Marsbugs: The Electronic Astrobiology Newsletter Volume 10, Number 37, 19 September 2003 (Special issue--Galileo's End) Editor/Publisher: David J. Thomas, Ph.D., Science Division, Lyon College, Batesville, Arkansas 72503-2317, USA. dthomas@lyon.edu Marsbugs is published on a weekly to monthly basis as warranted by the number of articles and announcements. Copyright of this compilation exists with the editor, except for specific articles, in which instance copyright exists with the author/authors. The editor does not condone "spamming" of subscribers. Readers would appreciate it if others would not send unsolicited e-mail using the Marsbugs mailing lists. Persons who have information that may be of interest to subscribers of Marsbugs should send that information to the editor. E-mail subscriptions are free, and may be obtained by contacting the editor. Information concerning the scope of this newsletter, subscription formats and availability of back-issues is available from the Marsbugs web page at http://www.lyon.edu/projects/marsbugs/. [http://www.hardyart.demon.co.uk/html/galileo.html] On 21 September 2003, the Galileo space probe will end its highly successful visit to Jupiter and its system of satellites by diving into the giant planet's atmosphere, its fuel and power exhausted. Despite the fact that its main antenna never deployed properly, Galileo has sent us the most wonderful images, and increased our knowledge enormously. It was launched from the Space Shuttle Atlantis in October 1989. This image shows how it may look as, glowing with friction, it begins to break up above the cloud belts. This process will of course begin much higher in the atmosphere, but it may survive to lower levels before vaporizing completely, and a little artist's license has been used! The scene may of course evoke sad memories of Columbia for many, though with no oxygen in this alien atmosphere Galileo cannot burn. It will glow and eventually vaporize, leaving an ionization trail. Galileo has been deliberately given a rather birdlike, symbolic appearance (a phoenix?), while remaining accurate. The volcanic moon Io appears at right, and lightning flashes in the clouds far below. Image credit: (c) David A. Hardy/AstroArt. ________________________________________________________________________ CONTENTS 1) GALILEO TO TASTE JUPITER BEFORE TAKING FINAL PLUNGE NASA release 2003-128 2) PLASMA BLOBS HINT AT NEW FORM OF LIFE By David Cohen 3) FAREWELL TO GALILEO By Cynthia Phillips 4) SURPRISING JUPITER: BUSY GALILEO SPACECRAFT SHOWED JOVIAN SYSTEM IS FULL OF SURPRISES NASA/JPL release ________________________________________________________________________ GALILEO TO TASTE JUPITER BEFORE TAKING FINAL PLUNGE NASA release 2003-128 17 September 2003 In the end, the Galileo spacecraft will get a taste of Jupiter before taking a final plunge into the planet's crushing atmosphere, ending the mission on Sunday, September 21. The team expects the spacecraft to transmit a few hours of science data in real time leading up to impact. The spacecraft has been purposely put on a collision course with Jupiter to eliminate any chance of an unwanted impact between the spacecraft and Jupiter's moon Europa, which Galileo discovered is likely to have a subsurface ocean. The long-planned impact is necessary now that the onboard propellant is nearly depleted. Without propellant, the spacecraft would not be able to point its antenna toward Earth or adjust its trajectory, so controlling the spacecraft would no longer be possible. "It has been a fabulous mission for planetary science, and it is hard to see it come to an end," said Dr. Claudia Alexander, Galileo project manager at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "After traversing almost 3 billion miles and being our watchful eyes and ears around Jupiter, we're keeping our fingers crossed that, even in its final hour, Galileo will still give us new information about Jupiter's environment." Although scientists are hopeful to get every bit of data back for analysis, the likelihood of getting anything is unknown because the spacecraft has already endured more than four times the cumulative dose of harmful jovian radiation it was designed to withstand. The spacecraft will enter an especially high-radiation region again as it approaches Jupiter. Launched in the cargo bay of Space Shuttle Atlantis in 1989, the mission has produced a string of discoveries while circling the solar system's largest planet, Jupiter, 34 times. Galileo was the first mission to measure Jupiter's atmosphere directly with a descent probe and the first to conduct long-term observations of the jovian system from orbit. It found evidence of subsurface liquid layers of salt water on Europa, Ganymede and Callisto and it examined a diversity of volcanic activity on Io. Galileo is the first spacecraft to fly by an asteroid and the first to discover a moon of an asteroid. The prime mission ended six years ago, after two years of orbiting Jupiter. NASA extended the mission three times to continue taking advantage of Galileo's unique capabilities for accomplishing valuable science. The mission was possible because it drew its power from two long-lasting radioisotope thermoelectric generators provided by the Department of Energy. From launch to impact, the spacecraft has traveled 4,631,778,000 kilometers (about 2.8 billion miles). Its entry point into the giant planet's atmosphere is about 1/4 degree south of Jupiter's equator. If there were observers floating along at the cloud tops, they would see Galileo streaming in from a point about 22 degrees above the local horizon. Streaming in could also be described as screaming in, as the speed of the craft relative to those observers would be 48.2 kilometers per second (nearly 108,000 miles per hour). That is the equivalent of traveling from Los Angeles to New York City in 82 seconds. In comparison, the Galileo atmospheric probe, aerodynamically designed to slow down when entering and parachute gently through the clouds, first reached the atmosphere at a slightly more modest 47.6 kilometers per second (106,500 miles per hour) when it was deployed in 1995. "This is a very exciting time for us as we draw to a close on this historic mission and look back at its science discoveries. Galileo taught us so much about Jupiter but there is still much to be learned, and for that we look with promise to future missions," said Dr. Charles Elachi, director of JPL. JPL, a division of the California Institute of Technology in Pasadena, manages the Galileo mission for NASA's Office of Space Science, Washington, DC. Additional information about the Galileo mission and its discoveries is available online at http://www.jpl.nasa.gov/galileo-legacy and http://galileo.jpl.nasa.gov. For information about NASA TV on the Internet, visit http://www.nasa.gov/multimedia/nasatv/index.html. For information about NASA, visit http://www.nasa.gov. Contacts: Carolina Martinez Jet Propulsion Laboratory, Pasadena, CA Phone: 818-354-9382 Donald Savage NASA Headquarters, Washington, DC Phone: 202-358-1547 Additional articles on this subject are available at: http://www.space.com/php/multimedia/imagegallery/ http://www.space.com/scienceastronomy/goodbye_galileo_030916.html http://www.spacedaily.com/news/galileo-03g.html http://www.spacedaily.com/news/galileo-03h.html http://www.spacedaily.com/2003/030917225334.z9pm5odx.html http://www.universetoday.com/am/publish/galileo_impact_soon.html ________________________________________________________________________ PLASMA BLOBS HINT AT NEW FORM OF LIFE By David Cohen From New Scientist 17 September 2003 Physicists have created blobs of gaseous plasma that can grow, replicate and communicate--fulfilling most of the traditional requirements for biological cells. Without inherited material they cannot be described as alive, but the researchers believe these curious spheres may offer a radical new explanation for how life began. Most biologists think living cells arose out of a complex and lengthy evolution of chemicals that took millions of years, beginning with simple molecules through amino acids, primitive proteins and finally forming an organized structure. But if Mircea Sanduloviciu and his colleagues at Cuza University in Romania are right, the theory may have to be completely revised. They say cell-like self-organization can occur in a few microseconds. The researchers studied environmental conditions similar to those that existed on the Earth before life began, when the planet was enveloped in electric storms that caused ionized gases called plasmas to form in the atmosphere. They inserted two electrodes into a chamber containing a low-temperature plasma of argon--a gas in which some of the atoms have been split into electrons and charged ions. They applied a high voltage to the electrodes, producing an arc of energy that flew across the gap between them, like a miniature lightning strike. Sanduloviciu says this electric spark caused a high concentration of ions and electrons to accumulate at the positively charged electrode, which spontaneously formed spheres (Chaos, Solitons & Fractals, 18:335). Each sphere had a boundary made up of two layers--an outer layer of negatively charged electrons and an inner layer of positively charged ions. Trapped inside the boundary was an inner nucleus of gas atoms. The amount of energy in the initial spark governed their size and lifespan. Sanduloviciu grew spheres from a few micrometers up to three centimeters in diameter. Split in two A distinct boundary layer that confines and separates an object from its environment is one of the four main criteria generally used to define living cells. Sanduloviciu decided to find out if his cells met the other criteria: the ability to replicate, to communicate information, and to metabolize and grow. He found that the spheres could replicate by splitting into two. Under the right conditions they also got bigger, taking up neutral argon atoms and splitting them into ions and electrons to replenish their boundary layers. Finally, they could communicate information by emitting electromagnetic energy, making the atoms within other spheres vibrate at a particular frequency. The spheres are not the only self-organizing systems to meet all of these requirements. But they are the first gaseous "cells". Sanduloviciu even thinks they could have been the first cells on Earth, arising within electric storms. "The emergence of such spheres seems likely to be a prerequisite for biochemical evolution," he says. Temperature trouble That view is "stretching the realms of possibility," says Gregoire Nicolis, a physical chemist at the University of Brussels. In particular, he doubts that biomolecules such as DNA could emerge at the temperatures at which the plasma balls exist. However, Sanduloviciu insists that although the spheres require high temperature to form, they can survive at lower temperatures. "That would be the sort of environment in which normal biochemical interactions occur." But perhaps the most intriguing implications of Sanduloviciu's work are for life on other planets. "The cell-like spheres we describe could be at the origin of other forms of life we have not yet considered," he says. Which means our search for extraterrestrial life may need a drastic re- think. There could be life out there, but not as we know it. Read the original article at http://www.newscientist.com/news/news.jsp?id=ns99994174. ________________________________________________________________________ FAREWELL TO GALILEO By Cynthia Phillips From Space.com 18 September 2003 September 21, 2003, will mark the end of an important era in space exploration, when the robotic spacecraft Galileo dives into Jupiter's atmosphere, ending its 8-year mission in the Jovian system. Galileo arrived at Jupiter in 1995, but its journey started long before that. Originally planned in the 1970s, the spacecraft was the first outer solar system orbiter; a follow-up to the flybys of Jupiter conducted by the Pioneer and Voyager spacecraft. Even before the wildly successful flybys of Jupiter conducted in 1979 and 1980 by the two Voyager spacecraft, scientists knew that Jupiter and its large Galilean satellites were likely to be interesting destinations, worthy of future scientific study. However, it's unlikely that the scientists originally designing Galileo knew just how exciting Jupiter's moons would turn out to be. Read the full article at http://www.space.com/searchforlife/seti_phillips_galileo_030918.html. ________________________________________________________________________ SURPRISING JUPITER: BUSY GALILEO SPACECRAFT SHOWED JOVIAN SYSTEM IS FULL OF SURPRISES NASA/JPL release 18 September 2003 After orbiting Jupiter 34 times and surviving four times the amount of radiation it was design to withstand, the resilient Galileo spacecraft is finally at the very end of its 14-year mission. To avoid even the most remote possibility of colliding with a pristine moon in the jovian system, the out-of-fuel spacecraft will dive into Jupiter on Sunday, September 21, 2003. Since its launch in 1989, the sturdy spacecraft traveled more than 4.6 billion kilometers (almost 2.8 billion miles), about the equivalent of seven times the distance between Earth and Jupiter. Despite communication problems and a temperamental tape recorder, Galileo returned 30 gigabytes of data, including 14,000 pictures. This wealth of information drastically expanded our understanding of the solar system's biggest planet and its moons. The mission was possible because it drew its power from two long-lasting radioisotope thermoelectric generators provided by the Department of Energy. Asteroids unveiled The exciting list of discoveries started even before Galileo was able to get a close glimpse of Jupiter. As it crossed the asteroid belt in October 1991, Galileo snapped images of Gaspra, returning the first ever close-up image of an asteroid. Less then a year later, the spacecraft got up close and personal with yet another asteroid, Ida. Images from Ida revealed the asteroid has its own little "moon," Dactyl, the first known moon of an asteroid. Location, location In 1994 the spacecraft was in the right place at the right time and made the only direct observation of a comet impacting a planet. It took images of fragments of comet Shoemaker-Levy 9 crashing into Jupiter. Images of the impact, which was not visible from Earth, helped scientists better understand this type of event. At Jupiter Galileo began its tour of the jovian system in December 1995. Carefully designed orbits allowed the spacecraft to observe Jupiter's atmosphere, revealing numerous large thunderstorms many times larger than those on Earth, with lightning strikes up to 1,000 times more powerful than terrestrial lightning. Data collected by the descent probe made the first in-place studies of the planet's clouds and winds, and it furthered scientists' understanding of how Jupiter evolved. The probe also made measurements designed to assess the degree of evolution of Jupiter compared to the Sun. As the first spacecraft in long-term residence in jovian orbit, Galileo also successfully studied the global structure and dynamics of Jupiter's magnetic field. Galileo also determined that Jupiter's ring system is formed by dust kicked up as interplanetary meteoroids smash into the planet's four small inner moons. Data also showed that Jupiter's outermost ring is actually made up of two rings, one embedded within another. Moons' wonders Galileo extensively investigated the geologic diversity of Jupiter's four largest moons: Ganymede, Callisto, Io and Europa. Stunning images revealed the contrasting and changing surfaces of these moons. Io has extensive volcanic activity, which is continually modifying the surface. The heat and the frequency of eruption can be 100 times more than that of Earth, something reminiscent of Earth's early days. The similarities make Io an ideal laboratory for the study of what Earth was like more than 3 billion years ago. The moon Europa, Galileo unveiled, could be hiding a salty ocean up to 100 kilometers (62 miles) deep underneath its frozen surface. Images also reveal ice "rafts" the size of cities that have broken and drifted apart to create a scalloped and broken surface. There are also indications of volcanic ice flows, with liquid water flowing across the surface. These discoveries are particularly intriguing since liquid water is a key ingredient in the process that may lead to the formation of life. The biggest discovery surrounding Ganymede was the presence of a magnetic field, the first moon of any planet known to have one. Images of this moon featured a faulted and fractured surface that demonstrated high tectonic activity. Like Europa and Io, Ganymede has a metallic core. Galileo magnetic data also provided evidence that Ganymede might have a liquid-saltwater layer as well. Galileo determined that, while Callisto doesn't have a metallic core, its surface shows evidence of extensive erosion. Data collected raise the question of whether Callisto's surface may also hide an ocean. Last dance Galileo's own discovery of a likely ocean hidden under Europa's surface raises the possibility of life there and concern about protecting it. For that reason, in its final victory lap the Galileo spacecraft will dive into the atmosphere of the gaseous planet and disintegrate. Predictably, some of the spacecraft findings raised intriguing questions that will have to be answered by future mission. But Galileo Galilei, the first modern astronomer, would be immensely proud of the discoveries made by the spacecraft that carries his name. Contact: Carolina Martinez, JPL Phone: 818-354-9382 ________________________________________________________________________ End Marsbugs, Volume 10, Number 37 2