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

Development of Superconducting NbSi TES Array and Associated Readout With SQUIDs and Integrated Circuit Operating at 2 K

International audienceTo further increase the sensitivity of future telescope projects dedicated to photometric astronomy observation at millimeter and sub-millimeter wavelengths, large number of bolometer is currently developed. In this context, The DCMB (Dévelopement Concerté de Matrice de Bolomètre) French collaboration makes an R&D effort to develop large bolometer arrays. This paper concentrates on a first demonstration of NbSi TES (Transition-Edge Sensors) array development: a 23 NbSi superconducting thermometer array. Firstly, the NbSi thin film alloy is described then the 23 TES array topology is presented. The readout of large TES arrays requires ultra low noise amplification and multiplexing electronics. The use of a first stage transducer such as a SQUID (Superconducting QUantum Interference Device) allows ultimate performances in terms of noise. However, the linearization of the SQUID characteristic requires a Low Noise Amplifier (LNA) to generate a Flux Lock Loop (FLL). We implement this component in a cryogenic SiGe Integrated Circuit (IC) that could also contains the control of the multiplexing. Using this readout chain, a one-pixel operation using NbSi thermometer readout by SQUID and a cryogenicLNAis demonstrated. Finally, the development of a specific cryogenic IC including amplifiers, addressing and switching current sources needed for a 24 to 1 time domain SQUID multiplexer is presente

NbSi TES development in the DCMB French collaboration

International audienc

WaVIL : a Differential Absorption LIDAR for Water Vapor and Isotope HDO Observation in the Lower Troposphere -Instrument Design

International audienceWe present the design of a differential absorption LIDAR targeting HDO/H 2 16 O isotopic ratio measurement with high vertical resolution. This approach is enabled by infrared water vapor spectroscopy and recent high power multi-species parametric emitter developments

Range-resolved detection of boundary layer stable water vapor isotopologues using a ground-based 1.98 µm differential absorption LIDAR

International audienceThis paper presents a first demonstration of range-resolved differential absorption LIDAR (DIAL) measurements of the water vapor main isotopologue H 2 16 O and the less abundant semi-heavy water isotopologue HD 16 O with the aim of determining the isotopic ratio. The presented Water Vapor and Isotope Lidar (WaVIL) instrument is based on a parametric laser source emitting nanosecond pulses at 1.98 µm and a direct-detection receiver utilizing a commercial InGaAs PIN photodiode. Vertical profiles of H 2 16 O and HD 16 O were acquired in the planetary boundary layer in the suburban Paris region up to a range of 1.5 km. For time averaging over 25 min, the achieved precision in the retrieved water vapor mixing ratio is 0.1 g kg −1 (2.5% relative error) at 0.4 km above ground level (a.g.l.) and 0.6 g kg −1 (20%) at 1 km a.g.l. for 150 m range bins along the LIDAR line of sight. For HD 16 O, weaker absorption has to be balanced with coarser vertical resolution (600 m range bins) in order to achieve similar relative precision. From the DIAL measurements of H 2 16 O and HD 16 O, the isotopic abundance δD was estimated as −51%₀ at 0.4 km above the ground and −119%₀ in the upper part of the boundary layer at 1.3 km a.g.l. Random and systematic errors are discussed in the form of an error budget, which shows that further instrumental improvements are required on the challenging path towards DIAL-profiling of the isotopic abundance with range resolution and precision suitable for water cycle studies