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Advances in contemporary physics and astronomy --- our current understanding of the Universe

Advances in contemporary physics and astronomy --- our current understanding of the Universe. Lecture 8: Are we Alone? . May 28 th , 2003. Extraterrestrial life at Earth? . Found in December 1984 in Antarctica by a U.S. meteorite-hunting expedition.

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Advances in contemporary physics and astronomy --- our current understanding of the Universe

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  1. Advances in contemporary physics and astronomy --- our current understanding of the Universe Lecture 8: Are we Alone? May 28th, 2003

  2. Extraterrestrial life at Earth? • Found in December 1984 in Antarctica by a U.S. meteorite-hunting expedition. • weighed about 4 and 3/4 pounds and was shaped like a rounded brick or a large potato, about 6 inches long by 4 inches by 3 inches. • inner color of ALH 84001 is green. • We know it (and about a dozen other meteorites) comes from Mars because it contains traces of gas that is just like the martian atmosphere obtained from Viking project. Mars Rock ALH84001 which contains rounded globules of carbonate minerals. The possible martian fossils are in these carbonate globules, leading to possible Evidence for Ancient Life on Mars

  3. Exploration to Mars

  4. Viking project: First Search for Life • The Viking project consisted of launches of two separate spacecraft to Mars, Viking 1 and Viking 2. Each spacecraft consisted of an orbiter and a lander. • Viking 1: launched on 08/20/1975, arrived at Mars on 06/19/1976 and landed on Mars on 07/20/1976. • Viking 2, launched on 09/09/1975, arrived at Mars on 08/07/1976 and landed on Mars on 09/03/1976. • Image of the entire surface of Mars at a resolution of 150 to 300 meters, and selected areas at 8 meters are obtained. Orbiter and Lander

  5. Viking’s scientific experiments • Imaging • Seismology • Magnetic Properties • Radio Science • Neutral Mass Spectrometer (NMS) • X-Ray Fluorescence Spectrometer (XRFS) • Physical Properties • Atmospheric Structure • Biology • Gas Chromatograph / Mass Spectrometer • Meteorology • Retarding Potential Analyzer (RPA) Viking found no life in Mars and there was confusion over early biological experiment results!

  6. Other missions to Mars • Mars Pathfinder How do we scout Mars? Earth's opposition to Mars in orbit occurs every 2 years. Launching 2 small missions every opposition has been our plan ever since the Viking spacecraft observed it. Here is the schedule: • -1997 Mars Pathfinder, Mars Global Surveyor (MGS) • - 1999 Polar Lander, orbiter • - 2001 Rover • -2003 Rover • - 2005 Sample Return Mission

  7. Round trip to Mars? • Can we send men to Mars? The first step of space colony. • Roundtrip possibilities? How to come back? No rockets. • Expenses and Cost. NASA estimates ~ $100 billion. • Fuel? Get fuel from Mars. 2H2+CO2 -> CH4 + O2 • Trip plans, Food, water, O2 , medicine, etc. • Safety. How many crew members? • First step on Mars probably after 2015.

  8. Where are we in the Universe?

  9. Origin of Life • How does life form on Earth, or maybe it comes from space? • When the Earth was formed, there exist various primordial atoms. Some of these atoms came to be arranged in the form of molecules of DNA, which is the essential building block of life. • Why the universe is such that life is possible? • The Anthropic Principle: If the conditions were not suitable for life, we would not be asking why they are as they are. ----- an idea originated P.A. M. Dirac

  10. Definition of life • What is(are) the essential character(s) of life? • What differentiate us from say, robots? The most important thing about DNA is its ability to copy itself! This makes reproduction possible. Evolution and mutation are then natural consequences of the copying process! Being able to reproduce itself is the most essential criterion for life!

  11. The Intelligence • Life has evolved in the planet of Earth for the past 4~5 billions of years. • It took a rather long period of time, two and a half billion years, to go from single cells to multi-cell beings, which are a necessary precursor to intelligence. • The evolution speeded up after intelligence appears.

  12. Life beyond solar system • Are there lives beyond solar system? • If there are, are they DNA based? • Do they have intelligence? • If they are intelligent, can we make contacts with them? • Have we been visited by some of them already? • Maybe we are descents of them?

  13. Drake’s equation "What do we need to know about to discover life in space?" N = R* • fp • ne • fl • fi • fc • L N = The number of civilizations in The Milky Way Galaxy whose electromagnetic emissions are detectable. R* =The rate of formation of stars suitable for the development of intelligent life ( #/yr). fp = The fraction of those stars with planetary systems. ne = The number of planets, per solar system, with an environment suitable for life. fl = The fraction of suitable planets on which life actually appears. fi = The fraction of life bearing planets on which intelligent life emerges. fc = The fraction of civilizations that develop a technology that releases detectable signs of their existence into space (for example, radio waves). L = The length of time such civilizations release detectable signals into space.

  14. Drake’s equation (2) fp is the number of suitable suns with planetary systems, now thought to be around 1/2 (i.e. 51 Pegasus discovery), a value that has made R is the average rate of star formation in the galaxy, equal to about 20 stars per year (i.e. recent HST observations of M16 showing star formation sites). scientists optimistic about the possibility of intelligent life elsewhere in the galaxy. fs is the fraction of stars that are suitable suns for planetary systems, approximately 0.1 (most stars belong to spectral type M ne is the mean number of planets that are located within the Continuously Habitable Zone (assuming liquid water is necessary for life) and are probably too small, whereas a few, such as O and B stars, are too short-lived). The circumstellar disk around Beta Pictoris is evidence of planetary formation.

  15. Drake’s equation (3) fl is the fraction of such planets on which life actually originates (given enough time primative organic substances will be synthesized into DNA and RNA, fi represents the fraction of such planets on which, after the origin of life, some form of intelligence arises (evolution probably occurs wherever life arises, and intelligence has survival value of 1.0. recent detection of the amino acid Glycene in the ISM by radio observations). fc is the fraction of such intelligent species that develop the ability and desire to communicate with other civilizations (they construct radio telescopes or laser systems) L is the mean lifetime (in years) of an advanced civilization (because it depends on the NATURE of the race ofintelligent beings it is the most uncertain factor in Drake's Equation)

  16. Project Phoenix • Search for radio signals from nearby stars. • In Southern hemisphere, Phoenix began observations in February, 1995 using the Parkes 210 foot radio telescope in New South Wales, Australia. • In Northern hemisphere, a 140 Foot Telescope at the National Radio Astronomy Observatory in Green Bank, West Virginia was online from September 1996 through April 1998. • Phoenix only scrutinizes the vicinities of nearby, sun-like stars. About 1000 stars have been targeted. All within 200 light years (well within our own galaxy). The 140 Foot Telescope at the National Radio Astronomy Observatory in Green Bank, West Virginia

  17. Project Phoenix(2) • In mid 1998, the Phoenix project moved to the world's largest antenna, the 1,000 foot diameter Arecibo Radio Telescope in Puerto Rico. • Radio frequency range: 1,000MHz to 3,000 MHz. • two three-week sessions each year. courtesy of the NAIC - Arecibo Observatory, a facility of the NSF

  18. Allen Telescope Array Problem: No funding and lack of observation time. Solution: Build dedicated telescope and ask Microsoft for money! (Paul Allen, and Nathan Myhrvold are former co-founder and CTO of Microsoft. Because of its ability to study many areas on the sky at once, with more channels and for 24 hours a day, the Allen Telescope Array will permit an expansion from Project Phoenix's stellar reconnaissance of 1,000 stars to 100 thousand or even 1 million nearby stars.

  19. The “WOW” event • The Wow! radio emission event entered the receiver of the Big Ear radio telescope at about 11:16 p.m, Aug. 15, 1977. • Location: right ascension was: 19h17m24s, declination was: -27 degrees and 3 minutes of arc (- 27d03m): in the direction of the constellation Sagittarius. Unfortunately, no signals resembling the Ohio State Wow were ever detected again.

  20. Message from Earth • What are these Earthlings trying to tell us? The above message was broadcast from Earth towards ther star cluster M13 in 1974. During the dedication of the Arecibo Observatory - still the largest radio telescope in the world - a string of 1's and 0's representing the above diagram was sent. This attempt at extraterrestrial communication was mostly ceremonial - humanity regularly broadcasts radio and television signals out into space accidentally. Even were this message received, M13 is so far away we would have to wait almost 50,000 years to hear an answer. The above message gives a few simple facts about humanity and its knowledge: from left to right are numbers from one to ten, atoms including hydrogen and arbon, some interesting molecules, DNA, a human with description, basics of our Solar System, and basics of the sending telescope. Severalsearches for extraterrestrial intelligence are currently underway, including Project Phoenix under the direction of Dr. Jill Tarter. (http://antwrp.gsfc.nasa.gov/apod/ap970717.html)

  21. Records on voyager • Voyager 1 and 2 are launched on August 20 and September 5, 1977. Gold-plated phonograph records contained in  aluminum cases were on board. • The Voyager Record contains images, sounds, and music of our planet selected by a committee headed by Carl Sagan. The Voyager records were attached to the outside of the Voyager 1 and 2 spacecraft. Contained in aluminum covers, the records are expected to survive in interstellar space for more than 1 billion years.

  22. Not the end • Are we alone? • If there is no other life, then it sure is a great waste of space(from the movie “contact”). Future of Human kind: dreams are maps --- Exploration of space and meaning of lives.

  23. References • http://www.seds.org/~rme/drakeeqn.htm • http://www.seti-inst.edu/seti/seti_science/Welcome.html • Viking project: http://nssdc.gsfc.nasa.gov/planetary/viking.html • Scientific results from Viking Project: Journal of Geophysical Research, "Scientific Results of the Viking Project", vol. 82, no. 28 • About Martian meteorite ALH 84001 http://www.lpi.usra.edu/lpi/meteorites/The_Meteorite.html • Steven Hawking’s public lectures: http://www.hawking.org.uk/lectures/lindex.html

  24. References (2) • Life in the universe: (a site of links) http://www.phys.ufl.edu/~avery/html/seti.html • On the “WOW” signal, http://www.setileague.org/articles/calibwow.htm • A site about Carl Sagan, http://www.planetary.org/html/news/subjectarchive/Sagan-idx.html

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