Lander overview
=============================================
The Philae Lander was a box-type unit with the dimensions
of 850 x 850 x 640 mm3. On the comet, it rested on a tripod
called Landing Gear, with a diameter of 2.6 m and was supposed to be fixed to
the comet's surface by harpoons.

Philae was composed of three different parts, corresponding to its
structural design:

1)    Internal compartment:
This compartment hosted almost all subsystems and most of the
experiment units. It provided a temperature controlled environment
for all electronics and was built by the structural elements of an
Instrument platform and so called Pi-plates. It was surrounded by
Multilayer Insulation built of 2 tents to achieve the required
insulation at a low power environment on the comet at 3 AU distance
from Sun.

2)    Solar Hood:
The solar hood was built around the internal compartment and its MLI
tents, the shape followed the overall Lander shape. It hosted the solar
arrays of the Lander composed by 6 different panels. In addition two
absorber foils were mounted on the solar hood lid. These foils were
built by thin copper foils with an external TINOX surface, high
absorptivity and low emissivity, used to collect solar irradiation
and transform it into heat radiated into the internal compartment.
The solar hood also carried the camera system of the Lander, with one
camera head on each panel, thus providing a 360 degrees panoramic
view.

3)    Baseplate / Balcony:
The baseplate was the central structural plate carrying the solar hood
with the internal compartment underneath and providing at one end a
special area called balcony. This area hosted all experiments or parts
of them, especially the sensors, which required direct access to the
comet environment and the comet surface.
The baseplate was also the interface panel to the Landing Gear.
In addition the baseplate hosted the Push plate, which was the
interface to the Orbiter during the 10 years cruise from Launch to
the Comet.

The Lander mass was around 100 kg.

In addition three units of the Lander system were mounted on the
Orbiter, and remained there after Lander separation for the comet.
These units provided the interfaces to the Orbiter: electrical and
data (ESS) and mechanical (MSS). The third system was a TxRx system
used to keep contact to the Lander during its operational phase on
the comet.


Lander Mission Requirements and Constraints
=============================================
The Lander was designed to fullfill the mission requirements given as:
- survive the 10 years cruise phase with long hibernation phases under
  autonomous thermal control powered by the Orbiter,
- land safely on the comet,
- provide a scientific phase after landing at 3 AU distance from Sun
  with online data transmission,
- provide a long term mission capability observing the comet on its
  way from 3 AU to the Sun


Lander Platform Definition
=============================================
The Lander platform was built by three major subsystems, required to
operate the Lander throughout the mission:
-    a Power subsystem (PSS) composed of a Battery system with a
        Primary Battery and a Secondary Battery, the later refilled
        by a Solar array generator, and the required electronics to
        distribute and control the power flow inside the Lander,
-    a Central Data Management System (CDMS), composed by two hot
        redundant computers, controlling all activities on the
        Lander, especially on the comet in an autonomous manner,
-    a Thermal Control System, composed by a 2-tent
        MultiLayerInsulation supported by two absorber foils and an
        electrical heater system. Additional independant heater
        systems were used during the cruise phase, especially when the
        Lander was in hibernation, and on the comet, when the Lander
        run out of power and changed into a so called Wake-up mode,
        to provide a thermal environment in the Internal compartment
        as required to switch-on the Lander electronics.


Subsystem Definition
=============================================
In addition to the already described platform units PSS, CDMS and TCS
and the On-Orbiter units ESS, MSS and ESS-TxRx, a set of subsystems
was installed on the Lander.

The Active Descent System ADS provided a 1-axis thruster system used
at touch-down to support the landing and prevent a rebounding until
the harpoons are shot.
An Anchoring system, built by two redundant harpoons, was used to fix
the Lander to the comet's surface after landing and provide the
required counter-force during drilling.
A Flywheel providing a 1-axis momentum wheel used to stabilize the
Lander's descent to the comet.
The Landing gear provided the necessary interface between the Lander
and the comet and supported Lander science operations by a rotation
and tilting capability.
The structure subsystem provided the required structural elements to
built up the Lander.
A TxRx system was installed to provide access to the Lander and enable
data retrieval during its mission phase on the comet.


Lander Reference Frame
=============================================
The Lander reference frame was defined as follows:
+Z-axis was perpendicular to the baseplate, generally pointing away
from the comet towards space, during cruise parallel to the Orbiter
+Z-axis, +X-axis was generally parallel to the comet surface, pointing
opposite of the Lander's balcony, into the direction of Lander
separation from the Orbiter, during cruise into Orbiter -X direction,
+Y-axis completed the right-handed frame.

The frame origin was located on the upper surface of the balcony
(Z = 0), in the middle of the balcony (Y = 0), at the outer end
(X = 0).



Lander Operating Modes
=============================================
The Lander was operated in the following modes:

Hibernation Mode:
This mode was defined as: Lander attached to the Orbiter, Orbiter LCL
5A or 5B ON, Lander Hibernation heater ON (dissipation > 12W at 28V),
no power on the Lander Primary Bus
In this mode the Lander was non-operational but under thermal control
with a hibernation temperature inside the internal compartment above
minus 55 degC at the reference point.

Wake-up Mode:
This mode was applied on the comet, substituting the Hibernation Mode.
The PSS wake-up thermostats were closed, because the temperature
inside the internal compartment was below minus 53 degC. In this mode
the Lander was non-operational, the Lander operational electronics were
disconnected from the Primary Bus and the wake-up heaters were
connected to the Primary Bus. In this mode NO thermal control was
possible, since the wake-up heaters would only dissipate, if the
Primary Bus was powered, which required Sun irradiation on the comet to
operate the solar arrays. Without dissipation the compartment
temperature would drop until the comet environmental temperature. When
the Lander was still attached to the Orbiter and powered from the
Orbiter-LCL 15A/B, an additional heater set would also dissipate.

Power Enough Mode:
This mode followed the Wake-up mode, the Lander Primary Bus was
powered, but the voltage was still below 18.5V, which corresponded to a
non-sufficient power situation. The available power was not lost,
since special Power Enough loads were used to dissipate and heat the
internal compartment.

Stand-by Mode:
The Lander was operational, since the Lander basic operational
electronics (PCU, CDMS and one TCU) were connected to the Primary Bus
and powered.
In this mode thermal control would be performed from the dissipation
of the activated units. If the temperature of the internal
compartment dropped below the TCU set-points, the respective TCU
heaters would also dissipate.

Operational Modes:
These modes defined Lander operation of Experiments.

APXS:
No activity during SDL and FSS.

CIVA:
CIVA-P mode Orbiter imaging : Imaging of the Orbiter after delivery
with camera 1 & 6.
CIVA-P mode Agilkia Landing site : Imaging of the Landing site Agilkia
just after touch-down Panorama with all 7 camera but only half of image
received.
CIVA-P mode Abydos location : Imaging of the Abydos after touch-down
and move on the comet Panorama with all 7 cameras.

CONSERT:
CONSERT Tuning mode: Instrument Switch ON and tuning of CONSERT
Lander & Orbiter clocks.
CONSERT Sounding during descent (SDL) mode: CONSERT Lander emission and
reception by CONSERT Orbiter. Active during the whole descent and stop during
the touch down window (CONSERT remaining active during this window but not
sounding (RF emission) for no interference with other instruments at time of
Landing. Lander and Orbiter in visibility during all this period as CONSERT
main objective was to monitor the Lander descent trajectory.
CONSERT Sounding after Landing mode: CONSERT Lander emission and reception by
CONSERT Orbiter. Lander and Orbiter in occultation permitting the sounding of
the comet structure.

COSAC:
COSAC Taping station test and sniff mode at Agilkia: Evaluation of the COSAC
taping station position and disengage of the possible taping station of an SD2
Carousel Oven (previous to any SD2 Carousel movement).
COSAC Abydos sniff mode: Analysis of the molecules present at the external
entry of the COSAS Mass Spectrometer done in Agilkia just after landing and
later on Abydos site.

MUPUS:
MUPUS Anchor mode:
Measurement of the acceleration sensors ANC-M inside the harpoons during
anchoring. Measurements of the temperature sensors ANC-T inside the harpoons.
MUPUS MAPPER mode:
Calibration of the Thermal Mapper during descent.
Two sub-mode to MAPPER mode
  TM blackbody sub-mode:
  Calibration of the Thermal Mapper with blackbody in the TM field of view
  (during descent).
  Infinite TEM sub-mode:
  Calibration of the Thermal Mapper with deep space in TM FOV (during descent)
MUPUS TEM mode:
Passive Thermal Measurement Mode.
MUPUS LONGTERM (-> MAPPER) mode:
Thermal Mapper longterm measurement after landing and during one comet
rotation.
MUPUS PENEL deployment mode:
Penetrator deployment.
MUPUS HAMMER mode:
Penetrator insertion to ground by hammering.

PTOLEMY:
PTOLEMY Sniff and CASE mode: Analyse of the molecules present at the external
entry of PTOLEMY Mass Spectrometer.
PTOLEMY Agilkia sniff mode and tapping station test: Analyse of the molecules
present at the external entry of PTOLEMY Mass Spectrometer done in Agilkia
just after landing. Evaluation of the PTOLEMY taping station position and
disengage of the possible taping station of an SD2 Carousel Oven (previous to
any SD2 Carousel movement).
PTOLEMY Abydos sniff mode: Analyse of the molecules present at the
external entry of PTOLEMY Mass Spectrometer done in Abydos site.
PTOLEMY Oven mass spectrum analysis:
Analyse of the molecules present in the Oven by PTOLEMY Mass
Spectrometer done in Abydos site.

ROLIS:
ROLIS DIT mode: ROLIS imaging during descent Agilkia touch down
location in the field of view.
ROLIS DIS mode: ROLIS imaging during descent once landed.
ROLIS CUC mode: ROLIS imaging once on COMET in Abydos site during night period
with illumination by LED sources (blue, green dark, red, IR) Images of Abydos
site.

ROMAP:
ROMAP Slow Mode: Magnetometer in Slow mode
 (1Hz sampling 512 octet / mn).
ROMAP Fast Mode: Magnetometer in Fast mode (916 octet / mn).
ROMAP Surface Mode SPM: Magnetometer and channeltron after Touch
Down from Noon to Day/Night transition.

SD2:
SD2 Drill downward and upward for COSAC: Carousel movements to zero
position Drill roto-translations downward and Sampling at 560 mm,
translation upward to 0mm, sample in Oven#17(SD2 count, HTO) delivered
to COSAC.
SD2 Carousel movements: Carousel movement for PTOLEMY with rotation to
0 arcmin.

SESAME:
SESAME CASSE mode:  Measurements executed to register the vibration
environment generated by the Philae flywheel, intra-foot Soundings and
inter-foot Soundings, touchdown impact, the cometary vibration background and
any particles possibly dropping on the sole covers.
SESAME PP Passive Mode : Measurements conducted in order to determine
the electromagnetic environment close to the orbiter.
SESAME PP Active Mode : PP calibrations, determine the permittivity
of the comet surface material, monitor variations in the local
plasma environment.
SESAME DIM mode: DIM  conducted to measure the particle environment.