Did life on Earth begin in a rudimentary form in outer space, brought to Earth billions of years ago? In August 1996, a team of scientists discovered that a Martian rock found in Antarctica contained evidence of fossilized life. The four-pound rock showed the presence of carbonate globules excreted by microbes when they were alive on Mars 3.6 billion years ago, at a time the climate on Mars could sustain life as we know it. This discovery proved cross-contamination between Mars and Earth which possibly could have led to the evolution of life on this plant.

Panspermia is the hypothesis that "seeds" of life exist already all over the Universe, that life on Earth may have originated through these "seeds", and that they may deliver or have delivered life to other habitable bodies.

The related but distinct idea of exogenesis (outside origin) is a more limited hypothesis that proposes life on Earth was transferred from elsewhere in the Universe but makes no prediction about how widespread it is. Because the term "exogenesis" is more well-known, it tends to be used in reference to what should strictly speaking be called panspermia. Panspermia does not necessarily suggest that life originated only once and subsequently spread through the entire Universe, but instead that once started, it may be able to spread to other environments suitable for replication.

Some bacteria and animals have been found to thrive in oceanic hydrothermal vents above 100 ¡C; a study revealed that a fraction of bacteria survive heating pulses up to 250¡C in vacuum, while similar heating at normal atmospheric pressure leads to the total sterilization of samples. Other bacteria can thrive in strongly caustic environments, others at extreme pressures 11 km under the ocean. Recent experiments suggest that if bacteria were somehow sheltered from the radiation of space, perhaps inside a thick meteoroid or an icy comet, they could survive dormant for millions of years.

Building Blocks of DNA Found in Meteorites from Space   Live Science - August 8, 2011
The components of DNA have now been confirmed to exist in extraterrestrial meteorites, researchers announced. A different team of scientists also discovered a number of molecules linked with a vital ancient biological process, adding weight to the idea that the earliest forms of life on Earth may have been made up in part from materials delivered to Earth the planet by from space. Past research had revealed a range of building blocks of life in meteorites, such as the amino acids that make up proteins. Space rocks just like these may have been a vital source of the organic compounds that gave rise to life on Earth.

Meteorites 'could have carried nitrogen to Earth'   BBC - March 1, 2011
A meteorite found in Antarctica could lend weight to the argument that life on Earth might have been kick-started from space, scientists are claiming. Chemical analysis of the meteorite shows it to be rich in the gas ammonia. It contains the element nitrogen, found in the proteins and DNA that form the basis of life as we know it.

Life Ingredients Found in Superhot Meteorites - A First   National Geographic - December 20, 2010
New evidence that space rocks may have seeded life on Earth.

'Necropanspermia' suggested as a way of seeding life on Earth   PhysOrg - November 12, 2010
Panspermia is a mechanism for spreading organic material throughout the galaxy, but the destructive effects of cosmic rays and ultraviolet light tend to mean most organisms would be destroyed or arrive on a new world broken and dead. Now Paul S. Wesson, a visiting researcher at the Herzberg Institute of Astrophysics in Canada, suggests the information contained within damaged organic material could seed new life. He terms this process necropanspermia.