Small Space Vehicles Research Articles

Experimental Testing of Electrothermal Microthrusters with Autonomous Heating Elements for Orbital Maneuvering of Small Space Vehicles

Background/Objectives: The paper considers the results of the experimental tests on Electrothermal Microthrusters (ETMT) with Autonomous Heating Elements (AHE) of various designs for Corrective Propulsion Systems (CPS) of maneuverable Small Space Vehicles (SSV). The experimental tests are of major importance for developing ETMT with AHE and of particular interest for designing CPS for maneuverable SSVs, including ultralight SSVs (under 10 kg). Method: The design parameters have been determined and the experimental ETMTs of four different designs have been manufactured using the multipurpose structural design method. Among them, ETMT with AHE, ETMT with AHE having a combined thruster-evaporator circuit, ETMT with AHE having a combined thruster-evaporator circuit and a possibility for connection of external devices, as well as ETMT with AHE having a combined thruster-evaporator circuit and an integrated throttle. Findings: The experimental ETMTs meet the minimum weight and size requirements and are capable of generating a high specific impulse while consuming little electrical power. The paper looks at the results of the ground tests, including the tests in a vacuum chamber with liquid gasified ammonia and nitrogen used as operating gases. The tests have proven that ETMT with AHE can operate at 5 to 70 W as part of SSV CPS. The recommendations have been given with regard to the use of ETMTs with AHEs as part of SSVs with different weight characteristics, as well as the amount of electrical power required for CPS operation.

Design Features and Studies of Ammonia Electrothermal Microthrusters with Tubular Heating Elements for Small Space Vehicles

Background/Objectives: The article studies the definition of structural appearance of Electro Thermal Micro Thrusters (ETMT) with Tubular Heating Elements (THE) for Correcting Propulsion Systems (CPS) of maneuverable Small Space Vehicles (SSV). Methods: On the basis of an integrated approach we have defined structural appearance of ETMT with THE, conforming to the requirements to ensure minimum weight, manufacturability and maintainability. Findings: Structural diagrams of ETMT with THE having various lengths have been developed that provide increase in specific burst of power of ETMT in conditions of limited power consumption. Ammonia-operated prototypes of ETMT with THE have been manufactured and tested in a vacuum chamber under conditions most closely resembling the operational ones. The conducted experimental studies have shown the possibility of using ETMT with THE as part of CPS SSV in ETMT power consumption range varying from 60 to 70 W. Application/Improvements: These experimental studies are a continuation of works in creating ETMT of various designs and are of practical interest when developing CPS for maneuvering SSV 7 .

Исследование теплового состояния малого космического аппарата

Исследование теплового состояния малого космического аппарата

Design Features and Research of Electrothermal Microthrusters with Autonomous Heating Elements for the Purposes of Small Space Vehicle Orbital Manoeuvring

The paper studies the definition of design-basis appearance of Electrothermal Microthrusters (ETMT) with Autonomous Heating Elements (AHE) for Correcting propulsion System (CPS) of manoeuvrable Small Space Vehicles (SSV). The findings of present study are of particular practical interest in connection with creation of CPS for manoeuvrable SSV of ultra-low mass (under 10 kg). In the framework of the taken approach, multipurpose method of structural design has defined design parameters and design appearance of ETMT. Different characteristics of ETMT are provided due to replaceable conical and bell nozzle linings’ usage without change of ETMT basic design. Design maps of ETMT with AHE have been developed, aimed to specific performances’ upgrade of CPS in conditions of low power consumption. The results of undertaken land experimental study are quoted, including conditions of vacuum-chamber using nitrogen and air as working medium of CPS. Basing on the undertaken experimental study the possibility in principle of the usage of ETMT with AHE as part of CPS for space vehicles of gross mass under 10 kg is shown. Moreover, design map, implementation approach and further upgrade of ETMT with AHE are defined, among which it is possible to emphasize the design map of ETMT integrated with evaporator, providing the increase of specific burst of power up to 30-35 % within allocated power consumption as part of SSV

The Studies of Small Space Vehicles Ammoniac Electrothermal Engine Units Design and Structural Layout

The paper studies the issues of design and structural layout of ammoniac corrective engine units (CEU) with electrothermal micromotors (ETMM) for manoeuvrable small space vehicles (SSV) using all-purpose approach. CEU and ETMM structural schemes are defined, adaptation questions of CEU to SSV are addressed, CEU mass analysis is carried out, and experimental study’s findings are given.

Standing ballistocardiography measurements in microgravity.

The performance and practicality of a scale-based ballistocardiogram (BCG) system for hemodynamic monitoring of astronauts on extended space missions was demonstrated. The system consists of a modified electronic weighing scale fitted with foot bindings to mechanically couple the subject to the scale. This system was tested on a recent series of parabolic flights in which scale-based and accelerometry-based free-floating BCG of 10 subjects was measured in microgravity. The signal-to-noise ratio (SNR) of the scale-based BCG was, on average, a factor of 2.1 (6.3 dB) higher than the free-floating method, suggesting that the tethered scale approach might be more robust in terms of signal quality. Additionally, this approach enables practical BCG-based hemodynamic monitoring in fractional-g environments, and on small space vehicles such as NASA's upcoming Orion capsule. The scale-based results in microgravity were also compared to ground measurements (1 g), where there was an average 38.7 ms RJ interval reduction from ground to microgravity environments that is consistent across 9 of 10 subjects. This phenomenon is likely due to the transient increase in venous return, and consequent decrease in pre-ejection period, experienced during the microgravity time intervals.

Methods of the analysis of motion of small space vehicles around the centre of masses at deployment of space tether system

This paper studies analytical and numerical methods of the analysis of spatial motion concerning centre of mass of small space vehicles at deployment of space tether system. Deployment of space tether system is executed from the base space vehicle. The set angular orientation of the base space vehicle concerning a local vertical is provided by means of own system of stabilisation. The small space vehicle (or freight) represents a descent capsule returned to the Earth or the space vehicle transferred into higher orbit. It is supposed that the weight of the base space vehicle is much more than weight of freight. The angular position of freight is described by classical Euler’s angles determined concerning a direction of a tether. Analytical methods of the analysis of angular motion are based on an averaging method (for small angles of nutation) and on a method integral of manifolds which allows to investigate the nonlinear equations of angular motion of freight. The major factors influencing stability of angular motion of freight concerning a direction of a tether are considered. Results of numerical modelling of angular motion of the small space vehicle are presented.

Thermo-electrical motor for small and xsmall space vehicles

Thermo-electrical motor for small and xsmall space vehicles

Экспериментальное моделирование тепловых режимов малогабаритных космических аппаратов и их внешних тепловых потоков. II. Результаты тепловакуумных испытаний макета микроспутника типа МС-1-ТК-ТВ

Экспериментальное моделирование тепловых режимов малогабаритных космических аппаратов и их внешних тепловых потоков. II. Результаты тепловакуумных испытаний макета микроспутника типа МС-1-ТК-ТВ

Экспериментальное моделирование тепловых режимов малогабаритных космических аппаратов и их внешних тепловых потоков. I. Термовакуумная установка ТВК-2.5

Экспериментальное моделирование тепловых режимов малогабаритных космических аппаратов и их внешних тепловых потоков. I. Термовакуумная установка ТВК-2.5

A model for a regional transportation system within the geostationary space complex

The geostationary orbit about the Earth is presently used by a great number of communication and observation satellites. These nearly one hundred satellites have a limited lifetime and are expected to be replaced in due time by unmanned platforms of increasing size. Maintenance, repair and removal of these platforms by unmanned and manned space vehicles is one of the options discussed with increasing frequency. Another space system envisioned for the geostationary orbit are space solar power plants (SSPS). They have been investigated during the last two decades to find out whether there are any technical or financial problems which have to be overcome before a SSPS can materialize sometime in the next century. So far, none have been discovered, but proof is lacking that a SSPS is technically feasible and competitive if compared with other options to solve the energy problem on this planet in the next century. A partial problem for the acquisition and operation of a system of space power satellites is their assembly, maintenance and repair. Most of it must be done automatically but a sizable crew would probably have to be in GEO for quick action. Such a crew requires not only habitats, storages and a local energy supply, but also a regional space transportation system to transport spares, tools and people between the individual power plants and the other elements of the geostationary infrastructure. Such a regional transportation system for local transportation in the geostationary orbit (GRET) was recently studied at the Aerospace Institute of the Technical University of Berlin. It envisions a fleet of small space vehicles for interorbital transfer requiring modest velocity changes and flight times. The fleet comprises taxis for passenger transport, tugs for cargo transport and several unmanned and manned services vehicles of different sizes. These vehicles are housed in a special GEO space facility connected directly to the GEO spaceport. A SSPS driven market model assumes the initial operational capability for the year 2004. The GEO crew might have two hundred people by 2010 and several thousand tons of construction materials and spares would have to be transported by that time. The regional transportation system including GEO facilities and space vehicles will require approximately 1000 tons within the first decade of operation, not counting the propellants. The results of a preliminary cost model indicate acquisition cost in the order of 28 × 10 9 dollars. If the acquisition and operating costs of a commercial entity of this kind are to be covered by the services rendered to the company operating the SSPS, then transportation prices of 15,000 $/trip and 50,000 $/metric ton moved between the GEO facilities would have to be charged. This system model might not be the best way for solving the local transportation problem in GEO, but this kind of overhead cost must be included in any future system analysis of the SSPS.