Mars Polar Lander: Difference between revisions
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{{Infobox spaceflight
| name = Mars Polar Lander
| names_list = Mars Surveyor '98<!--list of previous names if the spacecraft has been renamed.
Include the dates applicable if possible, and separate each name with a linebreak.
Omit if the spacecraft has only ever been known by one name.
Do not include Harvard, COSPAR/NSSDC or SATCAT/NORAD/NASA designations as alternative names-->
<!--image of the spacecraft/mission-->
| image = [[Image:Mars Polar Lander - artist depiction.png|290px|]]
| image_caption = Artist's depiction of the Mars Polar Lander on Mars
| image_alt = <!--image alt text-->
| image_size = <!--include px/em; defaults to 220px-->
<!--Basic details-->
| mission_type = [[Lander (spacecraft)|Lander]]
| operator = [[NASA]] / [[JPL]]
| Harvard_designation = <!--spacecraft launched 1962 and earlier only (eg. 1957 Alpha 2)-->
| COSPAR_ID = 1999-001A
| SATCAT = 25605
| website = [http://mars.jpl.nasa.gov/msp98/lander/ Mars Polar Lander website]
| mission_duration = {{age in days|1999|01|03|1999|12|03}} days
| distance_travelled = <!--How far the spacecraft travelled (if known)-->
| orbits_completed = <!--number of times the spacecraft orbited the Earth - see below for spacecraft beyond Earth orbit-->
| suborbital_range = <!--downrange distance reached if spacecraft did not enter orbit-->
| suborbital_apogee = <!--altitude reached if spacecraft did not enter orbit-->
<!--Spacecraft properties-->
| spacecraft = <!--Spacecraft name/serial number (eg. Space Shuttle ''Discovery'', Apollo CM-118), etc-->
| spacecraft_type = <!--eg. GPS Block II, Kobalt-M, US-K, etc-->
| spacecraft_bus = <!--eg. A2100M, Star-2, etc-->
| manufacturer = [[Martin Marietta]]
| launch_mass = {{convert|290|kg|lb}}
| BOL_mass = <!--spacecraft mass in orbit at beginning of operational life, after LEOP phase-->
| landing_mass = <!--Mass after landing (recovered spacecraft only)-->
| dry_mass = <!--spacecraft mass in orbit without fuel-->
| payload_mass = <!--Mass of cargo carried by spacecraft (eg. for Space Shuttle), or total mass of instrumentation/equipment/experiments for mission-->
| dimensions = <!--body dimensions and solar array span-->
| power = 200 W [[solar array]] and [[Nickel hydrogen battery|NiH{{small|<sub>2</sub>}} battery]]
<!--Launch details-->
| launch_date = {{start date|1999|01|03|20|21|10|TZ=Z}}
| launch_rocket = [[Delta II|Delta II 7425]]
| launch_site = [[Cape Canaveral Air Force Station Space Launch Complex 17|Cape Canaveral AFS SLC-17A]]
| launch_contractor = <!--organisation(s) that conducted the launch (eg. United Launch Alliance, Arianespace, etc)-->
| deployment_from = <!--place where deployed from-->
| deployment_date = <!--date deployed-->
| entered_service = <!--date on which the spacecraft entered service, if it did not do so immediately after launch-->
<!-- * - e.g. Proton-M/Briz-M not Proton-M, but Titan IV(401)A not Titan IV(401)A-Centaur-->
<!--end of mission-->
| disposal_type = failure at landing
| deactivated = <!--when craft was decommissioned-->
| destroyed = <!--when craft was destroyed (if other than by re-entry)-->
| last_contact = {{end date|1999|12|3|20|00|TZ=Z}}
| recovery_by = <!--recovered by-->
| recovery_date = <!--recovery date-->
| decay_date = <!--when craft re-entered the atmosphere, not needed if it landed-->
| landing_date = <!--when the spacecraft made a controlled landing, not needed if it did not return intact-->
| landing_site = <!--where the craft landed; site/runway or coordinates-->
<!--
The following template should be used for ONE of the three above fields "end_of_mission", "decay" or "landing" if the spacecraft is no longer operational.
If it landed intact, use it for the landing time, otherwise for the date it ceased operations, or the decay date if it was still operational when it re-entered.
{{end date|YYYY|MM|DD|hh|mm|ss|TZ=Z}} (for Zulu/UTC) or {{end date|YYYY|MM|DD}} (if time unknown)
-->
<!--orbit parameters-->
<!--as science-related articles, SI units should be the principal units of measurement, however we usually use {{convert}} to display imperial units in parentheses after the initial values-->
| orbit_reference = <!--geocentric, selenocentric, etc - please link (e.g. [[Geocentric orbit|Geocentric]])-->
| orbit_regime = <!--high, low, medium, molniya, GSO - please link (e.g. [[Low Earth orbit|Low Earth]] - please don't use acronyms-->
| orbit_longitude = <!--geosynchronous satellites only-->
| orbit_slot = <!--Designation of orbital position or slot, if not longitude (e.g plane and position of a GPS satellite)-->
| orbit_semimajor = <!--semimajor axis-->
| orbit_eccentricity = <!--orbital eccentricity-->
| orbit_periapsis = <!--periapsis altitude-->
| orbit_apoapsis = <!--apoapsis altitude-->
| orbit_inclination = <!--orbital inclination-->
| orbit_period = <!--time taken to complete an orbit-->
| orbit_RAAN = <!--right ascension of the ascending node-->
| orbit_arg_periapsis = <!--argument of perigee/periapsis-->
| orbit_mean_anomaly = <!--mean anomaly at epoch, only use in conjunction with an epoch value-->
| orbit_mean_motion = <!--mean motion of the satellite, usually measured in orbits per day-->
| orbit_repeat = <!--repeat interval/revisit time-->
| orbit_velocity = <!--speed at which the spacecraft was travelling at epoch - only use for spacecraft with low orbital eccentricity-->
| orbit_epoch = <!--the date at which the orbit parameters were correct-->
| orbit_rev_number = <!--revolution number-->
| apsis = <!--planet specific apsis term (eg. gee/helion/selene/etc - defaults to generic "apsis")-->
|interplanetary = <!--Infobox spaceflight/IP can be called multiple times for missions with multiple targets or combined orbiter/lander missions, etc-->
{{Infobox spaceflight/IP
|type = lander
|object = [[Mars]]
|orbits = <!--number of orbits completed at target body (if applicable and known)-->
|component = <!--part of the spacecraft involved, if spacecraft split into multiple components-->
|arrival_date = ~20:15 UTC [[Spacecraft Event Time#SCET versus Earth time|ERT]], December 3, 1999
|departure_date = <!--Date of leaving orbit for orbiters, date of launch for landers which took off again-->
|location = [[Ultimi Scopuli]], {{coord|76|S|195|W|globe:Mars|name=Mars Polar Lander}} (projected)
|distance = <!--closest approach distance for flybys, distance travelled on surface for rovers, omit for others-->
}}
<!--transponder parameters-->
| trans_band = <!--Transponder frequency bands-->
| trans_frequency = <!--specific frequencies-->
| trans_bandwidth = <!--bandwidth-->
| trans_capacity = <!--capacity of the transponders-->
| trans_coverage = <!--area covered-->
| trans_TWTA = <!--TWTA output power-->
| trans_EIRP = <!--equivalent isotropic power-->
| trans_HPBW = <!--half-power beam width-->
<!--Only use where a spacecraft/mission is part of a clear programme of sequential missions.
If in doubt, leave it out-->
| programme =
| previous_mission =
| next_mission =
<!--mission insignia or patch-->
| insignia = [[File:M98patch.png|180px]]
| insignia_caption =''Mars Surveyor 98'' mission logo
| insignia_alt = <!--image alt text-->
| insignia_size = <!--include px/em; defaults to 180px-->
}}
The '''Mars Polar Lander''', also known as the '''Mars Surveyor '98 Lander''', was a 290-kilogram [[robotic spacecraft]] [[Lander (spacecraft)|lander]] launched by [[NASA]] on January 3, 1999 to study the [[Martian soil|soil]] and [[Climate of Mars|climate]] of [[Planum Australe]], a region near the south pole on [[Mars]]. It formed part of the [[Mars Surveyor '98 program|Mars Surveyor '98 mission]]. On December 3, 1999, however, after the descent phase was expected to be complete, the lander failed to reestablish communication with Earth. A post-mortem analysis determined the most likely cause of the mishap was premature termination of the engine firing prior to the lander touching the surface, causing it to strike the planet at a high velocity.<ref name="LossReport">{{cite web |url=ftp://ftp.hq.nasa.gov/pub/pao/reports/2000/2000_mpl_report_1.pdf |title=Report on the Loss of the Mars Polar Lander and Deep Space 2 Missions |publisher=[[Jet Propulsion Laboratory]] |date=22 March 2000}}</ref>
==Mission background==
===History===
As part of the [[Mars Surveyor '98 program|Mars Surveyor '98 mission]], a lander was sought as a way to gather climate data from the ground in conjunction with an orbiter. [[NASA]] suspected that a large quantity of frozen water may exist under a thin layer of dust at the south pole. In planning the Mars Polar Lander, the potential water content in the Martian south pole was the strongest determining factor for choosing a landing location.<ref name="Surveyor98Launch"/> A CD-ROM containing the names of one million children from around the world was placed on board the spacecraft as part of the "Send Your Name to Mars" program designed to encourage interest in the space program among children.<ref>{{cite news | author=Ben Huh | title=Kids' Names Going To Mars | url=http://articles.sun-sentinel.com/1998-03-03/lifestyle/9803020131_1_martian-surface-robotic-arm-space-program | publisher=SunSentinel | date=3 March 1998 | accessdate=2013-05-30}}</ref> <!--needs expansion-->
The primary objectives of the mission were to:<ref name="MPLDS2Landing"/>
* land on the layered terrain in the south polar region of Mars;
* 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; and
* study surface [[Geomorphology|morphology]] (forms and structures), geology, [[topography]], and weather of the landing site.
===Deep Space 2 Probes===
{{main|Deep Space 2}}
The Mars Polar Lander carried two small, identical [[impactor (spacecraft)|impactor]] probes known as "Deep Space 2 A and B". The probes were intended to strike the surface with a high velocity at approximately {{Coord|73|S|210|W|globe:Mars|name=Deep Space 2}}, 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.<ref name="Surveyor98Launch"/>
===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 of these components included redundant units in the event that one may fail.<ref name="Surveyor98Launch">{{cite press release| publisher= [[NASA]]| year= 1998| format= PDF| title= 1998 Mars Missions Press Kit| url= http://www.jpl.nasa.gov/files/misc/mars98launch.pdf| accessdate= 2011-03-12}}</ref><ref name="NSSDCMissionInfo">{{cite web |url= http://nssdc.gsfc.nasa.gov/nmc/masterCatalog.do?sc=1999-001A|title= Mars Polar Lander|publisher= NASA/National Space Science Data Center|accessdate= 2011-03-12}}</ref><ref name="MPLWebsiteSpacecraftInfo">{{cite web|url= http://lunar.ksc.nasa.gov/mars/msp98/lander/bus.html|title= MPL: Lander Flight System Description|year= 1998|publisher= NASA / JPL|accessdate= 2011-03-12|deadurl= yes|archiveurl= https://web.archive.org/web/20110721051047/http://lunar.ksc.nasa.gov/mars/msp98/lander/bus.html|archivedate= 2011-07-21|df= }}</ref>
====Attitude control and propulsion====
While traveling to Mars, the cruise stage was three-axis stabilized with four [[hydrazine]] [[monopropellant rocket|monopropellant]] reaction engine modules, each including a 22-[[Newton (unit)|newton]] trajectory correction maneuver thruster for propulsion and a 4-newton reaction control system thruster for [[attitude control]]. Orientation of the spacecraft was performed using redundant [[Attitude control#Sun sensor|Sun sensors]], [[Attitude control#Star tracker|star trackers]], and [[Attitude control#Gyroscopes|inertial measurement units]].<ref name='NSSDCMissionInfo'/>
During descent, the lander used three clusters of pulse modulated engines, each containing four 266-newton hydrazine monopropellant thrusters. Altitude during landing was measured 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.<ref name="Surveyor98Launch"/><ref name='NSSDCMissionInfo'/><ref name="MPLWebsiteSpacecraftInfo"/>
The lander was launched with two hydrazine tanks containing 64 kilograms of propellant and pressurized using [[helium]]. Each spherical tank was located at the underside of the lander and provided propellant during the cruise and descent stages.<ref name="Surveyor98Launch"/><ref name='NSSDCMissionInfo'/><ref name="MPLWebsiteSpacecraftInfo"/>
====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.<ref name="Surveyor98Launch"/>
The lander was originally intended to communicate data through the failed [[Mars Climate Orbiter]] via the [[Ultra high frequency|UHF]] antenna. With the orbiter 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. The direct-to-Earth medium-gain antenna provided a 12.6-kbit/s [[return channel]], and the UHF relay path
provided a 128-kbit/s return channel. 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.<ref name="Surveyor98Launch"/><ref name="MPLDS2Landing"/><ref name='NSSDCMissionInfo'/><ref name="MPLWebsiteSpacecraftInfo"/>
====Power====
The cruise stage included two [[gallium arsenide]] [[Photovoltaic system|solar arrays]] to power the radio system and maintain power to the batteries in the lander, which kept certain electronics warm.<ref name="Surveyor98Launch"/><ref name='NSSDCMissionInfo'/>
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 auxiliary solar arrays were located on the side to provide additional power for a total of an expected 200 watts and approximately eight to nine hours of operating time per day.<ref name="Surveyor98Launch"/><ref name='NSSDCMissionInfo'/>
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 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.<ref name="Surveyor98Launch"/><ref name='NSSDCMissionInfo'/><ref name="MPLWebsiteSpacecraftInfo"/>
<!--====Computer====-->
====Scientific instruments====
{{Gallery|align=center
|title=Scientific instruments
|file:Mars Polar Lander - MARDI instrument photo - mardi.jpg|Mars Descent Imager
|file:Mars Polar Lander - SSI instrument photo - ssi closeup s.jpg|Stereo Surface Imager
|file:Mars Polar Lander - LIDAR instrument photo - mpl lidar.gif|LIDAR
|file:Mars Polar Lander - RA instrument photo - arm.png|Robotic Arm
|file:Mars Polar Lander - RAC instrument photo.png|Robotic Arm Camera
|file:Mars Polar Lander - MET instrument photo - mettop.png|Meteorological Package
|file:Mars Polar Lander - TEGA instrument photo.png|Thermal and Evolved Gas Analyzer
|file:Mars Polar Lander - Mars Microphone instrument photo - microphone.jpg|Mars Microphone
}}
{{Gallery|align=center
|title=Images of the spacecraft
|File:Mars Polar Lander - spacecraft diagram.png|Annotated diagram of the Mars Polar Lander spacecraft
|File:Mars Polar Lander close-up.jpg|The spacecraft in stowed position just prior to encapsulation
|File:Mars Polar Lander undergoes testing.jpg|Testing performed at the Spacecraft Assembly and Encapsulation Facility
|File:Mars Polar Lander prelaunch.jpg|The ''Mars Polar Lander'' entry capsule, just prior to being mounted to the [[Star 48]] upper stage
}}
; [[Mars Descent Imager#Mars Descent Imager .28MARDI.29|Mars Descent Imager]] (MARDI): Mounted to the bottom of the lander, the camera was intended to capture 30 images as the spacecraft descended to the surface. The images acquired would be used to provide geographic and geologic context to the landing area.<ref name="NSSDCMARDI">{{cite web |url= http://nssdc.gsfc.nasa.gov/nmc/experimentDisplay.do?id=1999-001A-02|title= Mars Descent Imager (MARDI)|publisher= NASA/National Space Science Data Center|accessdate= 2011-03-17}}</ref>
; [[Phoenix (spacecraft)#Surface stereo imager|Surface Stereo Imager]] (SSI): Using a pair of [[charge coupled device]]s (CCD), the stereo [[panoramic camera]] was mounted to a one-meter-tall mast and would aid in the thermal evolved gas analyzer in 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 [[aerosol]]s, and slant column abundances of water vapor using narrow-band imaging of the Sun.<ref name="NSSDCMVACS">{{cite web |url=http://nssdc.gsfc.nasa.gov/nmc/experimentDisplay.do?id=1999-001A-01 |title=Mars Volatiles and Climate Surveyor (MVACS) |publisher= NASA/National Space Science Data Center|accessdate= 2011-03-17}}</ref>
; [[Lidar|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.<ref name="NSSDCLIDAR">{{cite web |url=http://nssdc.gsfc.nasa.gov/nmc/experimentDisplay.do?id=1999-001A-03 |title=Light Detection and Ranging (LIDAR) |publisher= NASA/National Space Science Data Center|accessdate= 2011-03-17}}</ref>
; [[Robotic arm|Robotic Arm]] (RA): Located on the front of the lander, the robotic arm was 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 the 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.<ref name="NSSDCMVACS"/>
; Robotic Arm Camera (RAC): Located on the robotic arm, the charge coupled camera included two red, two green, and four blue lamps to illuminate soil samples for analysis.<ref name="NSSDCMVACS"/>
; 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.<ref name="NSSDCMVACS"/>
; [[Thermal and Evolved Gas Analyzer]] (TEGA): The instrument was intended to measure abundances of water, water ice, adsorbed carbon dioxide, oxygen, and volatile-bearing minerals in surface and subsurface soil samples collected and transferred by the robotic arm. Materials placed onto a grate inside one of the eight ovens, would be heated and vaporized at 1,000 °C. The evolved gas analyzer would then record measurements using a [[spectrometer]] and an [[Electrochemistry|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.<ref name="NSSDCMVACS"/>
; 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 aid]]s, 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.<ref name="NSSDCMIC">{{cite web |url=http://nssdc.gsfc.nasa.gov/nmc/experimentDisplay.do?id=1999-001A-04 |title=Mars Microphone |publisher= NASA/National Space Science Data Center|accessdate= 2011-03-17}}</ref> The microphone was built using off-the-shelf parts including a [[Sensory, Inc.]] RSC-164 integrated circuit typically used in speech-recognition devices.<ref name= "Planetary Society article">{{Cite web |url=http://www.planetary.org/programs/projects/planetary_microphones/mars_microphone.html |publisher=[[The Planetary Society]] |title=Projects: Planetary Microphones -- The Mars Microphone |archiveurl=https://web.archive.org/web/20060818152601/http://www.planetary.org/programs/projects/planetary_microphones/mars_microphone.html |archivedate=2006-08-18}}</ref>
==Mission profile==
{| style="float: right;"
! colspan="2" | Timeline of observations
|-
|
{| cellspacing="0" cellpadding="0" align="center" width="100%" style="border:0px solid #e6e6e6"
|-
| colspan="2" |
----
|-
! scope="col" width="75" | Date
! scope="col" width="350" | Event
|-
| colspan="2" |
----
<!--Main table data-outside collapsible-->
|-
| {{center|1999-01-03}}
| style="background-color:#f2f2f2;" | Spacecraft launched at 20:21:10 UTC
|-
| {{center|1999-12-03}}
|
<!--Collapsable data header-->
{| class="collapsible collapsed" align="center" width = "100%"
! colspan="2" style="background-color:#e9e9e9;font-weight:normal;" | {{pad|2em}} Begin atmospheric entry and landing
|-
| colspan="2" |
----
|- style="background-color:#e0e0e0"
! scope="col" width="75" | Time
! scope="col" width="230" | Event {{pad|6em}}
|-
| colspan="2" |
----
<!--Collapsable data input-copy for more entries-->
|-
| {{center|'''1999-12-03'''}}
|
|-
| {{center|14:39:00}}
| {{small|Turn spacecraft away from Earth for final stellar data acquisition, signal loss from spacecraft}}
|-
| {{center|14:42:00}}
| {{small|Turn on heaters on descent engine}}
|-
| {{center|17:34:00}}
| {{small|Turn on heaters on descent camera (MARDI)}}
|-
| {{center|18:49:00}}
| {{small|Turn spacecraft back to Earth point, acquire spacecraft signal, acquire health & status}}
|-
| {{center|19:21:00}}
| {{small|Begin Entry, Descent, Landing sequence}}
|-
| {{center|19:26:00}}
| {{small|Pyros fire to pressurize helium tank}}
|-
| {{center|20:00:00}}
| {{small|Guidance system initialization (2210 km, 6.2 km/s)}}
|-
| {{center|20:03:00}}
| {{small|Turn spacecraft to entry attitude, loss of signal. We won't hear from the spacecraft again until after landing (1426 km, 6.4 km/s)}}
|-
| {{center|20:05:00}}
| {{small|Cruise ring/Deep Space 2 probes separate from lander (959 km, 6.6 km/s)}}
|-
| {{center|20:10:00}}
| {{small|Atmospheric entry (142 km, 6.9 km/s)}}
|-
| {{center|20:11:00}}
| {{small|Descent radar powered on}}
|-
| {{center|20:12:00}}
| {{small|MARDI instrument powered on}}
|-
| {{center|20:13:00}}
| {{small|Parachute deployed (9.0 km, 496 m/s)}}
|-
| {{center|20:13:00}}
| {{small|Descent imaging begins, heatshield jettisoned (8.0 km, 286 m/s)}}
|-
| {{center|20:13:00}}
| {{small|Lander legs deployed, descent radar activated}}
|-
| {{center|20:14}}
| {{small|Radar ground acquisition, altitude (2.438 km, 80 m/s)}}
|-
| {{center|20:14:00}}
| {{small|Lander separates from backshell, powered descent begins (1.628 km, 78 m/s)}}
|-
| {{center|20:14:00}}
| {{small|Radar ground acquisition, speed & direction (1.425 km, 82 m/s)}}
|-
| {{center|20:14}}
| {{small|Gravity turn begins (1.394 km, 83 m/s)}}
|-
| {{center|20:14:00}}
| {{small|Roll to landed orientation (1.307 km, 79 m/s)}}
|-
| {{center|20:14:00}}
| {{small|Radar cutoff (40 meters, 13 m/s)}}
|-
| {{center|20:15:00}}
| {{small|Constant Velocity Phase (12 meters, 2.4 m/s)}}
|-
| {{center|20:15:00}}
| {{fontcolor|red|{{small|'''Touchdown. Mars Polar Lander on Mars surface.'''}}}}
|-
| {{center|20:20:00}}
| {{fontcolor|red|{{small|Lander unfolds solar panels}}}}
|-
| {{center|20:20:00}}
| {{fontcolor|red|{{small|Medium gain antenna pointed at Earth}}}}
|-
| {{center|20:39:00}}
| {{fontcolor|red|{{small|'''Lander begins 1st transmission to Earth (45 minutes). Sends health & status, meteorology & 1 b/w image'''}}}}
|-
| {{center|21:24:00}}
| {{fontcolor|red|{{small|Lander ends transmission to Earth}}}}
|-
| {{center|21:45:00}}
| {{fontcolor|red|{{small|Lander powers down to sleep so it can recharge}}}}
|-
| {{center|22:10:00}}
| {{fontcolor|red|{{small|Start of 1 hour backup downlink opportunity (if spacecraft went into safemode during landing)}}}}
|-
| {{center|'''1999-12-04'''}}
|
|-
| {{center|02:50:00}}
| {{fontcolor|red|{{small|Lander wakes up, receives instructions from Earth}}}}
|-
| {{center|03:25:00}}
| {{fontcolor|red|{{small|'''Begin DS2 microprobe data reception via Mars Global Surveyor relay (15 minute transmission)'''}}}}
|-
| {{center|04:25:00}}
| {{fontcolor|red|{{small|2.5 hour downlink begins, could include lander and descent images}}}}
|-
| {{center|06:25:00}}
| {{fontcolor|red|{{small|Lander shuts itself down until next day. End of Sol 0 activities.}}}}
|-
| colspan="2" | {{center|<small>Items in {{fontcolor|red|'''red'''}} were planned events.</small>}}
|}
|-
| {{center|1999-12-03}}
|
<!--Collapsable data header-->
{| class="collapsible collapsed" align="center" width = "100%"
! colspan="2" style="background-color:#e9e9e9;font-weight:normal;" | Failure to regain communication after landing
|-
| colspan="2" |
----
|- style="background-color:#e0e0e0"
! scope="col" width="75" | Time
! scope="col" width="230" | Event {{pad|6em}}
|-
| colspan="2" |
----
<!--Collapsable data input-copy for more entries-->
|-
| {{center|'''1999-12-03'''}}
|
|-
| {{center|20:39:00}}
| {{small|First communication from lander missed}}
|-
| {{center|22:04:00}}
| {{small|Second communication from lander missed}}
|-
| {{center|'''1999-12-04'''}}
|
|-
| {{center|04:08:00}}
| {{small|Third communication from lander missed}}
|-
| {{center|'''1999-12-05'''}}
|
|-
| {{center|04:30:00}}
| {{small|Fourth communication from lander missed}}
|-
| {{center|18:50:00}}
| {{small|First attempt to detect automatic fail-safe UHF communication to Mars Global Surveyor failed}}
|-
| {{center|'''1999-12-06'''}}
|
|-
| {{center|06:10:00}}
| {{small|Second attempt to detect automatic fail-safe UHF communication to Mars Global Surveyor failed}}
|-
| {{center|'''1999-12-07'''}}
|
|-
| {{center|08:20:00}}
| {{small|Third attempt to detect automatic fail-safe UHF communication to Mars Global Surveyor failed}}
|-
| {{center|'''1999-12-08'''}}
| {{small|Radio sweeps of the surface by the Deep Space Network failed. Repeat of prior procedures to exhaust all possibilities of regaining contact.}}
|}
|-
| {{center|2000-01-17}}
| style="background-color:#f2f2f2;" | Mission declared a loss. No further attempts to contact.
|}
|}
===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 [[Cape Canaveral Air Force Station Space Launch Complex 17|Space Launch Complex 17B]] at the [[Cape Canaveral Air Force Station]] in Florida, aboard a [[Delta II|Delta II 7425]] launch vehicle. The complete burn sequence lasted for 47.7 minutes after a [[Thiokol]] [[Star 48]]B 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 a segment known as the ''cruise stage'' provided power and communications with Earth.<ref name="Surveyor98Launch"/><ref name="MPLDS2Landing">{{cite press release| publisher=NASA| year=1999| format=PDF| title=Mars Polar Lander/Deep Space 2 Press Kit| url=http://www.jpl.nasa.gov/files/misc/mpl-ds2hq.pdf| accessdate=2011-03-12}}</ref><ref name='NSSDCMissionInfo'/>{{Clear}}
<!--Gallery of launch and trajectories at end of section-->
{{Gallery|align=center
|width=175 |lines=2
|File:Mars Polar Lander - launch configuration diagram.png|alt1=Diagram of the configured positions of Mars Polar Lander within a Delta II launch vehicle |{{small|Launch configuration diagram.}}
|File:Mars Polar Lander - launch photo.png|alt2=Launch photo of Mars Polar Lander being lifted into space by a Delta II launch vehicle |{{small|Launch photo of Mars Polar Lander aboard a Delta II launch vehicle.}}
|File:Mars Polar Lander - interplanetary trajectory.png|alt3=Diagram of the interplanetary trajectory of Mars Polar Lander |{{small|Diagram of the interplanetary trajectory of Mars Polar Lander.}}
}}
===Landing zone===
The target landing zone was a region near the [[Planum Australe|south pole]] of Mars, called ''Ultimi Scopuli'', because it featured a large number of [[Scopulus|scopuli]] ([[wikt:lobe|lobate]] or irregular [[escarpment|scarp]]s).{{cn|date=July 2016}}
===Landing attempt===
{{further|Exploration of Mars}}
{{multiple image
| footer = Mars Polar Lander entered the Martian atmosphere with an aeroshell for protection from atmospheric friction.
| image1 = Mars Polar Lander - cruise configuration.png
| width1 = 90
| alt1 = Cruise configuration diagram of Mars Polar Lander.
| caption1 = <small>Cruise configuration</small>
| image2 = Mars Polar Lander - landing diagram.png
| width2 = 102
| alt2 = Diagram of landing prodedures of Mars Polar Lander as it would pass through the atmosphere and land on the surface.
| caption2 = <small>Landing procedure</small>
| image3 = Mars Polar Lander - targeted landing sector.png
| width3 = 84
| alt3 = Map of the region targeted for landing by the Mars Polar Lander.
| caption3 = <small>Landing region</small>
}}
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 [[wikt:jettison#Verb|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 1,650 °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 [[Atmosphere of Mars|Martian atmosphere]] at 20:10:00 UTC and was expected to land in the vicinity of {{Coord|76|S|195|W|globe:Mars|name=Mars Polar Lander}} 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 was possible with the spacecraft and the lander was declared lost.<ref name="Surveyor98Launch"/><ref name="MPLDS2Landing"/><ref name='NSSDCMissionInfo'/>
On May 25, 2008 the [[Phoenix (spacecraft)|Phoenix]] lander arrived at Mars, and has subsequently completed most of the objectives of the ''Mars Polar Lander'', carrying several of the same or derivative instruments.
{{Features and artificial objects on Mars}}
===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 powering 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.<ref name="Surveyor98Launch"/><ref name="MPLDS2Landing"/><ref name='NSSDCMissionInfo'/><ref name="MPLWebsiteSpacecraftInfo"/>
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 UTC, a 45-minute transmission was to be broadcast to Earth, transmitting the expected 30 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 [[Timekeeping on Mars#Sols|Martian Sols]], with the possibility of an extended mission.<ref name="Surveyor98Launch"/><ref name="MPLDS2Landing"/><ref name='NSSDCMissionInfo'/><ref name="MPLWebsiteSpacecraftInfo"/>
==Loss of communications==
On 3 December 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 in which the lander was believed to be. An object was visible and believed to be the lander. However, subsequent imaging performed by [[Mars Reconnaissance Orbiter]] resulted in the identified object being ruled out. ''Mars Polar Lander'' remains lost.<ref>{{cite news| author=Editors | title=Mars Polar Lander Found at Last? | url=http://skyandtelescope.com/news/article_1509_1.asp | work=[[Sky and Telescope]] | date=6 May 2005 | accessdate=2009-04-22}}</ref><ref>{{cite web | author= | title=Release No. MOC2-1253: Mars Polar Lander NOT Found | url=http://www.msss.com/mars_images/moc/2005/10/17/ | work=Mars Global Surveyor / Mars Orbiter Camera | publisher=NASA/JPL/Malin Space Science Systems | date=17 October 2005 | accessdate=2009-04-22}}</ref>
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.<ref name="NASA 3: Mission Failures">[https://www.youtube.com/watch?v=YJ6pbCHpXEI] Youtube - NASA 3: Mission Failures</ref> 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.<ref>{{cite journal | author=Nancy G. Leveson | title=The Role of Software in Recent Aerospace Accidents| url=http://sunnyday.mit.edu/accidents/issc01.pdf}}</ref>''
In addition to the premature shutdown of the descent engines, the Failure Review Board also assessed other potential modes of failure.<ref name="LossReport"/> Lacking substantial evidence for the mode of failure, the following possibilities 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; or
* 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.<ref>{{cite journal | author=Thomas Young | title=Mars Program Independent Assessment Team Summary Report | version=Draft #7 3/13/00 | publisher=House Science and Technology Committee | url=http://www.spaceref.com/news/viewpr.html?pid=1444 | date=14 March 2000 | accessdate=2009-04-22}}</ref> According to Thomas Young, chairman of the Mars Program Independent Assessment Team, the program "was under funded by at least 30%."<ref>{{cite news | author=Jeffrey Kaye | title=NASA in the Hot Seat | url=https://www.pbs.org/newshour/bb/science/jan-june00/nasa_4-14.html | format=transcript | work=NewsHour with Jim Lehrer | publisher=PBS | date=14 April 2000 | accessdate=2009-04-22}}</ref>''
<center>
{| class="wikitable"
! Quoted from the report<ref name="LossReport"/>
|-
| scope="col" width="750" |
"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|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."
|}
</center>
==See also==
{{Portal|Spaceflight}}
{{div col|colwidth=30em}}
* [[Mars Surveyor 2001 Lander]], similar design lander, mission cancelled. Lander used for Phoenix.
* [[Phoenix (spacecraft)|''Phoenix'' lander]], 2008
* [[Exploration of Mars]]
* [[ExoMars]] rover
* [[List of missions to Mars]]
* [[Mars Science Laboratory]] rover
{{div col end}}
==References==
{{Reflist|2}}
==Further reading==
* {{cite web | title=Mars Polar Lander (1999-001A) | work=NSSDC Master Catalog | publisher=NASA | url=http://nssdc.gsfc.nasa.gov/nmc/spacecraftDisplay.do?id=1999-001A | year=2001 | accessdate=2009-04-22}}
* {{cite journal | author=Michael C. Malin | title=Hidden in Plain Sight: Finding Martian Landers | journal=Sky and Telescope | volume=110 | issue=7| date=July 2005 | pages=42–46 | issn=0037-6604}}
* {{cite press release | author= | title=Press Kit: 1998 Mars Missions | version= | format=.PDF | publisher=National Aeronautics and Space Administration | url=http://www2.jpl.nasa.gov/files/misc/mars98launch.pdf | date=8 December 1998 | accessdate=2009-04-22}}
==External links==
{{Commons category}}
* [http://mpfwww.jpl.nasa.gov/msp98/ Mars Polar Lander site] at [[Jet Propulsion Laboratory]]
* [http://solarsystem.nasa.gov/missions/profile.cfm?MCode=MPL Mars Polar Lander Mission] at The NASA Solar System Exploration Home Page
{{clear}}
==Features and artificial objects on Mars - clickable map==
{{Features and artificial objects on Mars}}
{{Mars spacecraft}}
{{Orbital launches in 1999}}
{{Jet Propulsion Laboratory}}
[[Category:Missions to Mars]]
[[Category:NASA space probes]]
[[Category:Derelict landers (spacecraft)]]
[[Category:Mare Australe quadrangle]]
[[Category:Spacecraft launched in 1999]]
[[Category:Spacecraft launched by Delta II rockets]]
[[Category:Space accidents and incidents in the United States]]
[[Category:Attached spacecraft]]
{{En-WP-Attrib}}
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