A set of optical fiber assemblies has been developed and successfully qualified for its use on a European space science mission to the icy moons of Jupiter (Jupiter Icy Moons Explorer, JUICE), to be launched in 2022. The paper gives an overview of the design challenges, the test methods used for failure detection and screening of the optical fiber cable assemblies as well as the further testing performed in the frame of a lot acceptance qualification.
The JUICE (JUpiter ICy moon Explorer) mission features instrument designs tailored to meet the specific challenges of the respective measuring environment, including EMC constraints. We describe the magnetic field science requirements for this mission and show how they drive the EMC requirements on the spacecraft and selected in-situ instrument configurations. We describe the results of two mutual interference campaigns and discuss the design mitigations employed in order to realise in-situ magnetic and electric field data in-flight with the accuracy required to meet very challenging mission science goals.
We performed an endurance test with single-mode vertical-cavity surface-emitting lasers (VCSEL) under vacuum condition and increased operational parameters (laser current and laser temperature) to accelerate the aging of the lasers. During the endurance test the emitted polarization-dependent and polarization-independent optical light power from the lasers was detected. Additionally, electro-optical characterisations including measurements of the combination of laser current and laser temperature to excite the 87 Rb D 1 transition ( λ = 795 nm), the current and temperature tuning coefficients, laser line width, threshold current and the polarization ellipse were performed for the aged lasers. The test was started with a number of 12 VCSELs consisting of 4 lasers each from 3 different suppliers. The aging behaviour of VCSELs was investigated with respect to the development of a new optical magnetometer prototype for space missions with a mission duration of up to 17 years. Only a limited change of the electro-optical parameters can be tolerated by the instrument design over the mission duration. The endurance test and the electro-optical characterizations revealed clear differences in the aging behaviour of the three suppliers. Lasers from one supplier showed that they can be operated for more than 17 years under vacuum conditions without major degradation of their operational parameters.
Scalar magnetometers measure the magnitude of the magnetic field, while vector magnetometers (mostly fluxgate magnetometers) produce three-component outputs proportional to the magnitude and the direction of the magnetic field. While scalar magnetometers have a high accuracy, vector magnetometers suffer from parameter drifts and need to be calibrated during flight. In some cases, full science return can only be achieved by a combination of vector and scalar magnetometers.
We propose a dual-rendezvous mission, targeting near-Earth asteroids, including sample-return. The mission, Asteroid Sampling Mission (ASM), consists of two parts: (i) flyby and remote sensing of a Q-type asteroid, and (ii) sampling of a V-type asteroid. The targeted undifferentiated Q-type are found mainly in the near-Earth space, and to this date have not been the target of a space mission. We have chosen, for our sampling target, an asteroid from the basaltic class (V-type), as asteroids in this class exhibit spectral signatures that resemble those of the well-studied Howardite–Eucrite–Diogenite (HED) meteorite suite. With this mission, we expect to answer specific questions about the links between differentiated meteorites and asteroids, as well as gain further insight into the broader issues of early Solar System (SS) evolution and the formation of terrestrial planets. To achieve the mission, we designed a spacecraft with a dry mass of less than 3 tonnes that uses electric propulsion with a solar-electric power supply of 15kW at 1Astronomical Unit (AU). The mission includes a series of remote sensing instruments, envisages landing of the whole spacecraft on the sampling target, and employs an innovative sampling mechanism. Launch is foreseen to occur in 2018, as the designed timetable, and the mission would last about 10 years, bringing back a 150g subsurface sample within a small re-entry capsule. This paper is a work presented at the 2008 Summer School Alpbach,“Sample return from the Moon, asteroids and comets” organized by the Aeronautics and Space Agency of the Austrian Research Promotion Agency. It is co-sponsored by ESA and the national space authorities of its Member and Co-operating States, with the support of the International Space Science Institute and Austrospace.
The Magnetometer Front-end ASIC (MFA) is a device for reading out magnetic field sensors which are based on the fluxgate principle. The instrument was developed at the Space Research Institute (IWF) of the Austrian Academy of Sciences and is part of the Magnetospheric Multi Scale (MMS) mission organized by NASA.In the MMS configuration the ASIC is positioned inside the spacecraft while the sensor is located remotely at the tip of a radially extended five meter long boom to achieve magnetic cleanliness requirements. Several shielded twisted pair wires are required for connection.In a possible future configuration the front-end ASIC might be located quite close to the sensor to minimize the effort of cabling and to reduce overall weight. It was the objective to investigate options for this new configuration and to develop and implement a solution for test purposes in laboratory with focus on minimizing the number of required wires and considering the harsh environment in space.The result of the investigation is a communication and power supply system based on an FPGA design, a specific driver circuit and a single twisted pair cable which provides the required power of 300mW for components at the remote location and which enables the transport of information in both directions up to a maximum distance of 30 meters.