Mars Polar Lander
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Mars Polar Lander
Artist depiction of Mars Polar Lander on Mars.
Operator
NASA / JPL
Major contractors
Martin Marietta
Mission type
Lander
Orbital insertion
Year-Month-Day
date
Hour:Minute:Second UTC
Launch date
1999-01-03 20:21:10 UTC
(13 years, 1 month and 6 days ago)
Launch vehicle
Launch site
Delta II 7425
Space Launch Complex 17A
Cape Canaveral Air Force Station
(failure in transit)
Mission duration
Last contact on day 334
1999-12-03 20:00:00 UTC
Landing site
Ultimi Scopuli, 76°S 195°W76°S
195°W (projected)
COSPAR ID
1999-001A
Homepage
Mars Polar Lander Website
Mass
290 kilograms (640 lb)
Power
200 W
(Solar array / NiH2 battery)
The Mars Polar Lander, also referred to as the Mars Surveyor '98 Lander, was a 290-kilogram
robotic spacecraft lander, launched by NASA on January 3, 1999, to study the soil and climate of
Planum Australe, a region near the south pole on Mars, as part of the Mars Surveyor '98 mission.
However, on December 3, 1999, after the descent phase was expected to be complete, the lander
failed to reestablish communication with Earth. It was determined the most likely cause of the
mishap was an improperly ceased engine firing prior to the lander touching the surface, causing
the lander to impact at a high velocity.
Contents
[hide]


1 Mission background
o 1.1 History
o 1.2 Deep Space 2 Probes
o 1.3 Spacecraft design
 1.3.1 Attitude control and propulsion
 1.3.2 Communications
 1.3.3 Power
 1.3.4 Scientific instruments
2 Mission profile
o 2.1 Launch and trajectory
o





2.2 Landing encounter with Mars
 2.2.1 Intended operations
3 Communications loss
4 See also
5 References
6 Further reading
7 External links
[edit] Mission background
[edit] History
As part of the intended goals of the Mars Surveyor '98 mission, a lander was sought as a way to
gather climate data from the ground in conjunction with an orbiter. It was suspected that a large
quantity of frozen water may exist under a thin layer of dust at the south pole. If that were true,
then why does it differ from the Martian north pole, a region suspected to contain much less
frozen water. In planning Mars Polar Lander, the potential water content in the Martian south
pole was the strongest determining factor for choosing a landing location.[1]
The primary objectives of the mission included:[2]





Land on the layered terrain in Mars’ south polar region.
Search for evidence related to ancient climates and more recent periodic climate change.
Give a picture of the current climate and seasonal change at high latitudes and, in particular,
the exchange of water vapor between the atmosphere and ground.
Search for near-surface ground ice in the polar regions, and analyze the soil for physically
and chemically bound carbon dioxide and water.
Study surface morphology (forms and structures), geology, topography and weather of the
landing site.
[edit] Deep Space 2 Probes
Main article: Deep Space 2
Mars Polar Lander carried two, small, identical impactor probes known as Deep Space 2 A and
B. The probes were intended to impact the surface with a high velocty at approximately 73°S
210°W73°S 210°W, to penetrate the Martian soil and study the subsurface composition up to a
meter in depth. However, after entering the Martian atmosphere, attempts to contact the probes
failed.[1]
[edit] Spacecraft design
The spacecraft measured 3.6 meters wide and 1.06 meters tall with the legs and solar arrays fully
deployed. The base was primarily constructed with an aluminum honeycomb deck, composite
graphite epoxy sheets forming the edge, and three aluminum legs. During landing, the legs were
to deploy from stowed position with compression springs and absorb the force of the landing
with crushable, aluminum honeycomb inserts in each leg. On the deck of the lander, a small
thermal, Faraday cage enclosure housed the computer, power distribution electronics and
batteries, telecommunication electronics, and the Capillary Pump Loop Heat Pipe (LHP)
components which maintained operable temperature. Each these components included redundant
units in the event that one may fail.[1][3][4]
[edit] Attitude control and propulsion
While traveling to Mars, the Cruise Stage was three-axis stabilized with four hydrazine
monopropellant reaction engine modules, each including a 22-newton trajectory
correction maneuver thruster for propulsion and a 4-Newton reaction control system
thruster for attitude control. Orientation of the spacecraft was obtained using redundant
Sun sensors, star trackers, and inertial measurement units.[3]
During descent, the lander used three clusters of pulse modulated engines, each
containing four 266-Newton hydrazine monopropellant thrusters. Altitude during landing
was provided by a doppler radar system and an Attitude and Articulation Control
subsystem (AACS) controlled the attitude to ensure the spacecraft landed at the optimal
azimuth to maximize solar collection and telecommunication with the lander.[1][3][4]
The lander was launched with two hydrazine tanks containing 64 kilograms of propellant
and pressurized using helium. Each spherical tank was located the underside of the lander
and provided propellant during the cruise and descent stages.[1][3][4]
[edit] Communications
During the cruise stage, communications with the spacecraft were conducted over the X
band using a medium-gain, horn-shaped antenna and redundant solid state power
amplifiers. For contingency measures, a low-gain omni-directional antenna was also
included.[1]
The lander was originally intended to communicate data through the failed Mars Climate
Orbiter via the UHF antenna. With the orbiter being lost on September 23, 1999, the
lander would still be able to communicate directly to the Deep Space Network through
the Direct-To-Earth (DTE) link, an X band, steerable, medium-gain, parabolic antenna
located on the deck. Alternatively, Mars Global Surveyor could be used as a relay using
the UHF antenna at multiple times each Martian day; however the Deep Space Network
could only receive data from and not send commands to the lander using this method.
Communicating using the medium-gain antenna provided a 12.6-KB/s link and the UHF
relay provided 128-KB/s uplink. Communications with the spacecraft would be limited to
one-hour events, constrained by heat-buildup that would occur in the amplifiers; the
number of communication events would also be constrained by power limitations.[1][2][3][4]
[edit] Power
During cruise, the Cruise Stage included two gallium arsenide solar arrays to power the
radio system and maintain power to the batteries in the lander which kept certain
electronics warm.[1][3]
After descending to the surface, the lander was to deploy two, 3.6-meter wide gallium
arsenide solar arrays, located on either side of the spacecraft. Another two auxilary solar
arrays are located on the side to provide additional power for a total of an expected 200
watts and approximately 8-9 hours of operating time per day.[1][3]
While the Sun would not have set below the horizon during the primary mission, too little
light would have reached the solar arrays to remain warm enough for certain electronics
to continue functioning. To avoid this problem, a 16-amp-hour nickel hydrogen battery
was included to be recharged during the day and used to power the heater for the thermal
enclosure at night. This solution also was expected to limit the life of the lander. As the
Martian days would grow colder in late summer, too little power would be supplied to the
heater to avoid freezing, resulting in the battery also freezing and signaling the end of the
operating life for the lander.[1][3][4]
[edit] Scientific instruments
Mars Descent Imager (MARDI)
Mounted to the bottom of the
lander, the camera was
intended to capture thirty
images as the spacecraft
descended to the surface. The
images acquired would be used
to provide geographic and
geologic context to the landing
area.[5]


Principal investigator: Michael
Malin / Malin Space Science
Systems (website)
reincorporated on Phoenix and
Mars Science Laboratory
Stereo Surface Imager (SSI)
Using a pair of charge coupled
devices (CCD), the stereo
panoramic camera was
mounted to a one-meter tall
mast and would aid in the
Thermal Evolved Gas Analyzer
and determining areas of
interest for the Robotic Arm. In
addition, the camera would be
used to estimate the column
density of atmospheric dust, the
optical depth of aerosols, and
slant column abundances of
water vapor using narrow-band
imaging of the Sun.[6]


Principal investigator: David
Paige / UCLA / University of
Arizona (website)
reincorporated on Phoenix
Light Detection and Ranging (LIDAR)
The laser sounding instrument
was intended to detect and
characterize aerosols in the
atmosphere up to three
kilometers above the lander.
The instrument operated in two
modes: active mode using an
included laser diode and
acoustic mode using the Sun as
the light source for the sensor.
-In active mode, the
laser sounder was to
emit 100-nanosecond
pulses at a wavelength
of 0.88-micrometer into
the atmosphere, and
then record the duration
of time to detect the
light scattered by
aerosols. The duration
of time required for the
light to return could
then be used to
determine the
abundance of ice, dust
and other aerosols in the
region.
-In acoustic mode, the
instrument measures the
brightness of the sky as
lit by the Sun and
records the scattering of
light as it passes to the
sensor.[7]

Principal investigator:
Viacheslav Linkin /
IKI/RSA
Robotic Arm (RA)
Located on the front of
the lander, the Robotic
Arm is a meter-long
aluminum tube with an
elbow joint and an
articulated scoop
attached to the end. The
scoop was intended to
be used to dig into the
soil in direct vicinity of
the lander. The soil
could then be analyzed
in the scoop with the
Robotic Arm Camera
or transferred into the
Thermal Evolved Gas
Analyzer.[6]


Principal investigator:
David Paige / UCLA
(website)
reincorporated on
Phoenix
Robotic Arm Camera (RAC)
Located on the Robotic
Arm, the charge
coupled camera
includes 2 red, 2 green,
and 4 blue lamps to
illuminate soil samples
for analysis.[6]


Principal investigator:
David Paige / UCLA /
University of Arizona
(website, UA website)
reincorporated on
Phoenix
Meteorological Package (MET)
Several instruments
related to sensing and
recording weather
patterns, were included
in the package. Wind,
temperature, pressure
and humidity sensors
were located on the
Robotic Arm and two
deployable masts: a
1.2-meter 'main' mast,
located on top of the
lander and a 0.9-meter
secondary 'submast'
that would deploy
downward to acquire
measurements close to
the ground.[6]
"Wind speed and
direction is measured
by a nine-element hot
wire array wind sensor
mounted on the main
mast and a two-element
wind sensor mounted
on the submast. Three
fast thermocouple
assembly temperature
sensors are mounted at
different heights on the
main mast. Two
temperature sensors are
also located on the
submast and one on the
elbow joint of the
robotic arm. A soil
temperature probe on a
15 cm fiberglass tube is
mounted on the back of
the robotic arm scoop
and can be pushed into
the ground by the arm.
A barocap atmospheric
pressure sensor is
located inside the
Payload Electronics
Box. A tunable diode
2.656 and 2.729
micrometer laser is
mounted on the main
mast to measure the
abundance of
atmospheric water and
carbon dioxide and to
measure the isotopic
ratios carbon13/carbon-12 and
oxygen-18/oxygen-16
in atmospheric carbon
dioxide, and
deuterium/hydrogen
and oxygen-18/oxygen16 in atmospheric
water."[6]


Principal investigator:
David Paige / UCLA
(website)
reincorporated on
Phoenix
Thermal and Evolved Gas Analyzer (TEGA)
The instrument was
intended to measure
abundances of water,
water ice, adsorbed
carbon dioxide,
oxygen, and volatilebearing minerals in
surface and subsurface
soil samples collected
and transferred by the
Robotic Arm.
To do this, materials
placed onto a grate
inside one of the eight
ovens, would be heated
and vaporized at 1000
°C. The Evolved Gas
Analyzer would then
record measurements
using a spectrometer
and an electrochemical
cell. For calibration, an
empty oven would also
be heated during this
process for differential
scanning calorimetry.
The difference in the
energy required to heat
each oven would then
indicate concentrations
of water ice and other
minerals containing
water or carbon
dioxide.[6]


Principal investigator:
David Paige / UCLA
(website)
reincorporated on
Phoenix
Mars Microphone
The microphone was
intended to be the first
instrument to record
sounds on another
planet. Primarily
composed of a
microphone generally
used with hearing aids,
the instrument was
expected to record
sounds of blowing dust,
electrical discharges
and the sounds of the
operating spacecraft in
either 2.6-second or
10.6-second, 12-bit
samples.[8] The
microphone used
speech recognition
from technology
Sensory, Inc.[9]


Images of the spacecraft
Annotated diagram of the Mars
Polar Lander spacecraft.
The spacecraft in stowed
position just prior to
encapsulation.
Principal investigator:
Louis Friedman / SSL
Berkeley / The
Planetary Society
(website)
reincorporated on
Phoenix
Testing performed at the
Spacecraft Assembly and
Encapsulation Facility
The Mars Polar Lander entry
capsule, just prior to being
mounted to the Star 48 upper
stage.
[edit] Mission profile
Timeline of observations
Date
Event
1999-01Spacecraft launched at 20:21:10 UTC
03
1999-12[show] Begin atmospheric entry and landing
03
1999-12[show]Failure to regain communication after
03
landing
2000-01- Mission declared a loss. No further attempts to
17
contact.
[edit] Launch and trajectory
Mars Polar Lander was launched on January 3, 1999, at
20:21:10 UTC by the National Aeronautics and Space
Administration from Space Launch Complex 17B at the Cape
Canaveral Air Force Station in Florida, aboard a Delta II 7425
launch vehicle. The complete burn sequence lasted for 47.7
minutes after a Thiokol Star 48B solid-fuel third stage booster
placed the spacecraft into an 11 month, Mars transfer trajectory
at a final velocity of 6.884 kilometers per second with respect to
Mars. During cruise, the spacecraft was stowed inside an
aeroshell capsule and was powered and communicated with
Earth with the a segment known as the cruise stage.[1][2][3]
Launch configuration diagram.
Launch photo of Mars Polar
Lander aboard a Delta II
launch vehicle.
Diagram of the interplanetary
trajectory of Mars Polar Lander.
[edit] Landing encounter with Mars
Main article: Exploration of Mars
Cruise configuration
Landing procedure
Landing region
Mars Polar Lander enterted the Martian atmosphere with an
aeroshell for protection from atmospheric friction.
On December 3, 1999, Mars Polar Lander encountered Mars
while mission operators began preparing for landing operations.
At 14:39:00 UTC, the cruise stage was jettisoned, beginning a
planned communication dropout until the spacecraft had touched
down on the surface. Six minutes prior to atmospheric entry, a
programmed 80-second thruster firing turned the spacecraft to
the proper entry orientation, with the heat shield oriented to
absorb the intense, 1650 °C heat that would be generated as the
descent capsule passed through the atmosphere. Traveling at 6.9
kilometers per second, the entry capsule entered the Martian
atmosphere at 20:10:00 UTC and was expected to land in the
vicinity of 76°S 195°W76°S 195°W in a region known as
Planum Australe. Communication was expected to be
reestablished with the spacecraft at 20:39:00 UTC after having
landed. However, no communication attempt was successful
with the spacecraft.[1][2][3]
The Phoenix lander has subsequently completed most of the
objectives of Mars Polar Lander, carrying several of the same or
derivative instruments. Phoenix landed successfully on May 25,
2008.
[edit] Intended operations
Traveling at approximately 6.9 kilometers/second and 125
kilometers above the surface, the spacecraft entered the
atmosphere and was initially decelerated by using a 2.4 meter
ablation heat shield, located on the bottom of the entry body, to
aerobrake through 116 kilometers of the atmosphere. Three
minutes after entry, the spacecraft had slowed to 496 meters per
second signaling an 8.4-meter, polyester parachute to deploy
from a mortar followed immediately by heat shield separation
and MARDI being powered on, while 8.8 kilometers above the
surface. The parachute further slowed the speed of the spacecraft
to 85 meters per second when the ground radar began tracking
surface features to detect the best possible landing location.
When the spacecraft had slowed to 80 meters per second, one
minute after parachute deployment, the lander separated from the
backshell and began a powered descent while 1.3 kilometers
aloft. The powered descent was expected to have lasted
approximately one minute, bringing the spacecraft 12 meters
above the surface. The engines were then shut off and the
spacecraft would expectedly fall to the surface and land at
20:15:00 UTC near 76°S 195°W in Planum Australe.[1][2][3][4]
Lander operations were to begin five minutes after touchdown,
first unfolding the stowed solar arrays followed by orienting the
medium-gain, Direct-To-Earth antenna to allow for the first
communication with the Deep Space Network. At 20:39:00
UTC, a 45-minute transmission was to be broadcast to Earth,
transmitting the expected thirty landing images acquired by
MARDI and signaling a successful landing. The lander would
then power down for six hours to allow the batteries to charge.
On the following days, the spacecraft instruments would be
checked by operators and science experiments were to begin on
December 7 and last for at least the following 90 Martian Sols,
with the possibility of an extended mission.[1][2][3][4]
[edit] Communications loss
On December 3, 1999, at 14:39:00 UTC, the last telemetry from
Mars Polar Lander was sent, just prior to cruise stage separation
and the subsequent atmospheric entry. No further signals were
received from the spacecraft. Attempts were made by Mars
Global Surveyor, to photograph the area the lander was believed
to be. An object was visible and believed to possibly be the
lander; however, subsequent imaging performed by Mars
Reconnaissance Orbiter resulted in the identified object to be
incorrect. Mars Polar Lander remains lost.[10][11]
The cause of the communication loss is not known. However, the
Failure Review Board concluded that the most likely cause of the
mishap was a software error that incorrectly identified vibrations,
caused by the deployment of the stowed legs, as surface
touchdown.[12] The resulting action by the spacecraft was the
shutdown of the descent engines, while still likely 40 meters
above the surface. Although it was known that leg deployment
could create the false indication, the software's design
instructions did not account for that eventuality.[13]
In addition to the premature shutdown of the descent engines, the
Failure Review Board also assessed other potential modes of
failure.[14] Lacking substantial evidence for the mode of failure,
the following possibilies could not be excluded:






Surface conditions exceed landing design capabilities.
Loss of control due to dynamic effects.
Landing site not survivable.
Backshell/parachute contacts lander.
Loss of control due to center-of-mass offset.
Heatshield fails due to micrometeoroid impact.
The failure of the Mars Polar Lander took place two and a half
months after the loss of the Mars Climate Orbiter. Inadequate
funding and poor management have been cited as underlying
causes of the failures.[15] According to Thomas Young, chairman
of the Mars Program Independent Assessment Team, the
program "was under funded by at least 30%."[16]
Quoted from the report[14]
"A magnetic sensor is provided in each of the three landing legs
to sense touchdown when the lander contacts the surface,
initiating the shutdown of the descent engines. Data from MPL
engineering development unit deployment tests, MPL flight unit
deployment tests, and Mars 2001 deployment tests showed that a
spurious touchdown indication occurs in the Hall Effect
touchdown sensor during landing leg deployment (while the
lander is connected to the parachute). The software logic accepts
this transient signal as a valid touchdown event if it persists for
two consecutive readings of the sensor. The tests showed that
most of the transient signals at leg deployment are indeed long
enough to be accepted as valid events, therefore, it is almost a
certainty that at least one of the three would have generated a
spurious touchdown indication that the software accepted as
valid.
The software—intended to ignore touchdown indications prior to
the enabling of the touchdown sensing logic—was not properly
implemented, and the spurious touchdown indication was
retained. The touchdown sensing logic is enabled at 40 meters
altitude, and the software would have issued a descent engine
thrust termination at this time in response to a (spurious)
touchdown indication.
At 40 meters altitude, the lander has a velocity of approximately
13 meters per second, which, in the absence of thrust, is
accelerated by Mars gravity to a surface impact velocity of
approximately 22 meters per second (the nominal touchdown
velocity is 2.4 meters per second). At this impact velocity, the
lander could not have survived."
[edit] See also


Exploration of Mars
Phoenix lander, 2008
[edit] References
1.
2.
3.
^ a b c d e f g h i j k l m n "1998 Mars Missions Press Kit" (PDF) (Press
release). NASA. 1998.
http://www.jpl.nasa.gov/files/misc/mars98launch.pdf. Retrieved
2011-03-12.
^ a b c d e f "Mars Polar Lander/Deep Space 2 Press Kit" (PDF) (Press
release). NASA. 1999. http://www.jpl.nasa.gov/files/misc/mplds2hq.pdf. Retrieved 2011-03-12.
^ a b c d e f g h i j k l "Mars Polar Lander". NASA/National Space
Science Data Center.
http://nssdc.gsfc.nasa.gov/nmc/masterCatalog.do?sc=1999-001A.
Retrieved 2011-03-12.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
^ a b c d e f g "MPL: Lander Flight System Description". NASA / JPL.
1998. http://lunar.ksc.nasa.gov/mars/msp98/lander/bus.html.
Retrieved 2011-03-12.
^ "Mars Descent Imager (MARDI)". NASA/National Space Science
Data Center.
http://nssdc.gsfc.nasa.gov/nmc/experimentDisplay.do?id=1999001A-02. Retrieved 2011-03-17.
^ a b c d e f "Mars Volatiles and Climate Surveyor (MVACS)".
NASA/National Space Science Data Center.
http://nssdc.gsfc.nasa.gov/nmc/experimentDisplay.do?id=1999001A-01. Retrieved 2011-03-17.
^ "Light Detection and Ranging (LIDAR)". NASA/National Space
Science Data Center.
http://nssdc.gsfc.nasa.gov/nmc/experimentDisplay.do?id=1999001A-03. Retrieved 2011-03-17.
^ "Mars Microphone". NASA/National Space Science Data Center.
http://nssdc.gsfc.nasa.gov/nmc/experimentDisplay.do?id=1999001A-04. Retrieved 2011-03-17.
^ The Planetary Society. “[1].” .
^ Editors (6 May 2005). "Mars Polar Lander Found at Last?". Sky
and Telescope. http://skyandtelescope.com/news/article_1509_1.asp.
Retrieved 2009-04-22.
^ "Release No. MOC2-1253: Mars Polar Lander NOT Found". Mars
Global Surveyor / Mars Orbiter Camera. NASA/JPL/Malin Space
Science Systems. 17 October 2005.
http://www.msss.com/mars_images/moc/2005/10/17/. Retrieved
2009-04-22.
^ [2] Youtube - NASA 3: Mission Failures
^ Nancy G. Leveson. The Role of Software in Recent Aerospace
Accidents. http://sunnyday.mit.edu/accidents/issc01.pdf.
^ a b "Report on the Loss of the Mars Polar Lander and Deep Space 2
Missions". Jet Propulsion Laboratory. 22 March 2000.
ftp://ftp.hq.nasa.gov/pub/pao/reports/2000/2000_mpl_report_1.pdf.
^ Thomas Young (14 March 2000). Mars Program Independent
Assessment Team Summary Report. Draft #7 3/13/00. House Science
and Technology Committee.
http://www.spaceref.com/news/viewpr.html?pid=1444. Retrieved
2009-04-22.
^ Jeffrey Kaye (14 April 2000). "NASA in the Hot Seat" (transcript).
NewsHour with Jim Lehrer (PBS).
http://www.pbs.org/newshour/bb/science/jan-june00/nasa_4-14.html.
Retrieved 2009-04-22.
[edit] Further reading


"Mars Polar Lander (1999-001A)". NSSDC Master Catalog.
NASA. 2001.
http://nssdc.gsfc.nasa.gov/nmc/spacecraftDisplay.do?id=199
9-001A. Retrieved 2009-04-22.
Michael C. Malin (July 2005). "Hidden in Plain Sight:
Finding Martian Landers". Sky and Telescope 110 (7): 42–
46. ISSN 00376604.

"Press Kit: 1998 Mars Missions" (.PDF) (Press release).
National Aeronautics and Space Administration. 8 December
1998. http://www2.jpl.nasa.gov/files/misc/mars98launch.pdf.
Retrieved 2009-04-22.
[edit] External links
Wikimedia Commons has media related to: Mars Polar
Lander


Mars Polar Lander site at Jet Propulsion Laboratory
Mars Polar Lander Mission at The NASA Solar System
Exploration Home Page
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

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