22 research outputs found

    In-Orbit Demonstration of an In-Space Manufactured Selfie Stick forSmallSats

    Get PDF
    The poster presents a demonstration mission of an in-space manufacturing technology to extrude tube-shaped photopolymer boom structures for satellites. On the end of the boom a camera will be mounted to simulate a payload and to observe the manufacturing process. The boom is manufactured in a continuous motion and therefore higher manufacturing speeds are archivable than by comparable additive manufacturing methods. The photopolymer curing mechanism makes the process energy- and packaging efficient which enables in-space manufacturing also for small satellites. In-space manufacturing will be one of the key technologies for the future space economy. Large and lightweight structures can be manufactured on demand, to safe volume and costs at launch. Compared to deployable structures, which are commonly used on spacecraft, in-space manufacturing enables a large scalability and low development costs. The demonstrator will be mounted on the upper stage of the HyImpulse SL1 rocket which is scheduled to launch in the fourth quarter of 2025

    Design and Operational Elements of the Robotic Subsystem for the e.deorbit Debris Removal Mission

    Get PDF
    This paper presents a robotic capture concept that was developed as part of the e.deorbit study by ESA. The defective and tumbling satellite ENVISAT was chosen as a potential target to be captured, stabilized, and subsequently de-orbited in a controlled manner. A robotic capture concept was developed that is based on a chaser satellite equipped with a seven degrees-of-freedom dexterous robotic manipulator, holding a dedicated linear two-bracket gripper. The satellite is also equipped with a clamping mechanism for achieving a stiff fixation with the grasped target, following their combined satellite-stack de-tumbling and prior to the execution of the de-orbit maneuver. Driving elements of the robotic design, operations and control are described and analyzed. These include pre and post-capture operations, the task-specific kinematics of the manipulator, the intrinsic mechanical arm flexibility and its effect on the arm's positioning accuracy, visual tracking, as well as the interaction between the manipulator controller and that of the chaser satellite. The kinematics analysis yielded robust reachability of the grasp point. The effects of intrinsic arm flexibility turned out to be noticeable but also effectively scalable through robot joint speed adaption throughout the maneuvers. During most of the critical robot arm operations, the internal robot joint torques are shown to be within the design limits. These limits are only reached for a limiting scenario of tumbling motion of ENVISAT, consisting of an initial pure spin of 5 deg/s about its unstable intermediate axis of inertia. The computer vision performance was found to be satisfactory with respect to positioning accuracy requirements. Further developments are necessary and are being pursued to meet the stringent mission-related robustness requirements. Overall, the analyses conducted in this study showed that the capture and de-orbiting of ENVISAT using the proposed robotic concept is feasible with respect to relevant mission requirements and for most of the operational scenarios considered. Future work aims at developing a combined chaser-robot system controller. This will include a visual servo to minimize the positioning errors during the contact phases of the mission (grasping and clamping). Further validation of the visual tracking in orbital lighting conditions will be pursued

    Inflammation as a regulator of hematopoietic stem cell function in disease, aging, and clonal selection

    Get PDF
    Inflammation is an evolutionarily selected defense response to infection or tissue damage that involves activation and consumption of immune cells in order to reestablish and maintain organismal integrity. In this process, hematopoietic stem cells (HSCs) are themselves exposed to inflammatory cues and via proliferation and differentiation, replace mature immune cells in a demand-adapted fashion. Here, we review how major sources of systemic inflammation act on and subsequently shape HSC fate and function. We highlight how lifelong inflammatory exposure contributes to HSC inflamm-aging and selection of premalignant HSC clones. Finally, we explore emerging areas of interest and open questions remaining in the field

    Properties of aged forest fire plumes after intercontinental transport across the Atlantic Ocean

    No full text
    During the ICARTT study in summer 2004, measurements on the intercontinental transport of aerosols from biogenic and anthropogenic origin were performed at the European west coast as a part of the ICARTT-ITOP study (Intercontinental Transport of Ozone and Precursors). During the study the German Falcon 20 research aircraft was operating from an airport north of Paris. The aircraft was equipped with extensive in-situ aerosol and trace gas instrumentation. Additionally, a ground-based aerosol lidar at Palaiseau south of Paris monitored the vertical structure of the atmosphere. Trajectory analyses permitted the identification of the plume origin for several case events. During the ITOP activities in summer 2004, forest fire plumes from Canada and Alaska were transported very frequently in the free troposphere across the Northern Atlantic and probed by the Falcon and by the lidar. Physico-chemical properties of the forest fire plumes showed a strong absorption signal in the visible spectral range, the complete absence of nucleation mode particles, an almost depleted Aitken mode and an enhanced accumulation mode compared to the undisturbed background aerosol. Volatility analyses of Aitken and accumulation mode particles indicated the influence of ageing processes on the aerosol properties. It turned out that the accumulation mode aerosol inside these forest fire plumes was completely internally mixed with nonvolatile cores, while in the undisturbed background aerosol a considerable fraction of entirely volatile particles was found even in the accumulation mode. The forest fire plumes also showed enhanced CO mixing ratios. An overview over the aerosol properties as a function of the plume age will be given based on a large set of investigated plume events

    Spatially and functionally distinct subclasses of breast cancer-associated fibroblasts revealed by single cell RNA sequencing

    No full text
    Cancer-associated fibroblasts (CAFs) are a major constituent of the tumor microenvironment, although their origin and roles in shaping disease initiation, progression and treatment response remain unclear due to significant heterogeneity. Here, following a negative selection strategy combined with single-cell RNA sequencing of 768 transcriptomes of mesenchymal cells from a genetically engineered mouse model of breast cancer, we define three distinct subpopulations of CAFs. Validation at the transcriptional and protein level in several experimental models of cancer and human tumors reveal spatial separation of the CAF subclasses attributable to different origins, including the peri-vascular niche, the mammary fat pad and the transformed epithelium. Gene profiles for each CAF subtype correlate to distinctive functional programs and hold independent prognostic capability in clinical cohorts by association to metastatic disease. In conclusion, the improved resolution of the widely defined CAF population opens the possibility for biomarker-driven development of drugs for precision targeting of CAFs
    corecore