Life in outer space? A figment of our wildest imagination or reality? This age old question has been lingering in the heads of human minds since the beginning of reasonable thinking. Today, these questions still remain unanswered, although extensive research has been conducted by scientists across the globe for many years now. There is an immense amount of existing evidence that suggests to us that life exists beyond Earth’s boundaries, into the gigantic universe surrounding Earth itself.
In short, most biologists now believe that life is an inevitable consequence, given enough time and the right kind of environment, of the basic physical and chemical laws of the universe (Chandler, 3).
It is clear to present day scientists that the possibility of life flourishing in outer space relies on favorable conditions or environments within a given area in a solar system. There is even some present day proof that life can flourish in some not so favorable environments as found with the development of algae on many of Earth’s deep sea thermal vents, as well as bacteria that lives beneath the Earth’s icy polar tundra’s in the arctic and Antarctic. George W. Wetherill even notes that “Even if a planet or moon could not support life globally, each could contain a tiny niche where life could thrive (Science News, 328).
What are the most favorable conditions for life to develop? It is now known that life simply cannot emerge anywhere that does not contain water. It is mostly preferred that this water exists in liquid form, but
there are possibilities that life can form in freezing as well as boiling conditions. Water and energy, which both exist in many places in outer space, are prime biological prospecting sites. this ranges from deep sea thermal vents to the Martian tundra, yet unexplained (Mission To Mars, 4).
Many also feel that the discovery of life is all a matter of time and odds. Some feel that simply given enough time, some kind of life will emerge on a planet capable of sustaining it. One equation that has been made widely popular among the world’s extraterrestrial life hunters is one that was proposed by Francis Drake, now president of The Search for Extraterrestrial Intelligence Institute. “The Drake Equation, as it has come to be known, was first presented by Drake in 1961 and identifies specific factors thought to play a role in the development of such civilizations. Although there is no unique solution to this equation, it is a generally accepted tool used by the scientific community to examine these factors (Search For Extraterrestrial Intelligence Institute).
The Drake equation consists of several factors that are used to determine how possible it is for life to develop somewhere in outer space, beyond Earth’s boundaries. The first factor being the rate of formation of stars (stars per year) with a large enough “habitable zone” and long enough lifetime to be suitable for the development of intelligent life is considered. This simply means how many stars exist and how long they last before they die. Each star then, must contain a “habitable zone” where the temperatures are suitable so that water will exist in liquid form (SETI).
Secondly, the fraction of those stars with planets is taken into consideration. The fraction of Sun-like stars with planets is currently unknown. Recent models suggest that planets will form out of the leftover debris when a star coalesces out of a large cloud of gas and dust. Although there have been reports of planets around various stars in the past, none has withstood further testing to confirm them up until October 1995, when two Swiss astronomers: “Michel Mayor and Dider Queloz announced that they had detected periodic velocity changes in the star 51 Pegasi. These changes are caused by the star moving back and forth along our line of sight (SETI). It is believed that this movement is due to the gravitational pull of one or several planets around 51 Pegasi, a star similar to the sun in size as well as mass. Because this planet is so close to the star, it is concluded that its temperature is probably greater then 1500 degrees, thus making this particular planet incapable of sustaining life, but there is still a possibility that other planets might orbit 51 Pegasi (SETI).
At a meeting of the American Astronomical Society in January, Drs. Marcy and Butler reported the detection of two more planets orbiting solar-type stars. The stars are 70 Virginis and 47 Ursa Majoris.
Both planets are large, roughly six times the mass of Jupiter for the 70 Virginis planet. The planet orbiting 47 Ursa Majoris is about twice the mass of Jupiter (SETI).
Since January, two more planets have been discovered by Drs. Marcy and Butler, and now, more then ever, astronomers are feeling that many planets may exist in the universe, some possibly harboring life.
Knowing, now, that there are other planets beyond the solar system that Earth is a part of, the number of “earth’s” per planetary system must be considered. “All stars have a habitable zone where a planet would be able to maintain a temperature that would allow liquid water. A planet in the habitable zone could have the basic conditions for life as we know it” (SETI). Water is the basic condition that must exist for “life as we know it to occur, because it is the basic medium within which terrestrial biochemistry occurs. Because life flourishes in liquid water, a planet must be in a position relative to a star so that it is warm enough for water to not freeze, as well as cool enough for water to not evaporate.
“Although there are examples of terrestrial organisms that live in hot springs and in the ocean floor hydrothermal vents, it’s not clear whether they originated there or adapted to the extreme temperature environment. While we can’t rule out the origin of life on a large planet, we know that life can evolve on a planet like the Earth” (SETI).
The next part of the Drake equation is the fraction of stars with planets where life develops. Up until recently, this was one of the Drake equation’s weakest spots. SETI’s current outlook on this factor, though, is different than previous outlooks, because new evidence has been surfaced that greatly supports the possibility of life on mars.
“If this evidence proves to be true, it represents one of the most important discoveries in modern science. It will probably be some time before we will have a definitive answer on whether the organic materials and microscopic structures are of biological origin”(SETI).
Mars is one of the main planets that is being scoured by scientists for past or present life. This is mainly attributed to the fact that at one time Mars and Earth were virtual twins: warm, riddled with volcanoes and active thermal vents, and most importantly wet(Mission To Mars, 1). It is also now theorized that if life on mars did, in fact, originate in thermal vents [as it is thought to have done on earth], there is a reasonably high probability that organisms could have been fossilized(2).
“A group of scientists led by David McKay of NASA, Americas space agency, claimed to have found evidence of fossil microbes in a meteorite from mars (Fools Gold on Mars, 1). The reason Dr. McKay believed his team had found fossils was the rare presence of pyrite in the meteorite. One explanation for its presence is that it was made by Martian bacteria, similar to that of bacteria on Earth (1). This even further supports the premise that life can exist on another planet because there is now proof that life once did exist on another planet.
With the report in October of 1996 that life may have gained a toehold on mars 3.5 billion years ago, many scientists have concluded that “ If there was once life on Mars, and especially if there still is life on Mars, then the cataclysmic climate changes that turned the planet into a cold barren dessert, forced the organisms deep underground (Mission to Mars, 2-3). This further destroys the idea that because humans did not find life on their first visit to Mars, there is no life at all. In fact, it is believed that life may currently still exist deep underground in canyons, or underneath the frozen tundra of this once thought dead planet.
There is another sun-orbiting body that scientists now believe that may harbor life, at least on a microbial level, and possibly on a more advanced level as well. One of the most interesting aspects of this body is that it is not a planet, but it is a moon, otherwise known as Europa. As stated by SETI:
“Since the Pioneer and Voyager missions to Jupiter,
scientists have been intrigued with the moon Europa. It
has a smooth, icy surface with a fine network of dark
lines. Early theories suggested that variable tidal
forces cause by Jupiter and the other moons might heat
the interior of Europa to the point where ice would
melt” (SETI).
Some people even have pondered the possibility of an ocean beneath the icy surface of Europa, that could possibly sustain life. This is supported by recent findings of ice-spewing volcanoes and shifts in the moon’s icy crust that are not unlike earthquakes.
“The features provide evidence that water, heat and organic compounds may have combined to create an environment suitable for the start of life, Galileo scientists told a news conference at NASA’s Washington
headquarters” (CNN Interactive).
As each day passes, the worlds science society obtains more and more evidence that suggests the possibility of life beyond Earth. This all comes from expeditions such as the Galileo space probes around the Jovian planetary system, and the Voyager missions to Mars. As a result of this extensive and ongoing search for any extraterrestrial life, Humans have come a squeak closer to guessing weather or not another species is surviving in the cold wastes of outer space, as they ask “Is anyone out there?”