140 research outputs found
Coherent behavior of balls in a vibrated box
We report observations on very low density limit of one and two balls,
vibrated in a box, showing a coherent behavior along a direction parallel to
the vibration. This ball behavior causes a significant reduction of the phase
space dimension of this billiard-like system. We believe this is because the
lowest dissipation process along a non-ergodic orbit eliminates ball rotation
and freezes transverse velocity fluctuations. From a two-ball experiment
performed under low-gravity conditions, we introduce a "laser-like" ball system
as a prototype of a new dynamical model for very low density granular matter at
nonequilibrium steady state
Mobile Asteroid Surface Scout (MASCOT) - Design, Development and Delivery of a Small Asteroid Lander Aboard Hayabusa2
MASCOT is a small asteroid lander launched on December 3rd, 2014, aboard the Japanese HAYABUSA2 asteroid sample-return mission towards the 980 m diameter C-type near-Earth asteroid (162173) 1999 JU3.
MASCOT carries four full-scale asteroid science instruments and an uprighting and relocation device within a shoebox-sized 10 kg spacecraft; a complete lander comparable in mass and volume to a medium-sized science instrument on interplanetary missions.
Asteroid surface science will be obtained by: MicrOmega, a hyperspectral near- to mid-infrared soil microscope provided by IAS; MASCAM, a wide-angle Si CMOS camera with multicolour LED illumination unit; MARA, a multichannel thermal infrared surface radiometer; the magnetometer, MASMAG, provided by the Technical University of Braunschweig. Further information on the conditions at or near the lander‘s surfaces is generated as a byproduct of attitude sensors and other system sensors.
MASCOT uses a highly integrated, ultra-lightweight truss-frame structure made from a CFRP-foam sandwich. It has three internal mechanisms: a preload release mechanism, to release the structural preload applied for launch across the separation mechanism interface; a separation mechanism, to realize the ejection of MASCOT from the semi-recessed stowed position within HAYABUSA2; and the mobility mechanism, for uprighting and hopping. MASCOT uses semi-passive thermal control with Multi-Layer Insulation, two heatpipes and a radiator for heat rejection during operational phases, and heaters for thermal control of the battery and the main electronics during cruise. MASCOT is powered by a primary battery during its on-asteroid operational phase, but supplied by HAYABUSA2 during cruise for check-out and calibration operations as well as thermal control. All housekeeping and scientific data is transmitted to Earth via a relay link with the HAYABUSA2 main-spacecraft, also during cruise operations. The link uses redundant omnidirectional UHF-Band transceivers and patch antennae on the lander. The MASCOT On-Board Computer is a redundant system providing data storage, instrument interfacing, command and data handling, as well as autonomous surface operation functions. Knowledge of the lander’s attitude on the asteroid is key to the success of its uprighting and hopping function. The attitude is determined by a threefold set of sensors: optical distance sensors, photo electric cells and thermal sensors. A range of experimental sensors is also carried.
MASCOT was build by the German Aerospace Center, DLR, with contributions from the French space agency, CNES.
The system design, science instruments, and operational concept of MASCOT will be presented, with sidenotes on the development of the mission and its integration with HAYABUSA2
Higiene, tipologia da infância e institucionalização da criança pobre no Brasil (1875-1899)
A model of dissipative granular gas: the limit case of complete inelasticity of grain-grain collision
Experiments on vibrated granular matter and fluids in micro-gravity
International audienc
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