Catherin Fiona Hobbie

Bio: Catherin Fiona Hobbie is an academic researcher from German Aerospace Center. The author has contributed to research in topics: Software deployment & Payload. The author has an hindex of 3, co-authored 5 publications receiving 175 citations.

MASCOT—The Mobile Asteroid Surface Scout Onboard the Hayabusa2 Mission

Abstract: On December 3rd, 2014, the Japanese Space Agency (JAXA) launched successfully the Hayabusa2 (HY2) spacecraft to its journey to Near Earth asteroid (162173) Ryugu. Aboard this spacecraft is a compact landing package, MASCOT (Mobile Asteroid surface SCOuT), which was developed by the German Aerospace Centre (DLR) in collaboration with the Centre National d’Etudes Spatiales (CNES). Similar to the famous predecessor mission Hayabusa, Hayabusa2, will also study an asteroid and return samples to Earth. This time, however, the target is a C-type asteroid which is considered to be more primitive than (25143) Itokawa and provide insight into an even earlier stage of our Solar System. Upon arrival at asteroid Ryugu in 2018, MASCOT will be released from the HY2 spacecraft and gently descend by free fall from an altitude of about 100 m to the surface of the asteroid. After a few bounces, the lander will come to rest at the surface and perform its scientific investigations of the surface structure and mineralogical composition, the thermal behaviour and the magnetic properties by operating its four scientific instruments. Those include an IR imaging spectrometer (MicrOmega, IAS Paris), a camera (MASCAM, DLR Berlin), a radiometer (MARA, DLR Berlin) and a magnetometer (MASMAG, TU Braunschweig). In order to allow optimized payload operations the thermal design of MASCOT is required to cope with the contrasting requirements of the 4-year cruise in cold environment versus the hot conditions on the surface of the asteroid. Operations up to 2 asteroid days (∼16 hours) based on a primary battery are currently envisaged. A mobility mechanism allows locomotion on the surface. The mechanism is supported by an attitude and motion sensing system and an intelligent autonomy manager, which is implemented in the onboard software that enables MASCOT to operate fully independently when ground intervention is not available.

The Eu:Cropis Assembly, Integration and Verification Campaigns: Building the first DLR Compact Satellite

Abstract: Eu:CROPIS (Euglena Combined Regenerative Organic Food Production In Space) is the first mission of DLR's Compact Satellite program. The Compact Satellite is a small, highly customizable and high performance satellite bus, providing a platform for scientific research as well as for demonstration of innovative concepts in space tech-nology. The launch of Eu:CROPIS onboard a Falcon 9 is scheduled in Q4 2018 within Spaceflight Industries SSO-A mission. The name-giving primary payload features a biological experiment in the context of coupled life support systems. The stability of such kind of a system shall be proven under different gravity levels with a focus on long term operations. In this context the rotation of the spacecraft will be used to utilize simulated gravity for the first time. A further biological experiment dealing with synthetic biology comprising genetically modified organisms (GMOs) was provided by NASA Ames Research Center as secondary payload. The integration and acceptance of a satellite flight model containing biological experiments faces constraints regard-ing schedule, facility certification and process definition. The driving parameters for the Eu:CROPIS AIV campaign are the degradation time of chemicals stored inside the primary payload, the GMOs used in the secondary payload, which cause handling and transport restrictions due to biosafety regulations, as well as schedule constraints due to the chosen dedicated rideshare mission. Furthermore the development of a spin stabilized system for gravity simula-tion had impact on the overall verification approach, especially towards the attitude control subsystem. This paper describes the model and verification strategies to design and build the spacecraft under said constraints. The applied verification processes comprises the hardware, software as well as all third party payloads and focuses on the utilization of a flexible tabletop engineering model approach. To achieve a smooth transition to project phase E, this concept enables co-alignment of the ground segment development and verification with spacecraft AIV as of early phase C. Furthermore scientific projects like Eu:CROPIS, with small project teams and financial budgets, en-counter few personnel redundancy. The existing structural organization gets confronted with challenges where de-pendability, testability and safety of the processes and the product are expected to be achieved with minimal effort. The paper presents how the technical management adapts work flows, cooperation and tools in project phases C and D to achieve a reliable system realization.

The Tape Spring Hinge Deployment System of the EU:CROPIS Solar Panels

Abstract: Eu:CROPIS is a compact satellite featuring a biological. The cylindrical Satellite of 1m diameter has four deployable panels for power generation. Those panels are connected to the main structure by glassfiber reinforced polymer (GFRP) tape spring hinges. The hinges, comparable to curved metallic measuring tapes, have elastic energy stored when flattened and folded and thus deploy the panels by simply unfolding. When unfolded the hinges snap into their original shape and support the panels with considerable stiffness. No friction or mechanical locking is involved in the deploying process, which increases the systems reliability. Despite all these advantages other design aspects need special consideration. The GFRP needs to be protected against environmental influences like atomic oxygen and heat. Depending on the folded state and the hinge configuration the length of the hinges cannot be chosen freely. The installation process requires consideration as well. While the hinges are very flexible in the folded state they have to be installed quite accurately to be able to snap into their deployed position and fully support the panel. The panels do not deploy around one single axis but also do lateral movements. Even though the hinges are able to support the panels in the deployed position, they provide very low support during deployment. Therefore, gravity compensation is required for testing which should have a very low influence on the deployment. The presented paper gives an insight into the tape spring hinge deployment system of Eu:CROPIS. Design iterations are explained with the background of the decision making process influenced by the overall satellite configuration, tests and testability, experiences gained during integration and PA considerations. Further details of the manufacturing and integration process are described. The verification concept is outlined and explained. Tests performed for verification or gaining experience are described including the setup and considerations for the tests to be representative.

VIBRATION TESTING OF THE Eu:CROPIS SATELLITE TEST STRUCTURE

Abstract: In the DLR (German Aerospace Center) compact satellite program the life supporting experiment Eu:CROPIS is developed. It is a small satellite weighing slightly more than 200kg. The proposed launch option is the Falcon 9 using the CASA adapter where it is placed on a balcony like support structure. The Eu:CROPIS satellite is being designed, produced and tested by DLR. Structural test for qualification are static and random loads, the random loads being the most demanding test. The static loads are tested using a sine burst test. As the structural test model is a prototype and as the project does not provide much time to repeat tests, the test sequence has been carefully chosen so as to limit structural damages before the end of the test campaign. Thus as many tests as possible are performed before the most demanding tests. Loads, stresses and deformations have been simulated by FEM-analyses before the tests. Still there are some uncertainties in the simulation due to the predicted damping and due to assumptions made to reduce the size and complexity of the model. Especially the random loads transfer into structural strain responses is very sensitive to the dynamic behavior. Therefore it is of interest to compare the assumed finite element structural response to the real measured one. For this purpose the test structure has been equipped with strain gauges to measure the peak strains in the primary structural parts in addition to the usual acceleration sensors. In this paper the test philosophy is explained using the prediction of structural stresses to sort the tests by intensity and thus by potential damage done to the tested structure. The measured natural frequencies, acceleration loads and internal strains are compared to the predicted ones. Reasons for deviations are given. The last test run showed significant changes in some acceleration responses. The search for the cause by analyses of the different acceleration responses is described.

Hayabusa2 Mission Overview

Abstract: The Hayabusa2 mission journeys to C-type near-Earth asteroid (162173) Ryugu (1999 JU3) to observe and explore the 900 m-sized object, as well as return samples collected from the surface layer. The Haybusa2 spacecraft developed by Japan Aerospace Exploration Agency (JAXA) was successfully launched on December 3, 2014 by an H-IIA launch vehicle and performed an Earth swing-by on December 3, 2015 to set it on a course toward its target Ryugu. Hayabusa2 aims at increasing our knowledge of the early history and transfer processes of the solar system through deciphering memories recorded on Ryugu, especially about the origin of water and organic materials transferred to the Earth’s region. Hayabusa2 carries four remote-sensing instruments, a telescopic optical camera with seven colors (ONC-T), a laser altimeter (LIDAR), a near-infrared spectrometer covering the 3-μm absorption band (NIRS3), and a thermal infrared imager (TIR). It also has three small rovers of MINERVA-II and a small lander MASCOT (Mobile Asteroid Surface Scout) developed by German Aerospace Center (DLR) in cooperation with French space agency CNES. MASCOT has a wide angle imager (MasCam), a 6-band thermal radiator (MARA), a 3-axis magnetometer (MasMag), and a hyperspectral infrared microscope (MicrOmega). Further, Hayabusa2 has a sampling device (SMP), and impact experiment devices which consist of a small carry-on impactor (SCI) and a deployable camera (DCAM3). The interdisciplinary research using the data from these onboard and lander’s instruments and the analyses of returned samples are the key to success of the mission.

Low thermal conductivity boulder with high porosity identified on C-type asteroid (162173) Ryugu

Abstract: C-type asteroids are among the most pristine objects in the Solar System, but little is known about their interior structure and surface properties. Telescopic thermal infrared observations have so far been interpreted in terms of a regolith-covered surface with low thermal conductivity and particle sizes in the centimetre range. This includes observations of C-type asteroid (162173) Ryugu1–3. However, on arrival of the Hayabusa2 spacecraft at Ryugu, a regolith cover of sand- to pebble-sized particles was found to be absent4,5 (R.J. et al., manuscript in preparation). Rather, the surface is largely covered by cobbles and boulders, seemingly incompatible with the remote-sensing infrared observations. Here we report on in situ thermal infrared observations of a boulder on the C-type asteroid Ryugu. We found that the boulder’s thermal inertia was much lower than anticipated based on laboratory measurements of meteorites, and that a surface covered by such low-conductivity boulders would be consistent with remote-sensing observations. Our results furthermore indicate high boulder porosities as well as a low tensile strength in the few hundred kilopascal range. The predicted low tensile strength confirms the suspected observational bias6 in our meteorite collections, as such asteroidal material would be too frail to survive atmospheric entry7. The MASCOT lander observed a boulder on the surface of asteroid Ryugu up close. The boulder’s low thermal inertia is closer to fine regolith or comets rather than stony boulders, indicating high porosity and low tensile strength. Orbit measurements confirm that Ryugu’s surface is covered with similar boulders.

Highly porous nature of a primitive asteroid revealed by thermal imaging

Abstract: Additional co-authors: Tsuneo Matsunaga, Takeshi Imamura, Takehiko Wada, Sunao Hasegawa, Jorn Helbert, Thomas G. Muller, Jens Biele, Matthias Grott, Maximilian Hamm, Marco Delbo, Naru Hirata, Naoyuki Hirata, Yukio Yamamoto, Seiji Sugita, Noriyuki Namiki, Kohei Kitazato, Masahiko Arakawa, Shogo Tachibana, Hitoshi Ikeda, Masateru Ishiguro, Koji Wada, Chikatoshi Honda, Rie Honda, Yoshiaki Ishihara, Koji Matsumoto, Moe Matsuoka, Tatsuhiro Michikami, Akira Miura, Tomokatsu Morota, Hirotomo Noda, Rina Noguchi, Kazunori Ogawa, Kei Shirai, Eri Tatsumi, Hikaru Yabuta, Yasuhiro Yokota, Manabu Yamada, Masanao Abe, Masahiko Hayakawa, Takahiro Iwata, Masanobu Ozaki, Hajime Yano, Satoshi Hosoda, Osamu Mori, Hirotaka Sawada, Takanobu Shimada, Hiroshi Takeuchi, Ryudo Tsukizaki, Atsushi Fujii, Chikako Hirose, Shota Kikuchi, Yuya Mimasu, Naoko Ogawa, Go Ono, Tadateru Takahashi, Yuto Takei, Tomohiro Yamaguchi, Kent Yoshikawa, Fuyuto Terui, Takanao Saiki, Satoru Nakazawa, Makoto Yoshikawa, Seiichiro Watanabe & Yuichi Tsuda Output Status: Forthcoming/Available Online

Images from the surface of asteroid Ryugu show rocks similar to carbonaceous chondrite meteorites

Abstract: The near-Earth asteroid (162173) Ryugu is a 900-m-diameter dark object expected to contain primordial material from the solar nebula. The Mobile Asteroid Surface Scout (MASCOT) landed on Ryugu's surface on 3 October 2018. We present images from the MASCOT camera (MASCam) taken during the descent and while on the surface. The surface is covered by decimeter- to meter-sized rocks, with no deposits of fine-grained material. Rocks appear either bright, with smooth faces and sharp edges, or dark, with a cauliflower-like, crumbly surface. Close-up images of a rock of the latter type reveal a dark matrix with small, bright, spectrally different inclusions, implying that it did not experience extensive aqueous alteration. The inclusions appear similar to those in carbonaceous chondrite meteorites.

Review on solar sail technology

Abstract: This paper reviews solar sail trajectory design and dynamics, attitude control, and structural dynamics. Within the area of orbital dynamics, methods relevant to transfer trajectory design and non-Keplerian orbit generation are discussed. Within the area of attitude control, different control strategies, including utilisation of solar radiation pressure and conventional actuators, are discussed. Finally, the methods of modelling structural dynamics during and after deployment are discussed, before considering possible future trends in developing of solar sailing missions.