Forward-contamination
Encyclopedia
Forward-contamination is the contamination of other worlds with Terrestrial
microbes. The risk of forward-contamination is twofold: that human beings may accidentally seed a previously sterile world, thus creating "extraterrestrials" that are really of terrestrial origin (and which might even make it impossible to determine whether the life later found is terrestric or local); or that an actual alien biosphere
could be devastated by Earth's bacteria.
Forward-contamination may have been demonstrated by the apparent survival on the Moon
of Streptococcus
bacteria on Surveyor 3
, which is however the subject of some debate (see Reports of Streptococcus mitis on the moon
). Laboratory tests indicate that forward-contaminant DNA
can persist for considerable periods of time at the Martian surface, particularly if shielded from solar radiation.
Given the impossibility of sending a bacteria
-free human being into space, forward-contamination will remain an issue for as long as manned missions continue. Assuming a manned mission eventually reaches Mars
, for example, it is inevitable that a microbial soup will be released into the environment of the red planet.
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
microbes. The risk of forward-contamination is twofold: that human beings may accidentally seed a previously sterile world, thus creating "extraterrestrials" that are really of terrestrial origin (and which might even make it impossible to determine whether the life later found is terrestric or local); or that an actual alien biosphere
Biosphere
The biosphere is the global sum of all ecosystems. It can also be called the zone of life on Earth, a closed and self-regulating system...
could be devastated by Earth's bacteria.
Forward-contamination may have been demonstrated by the apparent survival on the Moon
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...
of Streptococcus
Streptococcus
Streptococcus is a genus of spherical Gram-positive bacteria belonging to the phylum Firmicutes and the lactic acid bacteria group. Cellular division occurs along a single axis in these bacteria, and thus they grow in chains or pairs, hence the name — from Greek στρεπτος streptos, meaning...
bacteria on Surveyor 3
Surveyor 3
Surveyor 3 was the third lander of the American unmanned Surveyor program sent to explore the surface of the Moon. Launched on April 17, 1967, Surveyor 3 landed on April 20, 1967 at the Mare Cognitum portion of the Oceanus Procellarum...
, which is however the subject of some debate (see Reports of Streptococcus mitis on the moon
Reports of Streptococcus mitis on the moon
As part of the Apollo 12 mission, the camera from the Surveyor 3 probe was brought back to Earth. On analyzing the camera it was found that the common bacterium Streptococcus mitis was alive on the camera...
). Laboratory tests indicate that forward-contaminant DNA
DNA
Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...
can persist for considerable periods of time at the Martian surface, particularly if shielded from solar radiation.
Given the impossibility of sending a bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
-free human being into space, forward-contamination will remain an issue for as long as manned missions continue. Assuming a manned mission eventually reaches Mars
Mars
Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance...
, for example, it is inevitable that a microbial soup will be released into the environment of the red planet.
See also
- AstrobiologyAstrobiologyAstrobiology is the study of the origin, evolution, distribution, and future of life in the universe. This interdisciplinary field encompasses the search for habitable environments in our Solar System and habitable planets outside our Solar System, the search for evidence of prebiotic chemistry,...
- Back-contaminationBack-contaminationBack-contamination is the informal but widely employed name for the hypothetical introduction of microbial extraterrestrial organisms into Earth's biosphere. It is assumed that any such contact will be disruptive or at least have consequences over which human beings will have little control...
- Living Interplanetary Flight ExperimentLiving Interplanetary Flight ExperimentThe Living Interplanetary Flight Experiment is an interplanetary mission developed by the Planetary Society. It consists of sending selected microorganisms on a three-year interplanetary round-trip in a small capsule aboard the Russian Fobos-Grunt spacecraft in 2011, which is a sample-return...
- Planetary protectionPlanetary protectionPlanetary protection is the term used to describe a guiding principle in design of an interplanetary mission that aims to prevent biological contamination of both the target celestial body and the Earth. This principle arises from the scientific need to preserve planetary conditions for future...
- Extraterrestrial lifeExtraterrestrial lifeExtraterrestrial life is defined as life that does not originate from Earth...
- Panspermia