| MISSION_DESCRIPTION |
Mission Overview
================
The Phoenix Mission was the first Scout class mission. It consisted of a
single lander with associated instrumentation. Phoenix was launched on
August 4, 2007 and landed on the northern plains of Mars (68.22 degrees
N, 234.25 degrees East Areocentric) on May 25, 2008. The Lander
operated until November 2, 2008, performing on the Martian surface for
152 sols (sols are Martian days, 1 sol equaling 24.66 hours). The
Phoenix Mission was divided into seven phases: Development, Launch,
Cruise, Approach, Entry Descent and Landing (EDL), Characterization, and
Surface Phase. The Surface Phase constituted the primary and extended
missions, and focused on testing the hypothesis that water ice exists
beneath a thin soil cover, evaluating evidence for habitability zones,
and monitoring weather during the northern summer. Hence, inferring the
presence of water and its interaction with the Martian soil was of
crucial importance [SMITHETAL2008].
Mission phases
=============
Development
-----------
The Development Phase began with the start of mission funding on January
15, 2003. During this phase, the science and technology requirements
were developed and analyzed, hardware was constructed and tested, and
the spacecraft trajectory and mission operations were determined. The
phase was concluded on August 3, 2007 [SMITHETAL2008].
Spacecraft Id : PHX
Target Name : MARS
Mission Phase Start Time : 2003-01-15
Mission Phase Stop Time : 2007-08-03
Spacecraft Operations Type : LANDER
Launch
------
The Phoenix Launch Phase began at the final countdown through
spacecraft separation from the upper stage. Phoenix was launched on
August 4, 2007, at 926 UTC (526 EDT) from launch complex 17A at Cape
Canaveral Air Force Station, Florida. The boost portion of the launch
vehicle trajectory took approximately 10 minutes, and was followed by
a short coast phase in a parking orbit for approximately 15 minutes.
After third stage burnout, the upper stage despun the stack using a
yo-yo despin system. Separation of the third stage occurred
approximately 36 minutes after launch [SMITHETAL2008].
Spacecraft Id : PHX
Target Name : MARS
Mission Phase Start Time : 2007-08-04
Mission Phase Stop Time : 2007-08-04
Spacecraft Operations Type : LANDER
Cruise
------
The Phoenix Cruise phase began soon after separation from the third
stage on August 4, 2007, and ended 60 days before entry into the Mars
atmosphere, on March 26, 2008. The duration of the cruise phase for
Phoenix was approximately 236 days. During this phase, Phoenix
performed a number of major activities, including checkout and
maintenance of the spacecraft in its flight configuration, the
monitoring characterization and calibration of the spacecraft and
payload systems, software parameter updates, attitude correction
turns, navigation activities for determining and correcting the
vehicle's flight path, and preparation for EDL and surface operations,
including EDL X-band communication tests. No science investigations
were conducted during the cruise phase, excepting instrument health
checkouts [SMITHETAL2008].
Spacecraft Id : PHX
Target Name : MARS
Mission Phase Start Time : 2007-08-04
Mission Phase Stop Time : 2008-03-26
Spacecraft Operations Type : LANDER
Approach
--------
The Approach Phase began on March 26, 2008, 60 days before entry into
the Martian atmosphere. This phase was dedicated to the activities
necessary to ensure a successful EDL for the spacecraft, which
included: acquisition and processing of navigation data to support
development of the final trajectory correction maneuvers, and
activities leading up to the final turn to the entry attitude and
separation from the cruise stage seven minutes before entry. The
Approach Phase ended at the atmospheric entry interface point 125 km
from the surface of Mars, on May 25, 2008 [SMITHETAL2008].
Spacecraft Id : PHX
Target Name : MARS
Mission Phase Start Time : 2008-03-26
Mission Phase Stop Time : 2008-05-25
Spacecraft Operations Type : LANDER
Entry, Descent, and Landing
---------------------------
The EDL phase began immediately following entry into the Martian
atmosphere on May 25, 2008, and lasted seven minutes from entry to
touchdown. This phase was broken into hypersonic, parachute, and
terminal descent subphases, all of which required the spacecraft to be
in a different configuration. Terminal descent on Phoenix was
accomplished using a pulsed propulsion system, based on the Mars
Polar Lander (MPL).
Communications throughout the EDL phase - spanning cruise stage
separation through landing plus one minute - were accomplished via
UHF relay between Phoenix and the orbiters Mars Odyssey (ODY), Mars
Express (MEX), and Mars Reconnaissance Orbiter (MRO). All X-band
capability was lost once the cruise stage was jettisoned. During most
of EDL, Phoenix used a UHF antenna that wrapped around the backshell
to give the Lander a wide field of view (FOV) for communications,
which provided the wide spread of off-boresight angles necessitated
by the geometry between Phoenix and the orbiters. During terminal
descent (approximately 30 seconds before landing), the Lander switched
to the landed Helix antenna and continued transmitting a UHF signal
until one minute after landing.
After waiting 20 minutes after touchdown for the dust to settle,
Phoenix began performing a number of critical activities. These 'sol
0' activities included deployments of the landed solar arrays, the
bio-barrier covering the RA, and the SSI and MET masts. The Stereo
Surface Imager (SSI) took images of the bio-barrier, solar arrays,
and part of the footpad and workspace. High priority EDL and sol 0
data were saved to flash memory within the first hour after touchdown,
after which the Lander went to sleep to conserve energy. The Lander
woke up for ten minutes for the first post-landed UHF communication
pass one MRO orbit period (approximately 2 hours) after landing. After
relaying data to the orbiter during that first pass, the Lander went
to sleep again. Payload heaters were on continuously from touchdown,
with Lander heaters kicking in around midnight for 4-5 hours of keep-
alive heating [DESAIETAL2008].
Spacecraft Id : PHX
Target Name : MARS
Mission Phase Start Time : 2008-05-25
Mission Phase Stop Time : 2008-05-25
Spacecraft Operations Type : LANDER
Characterization
----------------
The Characterization Phase began after the sol 0 activities were
completed and lasted for eight Martian sols. During this phase the
lander's power, thermal and UHF subsystems were characterized and
prepared for operation. The Robotic Arm (RA) system, Surface Stereo
Imager (SSI), Microscopy, Electrochemistry, Conductivity Analyzer
(MECA), Thermal and Evolved Gas Analyzer (TEGA), and Meteorological
Station (MET) instruments were also characterized and prepared. Data
collected on sol 0 were relayed to the ground, and the SSI imaged the
lander and the surrounding environment. The Robotic Arm was unstowed
and completed several practice sample transfers to prepare the Lander
equipment for the primary mission [SMITHETAL2008].
Spacecraft Id : PHX
Target Name : MARS
Mission Phase Start Time : 2008-05-26
Mission Phase Stop Time : 2008-06-05
Spacecraft Operations Type : LANDER
Primary Mission (Surface Phase)
-------------------------------
The SSI provided high-resolution, stereo, and panoramic images
throughout the Phoenix Mission. The SSI served a variety of purposes,
including surveying the local geomorphology of the landing site,
providing range coordinates for digging operations, and making
atmospheric dust and cloud measurements. The SSI included two cameras
that allowed for the capture of three-dimensional views of the
landing site. Multispectral filters enabled imaging at 12 wavelengths
(0.4 to 1.0 micrometers) of geological and atmospheric phenomena
[LEMMONETAL2008].
The Robotic Arm (RA) was successfully deployed and declared operational
on sol 1 and operated through sol 149. A detailed map of the
surrounding local geomorphology provided by the SSI allowed for the
specification of range coordinates to the RA for digging operations.
The RA and the associated Icy Soil Acquisition Device (ISAD)
excavated and delivered samples to the Microscopy, Electrochemistry,
and Conductivity Analyzer (MECA) and the Thermal Evolved Gas Analyzer
(TEGA). The Robotic Arm Camera (RAC) was attached above the RA scoop
and provided close-up, full-color images of various objects of
interest in the area immediately surrounding the lander, including
prospective soil and water ice samples in trenches dug by the RA,
verification of collected samples in the scoop prior to analysis by
MECA and TEGA, and the floor and side-walls of the trench to examine
fine-scale texturing and layering [KELLERETAL2008].
MECA was responsible for the analysis of soil samples in accordance
with the Surface Mission objectives, and consisted of onboard
instruments such as the Wet Chemistry Laboratory (WCL), Optical
Microscopy (OM)/Atomic Force Microscopy (AFM), and the Thermal and
Electrical Conductivity Probe (TECP).
WCL performed chemical analyses on three Martian soil samples. One
soil sample was obtained from the top ~2 cm of soil and two were
obtained at ~5 cm depth from the icy soil interface. When mixed with
water in a ~1.25 soil to solution ratio (by volume), a portion of the
soil components solvated. Ion concentrations were measured using an
array of ion selective electrodes. Solution conductivity was measured
using a conductivity cell [KOUNAVESETAL2009].
Nine soil samples were successfully delivered to the OM/AFM for
detailed microscopic examination [SMITHETAL2009].
The TECP was located on the RA and measured the temperature, thermal
conductivity, and volumetric heat capacity of the soil. It also
detected and quantified the population of mobile H2O molecules in the
soil, by measuring the electrical conductivity as well as the
dielectric permittivity. TECP measured atmospheric H2O vapor
abundance and augmented the wind velocity measurements from the
meteorology instrumentation. TECP was mounted near the end of the RA
and could be placed either in the soil or held aloft in the
atmosphere [ZENTETAL2009].
TEGA consisted of two separate components: a Differential Scanning
Calorimeter (DSC) and an Evolved Gas Analyzer (EGA) and was a
derivative of the instrument flown on the Mars Polar Lander
[BOYNTONETAL2009]. Samples delivered to TEGA by the RA were heated in
ovens to temperatures up to 950 deg C. Water and carbon dioxide
released during the heating were analyzed in the EGA. The power
required by the sample oven was continuously monitored during the
heating and compared to that required to heat a similar, but empty,
oven. The power difference was the output of the DSC. Both
endothermic and exothermic phase transitions could be detected, and
were used to identify the phases present. By correlating the gas
release with the calorimetry, the abundance of the volatile compounds
associated with the different phases was determined [SMITHETAL2009],
[BOYNTONETAL2009].
A dozen trenches were excavated at the Phoenix landing site and 31
samples were acquired for delivery to instruments on the Lander: six
to WCL, nine to OM/AFM, and seven to TEGA. Several rocks were also
moved to examine the underlying material. Samples delivered to TEGA,
OM/AFM, and WCL revealed that the Martian soil consists of an
approximately 3 cm deep surface layer of cloddy material above an
underlying icy soil substrate. Soil samples deposited via the sprinkle
technique indicated that the soil clods were weakly cohesive
[ARVIDSONETAL2009], [SMITHETAL2009].
The Meteorological Package (MET) consisted of three temperature
sensors, one pressure sensor, and the lidar system. Temperature was
measured by three temperature sensors fixed to the weather station
mast. These sensors measured temperature by monitoring its effect on
an electrical current through a closed circuit. Pressure was
monitored throughout each sol by a pressure sensor located on the
deck of the lander [TAYLORETAL2008].
The lidar system measured the height profile of backscattered laser
light from airborne dust and clouds. The system consisted of a
rapid-pulse laser and an optical telescope. The lidar's laser shot
rapid pulses of light into the atmosphere, which were reflected off
airborne particles back to the optical telescope, allowing the
composition, movement, and size of clouds and particles above the
lander to be determined. These data were coordinated with solar
radiation measurements and in situ sampling to study the climate and
the water cycle [WHITEWAYETAL2008]. The SSI also captured movies of
the Telltale wind indicator, providing additional information on wind
velocity and direction [MOORESETAL2010].
Spacecraft Id : PHX
Target Name : MARS
Mission Phase Start Time : 2008-06-05
Mission Phase Stop Time : 2008-11-02
Spacecraft Operations Type : LANDER
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