PDS_VERSION_ID = PDS3 LABEL_REVISION_NOTE = "2004-09-23 KW: Initial draft. 2005-12-09 AC: Orbiter Information Updated Added Inst_host for lander References TBD 2006-01-10 AC: Removed special characters 2006-02-15 PG: Added Inst_host for lander 2007-01-26 MB: 70 char line length 2007-08-14 MB: remove not ascii symbols 2008-02-02 Maud Barthelemy 2008-04-11 JL Vazquez, SA 2008-05-09, MB 2010-02-15, MB 2011-06-07, MB, editorial 2012-06-06, M. Barthelemy after AST2 review " RECORD_TYPE = STREAM OBJECT = INSTRUMENT_HOST INSTRUMENT_HOST_ID = RL OBJECT = INSTRUMENT_HOST_INFORMATION INSTRUMENT_HOST_NAME = "ROSETTA-LANDER" INSTRUMENT_HOST_TYPE = SPACECRAFT INSTRUMENT_HOST_DESC = " Lander overview ============================================= The Philae Lander is a box-type unit with the dimensions of 850 x 850 x 640 mm3. On the comet, it will rest on a tripod called Landing Gear, with a diameter of 2.6 m and will be fixed to the comet's surface by harpoons. Philae is composed of three different parts, corresponding to its structural design: 1) Internal compartment: This compartment hosts almost all subsystems and most of the experiment units. It provides a temperature controlled environment for all electronics and is built by the structural elements of an Instrument platform and so called Pi-plates. It is 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 is built around the internal compartment and its MLI tents, the shape follows the overall Lander shape. It hosts the solar arrays of the Lander composed by 6 different panels. In addition two absorber foils are mounted on the solar hood lid. These foils are 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 carries 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 is 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 hosts all experiments or parts of them, especially the sensors, which require direct access to the comet environment and the comet surface. The baseplate is also the interface panel to the Landing Gear. In addition the baseplate hosts the Push plate, which is the interface to the Orbiter during the 10 years cruise from Launch to the Comet. The Lander mass is around 100 kg. In addition three units of the Lander system are mounted on the Orbiter, and will remain there after Lander separation for the comet. These units provide the interfaces to the Orbiter: electrical and data (ESS) and mechanical (MSS). The third system is a TxRx system used to keep contact to the Lander during its operational phase on the comet. Lander Mission Requirements and Constraints ============================================= The Lander is 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 is 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 are used during the cruise phase, especially when the Lander is in hibernation, and on the comet, when the Lander runs out of power and changes 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 Definiton ============================================= 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 is installed on the Lander. The Active Descent System ADS provides 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, is 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 provides the necessary interface between the Lander and the comet and supports Lander science operations by a rotation and tiliting capability. The structure subsystem provides the required structural elements to built up the Lander. A TxRx system is installed to provide access to the Lander and enable data retrievel during its mission phase on the comet. Lander Reference Frame ============================================= The Lander reference frame is defined as follows: +Z-axis is perdendicular to the baseplate, generally pointing away from the comet towards space, during cruise parallel to the Orbiter +Z-axis, +X-axis is 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 completes the right-handed frame. The frame origin is 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 is operated in the following modes: Hibernation Mode: This mode is 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 is 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 is applied on the comet, substituting the Hibernation Mode. The PSS wake-up thermostats are closed, because the temperature inside the internal compartment is below minus 53 degC. In this mode the Lander is non-operational, the Lander operational electronics are disconnected from the Primary Bus and the wake-up heaters are connected to the Primary Bus. In this mode NO thermal control is possible, since the wake-up heaters will only dissipate, if the Primary Bus is powered, which requires Sun irradiation on the comet to operate the solar arrays. Without dissipation the compartment temperature will drop until the comet environmental temperature. When the Lander is still attached to the Orbiter and powered from the Orbiter-LCL 15A/B, an additional heater set will also dissipate. Power Enough Mode: This mode follows the Wake-up mode, the Lander Primary Bus is powered, but the voltage is still below 18.5V, which correspond to a non-sufficient power situation. The available power is not lost, since special Power Enough loads are used to dissipate and heat the internal compartment. Stand-by Mode: The Lander is operational, since the Lander basic operational electronics (PCU, CDMS and one TCU) are connected to the Primary Bus and powered. In this mode thermal control will be performed from the dissipation of the activated units. If the temperature of the internal compartment drops below the TCU set-points, the respcetive TCU heaters will also dissipate. Operational Modes: These modes define Lander operation of Experiments. ###########TO BE COMPLETED BY SONC ############ " END_OBJECT = INSTRUMENT_HOST_INFORMATION OBJECT = INSTRUMENT_HOST_REFERENCE_INFO REFERENCE_KEY_ID = "BIBRINGETAL2007B" END_OBJECT = INSTRUMENT_HOST_REFERENCE_INFO END_OBJECT = INSTRUMENT_HOST END