MASCOT thermal design: how to deal with late and critical changes

MASCOT is a lander built by DLR, embarqued on JAXA’s Hayabusa-2, a scientific mission to study the asteroid 162173 1999 JU3, launched on the 3rd of December 2014. As part of the project challenges, the short schedule for the whole development of the lander (2.5 years from PDR to launch), the strict and contrasting thermal requirements for different phases of the mission, mass&power/technology/volume limitations put the thermal design at the edge of the state of art technology solutions. As a result, the thermal system development has been on-going until the last phases of the project, on order to cope with late changes and technologies development. This presentation focusses on the thermal control system evolution during the last months before launch and just after it and the tight schedule available to cope with late system changes. It shows the design modifications and updates, together with thermal modelling changes following intensive testing phases, in particular for the lander battery pack and the heating/pre-heating strategy for different mission phases. Many thermal vacuum campaigns, modelling re-iterations, better understanding of the main S/C thermal behaviour, together with the great team determination helped reaching a succesfull launch followed by an on-flight system verification

MASCOT Thermal subsystem design

MASCOT is a lander built by DLR, embarked on JAXA’s Hayabusa-2, a scientific mission to study the asteroid 162173 1999 JU3. It is a small lander, less than 300x300x200mm?, with onboard payloads (camera, magnetometer, radiometer and IR spectrometer), developed in collaboration by DLR and CNES. MASCOT lands on the asteroid surface, after being released by Hayabusa-2 from a very close position above the asteroid surface, and investigates the asteroid surface. The thermal design of the lander represents one of the main challenges in the whole project because of multiple constraints, depending on the mission phase, mass, power and free space available. MASCOT, notwithstanding its small size, is equipped with redundant heat-pipe system, MLI blanket, heaters. The thermal design of the lander has been chosen after a trade-off phase concerning the technology which could suit better the opposing requirements of the mission: low heat exchange between the lander and the exterior (including the main spacecraft) in cruise, possibility to transfer all the heat dissipated by the internal paylaods and electronic boards during operations on asteroid surface. After selecting the heat-pipe technology as baseline, a development phase was undertaken by the partners both in terms of manufacturing, testing, thermal characterization phase and analitical modelling in order to match the thermal requirements. Heaters are used to assure the survival of the most delicated parts of the lander during cold cruise phases: the battery cells (only primary battery on-board), the electronic boards and the main payload. Strict requirements are given by the main spacecraft in terms of maximum power available to heat the lander during cruise. MLI blankets are used where the available space allows it, e.g. to extra insulate the Ebox from the rest of the lander creating a „hot compartment" and between the lander and the main spacecraft to reduce the heat exchange with it during cruise below the given limits. The whole thermal concept in all its parts undertook a detailed modelling phase in parallel to an experimental phase in vacuum chamber to improve the model and to qualify the system

THE 3 OMEGA TRANSIENT LINE METHOD FOR THERMAL CHARACTERIZATION OF SUPERINSULATOR MATERIALS DEVELOPED FOR SPACECRAFT THERMAL CONTROL

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