MARSBUGS: The Electronic Exobiology Newsletter Volume 4, Number 11, 9 July, 1997. Editors: David Thomas, Department of Biological Sciences, University of Idaho, Moscow, ID, 83844-3051, USA, thoma457@uidaho.edu or Marsbugs@aol.com. Julian Hiscox, Division of Molecular Biology, IAH Compton Laboratory, Berkshire, RG20 7NN, UK. Julian.Hiscox@bbsrc.ac.uk or Marsbug@msn.com 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. --------------------------------------------------------------- INDEX 1) ASTEROID MATHILDE REVEALS HER DARK PAST NASA release: 97-147 2) MARS GLOBAL SURVEYOR FLIGHT STATUS REPORT JPL release 3) MARS PATHFINDER MISSION STATUS REPORTS JPL releases 4) NASA RENAMES MARS LANDER IN HONOR OF LATE CARL SAGAN NASA release --------------------------------------------------------------- ASTEROID MATHILDE REVEALS HER DARK PAST NASA release: 97-147 More than 100 years after her discovery, asteroid 253 Mathilde has been sharing her secrets with scientists in the Science Data Center at the Johns Hopkins University Applied Physics Laboratory in Laurel, MD. A 25-minute flyby of the asteroid by NASA's Near Earth Asteroid Rendezvous (NEAR) spacecraft on June 27 has resulted in spectacular images of a dark, crater- battered little world assumed to date from the beginning of the solar system. The Mathilde flyby is the closest encounter with an asteroid to date and the first with a C-type asteroid. The asteroid's mean diameter was found to be 33 miles (52 kilometers), which is somewhat smaller than researchers originally estimated. A study of the asteroid's albedo (brightness or reflective power) shows that it reflects three percent of the Sun's light, making it twice as dark as a chunk of charcoal. Such a dark surface is believed to consist of carbon-rich material that has not been altered by planet-building processes, which melt and mix up the solar system's original building block materials. The Mathilde flyby met all its initial goals: getting a clear image of the sunlit side of the asteroid, getting color images that will give clues to the types of rock that make up the asteroid, and getting images that will help researchers determine if Mathilde has any moons. In the next month, scientists expect to complete initial analysis of their data and have improved measurements of Mathilde's volume, mass, and density. "The Mathilde encounter was one of the most successful flybys of all time," said Dr. Robert W. Farquhar, of the Applied Physics Laboratory, NEAR Mission Director. "We got images that were far better than we thought possible, especially since the spacecraft was not designed for a fast flyby." Only the multispectral imager, one of six instruments on the spacecraft, was used during the flyby in order to conserve power provided by solar-powered panels. The spacecraft was approximately 186 million miles from the Sun, too far to provide power for NEAR's other instruments. "Even though this was a very difficult undertaking," said Dr. Stamatios M. Krimigis, head of the APL Space Department that managed the program for NASA, "the NEAR Operations Team was so well prepared there was little doubt that it would succeed; not only that, but this was the smallest operations team of any planetary encounter, proving that the Discovery Program paradigm of 'smaller, faster, cheaper' is alive and well." Although Mathilde proved to be rounder than asteroids such as Gaspra and Ida, Dr. Joseph Veverka of Cornell University, Ithaca, NY, who leads the mission's imaging science team, said, "Mathilde turned out to be more irregularly shaped than most of us expected. The degree to which the asteroid has been battered by collisions is astounding. At first glance there are more huge craters than there is asteroid." The imager found at least five craters larger than 12 miles (20 kilometers) in diameter just on the lighted side of the asteroid. Scientists wonder how the asteroid can remain intact after having been hit by this many projectiles, each probably at least a mile wide. The craters reveal evidence of the asteroid's makeup. "We knew that C-asteroids are black, but we did not expect their surfaces to be as uniformly black and colorless as Mathilde's surface turned out to be," Veverka said. "This global blandness is an important clue telling us that asteroids such as Mathilde are made of the same dark, black rock throughout because none of the craters, which are punched deep into the asteroid, show evidence of any other kind of rock." Such uniformity seems to confirm that C-type asteroids are in fact pristine samples of the primitive building blocks of the larger planets. Dr. Donald K. Yeomans of the Jet Propulsion Laboratory, Pasadena, CA, who heads the radio science team formed to determine Mathilde's mass said, "Mathilde is an asteroid with a very tortured past." By determining the bulk density of the asteroid, researchers will have a clue to how it was formed. A composite of objects would have a lower density than a solid chunk from a larger asteroid. Data analysis to determine density will not be complete until later this year, but Dr. Yeomans said, "Preliminary results suggest that Mathilde is much less dense than we had thought." One mystery that remains is Mathilde's extraordinarily slow (17.4 days) rotation rate. Its collision history could be a factor, but more research needs to be done to determine what role such collisions have played. The search for Mathilde moons continues; none has yet been discovered. The next major event of the NEAR mission will occur on July 3, when the spacecraft's bi-propellant engine is fired to head NEAR back toward Earth. This deep-space maneuver will be the first time the engine has been fired and will keep both engineers and scientists in suspense for 11 minutes before they know if the maneuver was successful. An Earth gravity-assist maneuver on Jan. 23, 1998, will send the spacecraft toward its primary target, asteroid 433 Eros. NEAR will reach Eros nearly a year later and will remain locked in orbit around the asteroid until Feb. 6, 2000, when the mission ends. Commenting on the success of the Mathilde flyby soon after the first images were received, Dr. Wesley T. Huntress Jr., NASA Associate Administrator, Office of Space Science, said, "It's today that the Discovery Program really begins. NEAR was the first of our Discovery missions to be launched and it's the first to return scientific results." He said the APL-led team that managed the NEAR program proved the concept behind the Discovery Program: that exciting planetary missions can be done at low cost, in a short time. The NEAR spacecraft was launched Feb. 17, 1996, from Cape Canaveral Air Station in Florida. NEAR Science Team Group Leaders are: Joseph Veverka, Cornell University; Jacob I. Trombka, NASA/Goddard Space Flight Center, Greenbelt, MD; Mario H. Acuna, NASA/Goddard; Maria T. Zuber, MIT and NASA/Goddard; and Donald K. Yeomans, NASA/Jet Propulsion Laboratory, Pasadena, CA. Andrew Cheng, JHU/APL, is the Project Scientist. The Johns Hopkins University Applied Physics Laboratory operates the mission for NASA's Office of Space Science, Headquarters, Washington, DC. Mathilde flyby images and updates can be obtained on the Mathilde homepage at: http://sd-www.jhuapl.edu/NEAR/Mathilde --------------------------------------------------------------- MARS GLOBAL SURVEYOR FLIGHT STATUS REPORT JPL release Friday, 4 July 1997 Late Wednesday afternoon, the Mars Orbiter Camera aboard the Surveyor spacecraft imaged the red planet for the first time during the mission. This image was obtained by rotating the spacecraft into a position that pointed the camera directly at Mars for a period of one hour. Communications with the spacecraft during the imaging opportunity was not possible because the Mars-pointed orientation resulted in pointing the high-gain antenna away from the Earth. Consequently, all of the data from the camera was stored on Surveyor's solid-state recorders. This data was transmitted back to Earth approximately five hours after the image was taken. The playback of camera data required 55 minutes to complete. During that time, Surveyor transmitted more than 250 megabits of data at a downlink rate of 85,333 bits per second. The image, taken from a distance of 17.2 million kilometers, shows a global view of the planet centered on the Mars Pathfinder landing site at Ares Valles. Although Mars appears at lower resolution in this image as compared to those that will be taken from orbit later this year, the image allowed the Pathfinder team to ascertain that a recently detected dust storm brewing in the Valles Marineris canyon system will not affect weather conditions for today's scheduled landing. After a mission elapsed time of 239 days from launch, Surveyor is 175.03 million kilometers from the Earth, 16.72 million kilometers from Mars, and is moving in an orbit around the Sun with a velocity of 21.96 kilometers per second. This orbit will intercept Mars 69 days from now, slightly after 6:00 p.m. PDT on September 11th (01:00 UTC, September 12th). The spacecraft is currently executing the C9 command sequence, and all systems continue to be in excellent condition. The Mars Global Surveyor flight team would like to take this opportunity to extend our best wishes to our Mars Pathfinder colleagues for a safe landing today and a successful mission. The image of the Mars taken from Surveyor may be downloaded at: http://mgsw3.jpl.nasa.gov/sci/moc/approach/approach.html Status report prepared by: Office of the Flight Operations Manager Mars Surveyor Operations Project NASA Jet Propulsion Laboratory California Institute of Technology Pasadena, CA 91109 --------------------------------------------------------------- MARS PATHFINDER MISSION STATUS REPORTS JPL releases July 4, 1997, 7:30 a.m. Pacific Daylight Time Mars Pathfinder is right on course for a landing in Ares Vallis, an ancient outflow channel in the northern hemisphere of Mars, at 10:07 a.m. Pacific Daylight Time today. The navigation team reported that the final trajectory correction maneuver, which could have been performed either 12 hours or six hours prior to Pathfinder's entry into the upper atmosphere, was not necessary. An early morning orbital update indicated that Pathfinder was heading straight for the center of its 60-mile-by-120-mile landing ellipse and was expected to enter the upper atmosphere at a 13.9-degree angle, just three- quarters of a degree off its original entry angle of 14.2 degrees. Pieter Kallemeyn, navigation team chief, estimated that the spacecraft would touch down at 19.0 degrees north latitude, 326.3 degrees east longitude. "To give you an idea of the accuracy that we have achieved here, this is the equivalent of playing a round of golf in which the hole is in Houston, Texas, and the tee-off is in Pasadena, California," Kallemeyn said. "We're basically hitting a hole in one here." Spacecraft events prior to landing will include release of the cruise stage at about 9:32 a.m. PDT; entry into the upper atmosphere at about 10:02 a.m. PDT; and landing 4.5 minutes later. The spacecraft is currently about 198,000 kilometers (123,000 miles) from Mars, traveling at a velocity of about 24,500 kilometers per hour (15,277 miles per hour) with respect to Mars. The flight team expects to receive the first low-gain signal from the spacecraft at about 2:07 p.m. PDT. Contained in that transmission will be information about the spacecraft's entry, descent and landing, atmospheric science data and details on the health of the lander and rover. July 4, 1997, 4 p.m. Pacific Time Mars Pathfinder successfully landed on the surface of Mars at 10:07:25 a.m. Pacific time, marking NASA's historic return to the red planet after more than 20 years. The Pathfinder flight team received nearly instantaneous confirmation that the spacecraft had landed from an independent antenna mounted on one of the spacecraft's petals. Detection of the very weak signal, which came as a surprise, also indicated that the craft had landed on its base petal, thus eliminating the spacecraft's next task: to stand itself upright before deploying its petals. Approximately 90 minutes after landing, engineering data indicated that Pathfinder had fully deployed its petals and was awaiting sunrise on Mars to power up. The flight team reported that the lander came to rest about 12 miles southwest of its targeted landing spot and was resting on the surface at a very slight tilt of about 2.5 degrees. Pathfinder's first low-gain antenna transmission was received right on time at 2:07 p.m. PDT. The transmission contained preliminary information about the health of the spacecraft and rover, the spacecraft's orientation on the surface, data about its entry, descent and landing, and a first look at the density and temperatures of the Martian atmosphere. Preliminary data from the atmospheric science instrument indicated that temperatures are somewhat warmer than they were in the Viking days of the mid-1970s. Dr. Timothy Schofield, principal investigator of the atmospheric science team, said early data suggested it was about minus 220 degrees Celsius (minus 64 degrees Fahrenheit) at the landing site. July 4, 1997, 9:15 p.m. Pacific Time The Mars Pathfinder imaging team tonight unveiled the first photograph of Ares Vallis, an ancient water channel that at one time in Mars' early history carried more than 1,000 times the amount of flowing water carried by the Amazon River today. The color panorama, which drew enthusiastic applause at a 6:30 p.m. press briefing, was taken by the lander's Imager for Mars Pathfinder camera -- called the "IMP" -- before the camera was deployed on its mast. The photograph revealed a rocky desert scape with numerous large boulders and mountains on the horizon. The images were transmitted during Pathfinder's first high gain antenna transmission, which began at 4:28 p.m. PDT today. Totaling about 120, the postage stamp-sized black-and-white frames also included close-up photographs of the lander petals with the rover sitting in its stowed position in the foreground. Closer examination showed that one of the airbags did not fully retract and had become draped slightly over the edge of the rover's petal. The Pathfinder flight and rover teams decided to test a new command sequence that would pull the obstructed petal up about 45 degrees, further retract the airbag, then lay the petal down again. The team tested this command sequence before uplinking it to the spacecraft starting at about 7:08 p.m. PDT. Return images from that transmission will be used by the rover team to determine if the "petal move" sequence cleared the petal enough to allow for safe deployment of the rover ramps. Part of the image data were not received during the next downlink session due to a problem with the Deep Space Network tracking station. The remaining images were scheduled to be retransmitted during the last transmission of the day, which was to begin at 10 p.m. PDT. If ramp deployment is postponed, the flight team will perform this activity Saturday morning. The rover would then be ready to roll off its ramp and onto the surface of Mars by about 5 p.m. PDT July 5. July 5, 1997, Noon Pacific Daylight Time After receiving hundreds of new images of a boulder-strewn outflow channel known as Ares Vallis, NASA's Mars Pathfinder flight team spent the rest of Sol 1 -- the equivalent of one day on Mars -- rearranging an airbag that was covering the edge of the rover's petal so that the hearty, 23-pound vehicle can safely roll off its ramp later this afternoon. The rover team decided last night to conduct further airbag retraction after studying the first set of black-and-white images to be returned via Pathfinder's high-gain antenna. A new software sequence was prepared and tested prior to transmission at 7:08 p.m. PDT. The command instructed the lander to pull the obstructed petal up about 45 degrees, further retract the airbag underneath the petal, then lay the petal down again. Data later in the evening indicated that the maneuver had been successful in clearing the airbag from the edge of the rover's petal. Before Earth set on Mars at about 10:30 p.m. PDT, telecommunications engineers reported that Sojourner, which is programmed to communicate with the lander as frequently as every 10 minutes, was not "completing full sentences" in its transmissions to the lander. Dr. Jacob Matijevic, rover team leader, said at a 10 a.m. PDT press briefing today that the problem is most likely a software synchronization problem between the rover and lander. The team will conduct a brief communications session at 1 p.m. PDT to reset some of the modem parameters on the rover. Meanwhile, the team was still waiting to learn if a set of commands set last night to deploy the second ramp and unlatch the rover had been carried out. They expected confirmation one way or the other during the next high-gain antenna downlink session at 2:30 p.m. PDT today. Once the ramp has been unfurled, the rover will stand up to its full height of 1-foot tall and roll off the forward ramp. The rover team reported today that the front ramp appears to be the safest exit route with fewer rocks on the surface at the end of the ramp. Sojourner will not be deployed until about 7:40 p.m. and will spend about five minutes driving off its ramp. Scientists spent several hours last night comparing the landing site to Viking images of the region. Dr. Peter Smith, principal investigator on the lander camera team, said the lander is about 20 miles south of a large mountain peak and within about 3 to 4 kilometers (1.8 to 2.4 miles) northwest of the rim of a crater believed to be at least several miles in diameter. Dr. Matthew Golombek, the Mars Pathfinder project scientist, added that two rocks in the immediate vicinity of the lander, had been singled out as the first targets for the rover's travels, based on their varying colors and shapes, which may suggest different origins and compositions. Earth rise over Mars -- which brings Earth into the proper alignment for communications with the Pathfinder lander and rover -- began at 10:08 a.m. PDT today. The operations team has about 11 hours in which to conduct surface operations during this second day of Mars exploration. A press briefing to update the day's events will be held at 5 p.m. PDT and a final, wrap-up briefing will be held at 9 p.m. PDT. Both will be carried on NASA TV, which is available on GE-2, transponder 9C at 85 degrees west longitude, vertical polarization, with a frequency of 3880 MGz and audio of 6.8 MHz. 5 July 1997, 11:30 pm PDT After a very tense early morning, when communications with the still stowed Sojurner rover were intermittent and unreliable, the second sol on Mars has turned to triumph. At approximately 5:00 pm Pacific Daylight Time, confirmation that communications were reliably re-established with the rover was received in Mission Control. Two hours later, during the next downlink session, confirmation was received that the rover deployment ramps were deployed on both sides of the petal on which it rested. After careful analysis of the images provided by the IMP camera, rover controllers decided to deploy the rover off the right-hand ramp. Stand up was confirmed during the final downlink session of this historic day, and the IMP again provided dramatic pictures of the rover moving down the selected ramp onto the surface of the Red Planet. Clear tracks were visible in the dusty soil and the rover came to rest about 10 cm from a nearby rock. During the martian night it will deploy its Alpha Proton X-Ray Spectrometer (APXS) onto the surrounding soil for 10 hours, and finally go into "sleep" mode to await the dawn of the next exciting new sol. July 5, 1997, 11:50 p.m. PDT Mars Pathfinder's robust, 23-pound rover named Sojourner successfully rolled off its ramp tonight and onto the Martian surface, becoming the first robotic vehicle ever to explore the surface of another planet. The first image showing Sojourner with its six wheels firmly planted in sandy Martian terrain was received on Earth at about 10:59 p.m. PDT. The rover team did not know immediately what time the rover actually set foot on Martian soil. Rover deployment occurred within 10 minutes of Earth set, at which time telecommunications on Mars ceases as the Earth disappears below the horizon. Two-way communications resume at about 11 a.m. PDT on Sunday, July 6. The operations team examined a set of black-and-white images showing the ramp deployment before activating the command sequence to deploy the rover. More than 90 frames coming down during an 8 - 9:15 p.m. PDT transmission showed that both ramps were situated at angles well within the limits of safe deployment. The rover team sent Sojourner down the rear ramp, or the ramp on the right side of the lander, which was tilted at just 20 degrees from the surface. The rover would not have been able to roll off the ramps had they exceeded a 30-degree tilt. Sojourner made the trek down its ramp in two stages, first crawling half way down the ramp and stopping to take a photograph of the ramp, then continuing its 4-minute journey off the ramp. Additional images showed rover wheel tracks in soft Martian soil and the rover standing about 10 centimeters (0.3 feet) from the end of the ramp. The lander's camera also took photographs of the rover's exit. Once off the ramp, Sojourner unlatched its primary science instrument, an alpha proton X-ray spectrometer, and positioned it face down in the Martian soil to take 10 hours of measurements overnight. The first science investigations beginning on Sunday, July 6, the third day of surface operations, are likely to include a soil mechanics experiment to observe how the rover's wheels and mobility system operate on the Martian surface and a rover photography session to create a "monster pan" of the surface in multiple color, high resolution format. The operations team also plans to increase Pathfinder's data rate to 6,300 bits per second to retrieve as much data as possible over the next week, which marks the primary lifetime of the rover. A press briefing to announce science activities for day three is scheduled for 10 a.m. PDT on Sunday, July 6, in JPL's von Karman Auditorium. The public is encouraged to follow Mars Pathfinder mission activities via the World Wide Web by visiting the Pathfinder site at: http://mpfwww.jpl.nasa.gov. Status reports prepared by: Office of the Flight Operations Manager Mars Pathfinder Project NASA Jet Propulsion Laboratory California Institute of Technology Pasadena, CA 91109 --------------------------------------------------------------- NASA RENAMES MARS LANDER IN HONOR OF LATE CARL SAGAN NASA release July 5, 1997 NASA honored the legacy of Dr. Carl Sagan today when Administrator Daniel S. Goldin named the Mars Pathfinder lander the Carl Sagan Memorial Station. "Carl Sagan was a very unique individual who helped young and old alike to dream about the future and the possiblities it may hold," Goldin said. "Carl always liked to push the boundaries too, and the Mars Pathfinder mission, with its rover named Sojourner, clearly has done that. Even its very first images contain an array of fascinating scientific questions that he would have loved to debate. We will explore the area with his memory in mind." Goldin made the announcement at Planetfest '97 in Pasadena, CA, an event organized by the Planetary Society, the public space interest group that Sagan founded with Bruce Murrary and Lou Friedman in 1980. Sagan played a leading role in NASA's Mariner, Viking, Voyager and Galileo expeditions to other planets. He has received NASA Medals for Exceptional Scientific Achievement and twice for Distinguished Public Service, and the NASA Apollo Achievement Award. Sagan died on December 20, 1996, at age 62. The naming is reminiscent of the memorial dedication of the Mars Viking Lander 1 in January 1981 to Dr. Thomas Mutch, a NASA associate administrator for space science and former leader of the Viking Lander Imaging Science Team, who died on October 7, 1980, while climbing in the Himalayas. --------------------------------------------------------------- End Marsbugs, Vol. 4, No. 11