Spacecraft Construction Research Articles

TheGaiamission

Gaia is a cornerstone mission in the science programme of the European Space Agency (ESA). The spacecraft construction was approved in 2006, following a study in which the original interferometric concept was changed to a direct-imaging approach. Both the spacecraft and the payload were built by European industry. The involvement of the scientific community focusses on data processing for which the international Gaia Data Processing and Analysis Consortium (DPAC) was selected in 2007. Gaia was launched on 19 December 2013 and arrived at its operating point, the second Lagrange point of the Sun-Earth-Moon system, a few weeks later. The commissioning of the spacecraft and payload was completed on 19 July 2014. The nominal five-year mission started with four weeks of special, ecliptic-pole scanning and subsequently transferred into full-sky scanning mode. We recall the scientific goals of Gaia and give a description of the as-built spacecraft that is currently (mid-2016) being operated to achieve these goals. We pay special attention to the payload module, the performance of which is closely related to the scientific performance of the mission. We provide a summary of the commissioning activities and findings, followed by a description of the routine operational mode. We summarise scientific performance estimates on the basis of in-orbit operations. Several intermediate Gaia data releases are planned and the data can be retrieved from the Gaia Archive, which is available through the Gaia home page at http://www.cosmos.esa.int/gaia.

Effects of Radiation Damage on Polyimide Resistivity

How dielectric materials collect and store electrical charge is critical to spacecraft construction and operational anomaly resolution. Electrical conduction, and thus spacecraft potential, is known to change as materials are damaged by the space environment. However, the exact extent and nature of the aging is unknown and this dynamic aging is a major impediment to the modeling of a spacecraft’s behavior over its mission life. Here, an investigation is presented of the alteration of electrical conduction and chemistry composition of polyimide films after controlled radiation damage caused by exposure to 90 keV electrons. The conductivity of polyimide is found to increase dramatically (several orders of magnitude) with increased electron exposure. X-ray photoelectron spectroscopy suggests emission of carbon monoxide and carbon dioxide from the polymer at a low electron dose and loss of unsaturated hydrocarbons as the dose increases. No correlation is found between the composition of the surface and the electrical conductivity, indicating that many different damage states are playing a role in the increased conductivity.

Improvement of the atomic oxygen resistance of carbon fiber-reinforced cyanate ester composites modified by POSS-graphene-TiO2

Atomic oxygen (AO) in low Earth orbit (LEO) causes severe damages to the polymer materials used for the construction of spacecraft. To improve the AO resistance of cyanate ester (CE) which is ubiquitous in the space-structures, novel composites prepared by incorporating POSS, graphene and TiO2 (POSS-Graphene-TiO2, PGT) into CE matrix through a solution mixing method. The mass loss ratio of the resulting PGT/CE composites was significantly decreased in comparison to the pristine CE, which is due to the less surface damages. Chemical composition analysis shows that a surface passivation layer is formed on the PGT/CE composites upon exposure to the AO. Carbon fiber-reinforced PGT/CE composites (i.e., T700/PGT/CE) were fabricated. Compared with the T700/CE composite, the interlayer shear strength of the T700/PGT/CE composite was increased by 43% after the AO exposure. Our findings indicate that the PGT fillers contribute the improved AO resistance of the prepared carbon fiber/PGT/CE composites.

Research of the dynamics of condensed product deposition

The paper is devoted to the research of structural nonmetallic materials used in the construction of spacecraft for mass loss and gas release in a vacuum-thermal environment, as well as the research of the dynamics of deposition of gas release condensed products on the optical surfaces of optical equipment. A test bench has been developed for carrying out research of the dynamics of deposition of condensed products based on quartz crystal microbalance. In accordance with the State Standards GOST R 50109-92 mass loss and gas release tests of structural non-metallic materials (fiberglass, fiberglass honeycomb panel, polyurethane foam, tapes, textiles, adhesives, etc.) used in spacecraft construction have been carried out. The effect of the deposition of condensed products of gas release from these materials on the transmission coefficient of the optical element is determined. A conclusion about the possibility of using these materials in constructing spacecraft is made.

The future role of relay satellites for orbital telerobotics

Orbital robotics focuses on a variety of applications, as e.g. inspection and repair activities, spacecraft construction or orbit corrections. On-Orbit Servicing (OOS) activities have to be closely monitored by operators on ground. A direct contact to the spacecraft in Low Earth Orbit (LEO) is limiting the operational time of the robotic application. Therefore, geostationary satellites are desirable to relay the OOS signals and extend the servicing time window. A geostationary satellite in the communication chain not only introduces additional boundary conditions to the mission but also increases the time delay in the system. The latter is not very critical if the servicer satellite is operating autonomously. However, if the servicer is operating in a supervised control regime with a human in the loop, the increased time delay will have an impact on the operator’s task performance.This paper describes the challenges, which have to be met when utilizing a relay satellite for orbital telerobotics. It shows a series of ground experiments that were undertaken with a relay satellite in the communication chain to simulate the end-to-end system. This case study proves that complex robotic applications in Low Earth Orbit (LEO) are controllable by human operators on ground.

Human Factors for NASA's Space Exploration Vision the View from Inside

People are the critical element in human space exploration. Future missions will be designed to optimize uniquely human capabilities: creativity, ingenuity, intuition, learning, problem-solving, flexibility and determination. Human factors' role is to extend human capability with hardware and software; to create environments that maintain mental, emotional and physical fitness; to select and train crews capable of thriving in risky, long-duration missions; and to increase astronaut safety and reduce mission risk. This symposium will explore the research and technology development in NASA's Human-System Integration program. First, we will describe the missions that lead up the manned exploration of Mars. Detailed technical descriptions of NASA's current research and gaps will address physical, cognitive, and behavioral health and performance issues. Finally, we will describe the reinvention of NASA-STD-3000, Human-System Integration Standards, the medium by which research results are imposed on the design and construction of spacecraft, software, and operations concepts.

A Method for Calculating Absorbed Doses onboard Spacecraft for Interplanetary Missions

When developing the strategy of long-term interplanetary missions, minimization of risks associated with radiation hazard (for both the spacecraft systems and the crew) in manned expeditions is one of the most important conditions. In order to forecast such risks, one usually estimates the absorbed and equivalent doses that can be received by elements of devices and by astronauts, respectively. To take into account the numerous factors that influence the dose values inside a spacecraft is a laborious problem. The goal of this paper is to describe a technique developed for dose predictions in interplanetary space missions using computer versions of the models of particle fluences for radiation environment and spacecraft construction. In this paper the technique is applied for calculation of absorbed doses onboard the interplanetary space vehicle Fobos-Grunt (under development by the Lavochkin NPO), whose launch is planned in 2009. Currently, there are several alternative scenarios of this mission. One of the basic variants (its characteristics are presented in Table 1) was used to make calculations. The method of predicting the absorbed dose value includes the following four program levels of computation. 1. Calculation of energy spectra of particle fluences in the open space which act upon a spacecraft during its flight.

Distortion of Radio Reflections from Spacecraft Construction Elements by Plasma Jets and Structures: Physical Modeling

The methodology of physical modeling of scattering of electromagnetic waves by plasma jets and structures near a spacecraft's surface is developed. The effects of attenuation and distortion of radio signals reflected from spacecraft construction elements by plasma jets and artificial plasma structures, which arise during the operation of electric jet engines, injection of electron beams, and in the course of active and passive experiments in orbit, are experimentally investigated.

Conventional forces can explain the anomalous acceleration of Pioneer 10

Anderson, et al. find the measured trajectories of Pioneer 10 and 11 spacecraft deviate from the trajectories computed from known forces acting on them. This unmodelled acceleration (and the less well known, but similar, unmodelled torque) can be accounted for by non-isotropic radiation of spacecraft heat. Various forms of non-isotropic radiation were proposed by Katz, Murphy, and Scheffer, but Anderson, et al. felt that none of these could explain the observed effect. This paper calculates the known effects in more detail and considers new sources of radiation, all based on spacecraft construction. These effects are then modelled over the duration of the experiment. The model reproduces the acceleration from its appearance at a heliocentric distance of 5 AU to the last measurement at 71 AU to within 10 percent. However, it predicts a larger decrease in acceleration between intervals I and III of the Pioneer 10 observations than is observed. This is a 2 sigma discrepancy from the average of the three analyses (SIGMA, CHASMP, and Markwardt). A more complex (but more speculative) model provides a somewhat better fit. Radiation forces can also plausibly explain the previously unmodelled torques, including the spindown of Pioneer 10 that is directly proportional to spacecraft bus heat, and the slow but constant spin-up of Pioneer 11. In any case, by accounting for the bulk of the acceleration, the proposed mechanism makes it much more likely that the entire effect can be explained without the need for new physics.

Radiative Electrification of Spacecraft Construction Elements: Physical Modeling of Charge Accumulation and Neutralization

The basic principles of physical modeling of spacecraft radiative electrification in the ionosphere and the magnetosphere are formulated. It is shown that recorded cyclograms and current pulses of discharges provide complete information on the electrophysical properties of materials. The efficiency of plasma neutralization of electro-radiative effects depends on the density of low temperature plasma and the structure of the irradiated surface.

Composite materials for aerospace applications

Fibre-reinforced polymer composite materials are fast gaining ground as preferred materials for construction of aircraft and spacecraft. In particular, their use as primary structural materials in recent years in several technology-demonstrator front-line aerospace projects world-wide has provided confidence leading to their acceptance as prime materials for aerospace vehicles. This paper gives a review of some of these developments with a discussion of the problems with the present generation composites and prospects for further developments. Although several applications in the aerospace sector are mentioned, the emphasis of the review is on applications of composites as structural materials where they have seen a significant growth in usage. The focus of the paper is especially on the developments on the Indian aerospace scene. A brief review of composites usage in aerospace sector is first given. The nature of composite materials behaviour and special problems in designing and working with them are then highlighted. The issues discussed relate to the impact damage and damage tolerance in general, environmental degradation and long-term durability. Current solutions are briefly described and the scope for new developments is outlined. In the end, some directions for future work are given.

О специфике работы наземных испытательных комплексов при определении акустической устойчивости конструкции КА

О специфике работы наземных испытательных комплексов при определении акустической устойчивости конструкции КА

MeV proton irradiations and atomic oxygen exposure of spacecraft materials with SiO 2 protective coatings

Polymeric materials used for the construction of spacecraft include polymer-matrix composites for structural components, and backface-metallized plastic films such as DuPont Kapton ™ H polyimide, and Teflon ™ FEP fluoropolymer, as thermal control materials. In orbital space-flight, these polymers encounter a very destructive environment comprising ionizing radiation (keV electrons, MeV protons), ultraviolet photons, and hyperthermal atomic oxygen (AO). Therefore, the exposed surfaces of these polymers need to be protected by thin inorganic coatings, such as SiO 2. We report preliminary research results on possible synergistic effects of exposing SiO 2-coated polymers, first to MeV proton irradiation, then followed by high fluences of AO. The coatings, ≤ 0.5 μm thick, are applied by dual-frequency (MW/RF) plasma-enhanced CVD (PECVD). Samples of Kapton and Teflon were irradiated with 1-, and 20-year equivalent doses of 1 MeV protons (≈ 6.5, and 130 kGy, respectively), followed by ≥ 10 21 O atoms/cm 2. Irradiation effects are assessed by comparison with witness samples on the basis of microscopy and mechanical property measurements.

Physical simulation of meteoroid and space debris particles influence on spacecraft construction elements

Three methods of physical simulation of collision with barriers of meteoroid particles and space debris are given. The direct method is to accelerate a model particle by means of a gun or a cumulative device. The method of collision simulation by the barrier splinters when the barrier is broken through with a high-speed steel particle, accelerated as before. The method of hydrosimulation is to simulate the particle and the barrier by means of liquid substances. Theoretical foundation of hydrosimulation is given and the results of compairing the crater dimensions obtained by the impact of liquid and solid pairs are discussed. The boundaries of hydrosimulation of high-speed impact according to velocities for solid impact pairs are V = 2 – 12 km/sec and the dimensions ratio are r /r < 3.

Secondary-electron yield measurements of conducting polymers in the Scanning electron microscope

In recent years, research on conducting polymers has been motivated to a large extent by the prospect of developing low-cost, light-weight conducting polymeric materials for commercial use. Conducting polymers have potential uses as electrodes and/or electrolytes for rechargeable batteries, as power conductors andpowercable sheathing and as material for space photovoltaics and spacecraft-charging applications.The utilization of conducting polymers for spacecraft construction and instrumentation requires an understanding of how such materials respond to the spacecraft environment. Of particular importance is how and to what degree such a material will charge when exposed to the wide range of energetic fluxes of electrons and protons that characterize a typical satellite environment. For typical space plasma environments, the total charging current to a satellite is given by the net sum of the electron and proton particle currents from the ambient plasma to the satellite, the secondary-electron and backscatter-electron emission currents arising from ambient-particle impact, and the photoelectron emission current resulting from solar UV.

Sodart Telescope on Spectrum-Röntgen-Gamma and its Instrumentation

AbstractSPECTRUM-RÖNTGEN-GAMMA (SRG) is one of a new series of large astronomical missions being planned by the Soviet Union and is scheduled for launch in mid-1993. The Space Research Institute (IKI) of the Academy of Sciences of the USSR and the Babakin Center (BC) are responsible for the scientific supervision and spacecraft construction, respectively. Mission objectives include broad and narrow band imaging spectroscopy over a wide range of energies from EUV through gamma rays with particular emphasis on extragalactic objects. The design of the Soviet Danish Röntgen Telescope (SODART) consists of two thin foil, conical shell approximations to Wolter 1 geometry. The reflectors are rolled aluminum foils which have been dipped in acrylic lacquer and coated with gold resulting in a super smooth surface. Each telescope has an aperture of 60 cm, a focal length of 8 m, a field of view of 1 deg and is designed to have a halfpower width of ≤2 arcmin. The conical geometry contributes 15 arcsec and manufacturing tolerances in the support structure and the quality of the figure of the foil the rest. The contribution from X-ray scattering is insignificant. Focal plane slides can position one of four instruments at the focus of each telescope. Images and spectra will be recorded with position sensitive proportional counters with spectral resolution as good as 13% at 6 keV. Spectral resolution of 2.5% at 6 keV is provided by an array of 19 cooled silicon detectors. A broad band polarimeter will be sensitive to residual polarization as low as 1%. An objective Bragg crystal panel, placed in front of one of the telescopes, will be capable of high resolution spectroscopic studies ((E/ΔE)) ~1000) of point- and extended sources.

Radiation charging and breakdowns of insulators

An experimental investigation of the charge produced by photo-emission from insulators in vacuo is described. It is shown that the emission from materials commonly used in spacecraft construction, such as polyimide, is well described by solid state theory but that externally applied fields modify both the emission dynamics as well as eventual saturation charge density. The energetics of the electrical breakdown of such charged surfaces is analysed. Surface discharges can, of course, cause degradation of the quality of the insulation through erosion, puncture or formation of electrically conductive, carbonized tracks, producing concomitant reduction in electrical system performance. These processes, which result directly from chemical interaction or indirectly, thermally, are reviewed and means of minimizing the effects discussed. Avenues of further investigation are outlined.

Human Factors in Space

Space is a unique living and working environment. It is an environment that demands the highest level of performance from crewmembers and is very unforgiving of errors and inefficiency. The spacecraft that we build will have to sustain their inhabitants at a high level of productivity for missions of many months, perhaps longer. Clearly, human factors has a most important role to play in this area. In recognition of this fact, NASA has recently contracted for the writing of a single human factors standard to aid in the design and construction of manned spacecraft. This document is the Man/System Integration Standards, and is the subject of this symposium. Participating contractors include the Boeing Aerospace Company, Lockheed Missiles and Space Company, the Essex Corporation, and CAMUS, Inc. The six presentations in this session provide an overview of this project. We begin with a history of the manned space program. Then, through the use of a film shot on orbit, graphically demonstrate the need for human factors in space. The mechanics of organizing and managing a large scale project to create a new human factors standards document is outlined next. The final three presentations describe contents of the document. These include a description of how human performance in space differs from that on Earth, unique design requirements in zero-gravity, and human factors considerations of extravehicular activities.

An APL program for the distribution of energy deposition by charged particles passing through thin absorbers

An APL program which numerically evaluates the probability density function (PDF) for the energy deposited in a thin absorber by a charged particle is proposed, with application to the construction, pointing, and control of spacecraft. With this program, the PDF of the restricted energy loss distribution of Watts (1973) is derived, and Vavilov's (1957) distribution is obtained by proper parameter selection. The method is demonstrated with the example of the effect of charged particle induced radiation on the Hubble Space Telescope (HST) pointing accuracy. A Monte Carlo study simulates the photon noise caused by charged particles passing through the photomultiplier tube window, and the stochastic variation of energy loss is introduced into the simulation by generating random energy losses from a power law distribution. The program eliminates annoying loop procedures, and model parameter sensitivity can be studied using the graphical output.

Preliminary analysis of a baseline system model for lunar manufacturing

This paper describes a Lunar Base with a capability to produce 100,000 metric tons of raw materials and stock per year. This material can be used for the construction of solar power systems (SPS) or other spacecraft in the geostationary orbit or other space locations. The Lunar base consists of 19 elements. The Earth-Lunar Space Transportation System is supported by two Space Operations Centers in GEO and Lunar orbit. At the present time, this transportation system uses LOX/LH 2 propulsion systems only, to establish a base of reference with a high confidence level. LOX is produced on the lunar surface, the liquid hydrogen required by the space ferries is imported from Earth. Preliminary figures indicate lunar production cost of less than $5 (1980)/kg and specific transportation cost between the lunar surface and GEO in the order of $45/kg. Some 480 people are needed to operate the Lunar base, which has a power requirement of about 300 MW.