Saturday, August 7, 2010

Space Expolration Pioneers and the Quest for Extraterrestrial Life

Early Planet X - Pluto
Miller’s landmark work, carried out in 1953, meant that scientists could study the origins of life in a laboratory setting. Urey and Miller were interested in terrestrial life, but others soon explored the cosmic implications of their work. Life might appear in other regions of the universe where Earthlike conditions prevailed. It was no longer an exclusively terrestrial phenomenon. Carl Sagan started graduate work at the University of Chicago in the midst of these new developments on the origins of terrestrial and extraterrestrial life. Sagan’s mentor at Chicago was the astronomer Gerard Kuiper. While completing his doctoral studies with Kuiper, Sagan met the Nobel laureate geneticist Joshua Lederberg (1925–). The two men were brought together by their common interest in the origins of terrestrial life and the possibility of extraterrestrial life. Lederberg was a pioneer in the scientific study of extraterrestrial life. In 1960 he named the new science exobiology and used his considerable scientific reputation to enhance its credibility. Lederberg hoped that exobiology would give America’s space program a new focus. Instead of concentrating upon missiles and manned flight, the program would turn to scientific topics. From its beginnings, exobiology was a highly speculative and controversial field of study. Despite its uncertain status among scientists, exobiology found a home within the space sciences. NASA created an Office of Life Sciences in 1960, sponsored conferences on extraterrestrial life, and funded exobiological research. Upon Lederberg’s recommendation, Carl Sagan was asked to serve on a number of government panels and commissions that advised NASA on matters relating to space exploration and biology. Sagan worked with NASA during the directorship of James C. Fletcher. Fletcher was a very able administrator, a tireless advocate for space exploration, and a supporter of the search for extraterrestrial life. He was also a devout Mormon whose religion had long taught that inhabited worlds existed outside our solar system. For these varied reasons, Fletcher brought the Viking Mars missions to a successful completion and encouraged NASA-sponsored efforts to communicate with intelligent beings outside the solar system.

Viking images of Mars
Joshua Lederberg’s and Carl Sagan’s strong belief in the existence of extraterrestrial life found favor in some NASA circles, but it was disputed by officials and scientists preparing for the Apollo flights to the Moon from 1969 to 1972. The central issue of the dispute, microbial contamination, pitted exobiologists against geologists and engineers at the space agency. The exobiologists warned that terrestrial microbes carried to the Moon by Apollo spacecraft and astronauts could endanger lunar life forms. Likewise, lunar microbes accidentally brought back from the Moon might infect inhabitants of the Earth. Sagan urged the sterilization of all spacecraft traveling to the Moon. NASA officials ruled out sterilization of the Apollo lunar landers. It would have been very difficult, if not impossible, to place a sterile lander on the Moon. In order to protect humans from infection by lunar microbes, NASA agreed to quarantine returning Apollo astronauts and their cargo of lunar rocks. Appropriate tests made on the first astronaut team to visit the Moon showed no evidence of lunar life. NASA dropped the quarantine of returning astronauts after several more lunar missions. By 1972, when Apollo 16 flew to the Moon, virtually all scientists agreed that the Moon was lifeless. Carl Sagan was one of the few to dispute this conclusion. He maintained that microorganisms might live deep beneath the lunar surface. In the early 1970s, Sagan became a member of NASA’s imaging teams for Mariner 9 and the two Viking missions. The imaging team interpreted the pictures of the Martian surface recorded by the spacecraft’s electronic cameras. Sagan was the sole astronomer, and the only scientist with an extensive background in biology, on the team. Furthermore, he was a staunch believer in the existence of advanced Martian life at a time when most scientists considered it doubtful that microbes existed on the planet. One of his NASA colleagues explained Sagan’s position in these words: “Sagan struggles to create situations where life might exist. It’s a compulsion.”

Friday, August 6, 2010

Martian Life: Canals on Mars Evidence of Past Glories

Prof. Percival Lowell is certain that the canals on Mars are artificial. And nobody can contradict him. —Clipping from unidentified newspaper (summer 1905)

Canals on Mars
On May 19, 1910, less than two months before his death, Schiaparelli publicly stated that natural forces could account for the dark lines seen on Mars. However, he went on to suggest that someone assemble all evidence related to the existence of intelligent life on the planet. In the concluding paragraphs of his final communication on Mars, Schiaparelli mentions his admiration for the work of Percival Lowell. This praise for Lowell raises doubts about Schiaparelli’s acceptance of a natural explanation of the canali. Lowell was an outspoken defender of canals built by Martians throughout his scientific career (1894– 1916). Percival Lowell (1855– 1916) was the most powerful champion within the scientific community for the idea of intelligent Martian life. His claim that the Martian landscape included a global irrigation system influenced the conception of Mars held by scientists, government officials, and the general public well into the second half of the twentieth century. Unlike Schiaparelli, Lowell wrote popular books and magazine articles and lectured widely on Martians as canal builders. Lowell was an energetic and effective publicist for his views on Martian life. Some writers have called Lowell a newcomer to astronomy, an outsider, and even an amateur. When Lowell began his scientific career, entrance into the profession did not require an advanced degree in astronomy. A number of distinguished early twentieth-century astronomers, including directors of major observatories, never received advanced training in astronomy. Lowell’s credentials as an astronomer were not unusual for his times. Lowell studied mathematics at Harvard University under America’s premier mathematician, Benjamin Peirce. Peirce fully expected his brilliant student to succeed him as a professor of mathematics. Lowell had different plans for the future. After spending a year abroad, and the next six years attending to the business holdings of his illustrious and wealthy family, Lowell left America to study the Far East. In 1882 Lowell had attended a lecture on Japanese culture by zoologist Edward S. Morse. Morse’s lecture inspired Lowell to travel to Asiatic countries recently opened to the West. The dark regions of the planet observed by astronomers were areas of vegetation, not bodies of water. The melting of the polar ice caps during the warm season freed water to flow through the canal system. The flowing water irrigated the desiccated planet and brought life to its vegetation. Lowell’s theory, completed after a short stay at Flagstaff, changed little over the next twenty years. In describing the orderly arrangement of the Martian canals, Lowell compared them to trigonometric figures. Lowell’s maps of the canals are simpler and more geometrical than Schiaparelli’s. There are two explanations for Lowell’s schematic maps. First, Lowell studied Mars using Schiaparelli’s maps as his guide. Second, according to Carl Sagan, Lowell was a poor draftsman who drew polygonal blocks linked by many straight lines. Pickering and Douglass were no better at rendering details of the Martian surface than Lowell.

Ancient Martian City?
The unique physical conditions of the planet, Lowell declared, explained the social behavior and technology of the intelligent creatures who lived there. Lowell claimed that because Mars was smaller than the Earth, it evolved faster. Mars continued on its rapid evolutionary path and soon reached the final stages of planetary development. Lowell believed that Mars was older than the Earth. All planets, Lowell argued, become drier as they age. At one time, the Earth had much more water than land. On Mars, land had largely replaced water, leaving the planet covered with vast desert regions of a reddish-ochre color. This color reminded Lowell of the Sahara region of northern Africa or the Painted Desert of Arizona. Mars was dry but not without water. Lowell drew attention to Martian polar caps that melted during the warm seasons. As the polar caps retreated, a deep blue band appeared around the poles. This band was ice that melted with the rising temperature of the Martian spring and summer. Lowell dismissed the hypothesis that the polar caps were largely frozen carbon dioxide, not snow and ice. A desert planet with water frozen in polar ice caps is an unlikely habitat for life. However, Lowell assured us that Mars had enough water to sustain life. It also had an adequate supply of air, another crucial ingredient of life. Lowell’s telescopic study of the disk of Mars convinced him, if not other astronomers, that Mars had an atmosphere. Water circulated throughout the atmosphere in a vaporous form and condensed at the poles of the planet. The freezing and melting of water at the polar caps convinced Lowell that the average temperature of Mars was comparable to the Earth’s, if not higher. Hence, Martian polar caps shrink back far more drastically during the warm seasons than do the ice caps at the Earth’s poles. The existence of water and air on Mars, along with its mild climate, were essential to Lowell’s picture of the planet as a place of constant change. It was not static like the airless, waterless, and lifeless Moon. Lowell first described the physical characteristics of Mars. Then he was ready to introduce life there. The Martian climate, smooth terrain, and adequate supply of water and air indicated life could thrive on the planet. If astronomers properly examined Mars through their telescopes, evidence of life would emerge.

Lowell claimed that the dark, bluish green regions of Mars turn to shades of gray and brown seasonally. The dark areas are plants that flourished with warmth and moisture and faded when the frosts of the Martian autumn arrived. The changing colors of Martian vegetation reminded Lowell of American forests seen from a distance.

Tuesday, August 3, 2010

Alien Life on the Moon - New ways of seeing, Old ways of thinking

Ancient astronomers
The ancient astronomers and Copernicus made their great contributions to science before the invention of the telescope. They based their conceptions of the universe on astronomical data gathered by naked-eye observers. These observers used sighting and angle-measuring instruments that did not include magnifying lenses of any sort. The classic refracting telescope, consisting of a tube with an eyepiece at one end and a larger objective lens at the other, first appeared around 1609, more than sixty years after Copernicus’s death. The Copernican revolution did not originate in a new set of observations made with a novel scientific instrument. It was an intellectual revolution inspired by changes in the way early modern scientists thought about the structure of the universe. In any case, the telescope alone cannot supply crucial evidence for the Copernican system. A viewer cannot see either a heliocentric or geocentric universe through the eyepiece of a telescope. Observations made with the help of a telescope are like any other sets of observations. Astronomers gather their data and then interpret it within the framework of existing scientific theory and practice. This complex process ends with a majority accepting a given view of the workings of the universe. Historians divide observational astronomy into three periods. The first period, the era of naked-eye astronomy, dates from the earliest human observation of the skies and ends in 1609. This preoptical period included the work of Ptolemy (second century, a.d.) and Copernicus, two of the greatest figures in the history of astronomy. The second period began with Galileo’s use of a telescope in 1609 to study the major heavenly bodies. Telescope makers devised new and more powerful instruments during the following three centuries, when optical telescopes ruled the astronomical sciences. Then, in 1931, Karl Jansky of Bell Telephone Laboratories detected radio signals coming from regions beyond the solar system. Jansky’s discovery marks the beginning of the third period of observational astronomy, the era of the radio telescope. A radio telescope is essentially a large antenna, often shaped as a parabolic dish, used to detect, amplify, and analyze radio emissions from celestial sources. It is mounted so that it can be aimed at different portions of the sky.

Telescopes, both optical and radio, play an important part in the search for evidence of intelligent extraterrestrial life. However, astronomers must interpret the raw data collected with their instruments. The difficult process of interpretation yields ambiguous results that fuel scientific debates. Galileo’s telescopic observation of the Moon revealed large circular cavities on the lunar surface. Were these natural cavities of unknown origin, or did the inhabitants of the Moon build them? Late nineteenth-century telescopic observers of Mars saw a series of long dark lines on the surface of the planet. Were these lines generated by an observer’s visual response to the natural Martian landscape, or were they evidence of a network of canals built by Martian engineers? Late twentieth-century radio telescope operators recorded periodic signals coming from outer space. Were these signals due to physical changes occurring in a distant celestial body, or were they coded messages from extraterrestrial beings in the universe? In each of these cases, interpretation of the observational data depended upon the state of astronomical knowledge and current ideas about intelligent extraterrestrial life. Scientists can never escape the scientific, philosophical, and social assumptions that influence their best efforts to extract meaning from the observed world. In short, observations do not speak for themselves. Scientists shape their speech for them as they gain knowledge about the physical world.

Monday, August 2, 2010

Search for Advanced Extraterrestrial Life Stemming from Antiquity and the Middle Ages?

Ancient Aliens
Scientific perceptions of advanced extraterrestrial life are based upon a trio of ideas that first appeared in the religious and philosophical thought of antiquity and the Middle Ages. The first idea is that the universe is very large, if not infinite in extent. The second, that we are not alone in the universe, there are other inhabited worlds somewhere in the vastness of space. The third, that there is an essential difference between the superior beings of the celestial world and the inferior ones who live on Earth. These three ideas are relevant to the work of scientists today. Modern cosmologists have determined that the universe is expanding at an increasing rate and is unlikely to slow down and collapse on itself in a final Big Crunch. Within our immense universe, astronomers have recently identified more than 100 extrasolar planets. An extrasolar planet is one that orbits a star located far beyond our solar system. Some scientists believe that extrasolar planets are inhabited by creatures with a level of intelligence and civilization that surpasses the intellect and civilized life of humans. Astronomers, however, have just begun their investigations and have found no evidence of extraterrestrial civilizations. Any examination of extraterrestrial civilizations must begin with the debt modern science owes to the trio of ideas that shaped our ways of thinking about the universe and its inhabitants. These key assumptions, which appear so often in the modern search for extraterrestrial intelligence, arose in much earlier times and within different contexts.

The Infinitization of the Universe 

Aristotle's Universe
The ancient Greek atomists were among the first to introduce the idea of an infinite universe. In the fifth century b.c., they claimed that tiny bits of matter (atoms) moved randomly in infinite empty space. Because an infinite number of atoms collide an infinite number of times in an infinite void, an infinite number of universes exist. Each universe has its own sun, planets, stars, and life forms. A century later the influential philosopher Aristotle (384– 322 b.c.) rejected the atomists’ infinite void and their many universes. In its place, he put a single finite universe with the Earth located at its exact center. The planets, Sun, and stars all circle the motionless Earth. The stars marked the outer limits of Aristotle’s geocentric (Earth-centered) universe, and he refused to consider the existence of space beyond the stellar boundaries. There are no voids, vacuums, or empty spaces in Aristotle’s universe because the region between the Moon and the stars is filled with a solid, transparent, crystalline material. Aristotle’s view of the universe explained all known astronomical phenomena and satisfied the ordinary observer’s feeling that the Earth was at the center of things. It lasted for nearly two thousand years and inspired some of the greatest scientific, philosophical, theological, and literary minds in Western civilization. By the fourteenth century, however, critics argued that Aristotle was wrong to place limits on God by confining Him to a finite universe. God extends Himself, they said, filling infinite space with His immensity. Influenced by their conception of an infinite God, philosophers and theologians in the Middle Ages accepted a universe that was infinite in extent. The identification of God with infinite space, sometimes called the divinization of space, lasted well into the seventeenth century. Some Renaissance astronomers and philosophers were not satisfied with the medieval understanding of the cosmos. They more than a theological construct. By interpreting astronomical observations mathematically, they argued, it was possible to obtain a true picture of physical reality. The crucial figure in this intellectual revolution was the Polish astronomer and Church administrator Nicolaus Copernicus (1473– 1543). He proposed a heliocentric (Sun-centered) model of the universe. It featured a stationary Sun at the center of a system of orbiting planets that included the Earth. The Copernican universe remained finite, but it was substantially larger than the old geocentric model made popular by Aristotle. The infinitization of the universe grew out of the fundamental changes Copernicus made in the arrangement of the Sun, Earth, and planets and in the motions of the Earth. By the second half of the sixteenth century, followers of Copernicus claimed that the universe extended to infinity. The first printed illustration of an infinite universe dates to 1576, just thirty-three years after Copernicus published his theory of a heliocentric universe. Most astronomers, if not the general public, soon accepted the infinite nature of the universe. In the seventeenth century, Sir Isaac Newton made a static infinite universe an integral part of his new physics of moving bodies on Earth and in the heavens. Despite the work of generations of physicists and astronomers who succeeded Newton, the precise nature of the universe remains an unresolved problem for modern science.