Orbit design for the Spektr-R spacecraft of the ground-space interferometer

In order to carry out tasks of the RadioAstron mission, a high-apogee orbit was designed. On average, the period of its satellite’s orbit around the Earth is 8.5 days with evolution due to gravitational perturbations produced by the Moon and the Sun. The perigee and apogee of this orbit vary within the limits 7500–70000 km and 270000–333000 km, respectively. The basic evolution of the orbit represents a rotation of its plane around the line of apsides. Over 3 years, the plane normal to the orbit draws on the celestial sphere an oval with a semi-major axis of about 150° and semi-minor axis of about 45°.     

A technique for estimating the probability of radiation-stimulated failures of integrated microcircuits in low-intensity radiation fields: Application to the Spektr-R spacecraft

In developing radio-electronic devices (RED) of spacecraft operating in the fields of ionizing radiation in space, one of the most important problems is the correct estimation of their radiation tolerance. The “weakest link” in the element base of onboard microelectronic devices under radiation effect is the integrated microcircuits (IMC), especially of large scale (LSI) and very large scale (VLSI) degree of integration. The main characteristic of IMC, which is taken into account when making decisions on using some particular type of IMC in the onboard RED, is the probability of non-failure operation (NFO) at the end of the spacecraft’s lifetime. It should be noted that, until now, the NFO has been calculated only from the reliability characteristics, disregarding the radiation effect. This paper presents the so-called “reliability” approach to determination of radiation tolerance of IMC, which allows one to estimate the probability of non-failure operation of various types of IMC with due account of radiation-stimulated dose failures. The described technique is applied to RED onboard the Spektr-R spacecraft to be launched in 2007.     

Trajectory of spacecraft with photonic laser propulsion in the two-body problem

The photonic laser propulsion (PLP) system can produce continuous and constant thrust. This paper reviews its basics and then studies its application in the two-body interplanetary trajectory. This study also derives the equations of motion (EOM) for a spacecraft in an inertial frame and rotational frame for the two-body problem, and uses the Jacobi integral to investigate the spatial restrictions on trajectory. This study proposes a constraint on the smallest thrust at the launching stage, and finds the in-plane and out-of-plane equilibria. Numerical simulations confirm the validity of the derivations. The results of this paper are directly applicable to future PLP thrust missions, and particularly interplanetary travel.     

Operation of the Spektr-R orientation system

Errors in pointing and sustaining Spektr-R are estimated based on the data of star sensors and an angular velocity vector meter, and the calculated values are compared with the observed values. It has been indicated that the achieved pointing accuracy is significantly better than the required accuracy and is independent of the number of star sensors used for this purpose; finally, the stabilization parameters correspond to the anticipated parameters. The original method for processing adjustment observations of the space radio telescope in the 1.35-cm range used to find a systematic deviation of 2.5′ of the telescope real electric axis from the nominal angular position has been described.     

Informational approaches to angular motion control of spacecraft

Any information concepts may be used for motion control with respect to the center of masses of a reusable transport spacecraft (RTS). Using comparative analysis of the two concepts (the first one, based upon information about attitude parameters with respect to the inertial reference system and the second one, based upon parameters of angular motion with respect to wind-body coordinate system) for specific features of RTS dynamics and control at the stages of orbital flight, atmospheric flight under gas dynamic and aerodynamic control, and landing, paper demonstrates that information on angles of attack, slip and speed roll should be used for angular motion control at this stage of flight.     

Algorithms for the transport spacecraft descending stage lateral motion control

This report deals with the problems of synthesizing algorithms for controlling the attitude manoeuver of a transport spacecraft aimed at injecting the spacecraft into a closed terminal domain of “heading-range” phase coordinates which makes it possible to descend to the landing aerodrome region in accordance with a spiral trajectory tracking pattern. The descent trajectory is controlled by changing the roll angle. The principal distinguishing feature of the suggested method of transport spacecraft lateral motion control resides in guiding the spacecraft to a terminal curve and in providing an automatic transfer from roll control to interacting control of roll angle and angle of attack. The performance of the control algorithm under transient conditions are considered in detail.Algorithms controlling the longitudinal range by varing the magnitude of the roll angle and lateral range by selecting the respective sign of the roll control angle are thereafter synthesized separately. The major problem in designing the angular motion control system of transport spacecraft is the development of a high-rate roll axis turn control algorithm. To ensure high accuracy of lateral manoeuvering of the spacecraft it is expedient to accomplish the spacecraft reorientation in roll in a minimum time. It is therewith necessary to take into account with the sideslip angle limitation associated with the need of complying the design conditions of the spacecraft flowaround and with the spacecraft skin selected temperature conditions. It is expected that the total side slip angle is acceptable for measurement. Within the greater portion of the descent trajectory constant-thrust jet-reaction control engines are employed as actuators. Therefore, together with the high speed of response developed control algorithm provides an adequate efficiency of the system from the viewpoint of fuel consumption. The possibilities offered by the suggested algorithms controlling the lateral motions of the center of masses and around the center of masses during the descent stage and in the course of landing approach manoeuvering are illustrated by an example considering a hypothetical transport spacecraft featuring variable aerodynamics and a low frequency of natural oscillations of the angular motion loop. The suggested algorithms make it possible to fully employ the transport spacecraft maneuverability and to meet the terminal heading and velocity requirements within a wide class of disturbances.     

返回舱弹道重建与黑障区弹道再现研究

对于飞船返回舱，黑障区弹道再现是再人飞行试验气动分析工作的重要环节。利用舱上测量数据和有限的雷达测量数据重构飞行弹道，是黑障区弹道再现的有效方法。本文建立了返回舱弹道重建的数学模型，包括运动学模型、观测模型、测量误差模型，从而将返回舱弹道重建问题转化为一个非线性动态系统的参数辨识问题。给出了基于极大似然判据和Newton-Raphson迭代的弹道重建算法。对某飞船返回舱的飞行试验数据进行了计算和分析，结果证实了弹道重建数学模型的正确性和算法的可行性。通过弹道重建，不仅再现了黑障区的弹道，而且提供了可靠的、完整的弹道数据。     

Reconstruction of spacecraft rotational motion using a Kalman filter

Quasi-static microaccelerations of four satellites of the Foton series (nos. 11, 12, M-2, M-3) were monitored as follows. First, according to measurements of onboard sensors obtained in a certain time interval, spacecraft rotational motion was reconstructed in this interval. Then, along the found motion, microacceleration at a given onboard point was calculated according to the known formula as a function of time. The motion was reconstructed by the least squares method using the solutions to the equations of satellite rotational motion. The time intervals in which these equations make reconstruction possible were from one to five orbital revolutions. This length is increased with the modulus of the satellite angular velocity. To get an idea on microaccelerations and satellite motion during an entire flight, the motion was reconstructed in several tens of such intervals. This paper proposes a method for motion reconstruction suitable for an interval of arbitrary length. The method is based on the Kalman filter. We preliminary describe a new version of the method for reconstructing uncontrolled satellite rotational motion from magnetic measurements using the least squares method, which is essentially used to construct the Kalman filter. The results of comparison of both methods are presented using the data obtained on a flight of the Foton M-3.     

High-precision single-input control of relative motion in spacecraft formation

A Newton-type method is proposed to improve the accuracy of control for relative motion of two satellites in close formation. We assume that the deputy satellite is equipped with a passive attitude control system that provides one-axis stabilization, and one or two orbit control thrusters are installed along the stabilized axis. Previous studies show that it is possible to construct periodic relative trajectories both in case of passive magnetic and spin stabilization. However, the accuracy of the numerically obtained control is quite low due to modeling errors caused by linearization of the equations of relative motion. Therefore, a correction procedure is required to compensate for nonlinear effects. To this end we suggest a recently developed algorithm based on the Newton method for solving nonlinear systems with geometric constraints. Being implemented, this algorithm allows decreasing the modeling error by up to ten times. The previously found control and trajectory of the linearized system are used as initial approximations.     

Analysis of spacecraft motion under constant circumferential propulsive acceleration

This paper reassesses the classical circumferential-thrust problem, in which a spacecraft orbiting around a primary body is subjected to a propulsive acceleration of constant modulus, whose direction is in the plane of the parking orbit and orthogonal to the spacecraft-primary line. In particular, a new formulation is proposed to obtain a reduction in the number of differential equations required for the study of the spacecraft propelled trajectory. The mathematical complexity of the problem may be further reduced assuming that both the propulsive acceleration modulus and the spacecraft distance from the primary body are sufficiently small. In that case, an approximate model is able to accurately describe the characteristics of the propelled trajectory when the parking orbit is circular. Finally, using the data obtained by numerical simulations, the approximate model is extended to generate a set of semi-analytical equations for the analysis of a classical escape mission scenario.     

Features of rotational motion of a spacecraft descending in the Martian atmosphere

Angular motion at atmospheric entry is studied in the paper for a spacecraft with a bi-harmonic moment characteristic. Special attention is given to the case when the spacecraft possesses two stable balanced positions, and, hence, it can oscillate in dense atmospheric layers in the ranges of small or large angles of attack. The averaged equations of spacecraft motion are derived, which allow one to increase the speed of calculations by several orders of magnitude. A real example is presented, which concerns a spacecraft specially designed for descending in the Martian atmosphere.     

Research into the effects of astronaut motion on the spacecraft: a review

The paper reviews the research that has been undertaken to understand and quantify the disturbance effects of the astronaut's motion inside and outside the spacecraft on the vehicle's attitude and acceleratory environment. In early investigations, the dynamic interaction of astronauts, modeled as point masses, and the spacecraft, modelled as a rigid body, was analyzed. Through ground-based experiments and the modeling of astronaut-induced forces and moments as stochastic processes, it became possible to estimate the magnitude and energy content of the loads produced by the astronaut. The first experiment in space to measure the astronaut-induced disturbances was conducted on the Skylab orbital station. Loads generated while performing routine operations were measured on board the Space Shuttle in 1994 and on the space station Mir in 1996–1997.     

Analytical solutions for the relative motion of spacecraft subject to Lorentz-force perturbations

A spacecraft capable of producing higher-than-natural electrostatic charges may achieve propellantless orbital maneuvering via the Lorentz-force interaction with a planetary magnetic field. Development of maneuver strategies for these propellantless vehicles is complicated by the fact that the perturbative Lorentz force acts along only a single line of action at any instant. Relative-motion dynamical models are developed that lead to approximate analytical solutions for the motion of charged spacecraft subject to the Lorentz force. These solutions indicate that the principal effects of the Lorentz force on a spacecraft in a circular orbit are to change the intrack position and to change the orbit plane. A rendezvous example is presented in which a spacecraft with a specific charge of ?3.81 $\times$ 10^?4 C/kg reaches a target vehicle initially 10 km away (on the same equatorial low-Earth orbit) in 1 day. Fly-around maneuvers may be achieved in low-Earth orbit with specific charges on the order of 0.001 C/kg.     

Experimental investigation of the modes of operation of uncontrolled attitude motion of the Progress spacecraft

Results of in-flight tests of three modes of uncontrolled attitude motion of the Progress spacecraft are described. These proposed modes of experiments related to microgravity are as follows: (1) triaxial gravitational orientation, (2) gravitational orientation of the rotating satellite, and (3) spin-up in the plane of the orbit around the axis of the maximum moment of inertia. The tests were carried out from May 24 to June 1, 2004 onboard the spacecraft Progress M1-11. The actual motion of this spacecraft with respect to its center of mass, in the above-mentioned modes, was determined by telemetric information about an electric current tapped off from solar batteries. The values of the current obtained during a time interval of several hours were processed jointly using the least squares method by integration of the equations of the spacecraft’s attitude motion. The processing resulted in estimation of the initial conditions of motion and of the parameters of mathematical models used. For the obtained motions the quasi-static component of microaccelerations was computed at a point onboard, where installation of experimental equipment is possible.     

Controlling the motion of a spacecraft when approaching a large object of space debris

The problem of calculating the parameters of maneuvering a spacecraft as it approaches a large object of space debris (LOSD) in close near-circular noncoplanar orbits has been considered. In [1–4], the results of analyzing the problem of the flyby of the separated LOSD groups have been presented. It has been assumed that a collector spacecraft approaches the LOSD and captures it or it is inserted into the nozzle of a small spacecraft that has a proper propulsion system (PS). However, in these papers, the flight from one object to another was only analyzed and the problem of approaching to LOSD with a given accuracy was not considered. This paper is a supplement to the cycle of papers [1–4]. It is assumed that, the final stage of approaching the LOSD is implemented by maneuvering in many orbits (up to several dozens) with low-thrust engines, but the PS operating time is fairly small compared with the orbit period in order to make it possible to use impulse approximation in the calculations.     

Trajectory correction maneuver design using an improved B-plane targeting method

A spacecraft for interplanetary mission is usually perturbed by some disturbance sources. The trajectory correction maneuver (TCM) is required to adjust this trajectory error, and the B-plane targeting method is widely used in this field. However, this B-plane targeting method is based on the differential correction algorithm, and a numerical Jacobian matrix is usually used for this algorithm. Therefore, our main goal in this paper is to suggest the improved B-plane targeting method to overcome the disadvantages of the conventional B-plane method which requires a numerical Jacobian matrix for the initial perturbation selection and iterations. For this improvement, an analytical Jacobian matrix is introduced instead of the numerical Jacobian matrix. Then, another B-plane approach that offers an analytical solution is suggested using the target eccentricity instead of the target time of closest approach (TCA). Using a modified Kepler's equation, the previous B-plane targeting approach can be replaced with the new method through the analytical solution.     

Influence of disturbances on the angular motion of a spacecraft in the powered section of its descent

The motion of a variable-mass spacecraft is considered in the powered section of a descending trajectory. Approximate analytical solutions are obtained for the angles of spatial orientation of the spacecraft, which allows one to analyze the nutation motion and to develop recommendations on the spacecraft’s mass configuration, providing the smallest possible deviations of the longitudinal axis and thrust vector from specified directions. The errors of stabilization of the spacecraft’s longitudinal axis are calculated by means of numerical integration of complete models and using the obtained analytical solutions, the results being in good agreement.     

Adaptive sliding mode control for six-DOF relative motion of spacecraft with input constraint

This paper addresses the synchronized control problem of relative position and attitude for spacecraft with input constraint. First, using dual quaternion, the kinematic and dynamic models of the six-degree-of-freedom relative motion of spacecraft are introduced. Second, a new adaptive sliding mode control scheme is proposed to guarantee the globally asymptotic convergence of relative motion despite the presence of control input constraint, parametric uncertainties and external disturbances. A detailed stability analysis of the resulting closed-loop system is included. Finally, simulation results are presented to illustrate the validity and effectiveness of the proposed controller, which has the following properties: (1) explicit accounting for the problem of input constraint, (2) fast convergent rate and accurate results can be obtained, (3) no chattering phenomenon is present in the control torque and control force, (4) self-adaptive regulation law is dynamically adjusted to ensure the tracking errors tend to zero asymptotically, (5) the upper bounds of unknown variables are estimated dynamically.