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UPDATE #70 - April 4, 1998

PART 1: Upcoming webchats in English and Spanish!
PART 2: Global timezone information
PART 3: New and revised Mars Team bios
PART 4: New student artwork
PART 5: MGS to attempt imaging of features of public interest
PART 6: Background info about the "Face on Mars"
PART 7: Mars Global Surveyor imaging schedule
PART 8: Mars Global Surveyor flight status
PART 9: Subscribing & Unsubscribing: How to do it

[Note: We will begin to publish Mars Team Online updates a bit less frequently. Look for updates a couple times a month.]


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:

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: 

Beginning April 10, you can register for the chat with Jennifer at:


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).


This week we present you with three completely new biographies
and one revised bio. Dive in at: 

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:

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:

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:

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:


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.


[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: 

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:


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.


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:


[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:

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 

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 
                             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
                             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
                             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.)


[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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