Actual Space Environment Research Articles

Recent progresses on space life science research in China

In the past decades, China has made significant progress on space life science research. Since completing the construction of the China Space Station (CSS) at the end of 2022, space life science research in China has entered a new era. Through carrying out numerous experiments on space life sciences, space medicine, and space agriculture conducted aboard the Shenzhou series, the CSS, and ground-based space environment simulation platforms, Chinese scientists have uncovered the effects of the space environment on the physiological and molecular mechanisms of live organisms. These findings provide essential theoretical support for long-term manned space exploration. In this article, we review the new discoveries made by Chinese researchers, focusing on the impacts of both actual and simulated space environment on cells, microorganisms, plants, animals, and human health.

Nanocomposites for Space Applications

The drive to lower the cost of space launches has resulted in the use of polymer matrix composites with micro reinforcements such as carbon fibers. Further attempts to decrease the weight of spacecraft and to improve the performance have led to the addition of nano reinforcements to these composites. In this paper, the application of nanocomposites in spacecraft structures is reviewed. First, several nano reinforcements, such as graphene, fullerene, nanotubes, nanofibers, nanoclays and Polyhedral Oligomeric Silsesquioxane (POSS), are briefly reviewed. Then the stringent requirements of the space environment, in relation to material properties, are reviewed. The space environment poses several challenges such as ultraviolet radiation, temperature extremes, thermal cycling, charged particle radiation, impacts from micrometeoroids and orbital debris, and low earth orbital atomic oxygen. Next, the testing of candidate materials in actual space environment and at ground based testing facilities is reviewed. This is followed by specific applications of nanocomposites in space structures.

Correction of Atmospheric Model Through Data Mining With Historical Data of Two-Line Element

The existing atmospheric mass density models (AMDM) would produce considerable errors in orbital prediction for Low Earth Orbit (LEO) satellites. In order to reduce these errors and correct the AMDM, this paper presents methods based on data mining with historical data of two-line element (TLE). Starting from a typical LEO satellite, TIANHUI, two orbital dynamical models are firstly proposed as the simulation environment to generate training data. The historical TLE data are regarded as actual space environment and used to generate application data. Secondly, three data mining methods, Random Forest (RF), Artificial Neural Network (ANN) and Support Vector Machine (SVM), are combined with the training data to investigate their feasibility in recovering the known deviation of AMDM under simulation environment. Training results show that RF displays the best performance and achieves the accuracy of 99.99%, while the other two methods only achieve 86.83% and 71.90% respectively. Thirdly, under the actual space environment, this paper uses new training and application data to research the ability of the three methods in recovering the unknown deviation of the AMDM and improve the accuracy of orbital prediction. Numerical results are evidential to the accuracy of the proposed methods based on data mining. It is concluded that the capabilities of the data mining for correction for the atmospheric model are very promising, with great potential to advance practical applications on on-orbit propagation.

Comments on "New Concerns for Neurocognitive Function during Deep Space Exposures to Chronic, Low Dose Rate, Neutron Radiation".

Evaluations of the biological effects of space radiation must carefully consider the biological system response and the specific nature of the source term. Acharya et al. (2019) review neurocognitive function during deep space exposures to chronic, low dose rate, neutron radiation, but do not use a source term that reflects the actual space environment in terms of radiation types and their respective energies. In addition, important biological effects, including the adaptive response to the space radiation environment, are not addressed.

Variations in Cathodoluminescent Intensity of Spacecraft Materials Exposed to Energetic Electron Bombardment

Many contemporary spacecraft materials exhibit cathodoluminescence when exposed to electron flux from the space plasma environment. A quantitative physics-based model has been developed to predict the intensity of the total glow as a function of incident electron current density and energy, temperature, and intrinsic material properties. We present a comparative study of the absolute spectral radiance for more than 20 types of dielectric and composite materials based on this model, which spans more than three orders of magnitude. Variations in intensity are contrasted for different electron environments, different sizes of samples and sample sets, different testing and analysis methods, and data acquired at different test facilities. Together, these results allow us to estimate the accuracy and precision to which laboratory studies may be able to determine the response of spacecraft materials in the actual space environment. It also provides guidance as to the distribution of emissions that may be expected for sets of similar flight hardware under similar environmental conditions.

宇宙でのトライボロジー実験

Brief history of tribology experiments in space is described. Tribological performance in a high vacuum was a great concern in early stage of space development, and it was urgent task to verify whether the actual space environment can be simulated using ground-based vacuum facilities from tribological viewpoint. Some friction tests as well as bearing tests were carried out on board satellites in 1960s, and the conclusion was that the results of space experiments was very similar to those of ground-based comparison experiments. In 1980s, however, Space Shuttle flown in Low Earth Orbit (LEO) revealed a new problem; oxidization by active atomic oxygen, which is more than 90% constituent in the environment. Some types of solid lubricants might be oxidized, and thus lost tribological effectiveness. Efforts to clarify the effect of LEO environment on solid lubricants, as well as to simulate LEO environment properly, have been devoted including space experiments. Recent tribology-related space experiments are briefly reviewed.

Modeling solar cell degradation in space: A comparison of the NRL displacement damage dose and the JPL equivalent fluence approaches†

AbstractThe method for predicting solar cell degradation in space radiation environments developed recently at the US Naval Research Laboratory (NRL) is compared in detail with the earlier method developed at the US Jet Propulsion Laboratory (JPL). Although both methods are similar, the key difference is that in the NRL approach, the energy dependence of the damage coefficients is determined from a calculation of the nonionizing energy loss (NIEL) and requires relatively few experimental measurements, whereas in the JPL method the damage coefficients have to be determined using an extensive set of experimental measurements. The end result of the NRL approach is a determination of a single characteristic degradation curve for a cell technology, which is measured against displacement damage dose rather than fluence. The end‐of‐life (EOL) cell performance for a particular mission can be read from the characteristic curve once the displacement damage dose for the mission has been determined. In the JPL method, the end result is a determination of the equivalent 1 MeV electron fluence, which would cause the same level of degradation as the actual space environment. The two approaches give similar results for GaAs/Ge solar cells, for which a large database exists. Because the NRL method requires far less experimental data than the JPL method, it is more readily applied to emerging cell technologies for which extensive radiation measurements are not available. The NRL approach is being incorporated into a code named SAVANT by researchers at NASA Glenn Research Center. The predictions of SAVANT are shown to agree closely with actual space data for GaAs/Ge and CuInSe2 cells flown on the Equator‐S mission. Published in 2001 by John Wiley & Sons, Ltd.

In-Orbit Experiment of Space Robot Technologies on ETS-7

NASDA is now developing Engineering Test Satellite <I>#</I>7 (ETS-7) to perform Rendezvous Docking and Space robot technology experiments in the actual space environment. ETS-7’s space robot experiments include 1) performance evaluation of a robot arm and related equipment in the actual space environment, 2) cooperative control experiment between the satellite attitude and the robot arm, 3) teleoperation experiment of the satellite mounted robot system from a ground control station, and 4) demonstration of in-orbit satellite servicing using a robot arm. The satellite will be launched in 1997 by NASDA’s H-11 rocket into a low earth orbit.

Test methods for single event upset/latch-up

The best way of assessing semiconductor susceptibility to Single Event Phenomena (SEP) would be to measure their response while operating in the actual space environment. However, this a very expensive way to characterise semiconductors and has only been carried out on a very limited number of device types. Generally, the space radiation environment has been simulated in the laboratory and semiconductor characterisation has been carried out using differenct test systems and operating conditions. Where orbital upset data and ground simulation data exist, large variations were often found between observed and predicted upset rates. Better Single Event Upset (SEU) data and device technology information would help improve the prediction process. Here we concentrate on the ground testing itself and only touch on the prediction versus observation of a few devices. Heavy ion and proton test facilities used by ESA will be described together with test techniques and test procedures. Examples of Californium-252, recent heavy ion and proton SEU data on memories and microprocesors will also be presented.

Low Earth orbit effects on indium tin oxide and polyester and comparison with laboratory simulations

Abstract Laboratory simulation of the low Earth orbit (LEO) environment using oxygen plasma ashers are discussed. Their effectiveness as space simulators are compared with LEO through analysis of indium tin oxide (ITO) thin films and bulk polyester exposed to both environments. Spectrophotometry and atomic force microscopy have been used to characterize optical and microstructural changes as a result of exposure to the simulated (oxygen plasma asher) and the actual space environment aboard shuttle flight STS-46. Results show that the low Earth orbit space environment is much harsher than the plasma asher on the optical properties of ITO as well as the surface roughness of polyester. On space-exposed samples, a significant shift in the ITO absorption edge is seen for fluences of 2 × 10 20 atoms cm -2 but not on films exposed in the asher. The surface roughness of polyester exposed in the asher increase by a factor of 5.5, while that of polyester exposed in space increases by a factor of 20 for the same atomic oxygen fluence. The directional nature and higher kinetic energy of atomic oxygen in LEO serves to erode polyester more than in the asher. The different results obtained in the asher for both ITO and polyester bring into question the suitability of using plasma ashers as space simulators for these materials.

On Orbit Thruster Calibration with Applications to Gravity Probe B

A general procedure to determine accurately the true relationship between the commanded and the actual force output of a set of thrusters is presented. This relationship is determined from data generated from a spacecraft while it is on orbit. On orbit thruster calibration measures the true outputs of the thrusters in the actual space environment in which they operate. The feasibility of the calibration technique is verified by a digital simulation of the Gravity Probe B (GP-B) spacecraft dynamics. GP-B is an Earth orbiting experiment which will test several aspects of general relativity. A set of 18 proportional thrusters generates forces and moments for three degree of freedom attitude and three degree of freedom drag free translation control of the GP-B spacecraft. A total of 108 parameters are needed to characterize the magnitude and direction of both the force and moment outputs of the 18 thrusters. The ability to calibrate these parameters to an accuracy of better than 1%is demonstrated.