A. G. Tuchin

Navigation support for the RadioAstron mission

A developed method of determination of orbital parameters allows one to estimate, along with orbit elements, some additional parameters that characterize solar radiation pressure and perturbing accelerations due to unloadings of reactiion wheels. A parameterized model of perturbing action of solar radiation pressure on the spacecraft motion is described (this model takes into account the shape, reflecting properties of surfaces, and spacecraft attitude). Some orbit determination results are presented obtained by the joint processing of radio measurements of slant range and Doppler, laser range measurements used to calibrate the radio measurements, optical observations of right ascension and declination, and telemetry data on spacecraft thrusters’ firings during an unloading of reaction wheels.

Calculation of quasisynchronous orbits of a spacecraft around Phobos for solving the problem of landing on its surface

The problem of selecting quasi-synchronous orbits of a spacecraft around Phobos is considered. These quasi-synchronous orbits are far (with respect to the Hill’s sphere) quasi-satellite orbits with retrograde rotation in the restricted three body problem. The orbit should pass through a given point at a specified time instant. It should also possess a property of minimum distance from the Phobos surface at every passage above the region of planned landing. The equations of dynamics are represented in the form describing the orbit as a combination of motions in two drifting ellipses, inner and outer ellipses. The center of the outer ellipse is located on the inner ellipse. A formula is derived that relates averaged values of half-axes of the inner and outer ellipses. It is used for construction of the first approximation of numerically designed orbit, which makes it possible to simplify and speed up the computing process. The tables of initial conditions obtained as a result of calculations are presented.

Trajectory correction of the Spektr-R spacecraft motion

The results of refining the parameters of the Spektr-R spacecraft (RadioAstron project) motion after it was launched into the orbit of the Earth’s artificial satellite in July 2011 showed that, at the beginning of 2013, the condition of staying in the Earth’s shadow was violated. The duration of shading of the spacecraft exceeds the acceptable value (about 2 h). At the end of 2013 to the beginning of 2014, the ballistic lifetime of the spacecraft completed. Therefore, the question arose of how to correct the trajectory of the motion of the Spektr-R satellite using its onboard propulsion system. In this paper, the ballistic parameters that define the operation of onboard propulsion system when implementing the correction, and the ballistic characteristics of the orbital spacecraft motion before and after correction are presented.

A robust guidance algorithm for the moon landing

The paper deals with a choice of the rational trajectory of motion of a landing module designed for the Moon landing, from the moment of its de-orbiting from the near-lunar orbit up to landing. An integrated conceptual basis is used to develop multistep terminal algorithms for guidance for the three segments of the descent.

Primeval substance delivery from Phobos to the Earth—the Phobos-Soil project: Ballistics, navigation, and flight control

This paper is concerned with the problems of ballistics, navigation, and flight control of the space craft (SC) in the Phobos-Grunt mission. We consider an insertion into the Earth-Mars transfer trajectory, the Earth-Mars transfer, the strategy of corrections, and the accuracy of the insertion of the SC into Martian orbit. During the orbital maneuvering stage in the sphere of influence of Mars, we set up a scheme that allows for the insertion of the SC, with the prescribed accuracy, into a point 80-km above the Phobos surface over the theoretical landing area. We specify the sequence for a controlled landing and provide methods for solving the problems of navigation and control during a self-c ontained landing. We also consider the liftoff from Phobos, insertion into the parking orbit, and the Mars-Earth transfer.

The nature of terrains of different types on the surface of Venus and selection of potential landing sites for a descent probe of the Venera-D Mission

We discuss a change in the resurfacing regimes of Venus and probable ways of forming the terrain types that make up the surface of the planet. The interpretation of the nature of the terrain types and their morphologic features allows us to characterize their scientific priority and the risk of landing on their surface to be estimated. From the scientific point of view, two terrain types are of special interest and represent easily achievable targets: the lower unit of regional plains and the smooth plains associated with impact craters. Regional plains are probably a melting from the upper fertile mantle. The material of smooth plains of impact origin is a well-mixed and representative sample of the Venusian crust. The lower unit of regional plains is the most widespread one on the surface of Venus, and it occurs within the boundaries of all of the precalculated approach trajectories of the lander. Smooth plains of impact origin are crossed by the approach trajectories precalculated for 2018 and 2026.

Main methods of trajectory synthesis for scenarios of space missions with gravity assist maneuvers in the system of Jupiter and with landing on one of its satellites

The development of a methodology for designing trajectories of spacecraft intended for the contact and remote studies of Jupiter and its natural satellites is considered. This methodology should take into account a number of specific features. Firstly, in order to maintain the propellant consumption at an acceptable level, the flight profile, ensuring the injection of the spacecraft into orbit around the Jovian moon, should include a large number of gravity assist maneuvers both in the interplanetary phase of the Earth-to-Jupiter flight and during the flight in the system of the giant planet. Secondly, the presence of Jupiter’s powerful radiation belts also imposes fairly strict limitations on the trajectory parameters.

Ballistics, navigation, and motion control for a spacecraft during its landing on the surface of Phobos

Basic concepts and algorithms laid as foundations of the scheme of landing on the Martian moon Phobos (developed for the Phobos-Grunt project) are presented. The conditions ensuring the landing are discussed. Algorithms of onboard navigation and control are described. The equations of spacecraft motion with respect to Phobos are considered, as well as their use for correction of the spacecraft motion. The algorithm of estimation of the spacecraft’s state vector using measurements with a laser altimeter and Doppler meter of velocity and distance is presented. A system for modeling the landing with a firmware complex including a prototype of the onboard computer is described.

Attitude control algorithms for a descent vehicle returning from the moon

We consider the problem of attitude control of a descent vehicle in the Earth’s atmosphere returning from the Moon. A stabilization algorithm with a deadband and the optimal parameters, obtained with the numerical method, provide adequate landing accuracy and an allowable load factor under the influence of a set of disturbances. Using the method of mathematical simulation, it is shown that the fuel consumption is reduced by ~30% in comparison with the initial stabilization parameters for the descent from a near-Earth orbit.

A technique for designing highly inclined spacecraft orbits using gravity-assist maneuvers

A highly accurate algorithm for synthesizing chains of cranking gravity-assist maneuvers (GAMs) has been constructed using formalization of the search for ballistic scenarios followed by the adaptive involvement of tens of millions of variants. Its use results in a significant change in the orbital inclination of a research spacecraft without a significant expenditure of propellant with a reasonable mission time.