On-board Experiments Research Articles

Properties of dust particles in comets from photometric and polarimetric observations of 67P

Remote observations of the light scattered by dust particles in comet 67P/Churyumov–Gerasimenko (67P/C-G) (photometry and imaging polarimetry) allow us to compare the deduced physical properties of these particles with in situ measurements provided by the Rosetta mission. Onboard experiments on the dust confirm properties inferred from polarimetric observations and from laboratory experiments, namely the existence of large dark particles in the size range 10–500 μm, which could be fluffy and compact aggregates of smaller grains (submicron- to micron-sized) and possibly of compact particles. The 2008–2009 apparition of comet 67P/C-G allowed us to observe the comet with two telescopes under a French–Indian collaboration. From the photometric and polarimetric observations, we inferred the presence of slow-moving, large compact particles in the coma before perihelion and eventually after. The additional ejection of fluffy aggregates of submicron-sized grains was consistent with observations after perihelion. In 2014–2015, as part of a worldwide campaign, observations of 67P/C-G were carried out in order to follow the evolution of the dust coma during the Rosetta mission. The campaign included observations with the Hubble Space Telescope, and photometric observations with the Himalayan Chandra Telescope in India. The comet was very active for about three months after perihelion, showing collimated jets, the structure of which changed over time, and a long dust tail. Using new published polarization values for observations in 2010, we were able to compare pre- and post-perihelion data and also to build partial phase curves for 67P/C-G (limited to phase angles smaller than 40°).

Are subversion and conflict component parts of social cohesion?

This article focuses on the development of control mechanisms of open pit mine robotized transport system. Method for the state of the technological roads identification with the use of fuzzy inference mechanisms is discussed.The structure of the control system is presented. The possibilities of the use of telemetry data for a wide range of important technological problems, which, anyway, are reduced to problems of interpretation of the data, object identification, forecasting of parameters and the interaction of robotic agents control are discussed. The examples of the formal setting of some of these problems which based on the soft computing are presented. Considered in detail the problem of identification of the open pit mine roadway. The procedure for organizing and conducting dump truck onboard experiments is described. The features of the main control parameters are analyzed. The mechanism of using the telemetry data processing in common with fuzzy inference tools is presented. The main stages of the experiment telemetry data processing are described.

Constraining the Nordtvedt parameter with the BepiColombo Radioscience experiment

BepiColombo is a joint ESA/JAXA mission to Mercury with challenging objectives regarding geophysics, geodesy, and fundamental physics. The Mercury Orbiter Radioscience Experiment (MORE) is one of the on-board experiments, including three different but linked experiments: gravimetry, rotation, and relativity. The aim of the relativity experiment is the measurement of the post-Newtonian parameters. Thanks to accurate tracking between Earth and spacecraft, the results are expected to be very precise. However, the outcomes of the experiment strictly depend on our ``knowledge'' about solar system: ephemerides; number of bodies (planets, satellites, and asteroids); and their masses. In this paper we describe a semianalytic model used to perform a covariance analysis to quantify the effects on the relativity experiment, due to the uncertainties of Solar System bodies' parameters. In particular, our attention is focused on the Nordtvedt parameter $\ensuremath{\eta}$ used to parametrize the strong equivalence principle violation. After our analysis we estimated $\ensuremath{\sigma}[\ensuremath{\eta}]⪅4.5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$, which is about 1 order of magnitude larger than the ``ideal'' case where masses of planets and asteroids have no errors. The current value, obtained from ground-based experiments and lunar laser ranging measurements, is $\ensuremath{\sigma}[\ensuremath{\eta}]\ensuremath{\approx}4.4\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$. Therefore, we conclude that, even in the presence of uncertainties on Solar System parameters, the measurement of $\ensuremath{\eta}$ by MORE can improve the current precision of about 1 order of magnitude.

Active neutron sensing of the Martian surface with the DAN experiment onboard the NASA “Curiosity” Mars rover: Two types of soil with different water content in the gale crater

This paper presents the water and chlorine content estimates on the bottom of the Martian crater Gale obtained by processing the data of active neutron sensing with the DAN experiment onboard theNASA “Curiosity”Mars rover at 412 spots along the 11-kilometer track. For 78% of the examined spots the water distribution in depth is found to be homogeneous with a mean content of 2.1±0.5% by mass (here and elsewhere variations correspond to the mean square deviations). For 22% of the examined spots the data require a two-layer model of water distribution down to the sensitivity limit of about 60 сm. The mean water content in upper layer of these spots is about 2−3% by mass, which is close to the content for spots with the homogeneous water distribution. In 8% of the examined spots the water content in the bottom layer at a depth of 27 ± 18 сm increases to 5.6 ± 2.7%. In 14% of the examined spots the water content in the bottom layer at a depth of 14 ± 7 сm decreases to 1.2 ± 0.5%. For interpretation of these results we conclude that the Gale crater has areas both with high and low water content, which correspond to distinct sedimentary layers from different past epochs, when sedimentation process took place underwater and in air correspondingly.

SIMISS: A Model based Searching Strategy for Inventory Management Systems

Inventory management is critical in human space flight operations. Currently, we use the inventory management system (IMS) in keeping track of items on the International Space Station (ISS). One challenge is to discover lost or wrongly placed items when IMS fails to discover them due to human factors. In this paper, we will illustrate a model-based searching strategy called semantic inventory management for ISS (SIMISS), with which possible locations of lost items will be calculated based on contextual features in three dimensions: 1) spatial ; 2) temporal ; and 3) human . It contains ontologies, databases, machine learning algorithms, and ubiquitous client applications. We have implemented and tested SIMISS with the sample data from IMS, operation data files and onboard short term plan experiments have been carried out in a set of simulation scenarios.

The service telemetry and control device for space experiment “GRIS”

Problems of scientific devices control (for example, fine control of measuring paths), collecting auxiliary (service information about working capacity, conditions of experiment carrying out, etc.) and preliminary data processing are actual for any space device. Modern devices for space research it is impossible to imagine without devices that didn't use digital data processing methods and specialized or standard interfaces and computing facilities. For realization of these functions in “GRIS” experiment onboard ISS for purposes minimization of dimensions, power consumption, the concept “system-on-chip” was chosen and realized. In the programmable logical integrated scheme by Microsemi from ProASIC3 family with maximum capacity up to 3M system gates, the computing kernel and all necessary peripherals are created. In this paper we discuss structure, possibilities and resources the service telemetry and control device for “GRIS” space experiment.

Earth magnetic field as analyzer of the cosmic ray ion charge in MONICA experiment

The future onboard experiment MONICA (monitor of cosmic ray nuclei and ions) is aimed for studying the cosmic ray ion fluxes from H to Ni in the energy range 10-300 MeV/n in vicinity of Earth. It's main scientific objective is the measurement of ion ionization states, as well as elemental, isotope composition and energy spectra of Solar Energetic Particle (SEP) fluxes. The method of the ion ionization state measurement based on the usage of Earth magnetic field as a separator of particle charge will be utilized in this experiment. The present contribution is dedicated to investigate the possibilities and features of this method for the MONICA experiment. The real time dependences of inverse square of cut-off geomagnetic L-shell (LC-2) on magnetic rigidity (R) in rigidity range 640-2780 MV were studied experimentally during powerful SEP events December 13-15 2006. The possibility to simulate these dependences using the modern geomagnetic field models is analyzed as well.

Bayesian statistics for the calibration of the LISA Pathfinder experiment

The main goal of LISA Pathfinder (LPF) mission is to estimate the acceleration noise models of the overall LISA Technology Package (LTP) experiment on-board. This will be of crucial importance for the future space-based Gravitational-Wave (GW) detectors, like eLISA. Here, we present the Bayesian analysis framework to process the planned system identification experiments designed for that purpose. In particular, we focus on the analysis strategies to predict the accuracy of the parameters that describe the system in all degrees of freedom. The data sets were generated during the latest operational simulations organised by the data analysis team and this work is part of the LTPDA Matlab toolbox. A post-publication change was made to this article on 26 Jun 2020 to add an author.

Response of bacteria and phytoplankton from a subtropical front location Southern Ocean to micronutrient amendments ex-situ.

The effects of micronutrient amendments such as cobalt (Co), copper (Cu), iron (Fe) and their mixture (Co+Cu+Fe) on bacterial abundance, phytoplankton, bacterial community (BC) composition were examined at a subtropical front (STF) location in the Indian Sector of the Southern Ocean (ISSO) during the austral summer of 2012. From the 15-day on-board experiment it became evident that there was no significant increase in total chlorophyll a concentration or phytoplankton cell numbers in micronutrient enriched microcosms (MEM) compared to the control microcosms (CM) with no added micronutrients. Highest bacterial abundance was observed in the Fe-enriched microcosm within 5 days of incubation unlike in other microcosms. Interestingly, significant differences in the BC composition were observed between MEM and CM. In that an increase of ~10 unique phylotypes affiliated with Psychrobacter sp, Prochlorococcus sp, Burkholderia sp, Cytophaga−flavobactria cluster, Roseobacter sp, Bacillus sp and Vibrio sp was observed in the MEM. The phylotypes associated with Cyanobacteria preferentially responded to the Co and Fe additions, whereas the members of the Cytophaga−Flavobacteria cluster responded to the Cu, Fe and mixture amendments. Our results are useful to discern that availability of micronutrients, in particular of Fe, affects the bacterial abundance as well as BC composition, but not the phytoplankton growth/chlorophyll a concentration in the STF location. In addition, micronutrient amendments ex-situ appears to lead to predominance of only a few bacterial phylotypes. This shift in bacterial community composition might be due to preferential and/or versatile utilization of exogenously added micronutrients. Phylogenetic diversity of culturable bacterial populations from this sampling location was also assessed using 99 pure bacterial cultures. For this, a select set of biochemical characteristics was examined and numerical profiling was done before subjecting to 16S rRNA sequencing based identification. This effort yielded close to 20 clusters, and representative isolates from each cluster were subjected to molecular taxonomic analyses using 16S rRNA marker gene. From this analysis, ~90% of bacterial isolates were found to be affiliated with Firmicutes and ~10% to Gammaproteobacteria suggesting preponderance of only a few phylotypes in the deep chlorophyll maximum zone of this STF location.

The impact of wind mixing on the variation of bottom dissolved oxygen off the Changjiang Estuary during summer

Hypoxia off the Changjiang Estuary has been frequently reported using short time duration field data. However, its evolution was unknown because of a lack of long-term data and its associated dominant factor. A 104-day long dataset was collected with a bottom mounted system off the Changjiang Estuary in summer 2009. The monitored parameters were bottom dissolved oxygen (DO), temperature, pressure and current. Two hypoxia events were identified, showing that hypoxia was severe and lasted for more than a half month. The first event appeared on July 18 and lasted 17days. During this hypoxia period, the minimum DO was down to 0.17mg/L, which broke the historical record. The second hypoxia event appeared on August 30 and lasted 18days with a minimum DO of 1.29mg/L. The variation of bottom DO was closely related to that of stratification. The monitored data showed that almost every increase/decrease of DO was associated with a weakening/enhancing of stratification, which were recorded as many as 12 times during the monitoring period. Wind mixing modulated or broke the stratification, which affected the variation of bottom DO and hypoxia events. Using a lagged correlation analysis, the stratification and wind mixing were significantly correlated with a coefficient of determination r2=0.72, and stratification lagged wind by 35h. The bottom DO and wind mixing were significantly correlated with a coefficient of determination r2=0.65, and DO lagged wind by 33h. The formation periods of two hypoxia events estimated from monitored data were 20 and 15days, which were much shorter than that from on-board experiments. Strong wind mixing played a dual role on hypoxia. It could relieve hypoxia conditions by supplying DO through mixing. It accelerated the formation of hypoxia afterward as a result of the enhanced phytoplankton bloom induced by wind mixing and high organic decomposition rates consuming more DO.

Flight Results of Arcing Experiment Onboard High-Voltage Technology Demonstration Satellite Horyu-2

The High-Voltage Technology Demonstration Satellite Horyu-2 is a nanosatellite (30 cm cubic shape, 7 kg) developed by the Kyushu Institute of Technology. It is known that high-voltage power generation above 200 V in low Earth orbit induces arcing. The main mission of Horyu-2 is to demonstrate various high-voltage technologies. The satellite was launched on 18 May 2012 to the sun-synchronous orbit at an altitude of 680 km. The satellite succeeded in generating 350 V of photovoltaic power via a specially designed solar array. Using the generated voltage, experiments on arc inception on various types of solar arrays were conducted. The solar arrays tested consisted of a conventional design and two new designs that aimed at preventing arc inception. They were connected to the negative end of a 350 V solar array circuit. A semiconductive cover glass coating was the most effective at preventing arcing. Covering the solar array with a transparent film was effective at low latitudes but it suffered arcs at higher latitudes near the polar region.

The Compact Irradiator Modulus Designed for DNA Repair and Mutagenesis Studies in ISS Microgravity Environment Using UVA Emitted by Light-Emitting Diodes

This work presents the design and characteristics of a new compact ultraviolet (UV) irradiator used in a biological onboard space flight experiment. The experiment, called DRM, took place in the International Space Station research facility (ISS-13 expedition), during the Centenary Mission (Russian-Brazil) in March-April 2006. The DRM main objective was to correlate the DNA repair mechanism and mutagenesis with microgravity. A compact irradiator apparatus was designed for DRM to allow in situ induced radiation in space. This apparatus, called CIM, uses UV-A Light-emitting diodes (LEDs) with 375 nm wavelength as molecular lesions inducers on four bacterial E. coli strains. The manned space mission restrictions were focused on during the CIM main parts design. The ultraviolet dosimetry is also described in this document as DRM experiment results and the CIM operational data are reported to certify the CIM design and DRM protocol compatibility in space application.

Recent Developments in the Field of Shape Memory Epoxy Foams

Shape memory epoxy foams are a new class of materials for aerospace applications as light actuators, structural parts with reduced size during transport, and expandable/deployable structures. They were tested in an experiment onboard of the International Space Station in May 2011 (Shuttle Mission STS 134) and in April 2013, on board the BION-M1 capsule through the Soyuz-2 launch vehicle, with the aim to study the behavior in microgravity for future applications. The experiments were performed by an autonomous device which was in turn composed of control and heating system, battery pack and data acquisition system. Micro-gravity does not affect the ability of the foams to recover their shape but it poses limits for the heating system design because of the difference in heat transfer on earth and on orbit. This could be very significant for the behaviour of complex multi-functional structures in which shape memory epoxy foams are integrated. In this work, the main results of the experiments in microgravity are discussed and some results of tests on ground are shown in order to evaluate new possible developments in the field.

Application of a Heat Shock Protein Inducer to Remedy for an Atrophied Muscle Cell: A Basic Research for ISS/JEM Onboard Experiment

Application of a Heat Shock Protein Inducer to Remedy for an Atrophied Muscle Cell: A Basic Research for ISS/JEM Onboard Experiment

Overestimation of Downward Air-Sea Eddy CO<sub>2</sub> Flux Due to Optical Window Contamination of Open-Path Gas Analyzer

Open-path eddy-covariance CO2 flux over the ocean have been reported to be much larger in magnitude than the estimated bulk CO2 flux, and optical window contamination of the open-path gas analyzers has been reported as the cause of the overestimations. During an on-board experiment over the ocean, we manually cleaned the optical window and directly compared CO2 output signal before and after the window cleaning. It is found that both of the CO2 fluctuation amplitude and correlation coefficient between vertical wind velocity and CO2 mixing ratio have apparently increased, then resulting in the downward CO2 flux overestimation when the optical window contamination accumulate. These apparent increases were reset after the manual window cleaning. Correlation coefficients between CO2 and H2O output signals, which represent cross-sensitivity between CO2 and H2O, can be useful indicators of optical window contamination of the open-path gas analyzer.

Experimental Study on Underwater Transient Noise Generated by Water-Entry Impact

To study the water-entry impact noise, on-board experiment using a small launcher firing various objects was performed in the Yellow Sea. As the launcher fires a cylindrical object from the ship vertically, generated noise is measured with a hydrophone on the starboard of Chung-hae, Marine surveyor. Three types of cylindrical objects, which have noses of flat-faced, conical, and hemisphere, were used during the experiment. The measured noise exhibits a time-dependency which can be divided into three phases: (1) initial impact phase, (2) open cavity flow phase, (3) cavity collapse and bubble oscillation phase. In most cases, the waveform of bubble oscillation phase is dominant rather than that of initial impact phase. Pinch-off time, where a cavity begins to collapse, occurs at 0.18 ~ 0.2 second and the average lasting time of bubble was 0.9 ~ 1.3 second. The energy of water-entry impact noise is focused in the frequency region lower than 100 Hz, and the generated noise is influenced by the nose shapes, object mass, and launching velocity. As a result, energy spectral density on the bubble frequency is higher in the order of flat-faced, conical, hemisphere nose, and the increase of initial energy raises the energy spectral density on the bubble frequency in the cylinder body of same shape. Finally, we compare the measurements with the simulated signals and spectrum based on the bubble explosion physics, and obtain satisfactory agreements between them.

Sapphirinid copepods as predators of doliolids: Their role in doliolid mortality and sinking flux

We investigated predatory behavior of sapphirinid copepods on doliolids around the Kuroshio Extension at stations experiencing blooms of Dolioletta gegenbauri. Onboard observations showed that adult Sapphirina nigromaculata was an active predator of doliolids, with a preference for internal tissues. When entering a doliolid body cavity, sapphirinids left a characteristic bite mark around the fringe of oral and atrial aperture or hole on the tunic of the doliolid. In situ observations with a video plankton recorder (VPR) revealed that association between sapphirinids and doliolids was common in the field. Adult sapphirinids and doliolids exhibiting the characteristic evidence of an attack (bite mark or hole) were found in sediment traps at a depth of 50 m, indicating that the association between these taxa was due to predation. Early copepodites, which were not observed in sediment‐trap samples, appeared in the VPR observations to have a semi‐parasitic phase when they attached themselves to nurse chains. The maximal daily ration of sapphirinids estimated by onboard experiments ranged between 29% and 37% of their body carbon weight. Although the mean predation effect by sapphirinids on the doliolid population biomass was only 0.7% d−1, sapphirinids potentially had a greater effect on doliolid abundance at the termination of doliolid blooms. Some of the attacked doliolids were discarded by the sapphirinids and contributed to the sinking flux below 150 m, the importance of which as a source of detritus likely increased with depth. Sapphirinids, despite their relatively low abundance in the water column, play a specific role in driving community succession and biogeochemical cycling.

Экотоксикологический мониторинг арктических морей

For the first time the results of large-scale ecological and toxicological researches related to phytoplankton communities’ stability (ecological and toxicological monitoring) executed in the same season (summer period of succession) in all seas of Russian Arctic and Subarctic region — Baltic, White, Barents, Kara, Laptev, East Siberian, Chukchi and Bering Seas are presented. The experiments related to influence on primary production by copper’s (Cu) different concentrations were carried out in the conditions approached to natural ones during the voyages on Nikolay Kolomeytsev and Professor Shtokman research vessels. During 68 short-term toxicological onboard experiments the influence of some copper’s additives on the value of primary production of seas’ examined areas was studied.

Nonlinear sliding mode control of switched systems on continuously variable transmission shifting

The control of speed ratio on Continuously Variable Transmission (CVT) is one of the key problems for CVT development. In this paper, a nonlinear Sliding Mode Control (SMC) law of switched systems is designed and employed to control the CVT shifting. Because the CVT shifting control system contains discontinuous characteristics, the way of Filippov solution with discontinuous righthand side is used to design the sliding mode controller. Through the validation of simulation and on-board experiments, it can be concluded that the nonlinear SMC law is a better candidate to control the CVT shifting.

General Purpose Data-Driven Monitoring for Space Operations

As modern space propulsion and exploration systems improve in capability and efficiency, their designs are becoming increasingly sophisticated and complex. Determining the health state of these systems, using traditional parameter limit checking, model-based, or rule-based methods, is becoming more difficult as the number of sensors and component interactions grow. Data-driven monitoring techniques have been developed to address these issues by analyzing system operations data to automatically characterize normal system behavior. System health can be monitored by comparing real-time operating data with these nominal characterizations, providing detection of anomalous data signatures indicative of system faults or failures. The Inductive Monitoring System (IMS) is a data-driven system health monitoring software tool that has been successfully applied to several aerospace applications. IMS uses a data mining technique called clustering to analyze archived system data and characterize normal interactions between parameters. The scope of IMS based data-driven monitoring applications continues to expand with current development activities. Successful IMS deployment in the International Space Station (ISS) flight control room to monitor ISS attitude control systems has led to applications in other ISS flight control disciplines, such as thermal control. It has also generated interest in data-driven monitoring capability for Constellation, NASA's program to replace the Space Shuttle with new launch vehicles and spacecraft capable of returning astronauts to the moon, and then on to Mars. Several projects are currently underway to evaluate and mature the IMS technology and complementary tools for use in the Constellation program. These include an experiment on board the Air Force TacSat-3 satellite, and ground systems monitoring for NASA's Ares I-X and Ares I launch vehicles. The TacSat-3 Vehicle System Management (TVSM) project is a software experiment to integrate fault and anomaly detection algorithms and diagnosis tools with executive and adaptive planning functions contained in the flight software on-board the Air Force Research Laboratory TacSat-3 satellite. The TVSM software package will be uploaded after launch to monitor spacecraft subsystems such as power and guidance, navigation, and control (GN&C). It will analyze data in real-time to demonstrate detection of faults and unusual conditions, diagnose problems, and react to threats to spacecraft health and mission goals. The experiment will demonstrate the feasibility and effectiveness of integrated system health management (ISHM) technologies with both ground and on-board experiments.