(Asked by Charles Carman)
The Martian Rock: Are we alone?
In 1984, a softball-sized meteorite 1.9 kilograms in mass was discovered in
the frozen wastes of Antarctica. This unassuming chunk of space rock was
dubbed "ALH84001", but it is now known by a more common name, "The Mars Rock".
Why is it called The Mars Rock? Well, here's the story...
I'll just quote directly from my source: "Radiometric dating shows that ALH84001 congealed from magma to become part of the original Martian crust 4.5 billion years ago, just 100 million years after the planet formed, making it the oldest rock known from any planet. Still early in Martian history, a meteorite impact shattered the rock, leaving fractures where minerals--including the putative traces of life--formed perhaps 3.6 billion years ago. Much later, another impact launched the rock into space, where radioactive nuclei created by deep-space radiation show that it wandered for 16 million years before blazing through Earth's atmosphere and crashing into the Antarctic ice cap. There it lay buried for 13,000 years until scientists found it on wind-scoured ice in the Allan Hills region of Antarctica."
So the story is that upon closer analysis of this piece of the Martian planet, some scientists have concluded that there are traces of ancient Martian lifeforms found in the meteorite. According to David McKay of NASA's Johnson Space Center... "We are not claiming that we have found life on Mars... and we're not claiming that we have found the smoking gun, the absolute proof, of past life on Mars. We're just saying we have found a lot of pointers in that direction." The "pointers" that McKay speaks of are known as polycyclic aromatic hydrocarbons, or PAH's. PAH's are "large, complex organic molecules that are commonplace in some interplanetary dust particles, interstellar dust, and many organic-rich meteorites from the asteroid belt--the residue, it is thought, of non-biological chemical reactions among simpler carbon compounds."
However, there is not yet a consensus in the scientific community that these PAH's are definitive proof of ancient (or current) Martian life. When asked of the question as to whether or not the Mars Rock contains remnants of ancient Martian life the world famous astronomer and exobiologist Carl Sagan was quoted as saying "Extraordinary claims require extraordinary evidence."
If you'd like to know more about the debate over the Mars Rock, then check
out some of these links:
http://www.eurekalert.org/releases/mrel.html http://rsd.gsfc.nasa.gov/marsli fe/ Or go to any search engine and type in the phrase "Mars Rock" or "Martian Meteorite".