MARSBUGS: The Electronic Exobiology Newsletter Volume 3, Number 15, 13 November, 1996. Editors: David Thomas, Department of Biological Sciences, University of Idaho, Moscow, ID, 83844-3051, USA, thoma457@uidaho.edu. Julian Hiscox, Microbiology Department, BBRB 17, Room 361, University of Alabama at Birmingham, Birmingham, AL 35294-2170, USA, Julian_hiscox@micro.microbio.uab.edu. MARSBUGS is published on a weekly to quarterly basis as warranted by the number of articles and announcements. Copyright of this compilation exists with the editors, except for specific articles, in which instance copyright exists with the author/authors. E-mail subscriptions are free, and may be obtained by contacting either of the editors. Contributions are welcome, and should be submitted to either of the two editors. Contributions should include a short biographical statement about the author(s) along with the author(s)' correspondence address. Subscribers are advised to make appropriate inquiries before joining societies, ordering goods etc. Back issues may be obtained via anonymous FTP at: ftp.uidaho.edu/pub/mmbb/marsbugs. The purpose of this newsletter is to provide a channel of information for scientists, educators and other persons interested in exobiology and related fields. This newsletter is not intended to replace peer-reviewed journals, but to supplement them. We, the editors, envision MARSBUGS as a medium in which people can informally present ideas for investigation, questions about exobiology, and announcements of upcoming events. Exobiology is still a relatively young field, and new ideas may come out of the most unexpected places. Subjects may include, but are not limited to: exobiology proper (life on other planets), the search for extraterrestrial intelligence (SETI), ecopoeisis/ terraformation, Earth from space, planetary biology, primordial evolution, space physiology, biological life support systems, and human habitation of space and other planets. ----------------------------------------------------------------- 1) ASTEROID HIT AT DEADLY OBLIQUE ANGLE 65 MILLION YEARS AGO From The Brown University News Bureau 2) STARDUST COMET MISSION PASSES KEY MILESTONE JPL release 3) EARLIEST LIFE ON EARTH Communicated by Steve Mojzsis 4) FUTURE MOON, MARS EXPLORATION PLANS TO BE REVEALED Meeting announcement ----------------------------------------------------------------- ASTEROID HIT AT DEADLY OBLIQUE ANGLE 65 MILLION YEARS AGO From The Brown University News Bureau A new study says the asteroid that struck Earth 65 million years ago and wiped out the dinosaurs was particularly deadly to North America because it hit the Yucatan peninsula from the southeast at a 20- to 30-degree angle, spreading the devastating impact of its energy northwest. The oblique angle of the asteroid's contact with Earth coupled its impact energy with that of the atmosphere and planetary surface to send waves of ground-hugging, vaporous fireballs onward, the study says. This resulted in an extinction intensity most severe downrange of the impact in North America. The study suggests one rationale for the dire consequences of such an impact--the severity of extinctions that result from an object's impact on Earth may reflect the incoming object's angle. "This finding may help us determine what other impacts did to Earth in the past and what they may do in the future," said Peter Schultz, professor of geological sciences at Brown University. Schultz and Steven D'Hondt, professor of oceanography at the University of Rhode Island, are co-authors of the study in the November issue of the journal Geology. The researchers suggest that the relatively low angle of the Yucatan impact propelled a ballistic fireball downrange into North America. The fireball carried a two-mile-deep layer of vaporized rock and other material sheared off the Yucatan. The killing zone of matter cascaded through the atmosphere at near orbital speed, across North America and eventually around the globe. "It was like a nuclear explosion taken north on a jet-powered sleigh ride," Schultz said. "This was indeed the day the Earth shook." As evidence, the researchers show that the horseshoe-shaped Yucatan crater matches the structure of craters on the moon and Venus that were created when objects struck those heavenly bodies at oblique angles. Venus's thick atmosphere holds in place gases emitted from a crater after an impact. The researchers studied images of these corked-in Venusian vapors, which show that gaseous material is propelled in waves downrange after an object strikes a planetary surface at an oblique angle. Schultz used a high-powered gun to recreate the dynamics of an object striking Earth's surface at a 20- to 30-degree angle. The experiment produced horseshoe-shaped craters, while high-speed film captured gas and materials jettisoned downrange. The researchers said that biological evidence appears to support their oblique-impact hypothesis. North America, the first region to experience the fireball, had the most severe extinctions of plants. After the devastation, ferns dominated the flora of central North America. Ferns accounted for 70 to 100 percent of the spore- or pollen-producing plants in the region after the impact, compared with only 10 to 40 percent before it. At the base of the food chain, plants are considered sensitive indicators of environmental devastation. Because ferns reproduce through the use of hardy spores, the plants are regarded as key flora in colonizing the site of a natural disaster. Plants in parts of the world not downrange from the impact took a lesser hit from the corridor of incineration. For example, several ancient evergreen trees found in North America before the impact, but not after, still grow in parts of Australia and South America. Modern relatives of these trees, often called "primitive conifers," include the Norfolk Island pine, Chilean monkey puzzle and Wollemi pine. "The basic point of the study is that we can determine the impact angle of this object and that the angle matters," D'Hondt said. Most scientists study the aftermath of collisions that caused Earth's craters as if objects struck the planet at 90-degree angles, or from directly overhead. But such vertical impacts are very rare. An oblique angle of impact may have more deadly global consequences than a vertical impact, because an oblique impact should release a greater fraction of impact energy to the atmosphere and surface target, said Schultz and D'Hondt. "The study also underscores the point that regional repercussions can be expected from an Earth-object impact, something scientists have rarely considered in previous studies of this 65-million- year-old event," D'Hondt said. A link is provided for downloading the color transparencies in this release (see 2nd paragraph in heading). The URL is: http://www.brown.edu/Administration/News_Bureau/1996-97/96- 041g.html ----------------------------------------------------------------- STARDUST COMET MISSION PASSES KEY MILESTONE JPL release NASA's Stardust mission, which will gather samples of dust as it flies by a comet and return them to Earth, has passed a key milestone with completion of its preliminary design review. The project team got a thumbs up on its mission plans from an independent review board appointed by the space agency. Dr. Wesley T. Huntress, NASA's associate administrator for space science, confirmed the review board's conclusion that the project is ready to move forward into its development phase. "This tells us we are fully on track, ready to meet our schedule and cost control constraints," said Stardust Project Manager Ken Atkins of NASA's Jet Propulsion Laboratory, Pasadena, CA. Stardust is the latest in NASA's series of Discovery missions, which teams NASA with industry and universities to launch low- cost spacecraft in a short time frame with highly focused scientific goals. Successful completion of the review marks the end of the mission's concept definition phase--known in the aerospace industry as Phase B--and the start of design, development and fabrication, known as Phases C and D. NASA is committing nearly $118 million for Stardust development, with an additional $37 million necessary for mission operations. The next major review will come in June 1997 with a critical design review to confirm that design is complete and subsystems are on schedule for spacecraft integration, scheduled to begin in February 1998. Launch is planned for February 1999. During its journey through space, Stardust will loop twice around the Sun to collect interstellar dust particles before it flies past Comet Wild-2 in 2004. Stardust will gather dust and other materials spewed from the comet's tail and return the samples to Earth in 2006 for scientific study. The mission will be the first ever to return material from a solar system object other than the Moon. As the most primitive bodies in the solar system, comets hold great fascination for scientists, who believe they may reveal vital clues about the birth of the planets and the formation of life. The cosmic leftovers from planet formation, comets are rich in organic compounds and may have played a key role in the development of early life on Earth. Mission planners faced a tough challenge--how to capture comet dust as it whizzes by the spacecraft about seven times faster than a bullet fired from a rifle. The answer came in the form of aerogel, a sponge-like silica gel in which 99 percent of the volume is empty space. When a speck of comet dust hits the aerogel, it slows down gradually and comes to a stop, burying itself safely in the flexible material. Because aerogel is mostly transparent, scientists can trace the tracks to retrieve the comet dust. The minuscule bits of cargo will be stored in a capsule designed to separate from the spacecraft's main body and descend into Earth's atmosphere, landing in Utah. The main spacecraft will continue in orbit around the Sun indefinitely. Scientists are eagerly awaiting this opportunity to "get their hands on" particles of comet dust. "We guarantee the return of 1,000 particles larger than one-quarter the size of a human hair," said Stardust Principal Investigator Dr. Don Brownlee of the University of Washington. "Most likely there will be many additional particles of various sizes." Brownlee leads the team collaborating on Stardust. The spacecraft and sample return capsule are being built by Lockheed Martin Astronautics in Denver, CO. The mission is managed by NASA's Jet Propulsion Laboratory in Pasadena for NASA's Office of Space Science, Washington, DC; JPL is also developing the spacecraft's navigational camera. Stardust's cometary and interstellar dust analyzer instrument is provided by Jochen Kissel through the Max Planck Institute in Germany. ----------------------------------------------------------------- EARLIEST LIFE ON EARTH Communicated by Steve Mojzsis Evidence for life on Earth more than 3,800 million years ago is presented in a report on page 55 from Gustaf Arrhenius of the Scripps Institution of Oceanography in La Jolla, California and colleagues. Analysis of the oldest known sedimentary rocks, associated with a 3,800-year-old "banded iron" formation in Greenland, reveal tiny inclusions of carbonaceous material sealed within grains of apatite (calcium phosphate). The carbon is isotopically "light," that is, the "heavy" isotope of carbon, carbon 13, is less abundant, relative to carbon 12, than one would expect had the carbon been processed by known inorganic processes. The metabolic activities of living organisms are known to fractionate carbon isotopes in this way. Indeed, no inorganic process is known that can mimic this distinctive signature of life. This, together with the setting (within apatite grains) has all the hallmarks of past life. The Greenland rocks, which show signs of metamorphism consonant with their great age, bear no actual "fossils" of bacteria. The oldest known fossils come from the Apex Cherts of Australia, and are about 3,500 million years old (see Schopf, J. W., Science 260, 640-646; 1993). The new finds take the record of life right back to the formation of the earliest known sedimentary sequences. This raises challenging questions about the speed of the evolution of life, just two hundred million years or so after the young Earth had been subjected to a meteoritic bombardment of an intensity sufficient to sterilize the planet. John M. Hayes of the Woods Hole Oceanographic Institution, Woods Hole, Massachusetts discusses the research in an accompanying News and Views article. Full text of the report will be available online from midnight Wednesday 6 November: see Nature's web page at http://www.nature.com or http://www.america.nature.com CONTACT: Gustaf Arrhenius tel +1 619 534 2961, fax +1 619 534 2961, email arrhenius@ucsd.edu; John M. Hayes tel +1 508 289 2585; fax +1 508 457 2183; email jhayes@whoi.edu ----------------------------------------------------------------- FUTURE MOON, MARS EXPLORATION PLANS TO BE REVEALED Hotels on the Moon? What business ventures await entrepreneurs as Earth's Moon becomes a new site for "ROI": Return On Imagination? Is there presently life on Mars? What will the next wave of robot explorers find? Can a 21st century Mars be transformed into a second home for humanity? International Space Enterprises (ISE) and the National Space Society (NSS) announce the Third Annual International Lunar and Mars Exploration Conference, to be held in San Diego, California on November 17-20. Experts from industry, entrepreneurial firms, universities and NASA will review the promise of a rejuvenated space agenda for the 21st century in up- to-the-minute talks and discussion. Topics include establishing Lunar Base-1; low-cost robotic and human missions to Mars and the search for life; marketing space for commercial benefit; space tourism; and 21st century space transportation. Among the speakers: moonwalker, Apollo 17 astronaut Harrison Schmitt on future human presence on the Moon and Mars; Robert Zubrin, author of The Case for Mars--The Plan to Settle The Red Planet and Why We Must; Kenji Takaji & Shinji Matsumoto from Japan's Shimuzu Corporation on energy supplies for a lunar base; Michael Lawson of Space Marketing, Inc.; space tourism expert, Peter Diamandis of the X-Prize Foundation; John Kerridge, UCSD expert on the search for life on Mars; and Lockheed Martin's Jerry Rising to detail the X-33 project, stepping stone to single-stage-to-orbit rocketry. In a unique public demonstration, ISE will invite conference participants to view and operate the robotic Mars Seeker, a new prototype of a rover ISE hopes to deliver to Mars on a commercially financed, international voyage. The Mars Seeker prototype will be the centerpiece of a permanent interactive exhibit at NASA's Kennedy Space Center beginning in December. The conference, to be held at the beautiful Hyatt Islandia Hotel on San Diego's Mission Bay, will convene top lunar and planetary scientists and engineers. For registration details about the conference, or press information, please contact: Greg Nemitz of ISE [phone: (619) 637-5773, fax: (619) 637-5776]; via e-mail: isehq@aol.com] or call the National Space Society at (202) 543-1900. ----------------------------------------------------------------- End Marsbugs Vol. 3, No. 15.