Conference 7.286::space

Article: 6551
From: [email protected] (Ron Baalke)
Newsgroups: sci.space.news
Subject: Landing Site Selected for Mars Pathfinder
Date: 13 Oct 1994 20:53:33 -0700
Organization: Jet Propulsion Laboratory
Sender: [email protected]
 
From the "JPL Universe"
September 23, 1994
 
 
Landing site chosen for Pathfinder
 
   An ancient flood plain on Mars has been selected as the landing
site for the 1996 mission of JPL's Mars Pathfinder, one of the
first in a new generation of small, low-cost spacecraft.
   Eons ago, when water flowed on Mars, great floods inundated the
landing site, located on a rocky plain in an area known today as
Ares Vallis. The site is 850 kilometers (527 miles) southeast of
the location of Viking Lander 1, which in 1976 became the first
spacecraft to land on Mars. Pathfinder will be the first to land
on Mars since the twin Viking landers arrived almost 20 years ago.
   The spacecraft, scheduled to arrive at Mars on July 4, 1997,
will parachute down to Ares Vallis at the mouth of an ancient
outflow channel chosen for the variety of rock and soil samples it
may present.
   The purpose of the new Pathfinder mission is to demonstrate an
inexpensive system for cruise, entry, descent and landing on Mars,
said Project Manager Anthony Spear and Project Scientist Dr.
Matthew Golombek.
   The lander, carrying the microrover, will aerobrake in the
upper Martian atmosphere, using an aeroshell and a parachute.
   Just before impact, airbags will inflate to cushion the
landing. The microrover will then roll out to examine the rocks
and soil nearby.
   Both lander and rover will carry scientific instruments and
cameras.  The lander will make atmospheric and meteorological
observations during descent and function as a weather station on
the surface, as well as a radio relay station for the rover.
   The constraints on the location have to do with engineering
considerations, Spear said. Since the spacecraft are solar-
powered, the best site is one with maximum sunshine, and in July
1997, the sun will be directly over the 15 degrees-north latitude
region of the planet.
   The elevation must be as low as possible, Spear added, so the
descent parachute has sufficient time to open and slow the lander
to the correct terminal velocity. The landing will be within a
100- by 200-kilometer (60- by 120-mile) ellipse around the
targeted site due to uncertainties in navigation and atmospheric
entry.
   Ares Vallis, which meets the engineering constraints, was
chosen after a workshop earlier this year that involved the
invited participation of the entire scientific community concerned
with Mars. More than 60 scientists from the United States and
Europe attended.
   The Ares Vallis site, according to Golombek, is also a "grab
bag" location, set at the mouth of a large outflow channel in
which a wide variety of rocks is potentially within the reach of
the rover. Even though the exact origins of the samples would not
be known, he said, the chance of sampling a variety of rocks in a
small area could reveal a lot about Mars.
   The rocks would have been washed down from highlands at a time
when floods moved over the surface of Mars. Several potential
sites were listed where ancient flood channels emptied into Chryse
Planitia, having cut through crustal units and ridged plains where
the water would have picked up material and deposited it on the
plain.
   Other sites that were considered included Oxia Palus, a dark
highlands region that contains highland crust and dark wind-blown
deposits; Maja Valles Fan, a delta fan that drained an outflow
channel; and the Maja Highlands, just south of Maja Valles. All of
the sites were studied using Viking orbiter data.
   Both the Pathfinder lander and rover have stereo imaging
systems. The rover, additionally, carries an alpha proton X-ray
spectrometer with which it will examine the composition of the
rocks. The imaging system will reveal the mineralogy of surface
materials, as well as the geologic processes and surface-
atmosphere interactions that created and modified the surface.
   The instrument package will also enable scientists to determine
dust-particle size and water-vapor abundance in the atmosphere.
                               ###

Douglas Isbell
Headquarters, Washington, DC             June 14, 1995
(Phone:  202/358-1753)
 
Diane Ainsworth
Jet Propulsion Laboratory, Pasadena, CA
(Phone: 818/354-5011)
 
Lori Rachul
Lewis Research Center, Cleveland, OH
(Phone: 216/433-8806)
 
RELEASE:  95-94
 
MARS PATHFINDER PASSES MAJOR SET OF ENGINEERING MILESTONES
 
     Mars Pathfinder, a NASA Discovery program mission 
designed to deliver a lander, camera and instrument-laden 
rover to the Martian surface on July 4, 1997, has 
successfully completed an initial set of engineering 
tests intended to validate the spacecraft's unique 
atmospheric entry, descent and landing techniques.
 
     "Mars Pathfinder will employ a new and innovative 
approach to placing a lander on the surface of Mars, in 
keeping with NASA's 'faster, better and cheaper' 
philosophy of planetary exploration," said Tony Spear, 
Pathfinder project manager at NASA's Jet Propulsion 
Laboratory (JPL).
 
     "This series of diverse tests has given us great 
confidence that the spacecraft will arrive safely and 
securely on Mars," Spear said.  "A truly exciting 
scientific mission will then be ready to unfold."
 
     The Viking 1 and 2 Mars landers of the mid-1970s 
used a complex, computer-controlled liquid retrorocket 
system to achieve a soft landing at about five miles per 
hour (eight kilometers per hour).  In contrast, the 
smaller, tetrahedral-shaped Pathfinder lander will use a 
combination of parachutes, solid-fuel rockets and 
inflatable air bags to perform a safe, relatively hard 
landing at about 35 miles per hour (56 kilometers per hour).
 
      Recent parachute drop stability tests were 
performed by Pioneer Aerospace of Windsor, CT, in the 
desert near Yuma, AZ.  These tests successfully 
demonstrated the parachute configuration that will be 
used to bring the lander gracefully through the thin Martian
atmosphere, said Ann Mauritz, JPL lead subsystem engineer.
 
      Another element of the spacecraft's descent 
subsystems, the solid rocket motors, were tested at the 
China Lake Naval Weapons Center in Ridgecrest, CA. These 
tests involved dropping a simulated lander on a parachute 
from a helicopter and then firing three small prototype solid
rockets to further slow the craft's fall toward the surface.         
 
     "The tests went just as predicted," said Dr. Les 
Compton, JPL lead subsystem engineer, with the simulated 
lander essentially coming to a dead stop in mid-air while 
at the same time maintaining a stable orientation with 
respect to the ground.  Full-scale rocket prototypes, 
recently tested by Thiokol Corporation at Elkton, MD, 
will be used in full-scale subsystem tests to be carried 
out at China Lake later this summer.
 
      Pathfinder's landing will be cushioned by four 
large air bags completely surrounding the lander's 
exterior petals. The air bag-based soft landing was 
recently demonstrated by the air bag designers, ILC Dover 
of Frederica, DE, inside the 120-foot (36.5-meter) vacuum 
chamber at the NASA Lewis Research Center's Plum Brook 
Station near Sandusky, OH.  The vacuum chamber provides a 
way to simulate the very thin atmosphere of Mars, and the 
tests demonstrated the viability of the air bag design in 
softening the force of the impact on the lander and its 
delicate payload.
 
      The air bag was dropped from a height of 70 feet 
(21 meters) onto a 40-foot (12-meter) platform containing 
many large rocks similar to those found on Mars, 
according to Tom Rivellini, JPL lead subsystem engineer. 
"The initial full-scale prototype drop tests were very 
successful," Rivellini said.  "Engineers were able to 
test several air bag fabric construction techniques 
simultaneously.  The tests showed that air bags 
constructed of a double-layered fabric will be necessary 
to provide a sufficiently rugged cushioning effect."  A 
second phase of prototype drop testing later this year 
will demonstrate the durability of the new double-layered 
air bags, at even higher impact levels.
 
      Like Viking, the Pathfinder lander will arrive at 
Mars packaged inside a space capsule-shaped entry 
vehicle. Hitting the thin upper atmosphere of Mars at 
more than 17,000 miles per hour (27,000 kilometers per 
hour), the entry vehicle's heat shield will slow the 
craft to 900 miles per hour (1,450 kilometers per hour) 
in about two minutes. An onboard computer will sense the 
slow-down in speed and then deploy a large parachute. The 
parachute can slow the lander down to about 155 miles per 
hour (250 kilometers per hour) in the rarified atmosphere 
of Mars, which is only 1/100th as dense as Earth's.
 
     An onboard radar altimeter inside the lander will 
monitor the distance to the ground.  At about 330 feet 
(100 meters) above the surface, the computer will inflate 
the air bags.
 
     Seconds later, three solid rocket motors placed 
inside the top half of the entry vehicle above the lander 
will be fired.  In approximately two seconds, the rockets 
will bring the lander to a stop some 40 feet (12 meters) 
above the Martian ground. The parachute will be released, 
and the lander, nestled inside its protective air bag 
cocoon, will fall to the ground, bouncing and rolling 
until it stops.
 
      Within about an hour, the air bags will be deflated 
and partially retracted toward the lander.  Pathfinder 
will then open its three metallic petals and stand itself 
right side up from any side that it happens to be lying 
on.  The microrover, attached to the inside of one of the 
petals, will be exposed to the Martian terrain for the 
first time. After the lander camera has taken a 
photograph of its position on the Martian surface, 
engineers will instruct the rover to drive off and begin 
exploring the immediate surroundings, an ancient Martian 
flood plain known as Ares Vallis.
 
      Scheduled for launch in December 1996, Mars 
Pathfinder is part of a new generation of low-cost 
spacecraft with highly focused science goals designed to 
explore planets and other celestial bodies of the solar 
system.  Discovery missions are capped at $150 million 
(FY92) each in development costs and must be readied for 
launch within 36 months.
 
      Mars Pathfinder is managed by the Jet Propulsion 
Laboratory for NASA's Office of Space Science, 
Washington, DC.
 
                           -end-
 
 
EDITOR'S NOTE:  Images to illustrate this release are 
available for news media representatives by calling the 
Headquarters Broadcast and Imaging Branch on 202/358-
1900.  Photo numbers are:
 
Images of air bag testing:        Color                B&W
                                95-HC-323           95-H-332
                                95-HC-324           95-H-333
                                95-HC-325           95-H-334
 
Artist Concepts of Mars Pathfinder:
 
                                93-HC-405           93-H-449  
                                93-HC-406           93-H-450 
                                93-HC-407           93-H-451 

MARS PATHFINDER MISSION STATUS
24 January 1997

The spacecraft continues to function well and is currently 14 million 
kilometers from Earth. The major activity for last week was starting 
the performance testing of the K=15 R=1/6 convolutional code. Early 
tests results indicate that the Block III MCD is operating as expected 
and that the expected telecom link improvements match predicts. 

The project is investigating some minor anomalies which occurred this week
involving the spacecraft Command Detector Unit. The most serious of these
occurred on Monday, January 20 when the CDU transitioned to a lock state 
during a period when we were not uplinking to the spacecraft. The CDU 
lost lock as expected when we transmitted an uplink signal, but this 
"self-lock" behavior is not expected. In addition, we experienced two 
other episodes where commands were rejected by the spacecraft uplink 
hardware for unexplained reasons. The project has started a tiger team 
activity to further investigate these problems and determine potential 
causes. The possibility of solar flare induced SEUs is being assessed, 
but we are not ruling out other potential causes.

The flight team is also investigating an attitude control fault that we
experienced on Sunday, January 19. This fault occurred when estimates of 
the attitude covariance matrix inexplicably jumped by several orders of 
magnitude. The resulting fault response reinitialized attitude control 
flight software and turned off the Propulsion Drive Electronics. Analysis 
of telemetry before and after the fault did not show a definitive cause. 
We are currently planning to perform additional diagnostic tests to assess 
memory and software integrity in case SEUs or numerical divergence problems 
may have caused this problem.

Continuing EDL and surface operations planning. The Rover team completed a
successful Rover Operations Readiness Test, and planning is nearly complete 
for the first full team Surface Operations Readiness Test on January 27-28.

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MARS PATHFINDER MISSION STATUS
31 January 1997

The spacecraft continues to be in excellent health, and is now about 16 million
km from Earth. Key activities completed this week include successful completion
of the K=15, R=1/6 convolutional code tests and resolution of the attitude
control software glitch detected last week. Attitude control software has been
re-enabled and is currently operating nominally. In addition, we verified that
the noise seen during ASI/MET health checks is due to the Propulsion Drive
Electronics. This noise appears to be radiative in nature, and will not be an
issue for surface operations because the PDE is located on the cruise stage.

The Uplink Problem Tiger team has developed a plausible explanation for the
majority of the command rejections and the CDU In Lock conditions. It involves
harmonics from the uplink sweep locking up the CDU and pulling it away from the
nominal command frequency. The team is developing a test plan to confirm this
hypothesis and is also gathering information about the incidents where the CDU
went into lock while we were not tracking.

An Operational Readiness Test (ORT) of the Sol 1-2 sequences was run on Jan 27
and 28. The sequences used were identical to the last pre-launch surface ORT.
The ORT was successful in that all of the sequences were executed properly by
the simulated lander and rover. However, a number of relatively minor problems
were logged during the test. These problems were reviewed and action has been
assigned in all cases for problem resolution.

Nineteen investigators have been selected by NASA Headquarters in response to
the Announcement of Opportunity for selection of Mars Pathfinder Participating
Scientists and a Facility Instrument Science Team for the Atmospheric Structure
Instrument/Meteorology Package. An "All Hands" Pathfinder Science Team meeting
has been set up for Feb. 5-7, 1997 at JPL to begin integrating the new
investigators into the Experiment Operations Team.

For further information, please visit our website at http://mpfwww.jpl.nasa.gov.

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MARS PATHFINDER MISSION STATUS REPORT
4 February 1997

The Mars Pathfinder spacecraft is currently 19 million km (11 million miles)
from Earth traveling at 30 km/s on its trajectory to Mars. All spacecraft
subsystems continue to operate as expected.

At 5:00 PM PST on February 3, we successfully completed our second Trajectory
Correction Maneuver. This maneuver was designed to correct errors in the first
TCM performed on January 9, and move us closer to our final trajectory. The
spacecraft will not be placed on a Mars atmospheric entry trajectory until after
TCM-3 (currently scheduled for May 5) because of planetary quarantine
requirements. The TCM-2 design team, led by Flight Engineer Guy Beutelschies,
developed a two part approach to perform the maneuver. In the first part, the
spacecraft fired two of its forward facing thrusters continuously for five
minutes. The change in velocity for this "axial" component was about 1.5 m/s.
The second part of the maneuver was a smaller velocity correction of 0.1 m/s
performed in the "lateral" mode. In this mode, the spacecraft pulses all four
thrusters on one side of the spacecraft for five seconds. This pulse causes a
small change in the spacecraft velocity in the direction perpendicular to the
spacecraft spin axis. This mode will be used for all future maneuvers, so TCM-2
was a good proof-of-concept test. Early analysis of tracking data from NASA's
Deep Space Network indicates that both components were completed successfully.

Upon completing the maneuver, the spacecraft's spin axis was turned 15 degrees
back toward Earth so that we can perform radio navigation more effectively. The
spacecraft is currently pointed about 5 degrees from Earth and 2 degrees from
the Sun. We will remain in this attitude until late March.

The spacecraft will remain in a relatively quiescent mode for the next two to
three months. The flight team is currently working hard to complete planning for
Mars entry and surface operations.

For more information, please visit our website at http://mpfwww.jpl.nasa.gov.

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MARS PATHFINDER MISSION STATUS REPORT
7 February 1997

Successfully completed Trajectory Correction Maneuver #2 on February 3. 
The purpose of this maneuver was to clean up TCM-1 execution errors and 
had a magnitude of about 1.6 m/s. The maneuver consisted of two parts, 
an axial component of 1.5 m/s and a lateral component of 0.1 m/s. All 
spacecraft subsystems performed as expected, and the resulting maneuver 
execution error was less than 2%. The spacecraft was turned back to Earth
after the maneuver, and will remain in this attitude until late March.

The spacecraft computer reset during an off-track period on Wednesday, 
February 5. Analysis of post reset telemetry indicates that it was 
caused by a divide-by-zero fault in the attitude control flight software 
(ACS). The spacecraft responded as expected to this anomaly, and correctly 
enforced the early cruise boot configuration. This configuration idles 
ACS and reduces the uplink and downlink data rates from nominal cruise 
values. Several commands were sent on February 6 to increase the data 
rates and return diagnostic data, but attitude control is still idle. 
The spacecraft is in a safe attitude, however, so there is no compelling 
reason to restart ACS.

An all-hands science team meeting was held on February 5-7. All existing
investigators plus the newly selected ASI/MET FIST scientists and 
participating scientists were invited. The purpose of this meeting was 
to organize the science teams into a set of science operations groups 
and to review the current baseline plans for surface operations. A number 
of useful suggestions were made for modifying the nominal Sol 1-2 plans.

For further information on the Mars Pathfinder Mission, please visit 
our website at http://mpfwww.jpl.nasa.gov.

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Mars Pathfinder Mission Status
21 February 1997

The spacecraft remains in excellent health and is currently about 25
million kilometers from Earth. No significant operational activities were
conducted this week, and we have adopted a policy of unattended operations
for most of our tracking sessions.

The DSN Radiometric Tiger Team reported the cause of the ~500 Range Unit
bias seen in DSS 15 range data between TCM-1 and TCM-2 was caused by an
incorrect value for the signal inversion parameter in the SRA configuration
table. The error has been fixed and subseqent DSS 15 data looks good.

A set of improvements to the Flight System Testbed Ground Support Equipment
Software have been completed which will allow higher fidelity testing of
the EDL flight software. Robustness testing of the EDL software has now
been started and will continue for the next two months.

MARS PATHFINDER MISSION STATUS REPORT
28 February 1997

The spacecraft remains in excellent health and is currently about 32 
million kilometers from Earth. No significant operational activities 
were conducted this week. Continued investigation of the recent reset 
and attitude control software problems now indicates that they are related 
to the Command Detector Unit erroneous lock problem. A bug was found in 
the codeblock error detection software which causes a corruption to the 
floating point registers. The reset and attitude control problems were 
caused by floating point error conditions and can be tied directly to 
this corruption. We are currently in the process of developing a patch 
to correct this problem. Congratulations to Steve Stolper and Glenn Reeves 
for quickly identifying the problem and developing the required fix.

A combined Project Science Group meeting involving Mars Pathfinder, Mars
Global Surveyor, and Mars Surveyor '98 was held on Thursday and Friday,
February 27-28. Although there is not a great deal of overlap between 
Pathfinder and these other projects, there are some synergistic 
investigations that can be performed.

The Rover Operations Team completed a Rover Operational Readiness Test 
in the Mars Yard this week. Preparations are proceeding for next week's 
project wide surface Operations Readiness Test in the Pathfinder Sandbox. 
The current plan is to conduct nominal Sol 1 and 2 operations.

For further information, please visit our website at
http://mpfwww.jpl.nasa.gov.

MARS PATHFINDER MISSION STATUS
7 March 1997

The spacecraft is currently about 37 million kilometers from Earth and
continues to function as expected. The total travel distance covered since
launch is 248 million kilometers, which means that the spacecraft has
reached the halfway point to Mars. A set of Entry, Descent, and Landing
communications tests were started this week using the spacecraft and the
Deep Space Network Galileo Telemetry recorders at Goldstone. These tests
are meant to simulate the open loop strategy that we intend to use during
entry to record significant events.  The first test was successfully
completed on March 3, and three additional tests will be performed during
the next week.

The project completed Surface Operational Readiness Test #3 on March 6-7.
This test was the first formal operations test after launch, and was
designed to test the nominal Sol 1 and 2 sequences. Although there were a
few start up problems, the test was generally successful. All elements of
the project worked well together to complete the critical Sol 1 operations
and re-plan Sol 2.

The Rover Operations Team performed remote field testing on Monday and
Tuesday.  With the SIM Rover at Amboy Crater, the Operations Team ran four
Martian sol sequences from JPL. The sequences included navigation and
traverse activities, and science and technology experiments. The Pathfinder
Science Team also participated in the testing.

For more information, please visit our website at http://mpfwww.jpl.nasa.gov.

MARS PATHFINDER MISSION STATUS REPORT
14 March 1997

The spacecraft remains in good health and is currently about 44 million
kilometers from Earth.  We experienced a minor command error this week when
a command was sent to activate a sequence which was not on-board.  The
spacecraft rejected the command as expected, but we have tightened up our
command approval process to prevent future incidents.  The set of Entry,
Descent, and Landing (EDL) communications tests started last week were
completed this week.  All of the Deep Space Network hardware and software
elements required to support EDL communications are performing as expected.

EDL Flight software testing is progressing well, and has been the primary
focus of testbed activities this week.  A full scale airbag retraction test
is planned for Friday, March 14 in the Mars sandbox in Building 230.

For more information, please visit our website at http://mpfwww.jpl.nasa.gov.

Mime-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Date: Thu, 20 Mar 1997 14:52:38 -0800
To: MPF-Status <[email protected]>, [email protected]
From: David Dubov <[email protected]>
Subject: Mars Pathfinder Website Weekly Report - W/E 3/19/97
Sender: [email protected]
Precedence: bulk
Reply-To: [email protected]



Here are the statistics for the Mars Pathfinder website from 3/13-3/19/97:

Total number of accesses = 264848
Total number of visits = 23994 (A visit is a group of accesses separated by
180s.)
Total number of bytes transferred = 2779986076 (2.77 Gb)
Number of files accessed on this site = ~700
Highest number of hits per day = 3/19: 42334
Lowest number of hits per day = 3/15: 32383
Current mirror sites: JPL, NASA Ames, KSC, IKI, CNES, Cornell, NCAR, SDSU,
NCSA, Pittsburgh/Carnegie Mellon
Mars Pathfinder Status Mailing List: 2129 members

This averages out at about 37835 accesses per day, or about 3428 visits per
day.

This Week's Events:

A very quiet week. Mirror sites are still being added, but we are now
concentrating on foreign sites. Australia has expressed interest, as has
Japan, Germany and S. Korea.

Mars opposition was on Monday, March 17! Many fine images have been
submitted over the past few days. Also worth noting are the spectacular
images taken by HST on March 10 by our own Dave Crisp! Please go to
http://oposite.stsci.edu/pubinfo/PR/97/09.html#Photos for these sharpest
ever images of Mars...

The EDL page is up. Mini movies of each event are displayed with (of
course) excellent text by Rob Manning.

Concerns:

CNES did not send log data (again) for most of this week, but finally
responded at the end of the week. Other mirror sites are beginning to
provide log data as they come on-line.

Tasks this coming week:

More and more Mars images...

Other tasks include:

1. "Ships Passing in the Night" page: an animated graphic (updated twice per
day?) of the trajectories of MGS and MPF.
2. Recruiting team members for assisting with explanations of "what we're
seeing" as images and data come down (terrestrial analogs).
3. Recruiting team members to participate in live "chat" sessions during EDL,
sols 1 and 2 (and beyond?). Obviously, this will only be those team members who
do not have other tasks on those days (see number 5).
4. Other planning (ASI/MET data page, APXS data page, "What's happening
tomorrow?" page, etc.)


If you have suggestions or comments, please contact David at 3-0888.


--------------------------------------
Status report prepared by:

Office of the Flight Operations Manager
Mars Pathfinder Mission
NASA Jet Propulsion Laboratory
California Institute of Technology
Pasadena, CA 91109
--------------------------------------

Message-Id: <v03010d01af5870d37ca4@[137.78.78.190]>
Mime-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Date: Fri, 21 Mar 1997 09:08:43 -0800
To: MPF-Status <[email protected]>
From: David Dubov <[email protected]>
Subject: Mars Pathfinder Weekly Status Report - 21 March 1997
Sender: [email protected]
Precedence: bulk
Reply-To: [email protected]

MARS PATHFINDER WEEKLY STATUS REPORT
21 March 1997

The spacecraft remains in good health and is currently about 49 million
kilometers from Earth.  No significant spacecraft operations were performed
this week.

Entry, Descent, and Landing Flight Software Testing is progressing well.
We completed an airbag retraction test in the Building 230 Sandbox last
week, and have finished a set of parachute deploy and rocket ignition
algorithm robustness tests this week.  A couple of significant issues have
come up in this testing which are likely to cause us to change flight
software.  A flight software change board meeting will be held on April 1
to determine what changes to make and what regression tests to perform.

A telecon was held with NASA HQ on proposed funding for JPL PIO.
Significant scrubbing of this budget was performed and a new proposal from
PIO will be discussed with HQ early next week.


--------------------------------------
Status report prepared by:

Office of the Flight Operations Manager
Mars Pathfinder Mission
NASA Jet Propulsion Laboratory
California Institute of Technology
Pasadena, CA 91109
--------------------------------------

    Here's something I pulled off the sci.space.new newsgroup.
    Chronologically it's a little out of sequence, but I thought
    it would make interesting reading as it shows the efforts
    some of the folks who design and build these probes go to
    to make sure things will work when needed to do so.
    
    -Bob
    
From: [email protected] (Ron Baalke)
Subject: Emergency Repair Saves Mars Pathfinder Wind Instrument
Date: 11 Jan 1997 17:57 UT

Jet Propulsion Laboratory UNIVERSE  
Pasadena, California - Vol. 26, No. 24 - November 27, 1996
__________________________________________________________________

Emergency repair saves Pathfinder wind instrument
By MARK WHALEN

   It was an otherwise quiet Saturday morning for Gina Alleruzzo on Oct. 
12. She didn't have much planned for the day, maybe a little shopping.
   Then the phone rang about noon. It was her co-worker Colin Mahoney, 
cognizant engineer for a wind instrument aboard the Pathfinder spacecraft. 
Alleruzzo, a technician in the Electronics Packaging Group in Section 349, 
wondered what was up. "He never calls, especially on a Saturday," she 
noted.
   It turns out that her low-key weekend would soon be history. Mahoney 
explained that she was needed to perform a bit of emergency 
"microsurgery." The patient? The Atmospheric Structural Instrument/ 
Meteorology Experiment (ASI/ MET), which was already packed aboard 
Pathfinder at Cape Canaveral.
   A quality assurance inspection earlier that day by Don McQuarie of 
Section 506 revealed breakages in tiny wires on the instrument's wind 
sensor, which will measure wind speed and direction on Mars, as well as 
temperature.
   Alleruzzo, who built the instrument, was the logical choice to repair 
it. However, Pathfinder was just about to be mated to its heat shield at 
the Cape. 
   There was no time to lose-the sensor had to be repaired over the next 
two days or the spacecraft would have to fly with the instrument unable to 
measure wind speed or to detect wind direction as accurately as planned.
   The sensor has six elements, one of which is a wire around a fiberglass 
post. The elements are wired in a series; if one breaks, the sensor is not 
operational.
   Mahoney and Alleruzzo hopped a redeye flight to Florida that departed 
at 10:30 that night. With no rest, she arrived at the Cape armed with a 
strand of wire about .08 millimeters (.003 inches) thick, as well as a 
spare wind sensor. She then confronted further complications: Pathfinder's 
petals were already folded up into flight position, surrounding the broken 
sensor. 
   "I was worried because at first I couldn't see where it was broken," 
Alleruzzo said. "I also couldn't see if the broken wire was tangled with 
another element."
   Finally, with the aid of a microscope, she was able to see that only one 
of the six elements was broken. 
   But she was still faced with the daunting task of removing the damaged 
wire and then replacing it, having just 6 to 8 inches of work space between 
Pathfinder's closed petals.
   After installing a protective cover over the instrument and carefully 
positioning herself under the spacecraft, she reached her hand around a 
bracket to wrap the delicate wire.
   The job was completed in about an hour, and subsequent tests showed 
that the sensor was working once again.
   "The flight launch preparation team and senior project staff were 
dubious that Gina could fix it because of the physical restrictions and 
delicacy of the job and because the petals were already folded up," noted 
Clayton LaBaw, ASI/MET instrument manager .
   Alleruzzo's ability to perform the delicate work proved crucial to the 
survival of the instrument in part because of its position within the 
spacecraft. The sensor is poised atop a mast that will stand upright after 
the spacecraft lands and its petals open. "If the mast had to be removed 
from the petals, it might have taken two weeks to repair the instrument 
and reconfigure the spacecraft," Mahoney said. "So the only option was to 
repair it on the spacecraft already folded up."
   Alleruzzo's resourcefulness resulted in congratulations from Pathfinder 
Project Manager Tony Spear and Mars Program Manager Donna Shirley.
   Alleruzzo, who has worked at JPL for three and a half years and has 
supported instrument manufacturing for numerous Lab missions, seemed 
to take the whole episode in stride.
   "Whoever broke the wire probably didn't even know it happened," she 
said. "Thanks to Don's final viewing, we discovered the damaged wind 
sensor in time to repair it.
   "The flight team felt bad that the instrument was broken, but was elated 
that I was able to fix it," she said. "It wasn't exactly an easy thing to 
do, but I knew I could do it." 
                                 ###

MARS PATHFINDER WEEKLY STATUS REPORT
4 April 1997

The spacecraft remains in good health and is currently about 64 million
kilometers from Earth. The most significant spacecraft activity performed
this week was to switch to a new convolutional code, K=15, Rate 1/6, on our
downlink. This code gives us a significant increase in our downlink
capability. Mars Pathfinder is the first spacecraft to operationally use
this code with the DSN and we are very pleased with the results.

The project conducted a meeting to discuss Flight Software changes for
Entry, Descent and Landing (EDL) and Surface phases of the mission. These
changes are to correct bugs found during testing performed since launch. We
expect to finalize these changes and prepare for loading them onboard
within the next two months.

MARS PATHFINDER WEEKLY STATUS REPORT
11 April 1997

The spacecraft remains in good health and is currently about 71 million
kilometers from Earth. The only spacecraft activities performed this week
were a regular ASI/MET health check, a Heat Rejection System Pump B cycle,
and some modification to Attitude Control Subsystem fault protection
parameters. The total flight time since launch is now 128 days, and we 
have 85 days until Mars arrival.

We successfully completed an operational
readiness test of all activities from Mars entry -2 days through Sol 2.
This test was performed using the Pathfinder Testbed and Mars Sandbox. 
The Mars approach phase included periodic updates to the Entry, Descent, 
and Landing flight software parameter set and execution of a contingency
Trajectory Correction Maneuver #5. We are investigating a minor problem
which occurred during airbag retraction, which did not significantly effect
the test. The surface operations test included a planned failure of the
High Gain Antenna and subsequent Low Gain Antenna operations.

John Wellman and Matt Golombek attended a special Project Science Group 
meeting at NASA Headquarters to discuss data rights issues and the role 
of the participating scientists. A number of useful discussions were held 
and a draft policy on these issues was developed.

For more information please visit our website at http://mpfwww.jpl.nasa.gov.


--------------------------------------
Status report prepared by:
Office of the Flight Operations Manager
Mars Pathfinder Project
NASA Jet Propulsion Laboratory
California Institute of Technology
Pasadena, CA 91109
--------------------------------------

MARS PATHFINDER WEEKLY STATUS REPORT
18 April 1997

The spacecraft remains in good health and is currently about 80 million
kilometers from Earth. The only activity performed this week was to
continue gathering sun sensor data to characterize its performance at 
large sun angles. No additional degradation of the sun sensor has been 
observed since launch. The total flight time since launch is now 135 
days, and we have 78 days until Mars arrival.

The flight team is completing preparations for next week's Operational
Readiness Test #5. This test is a five day simulation of surface 
operations using the flight system testbed and Mars sandbox. A 
significant number of science team members and participating scientists 
will be in attendance, and are already here this week conducting test 
and training activities.

The project completed the first of two sessions on lessons learned 
during the Mars Pathfinder development effort. The first session 
focused on system level issues and was well received by a lab-wide 
audience. The second session is scheduled for April 28, and will 
cover subsystem lessons. Both sessions are being videotaped, and the 
presentation material will be gathered into a single "book".

For more information, please visit our website at http://mpfwww.jpl.nasa.gov.


--------------------------------------
Status report prepared by:
Office of the Flight Operations Manager
Mars Pathfinder Project
NASA Jet Propulsion Laboratory
California Institute of Technology
Pasadena, CA 91109
--------------------------------------

MARS PATHFINDER WEEKLY STATUS REPORT
25 April 1997

The spacecraft remains in good health and is currently about 88 
million kilometers from Earth. Major activities performed this week 
included a regularly scheduled attitude turn to maintain Earth point. 
We also transitioned to the Late Cruise mission phase and switched 
in the fourth and final solar panel quadrant. The total flight time 
since launch is now 142 days, and we have 71 days until Mars arrival.

We successfully completed a week long surface Operational Readiness 
Test. The purpose of this test was to train team members on operational 
processes and procedures and verify nominal surface operations plans. 
Although we had some early difficulties deploying the rover, the test 
was a great learning experience and an overall success. We did discover 
several issues with our tools and processes that we will correct prior 
to ORT #6 (scheduled for May 19).

For more information, please visit our website at http://mpfwww.jpl.nasa.gov.


--------------------------------------
Status report prepared by:
Office of the Flight Operations Manager
Mars Pathfinder Project
NASA Jet Propulsion Laboratory
California Institute of Technology
Pasadena, CA 91109
--------------------------------------

MARS PATHFINDER MISSION STATUS
2 May 1997

The spacecraft remains in good health and is currently about 98 million
kilometers from Earth.  No significant spacecraft activities were 
performed this week. The total flight time since launch is now 149 days, 
and we have 63 days until Mars arrival.

The EDL planning team completed a very successful Sequence of Events Peer
Review.  This review covered the detailed flight software sequence used
during EDL, recent changes in the EDL software, robustness and regression
testing performed since launch, and detailed operational plans for TCM-5
and EDL approach.  The review board, led by Jim Marr, agreed that no
significant holes exist in the EDL sequence and that we are well on our 
way to being prepared for EDL operations.

For further information, please visit our website at
http://mpfwww.jpl.nasa.gov.


--------------------------------------
Status report prepared by:
Office of the Flight Operations Manager
Mars Pathfinder Project
NASA Jet Propulsion Laboratory
California Institute of Technology
Pasadena, CA 91109
--------------------------------------

MARS PATHFINDER WEEKLY STATUS REPORT
16 May 1997

The spacecraft remains in good health and is currently about 115 million
kilometers from Earth (26 million km from Mars). The only major spacecraft
activity performed this week was a battery heating and solar array
characterization test. The total flight time since launch is now 163 days,
and we have 49 days until Mars arrival.

Successfully completed the Entry, Descent, and Landing (EDL) and Surface
Operations Readiness Review. The review board, led by Mike Sander, asked
many useful questions and generated several advisories, but agreed that the
project will be ready for pre-entry and surface operations by July 4.

Completed the second of three EDL Operations Readiness Tests (ORT). This
test used the testbed to simulate all pre-EDL operations, including TCM-5a.
In addition, we conducted a simultaneous EDL communications ORT using the
actual spacecraft to simulate the telecom behavior during EDL. Several
members of the EDL data acquisition team traveled to Madrid to support this
test. Although a number of lessons were learned during the ORT, both the
data acquisition and pre-EDL operations teams completed the test
successfully.

Completed a set of surface operations mini-ORTs which tested our strategy
for petal movements after landing, end-to-end image processing and rover
target designation, and the ramp deployment decision process. These three
issues were among the most significant concerns in ORT #5, and appear to be
resolved at this point.

For further information, please visit our website at
http://mpfwww.jpl.nasa.gov.


--------------------------------------
Status report prepared by:
Office of the Flight Operations Manager
Mars Pathfinder Project
NASA Jet Propulsion Laboratory
California Institute of Technology
Pasadena, CA 91109
--------------------------------------

MARS PATHFINDER WEEKLY STATUS REPORT
23 May 1997

The spacecraft remains in good health and is currently about 129 million
kilometers from Earth.  The only significant spacecraft activity performed
this week was a turn to maintain Earth point attitude.  In addition, we
have resumed nearly continuous DSN coverage.  The total flight time since
launch is now 170 days, and we have 42 days until Mars arrival.

Completed the sixth Surface Operations Readiness Test (ORT).  The purpose
of this test was to validate our low power and no battery contingency
scenarios and correct problems from ORT #5.  The test was hampered by a
recurring testbed hardware problem involving the Imager for Mars Pathfinder
(IMP) and the power support equipment. The problem caused the testbed
flight computer to reset several times and caused the flight team to invoke
reset recovery procedures instead of performing normal operations.  The
problem was fixed after Sol 3, at which time we restarted the test and ran
through Sol 1-2 operations.  In spite of this problem, the test was
generally a success in that we exercised all of our core operational
processes.  Several other minor problems occurred, and all will be
corrected by ORT #7.

For further information, please visit our website at
http://mpfwww.jpl.nasa.gov.


--------------------------------------
Status report prepared by:
Office of the Flight Operations Manager
Mars Pathfinder Project
NASA Jet Propulsion Laboratory
California Institute of Technology
Pasadena, CA 91109
--------------------------------------

MARS PATHFINDER WEEKLY STATUS REPORT
30 May 1997

The spacecraft remains in good health and is currently about 140 million
kilometers from Earth (17 million km from Mars).  Major spacecraft
activities performed this week included a turn to maintain Earth point
attitude and starting battery charge (see below).  The total flight time
since launch is now 175 days, and we have 35 days until Mars arrival.

The most significant project activity completed this week was to begin
charging the flight battery.  Approximately 22 amp-hours of capacity has
been taken out of the battery since installation, and the objective of
charging was to replace as much as possible.  Degradation of the total
battery capacity has occured over the six months since launch, but a total
capacity of at least 40 amp-hours should still be possible (compared to a
pre-launch capacity of 56 amp-hours).  A total of 7 amp-hours has been
added after two days of charging, so we are already above the 40 amp-hour
level.  The flight team is currently assessing whether additional charging
is warranted.

Completed updates to the final flight software load.  We are currently
performing a final set of regression tests prior to patching the software
next week.

Deep Space Network personnel corrected the final open ranging data accuracy
problem which has been a concern for the last several months.  This problem
involved larger than expected range jitter in the data acquired at
Goldstone.  The problem is related to a faulty board in the Sequential
Ranging Assembly.  All ranging data acquired for the project now meets the
pre-launch accuracy specifications.

For more information, please visit our website at http://mpfwww.jpl.nasa.gov.


--------------------------------------
Status report prepared by:
Office of the Flight Operations Manager
Mars Pathfinder Project
NASA Jet Propulsion Laboratory
California Institute of Technology
Pasadena, CA 91109
--------------------------------------