Interstellar space: Where No Earthly Bacterium Has Gone Before

William Atkins
Thursday, 10 May 2007 09:00

Science - Space

NASA’s Pioneer 10 was the first space probe sent from the Earth that traveled through the asteroid belt and the first spacecraft to directly observe the planet Jupiter. Launched from Cape Canaveral Air Force Station on March 2, 1972, Pioneer 10 is on its way out of the solar system.

Voyager 1 and Voyager 2 were launched by NASA in 1977; on September 5, 1977 and August 20, 1977, respectively. The Voyagers are among the most important space mission ever launched, collecting--among other information--detailed photographs of four planets (Jupiter, Saturn, Uranus, and Neptune) and dozens of moons. The Voyagers are coasting toward interstellar space—both are now in the Sun’s heliosheath, which is the termination shock region between the solar system and interstellar space.

On January 19, 2006, the NASA New Horizons space probe was launched from Cape Canaveral, Florida, for its mission to the dwarf planets Pluto and Charon—the first probe to explore the distant Pluto-Charon system. After leaving Pluto and Charon, the spacecraft will fly on to explore rocky objects in the Kuiper Belt, and then outward toward interstellar space.

However, all four space probes were propelled out into space by STAR upper rocket stages. NASA calls them informally “kick motors”. They performed their missions, and are also on their way out of the solar system and into interstellar space. However, these upper stages were not sterilized like their payloads. They may still contain live bacteria.

Scientists contend that bacteria are onboard after being placed there by the hands and breathe of engineers and technicians who built and put together the upper stages. Scientists realize that the very cold temperatures of space would very likely make these bacteria go into a hibernation-like condition (what is called spore state). They have also been exposed to radiation that would have killed humans—but bacteria are much more likely to have survived the radiation blasts.

However, we don’t know if eventually one of these upper stages will come in contact with a planet that is conducive to life, or maybe even contains life. It is too late now, but we may have bacteria that in millions or billions of years will make their alien entrance onto another planet.

These bacteria are now going: Where No Bacterium Has Gone Before.