone layer to an Everest-size asteroid slamming into the ocean, we'll reveal new information about how these unparalleled events drove life to the brink of total extinction. Out of this continuous devastation, how has our planet--and life--got to where it is today? Are the worst days behind us--or lurking in the distant future?

Many argue that flying saucers and other extra-terrestrial space ships continuously visit the earth. If that were true, what kinds of technologies would such alien spacecraft require? And do eyewitness reports of UFO sightings jibe with modern theories of how interstellar travel might be possible? Authors, astronomers and theoretical physicists weigh in with the blueprints for inertia-canceling devices, nuclear-powered craft, antimatter propulsion systems and even warp drives. Based on Einstein's theories and countless scientific studies, we'll find out how these visitors might bridge the vast distances between the stars. And if they could survive such hazardous journeys, are they flesh and blood or intelligent machines?

Perhaps the most mysterious structure on Earth, Stonehenge has stood on a plain in Southern England for 5000 years. Why is it there? In this episode we explore the possibility that this was a prehistoric astronomical observatory. Here ancient astronomer priests may have divined the complex movements of the Sun and Moon, recognizing patterns that would not be discovered elsewhere for thousands of years. The primitive Shamans may have also been the first astronomers to predict eclipses.

The Great Pyramids of Giza remain one of the enduring wonders of the ancient world. These mesmerizing monuments have eluded astronomers and archeologists for centuries. Why and how were they built? Were they merely burial tombs, or a cosmic vehicle to the celestial world? The world's renowned Egyptologists, astronomers and engineers join forces to solve some of the long-held mysteries about the pyramids. What were the motives and methods behind the orientation of the pyramids to face the four cardinal directions with extreme accuracy? Did the ancient Egyptians use the sun or nighttime stars in the orientation of the pyramids? Were the pyramids the pharaohs' portal to the nighttime stars? Or was the entire Giza complex built as a place of cult worship to the sun?

Sodom and Gomorrah–a terrifying Biblical tale of two cities incinerated by a hail of fire and brimstone. Was this a fantastic fable, or an actual apocalyptic disaster? Astronomers, archeologists and biblical scholars investigate the possible science behind the myth. Two separate archeological sites along the Dead Sea claim to hold the remains of the actual sin cities. Newly discovered ancient artifacts may even hold the secrets to their destruction? Could an asteroid be responsible for the destruction of Sodom and Gomorrah?

What was the astronomical reality behind the star that, according to the Gospel of Matthew, guided the Magi to the young Jesus? This episode examines almost 20 centuries of theories, including meteors, novae, supernovae and comets…but is the truth to be found in a combination of astronomy–and astrology? Recent theories suggest that the "star" was the planet Jupiter in a series of conjunctions with other planets, stars and constellations, and that these conjunctions were interpreted by the Magi–astrologers and priests of the Zoroastrian religion–as heralding the birth of the Jewish Messiah.

Scientists have no idea what it is, but Dark Matter and Dark Energy make up 96% of the Universe. Dark Matter is everywhere. It passes through everything we know on earth at billions of particles every second, yet no one has ever gotten a direct detection of this mysterious dark substance. An even more bewildering force is Dark Energy, which is rapidly pushing apart our Universe. Discovered only ten years ago, scientists are struggling to comprehend its unusual characteristics and answer the ultimate question; what is the fate of our Universe?

Does life exist on other planets? Astrobiology is a visionary new science that searches for life in space by combining the disciplines of astronomy, biology and geology. How did life evolve on Earth? What will life look like on other planets? These and other pertinent questions will be answered by a diverse group of scientists.

A closer look at the beacon in the dark sky reveals an ever-present source of myth, intrigue, controversy and unsolved mysteries

Travel from the inner solar system to the Kuiper Belt and explore the moons surrounding the planets of the solar system. Many of these moons that were once unknown are now on the cutting edge of astronomical study.