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 
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etc.  Back issues may be obtained via anonymous FTP at:  
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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.
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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
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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
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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
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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.
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End Marsbugs, Vol. 4, No. 11






