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PART 1: Upcoming webchats in English and
Spanish! [Note: We will begin to publish Mars Team Online updates a bit less frequently. Look for updates a couple times a month.] UPCOMING WEBCHATS IN ENGLISH AND SPANISH!
Wednesday, April 8, 1:00 p.m.- 2:00 p.m., Pacific Time: Cesar Sepulveda, optical engineer: Cesar Sepulveda is a member of the Optical Engineering technical staff at the NASA Jet Propulsion Laboratory in Pasadena, CA. He is part of a team that is responsible for designing and constructing the navigation cameras on the Mars Pathfinder and Rover. Cesar's team has also been part of the development of other lander and rover miniature cameras. Cesar will be accepting and responding to questions in both English and Spanish during the chat. Register for the webchat at: http://quest.arc.nasa.gov/mars/events/interact.html Friday, April 24, 12:00 p.m.- 1:00 p.m., Pacific Time: Jennifer Harris, lead integration and test engineer: Jennifer spends her days working on the Mars 2001 Rover Control and Navigation (C&N) Subsystem, which is basically "the brains" of the rover. Any computers, software, cameras, etc. necessary for the rover to make smart decisions about where to go and how to get there are in this subsystem. Jennifer also works on the Mars 2001 Mission Operations Team, trying to figure out how to fit all of the activities that the rover needs to do into a day and still have enough power for communications, battery charging, etc. Prior to the chat, please read Jennifer's biography at: http://quest.arc.nasa.gov/mars/team/harris.html Beginning April 10, you can register for the chat with Jennifer at: http://quest.arc.nasa.gov/mars/events/interact.html GLOBAL TIME ZONE INFORMATION
Do you want to participate in our webchats but find it difficult to translate our times to your local timezone? If so, check out the World Time Zones page at http://tycho.usno.navy.mil/tzones.html There you'll find listings and a map that will allow you to see the relationship between any two time zones. All of our chats are held in the Pacific timezone (Pacific Standard Time or Pacific Daylight Time). NEW AND REVISED MARS TEAM BIOS
This week we present you with three completely new biographies and one revised bio. Dive in at: http://quest.arc.nasa.gov/mars/team/ Dwight Holmes, Deep Space Network: Did you ever wonder how our Mars Team Members landed their jobs at NASA? "As miracles sometimes happen, I was in the right place at the right time. I was fresh with a masters degree in space physics with a background in communications systems. The Air Force had provided me with wonderful education in digital communications. (It's the 'in thing' today with cell phone technology, but only the military and NASA knew much about it back in the early 70s) JPL was looking for Voyager team members. The Voyager Radio Science team needed support staff to conduct the experiments, develop plans, verify the instrumentation and validate the data. The requirements for such a position just happened to be someone with a background in telecommunications and physics." Read more about Dwight's career in his bio at: http://quest.arc.nasa.gov/mars/team/holmes.html Kyle Martin, Real-time Operations Lead for MGS: Let Kyle set an example for your students. In one section of his bio, Kyle discusses his influences. "In junior high, I checked out a book from the library on World War II aviation. At that time I hated to read and since I had to do a book report, I grabbed the first book I saw. I fell in love with planes and aviation right there! After that, I bought or checked out every book on aviation I could put my hands on. I knew I wanted to be a military pilot and an aerospace engineer. That motivated me all the way through high school and into college." Read more about Kyle at: http://quest.arc.nasa.gov/mars/team/martin.html Nathan Bridges, Planetary Geologist: In his biography, Nathan describes the feeling of space exploration: "The landing on Mars on July 4, 1997 was one of the most spectacular days of my life and I shall never forget it. I can still remember the cheers and tears of joy when the first signals and pictures came back. It was exploration at its finest. However, despite all the excitement, I had a lot of work to do. During the first few weeks of operations I actually had very little time to devote to science. Much of my time was spent in meetings, where we discussed and decided upon future operations and heard what other scientists had found." Check out Nathan's full bio at: http://quest.arc.nasa.gov/mars/team/bridges.html Charles Whetsel, Chief Project Engineer for Mars Surveyor Operations: Learn just how much Charles likes his job. "I enjoy my job a lot because, in addition to all of the different kinds of technology it exposes me to, it also requires a lot of teamwork. A spacecraft itself (as well as many of the subsystems of which it is made) is so complicated that it is almost impossible for a single person to be able to understand everything that is required to complete the mission. I spend a large part of my time using both technical and communication skills (translating something from one technical specialist into something another specialist can understand). Sometimes, when you realize how complicated someone else's design really is, it can be a very humbling experience!" See Charles' newly-revised biography at: http://quest.arc.nasa.gov/mars/team/whetsel.html NEW STUDENT ARTWORK
Kids from the Compania de Maria school in Spain have submitted their drawings of Mars. Check them out in the Mars Team Online Student Gallery at: http://quest.arc.nasa.gov/mars/kids/work.html There you'll find all kinds of Mars-inspired creations including songs, poetry, and artwork. MARS GLOBAL SURVEYOR TO ATTEMPT IMAGING OF FEATURES OF PUBLIC INTEREST
[Editor's note: This MGS Press Release was written by Diane Ainsworth in the Media Relations Office of NASA'S Jet Propulsion Laboratory in Pasadena, CA. For additional information go to: http://www.jpl.nasa.gov] March 16, 1998 NASA's Mars Global Surveyor spacecraft is about to begin a summer-long set of scientific observations of the red planet from an interim elliptical orbit, including several attempts to take images of features of public interest ranging from the Mars Pathfinder and Viking mission landing sites to the Cydonia region. The spacecraft will turn on its payload of science instruments on March 27, about 12 hours after it suspends "aerobraking," a technique that lowers the spacecraft's orbit by using atmospheric drag each time it passes close to the planet on each looping orbit. Aerobraking will resume in September and continue until March 1999, when the spacecraft will be in a final, circular orbit for its prime mapping mission. It will not be possible to predict on which orbit the spacecraft will pass closest to specific features on Mars until Global Surveyor has established a stable orbit and flight controllers are able to project its ground track. This process should be completed in the next few days. The exact time of observations and the schedule for the subsequent availability of photographs on the World Wide Web are expected to be announced early next week. "Global Surveyor will have three opportunities in the next month to see each of the sites, including the Cydonia region, location of the so-called 'Face on Mars,' " said Glenn E. Cunningham, Mars Global Surveyor project manager at NASA's Jet Propulsion Laboratory, Pasadena, CA. "The sites will be visible about once every eight days, and we'll have a 30- to- 50-percent chance of capturing images of the sites each time." Several factors limit the chances of obtaining images of specific features with the high-resolution mode of the camera on any one pass. These factors are related primarily to uncertainties both in the spacecraft's pointing and the knowledge of the spacecraft's ground track from its navigation data. In addition, current maps of Mars are derived from Viking data taken more than 20 years ago. Data obtained by Global Surveyor's laser altimeter and camera during the last few months have indicated that our knowledge of specific locations on the surface is uncertain by 0.6 to 1.2 miles (1 to 2 kilometers). As a result, the locations of the landing sites and specific features in the Cydonia region are not precisely known. In addition, the Mars Pathfinder and Viking landers are very small targets to image, even at the closest distance possible, because they are the smallest objects that the camera can see. The Cydonia features, on the other hand, are hundreds to thousands of times larger and the camera should be able to capture some of the features in that area. Global Surveyor's observations of the Viking and Pathfinder landing sites will provide scientists with important information from which to tie together surface observations and orbital measurements of the planet. Data from landing sites provide "ground truth" for observations of the planet made from space. As for the "Face on Mars" feature, "most scientists believe that everything we've seen on Mars is of natural origin," said Dr. Carl Pilcher, acting science director for Solar System Exploration in NASA's Office of Space Science, Washington, DC. "However, we also believe it is appropriate to seek to resolve speculation about features in the Cydonia region by obtaining images when it is possible to do so." Information about Viking observations of the Cydonia region and a listing of those images are available on the World Wide Web at: http://www.hq.nasa.gov/office/pao/facts/HTML/FS-016-HQ.html New images of the landing sites and Cydonia region taken by Mars Global Surveyor will be available on JPL's Mars news site at: http://www.jpl.nasa.gov/marsnews and on the Global Surveyor home page at http://mars.jpl.nasa.gov . These sites will also carry detailed schedules of the imaging attempts once they have been determined. Images will also be available on NASA's Planetary Photojournal web site at: http://photojournal.jpl.nasa.gov . So far in the aerobraking process, Global Surveyor's orbit has been reduced from an initial 45-hour duration to less than 12 hours. During the aerobraking hiatus, the spacecraft will be orbiting Mars about once every 11.6 hours, passing about 106 miles (170 kilometers) above the surface at closest approach and about 11,100 miles (17,864 kilometers) at its farthest distance from the planet. The pause in aerobraking allows the spacecraft to achieve a final orbit with lighting conditions that are optimal for science observations. Mars Global Surveyor is part of a sustained program of Mars exploration, managed by JPL for NASA's Office of Space Science, Washington, DC. Lockheed Martin Astronautics, Denver, CO, which built and operates the spacecraft, is JPL's industrial partner in the mission. Malin Space Science Systems, Inc., San Diego, CA, built and operates the spacecraft camera. JPL is a division of the California Institute of Technology, Pasadena, CA. BACKGROUND INFO ABOUT THE "FACE ON MARS"
As NASA's Mars Global Surveyor spacecraft prepares to take new photos of the intriguing "Face on Mars," you may be looking for more information about the phenomenon. Check out: http://www.hq.nasa.gov/office/pao/facts/HTML/FS-016-HQ.html MARS GLOBAL SURVEYOR IMAGING SCHEDULE
[Editor's note: This MGS Press Release was written by Diane Ainsworth in the Media Relations Office of NASA'S Jet Propulsion Laboratory in Pasadena, CA. For additional information go to: http://www.jpl.nasa.gov] The Mars Global Surveyor project has resumed scientific observations of the surface of Mars and has scheduled opportunities to image four selected sites: the Viking 1 and 2 landing sites, the Mars Pathfinder landing site and the Cydonia region. Three opportunities to image each of the four sites using the spacecraft's high-resolution camera will take place over the next month, beginning on April 3 at 1:58 a.m. Pacific time, when Global Surveyor passes over the Viking 1 landing site. The spacecraft will next pass over the Viking 2 landing site at 1:37 p.m. Pacific time on April 3. On April 4, Global Surveyor will try to image the now-silent Mars Pathfinder spacecraft at 1:16 a.m. Pacific time. It will then capture a portion of the Cydonia region of Mars, location of the so-called "Face on Mars," on April 5 at 12:33 a.m. Pacific time. Attempts to rephotograph the sites will occur during two additional opportunities falling about nine days apart. A detailed schedule of the imaging attempts is listed below. Uncertainties in both the spacecraft's pointing and the knowledge of the spacecraft's ground track from its navigation data will provide only a 30- to- 50-percent chance of capturing the images of each site. All of the selected targets are located south of Global Surveyor's periapsis, or point of closest approach to the Martian surface. Shortly before the spacecraft reaches this point, the Global Surveyor spacecraft will rotate slightly so that when it nears the selected target, the camera's field-of-view will sweep across the target as the spacecraft flies south and rises away. The spacecraft will begin transmitting to Earth data stored on its onboard solid-state recorders about seven hours after the images are acquired, concluding about three hours later. Currently it takes radio signals from Mars Global Surveyor about 20 minutes to travel from the spacecraft to Earth. Data will be received at one of NASA's Deep Space Network tracking stations at Goldstone, CA, near Madrid, Spain or near Canberra, Australia, and then sent by satellite to NASA's Jet Propulsion Laboratory, Pasadena, CA. There the images, along with all of the rest of Global Surveyor's science and engineering data, are placed in the project database for access by flight controllers. This process takes only seconds for each bit of data. Consequently, the image data will not be available be on the ground until about 10.5 hours after they are acquired. Data received overnight will not be retrieved until 9 a.m. Pacific time on the following workday. When image data are retrieved by camera operators, the information is assembled into "raw" images. Raw images may contain data errors or drop-outs introduced by noise in the telecommunications channel between the spacecraft and the ground, as well as very slight picture element variations inherent in the camera. This data processing takes about 30 minutes. Raw images will posted on three web sites: JPL's Mars news site at http://www.jpl.nasa.gov/marsnews , the Mars Global Surveyor project home page at http://mars.jpl.nasa.gov , and NASA's Planetary Photojournal site at http://photojournal.jpl.nasa.gov . Information identifying the acquisition time, predicted center latitude and longitude of the target location, and the local solar time will accompany these images. Contrast enhancement will be performed by JPL's Multimission Image Processing Laboratory and posted on World Wide Web a few hours later. The Global Surveyor project home page also contains spacecraft orbital velocity and distance to the planet in real time. Images of the Viking and Mars Pathfinder landing sites will not be posted until image enhancement and identification of the vehicles have been completed, because the small spacecraft will be at the limits of the camera's resolution. This process will take about 24 hours. Mars Global Surveyor is part of a sustained program of Mars exploration known as the Mars Surveyor Program. The mission is managed by the Jet Propulsion Laboratory for NASA's Office of Space Science, Washington, DC. JPL's industrial partner is Lockheed Martin Astronautics, Denver, CO, which developed and operates the spacecraft. JPL is a division of the California Institute of Technology, Pasadena, CA. Mars Global Surveyor Imaging Schedule First opportunity Approximate Orbit Internet Date Time (UTC/Pacific) Number Target Posting 4-3-98 09:58/1:58 a.m. 216 Viking Lander 1 April 6 4-3-98 21:37/1:37 p.m. 217 Viking Lander 2 April 7 4-4-98 09:16/1:16 a.m. 218 Mars Pathfinder April 7 4-5-98 08:33/12:33 a.m. 220 Cydonia April 6 (mid-a.m.) Second opportunity Approximate Orbit Internet Date Time (UTC/Pacific) Number Target Posting 4-12-98 15:23/ 8:23 a.m. 235 Viking Lander 1 April 14 4-13-98 03:01/ 8:01 p.m. 236 Viking Lander 2 April 15 4-13-98 14:40/ 7:40 a.m. 237 Mars Pathfinder April 15 4-14-98 13:57/ 6:57 a.m. 239 Cydonia April 14 (mid-p.m.) Third opportunity Approximate Orbit Internet Date Time (UTC/Pacific) Number Target Posting 4-21-98 20:45/1:45 p.m. 254 Viking Lander 1 April 23 4-22-98 08:23/1:23 a.m. 255 Viking Lander 2 April 24 4-22-98 20:02/1:02 p.m. 256 Mars Pathfinder April 24 4-23-98 19:18/12:18 p.m. 258 Cydonia April 24 (mid-a.m.) MARS GLOBAL SURVEYOR FLIGHT STATUS
[Editor's note: This flight status report was prepared by the
Office of the Flight Operations Manager, Mars Surveyor
Operations Project, Jet Propulsion Laboratory.]
March 27, 1998
Nearly six months of aerobraking operations concluded today as the
flight team raised the low point of Surveyor's orbit out of the Martian
atmosphere. This maneuver was accomplished shortly after 1:00 a.m. PST as
the spacecraft's onboard flight computer commanded the main rocket engine
to fire for 6.6 seconds. The burn occurred at the high point of the 201st
orbit and raised the low point of the orbit from 77.7 miles (125.0 km) up
to 106.0 miles (170.6 km).
"From my point of view, it was an excellent execution of the
maneuver," commented Surveyor's navigation chief, Dr. Pat Esposito.
According to the navigation team, the burn altered the spacecraft's
velocity by 9.8 miles per hour (4.4 meters per second) and was precisely
executed. Compared to the original 45-hour orbit after arrival at the red
planet last September, this post-aerobraking orbit takes 11 hours, 38
minutes, and 38 seconds to complete.
Later in the afternoon on the 202nd orbit, the flight team
transmitted commands to activate the science payload. At this time,
active instruments include the Magnetometer, Mars Orbiter Camera, and the
Mars Orbiter Laser Altimeter. The Thermal Emission Spectrometer will be
activated the week of March 29th. In addition, the radio science team
continues to collect data about Mars' gravity and atmosphere by analyzing
the radio signals that Surveyor transmits back to Earth.
For the next five months, the temporary aerobraking hiatus will
allow the science teams to collect data near the low point of every
orbit. Aerobraking will resume on September 11th with the goal of reducing
the orbit period to less than two hours by February 1999. The current
hiatus is necessary so that Mars will be in the proper position in its
orbit around the Sun when mapping commences next spring.
Some of the payload activity highlights this month include
measurements of the thickness of the north polar ice caps by the laser
altimeter, and attempted targeting of the Viking 1, Viking 2, and Mars
Pathfinder landing sites by the camera. Imaging of the Cydonia region,
location of the so-called "face on Mars," will also be attempted. Because
targeting exact locations on the ground from orbit requires extreme
precision, normal uncertainties in the spacecraft's position and pointing
capability will limit the probability of success to between 30% to 50%.
After a mission elapsed time of 505 days from launch, Surveyor is
222.10 million miles (357.43 million kilometers) from the Earth and in an
orbit around Mars with a high point of 11,100 miles (17,865 km), a low
point of 106.0 miles (170.6 km), and a period of 11.6 hours. The
spacecraft is currently executing the P203 command sequence, and all
systems continue to perform as expected. The next status report will be
released on April 17th.
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