New Delhi: December 20, 2021 is the 25th death anniversary of popular American astronomer and planetary scientist Carl Edward Sagan, famous for his books and television series 'Cosmos'. He was also a cosmologist, astrophysicist, astrobiologist, and science communicator.
Sagan, whose contributions to the field of planetary science are remarkable, was a pioneer in the American space program.
He had famously said, "Imagination will often carry us to worlds that never were. But without it we go nowhere."
Born on November 9, 1934 in Brooklyn, New York, Sagan studied physics at the University of Chicago.
He described himself as a childhood science fiction addict who became intrigued by astronomy when he learnt that every star in the night sky was a distant Sun.
Due to his scientific curiosity, he earned four degrees in physics, astronomy and astrophysics from the University of Chicago. He became a doctorate in astronomy and astrophysics in 1960, according to earthsky.org.
Sagan's Prominent Research Work
In the 1960s, one of Sagan's earliest works in professional astronomical research was on the atmosphere of our solar system's planets. The world knows that the atmospheres of Mars and Venus resemble that of Earth. But during Sagan's time, scientists were trying to decipher why the Martian atmosphere is so cold, while the atmosphere of Venus is extremely hot.
Sagan used data from tables for steam boiler engineering, and successfully confirmed that Venus could be a greenhouse furnace.
Through his research, he found that the mysteries of the high temperature of Venus could be attributed to a massive greenhouse effect. He also found that windblown dust is responsible for the seasonal changes on Mars, and that complex organic molecules cause the reddish haze of Saturn's Moon, Titan.
Sagan also taught and conducted research at Harvard University. However, in 1971, he was denied tenure at Harvard University.
He went on to become a Professor at Cornell University, where he was also the director of the Laboratory for Planetary Studies.
Sagan also conducted research in the field of exobiology, which is the study of the possibility of extraterrestrial life. He urged NASA to extend its exploration of the Universe, and was among the first to determine that life could have existed on Mars.
Due to his interest in the search for extraterrestrial intelligent (SETI), Sagan contributed a lot to the field, and proved that exposure of simple chemicals to UV light could easily create the building blocks of life.
'Intelligent Life in the Universe', a book on extraterrestrial life written by Soviet astronomer IS Shklovskii, was revised and expanded by Sagan.
Sagan founded The Planetary Society with Louis Friedman and Bruce Murray in 1980, according to NASA. It is a public membership organisation which inspires, informs, and involves the public in the wonders of space exploration.
Sagan's Contributions To NASA's Space Program
Since the early 1950s, Sagan was a consultant and adviser to NASA. He contributed heavily to the US space program. He briefed Apollo astronauts before their voyage to the Moon, and was also a pioneer of the Mariner, Viking, Galileo, and Voyager space missions. The Viking missions sent two probes to explore Mars in the 1970s. Sagan advised NASA on the choice of ideal landing sites.
Sagan cherished his relationship with the NASA Ames Research Center, the US space agency website quoted Ann Druyan, Sagan's wife and collaborator for 20 years, as saying.
He was also a visiting scientist at the Jet Propulsion Laboratory (JPL) in Pasadena, California. He helped design and manage the Mariner 2 mission to Venus, the Mariner 9 and Viking 1 and Viking 2 trips to Mars. He played an important role in the Voyager 1 and Voyager 2 missions to the outer solar system, and the Galileo mission to Jupiter.
Torrence Johnson, a Galileo mission team member, said Sagan was one of the greatest intellects behind the genesis of space exploration generally, as well as specifically for the Galileo mission, according to NASA. He called Sagan a great human being who shared with everyone his excitement about the exploration of the Universe.
Sagan's actual messages to the cosmos were placed aboard the Voyager Golden Records and Pioneer Plaques.
Journalist and consultant Eric Burgess approached Sagan about the original idea for the Pioneer Plaques, which are a pair of gold-anodized aluminium plaques carrying messages from humankind, placed aboard the 1972 Pioneer 10 and 1973 Pioneer 11 spacecraft.
The Pioneer Golden Plaque was the brainchild of Carl Sagan who wanted any alien civilization, who might encounter the craft, to know who made it and how to contact them.
Sagan, together with astronomer Frank Drake, designed the plaque.
In the late 1970s, Sagan, and his wife-to-be, Ann Druyan, contributed to the design of the Voyager Golden Records, which are two phonograph records that were included aboard the Voyager proves launched in 1977, and contain messages from humankind to outer space.
The contents of the Voyager Golden Record were selected for NASA by a committee chaired by Sagan. Each Golden Record contains 116 images that depict historical scientific works, a variety of natural sounds, such as those made by surf, wind and thunder, birds, whales, and other animals, and musical selections from different cultures and eras.
"The spacecraft will be encountered and the record played only if there are advanced spacefaring civilizations in interstellar space," Sagan noted.
On November 9, 2001, on what would have been Sagan's 67th birthday, the NASA Ames Research Center dedicated the site for the establishment of the Carl Sagan Center for the Study of Life in the Cosmos.
Sagan, The Author
Sagan, during the 1980s, encouraged nuclear disarmament, and was one of the five authors of the concept of nuclear winter, which describes the aftermath of a nuclear war.
Sagan wrote more than 600 professional research papers and 20 papers over the course of his life. He has been an inspiration to many. He encouraged scientific responsibility by promoting nuclear disarmament. Due to his work, science literacy was promoted among the entire human race.
He said many wonderful things. For instance, Sagan said, "Somewhere, something incredible is waiting to be known."
Sagan asserted that the Earth is a tiny speck in the entirety of the Universe. He said, "Our planet is a lonely speck in the great enveloping cosmic dark. In our obscurity, in all this vastness, there is no hint that help will come from elsewhere to save us from ourselves."
Carl suffered from a rare bone marrow disease called myelodysplasia. He suffered from pneumonia due to complications from this disease. He died on December 20, 1996, at age 62 from pneumonia.