The paper focusses on the procedure and analysis of the results of ballistic studies on near-Earth space filling with orbits of communications satellites, navigational satellites, and Earth remote sensing satellites. The study presents the near-Earth orbits classification. In the present work, composed histograms of spacecraft orbits distributions on Keplerian orbital elements have been used to analyze from the data of an actual dynamic base of space objects. The ballistic analysis of near-Earth space filling with spacecraft orbits emerged the special features and variations in their space distribution. The research results can be used to emerge the regions of an increased probability of conflicts between the existing and designed spacecraft, to formulate requirements for inter-orbital maneuvers, as well as to schedule and perform alternative space activities.

At present, a significant increase in the cost of spacecraft is observed. Due to this fact the requirements for their active life duration, operational reliability, and operational cost reduction become more and more stringent. A promising way to meet these requirements is the introduction of on-orbit service (OOS). OOS allows one to solve technical and economic problems by performing service operations in space. The introduction of OOS contributes to extending the active life of spacecraft, increasing their operational reliability, and reducing the service maintenance cost of orbital satellite systems of various purposes. OOS programs on the deorbit of used or damaged spacecraft help in the mitigation of space debris problem. The composition of an OOS system depends on the service tasks to be performed and the ballistic capabilities of disposable or reusable service spacecraft. The realizability and character of the ballistic maneuvers of service spacecraft are largely determined by the type and characteristics of their sustainer engines. The aim of this paper is to assess the ballistic potential of modern and prospective OOS spacecraft and to develop a methodology for planning rational OOS routes. Various ground-and space-based OOS systems are considered and analyzed. The expediency of their use is estimated depending on the service tasks to be performed. The most promising OOS schemes are identified. A technique for planning a rational sequence of orbit transfers between the orbits of the spacecraft to be serviced is proposed and illustrated by the example of a test calculation. The technique is based on the solution of a multi-criteria traveling salesman problem, which is formulated in terms of integer linear programming and reduced to a single-criterion problem by the additive convolution method. The novelty of the proposed technique lies in reducing the original problem to a multi-criteria traveling salesman problem. The results obtained may be used in the justification, planning, and implementation of service space operations.

At present, the requirements for increasing spacecraft active life and operational reliability and reducing spacecraft operation costs become more and more stringent. Because of this, on-orbit servicing becomes more and more attractive. One of the most promising ways to increase the efficiency of transport operations in space is to carry out on-orbit servicing using reusable spacecraft with low-thrust solar electrojet engines. The aim of this paper is to develop a mathematical model for the choice of an optimal low near-Earth parking orbit for a reusable service spacecraft. The case of noncoplanar near-circular orbits of spacecraft and a shuttle scenario of their servicing is considered. The solution of the problem of choosing an optimal parking orbit for a reusable service spacecraft involves repeated solutions of the problem of determining the delta-velocity of the service spacecraft’s orbital transfers between its parking orbit and the orbits of the serviced spacecraft. In this connection, using the averaging method, a mathematical model is developed for the analytical determination of orbital transfer program controls and trajectories and assessing orbital transfer energy expenditures. With its use, a mathematical model is developed for the choice of a service spacecraft’s optimal parking orbit. The objective function is the total delta-velocity of the service spacecraft’s orbital transfers from its parking orbit to the orbits of the serviced spacecraft and vice versa with the inclusion of the orbital transfer frequency. The optimizable parameters are the service spacecraft parking orbit parameters. The use of the proposed models is illustrated by an example of service spacecraft parking orbit optimization. What is new is the mathematical models developed. The results obtained may be used in the preliminary planning of on-orbit servicing operations.

Technogenic pollution of the near-Earth space by fragments of space debris of various sizes significantly limits the possibilities for implementing space activities and represents a great danger to objects on Earth. Low orbits with heights up to 2000 km are particularly heavily clogged. The Inter-Agency Space Debris Coordination Committee recommends removing fragments of space debris from the area of working orbits. Currently, promising ways of space debris removing are considered: descent into the Earth’s atmosphere, relocation to an orbit with a lifetime less than twenty-five years, relocation to an utilization orbit, and orbital disposal. Orbital utilization considers space debris as a resource for the industry in orbit. The objectives of the article are to assess the perspectives for the orbital utilization of space debris and to develop a method for choosing the number and placement of safe recycling orbits in the area of low near-Earth orbits. The paper analyses the prospects for the use of orbital utilization of space debris and the assessment of the possibilities of using orbital storage and subsequent reuse of dismantled space objects, instruments and materials. A number of problems of planning and organizing the orbital utilization of space debris are formulated and solved. A method for determining safe orbits of space debris utilization in the area of low near-Earth orbits based on a criteria system developed. Using the developed method and software package, the possible orbits of space debris utilization in the area of low near-Earth orbits are determined. The lifetime of a space object in the utilization orbit, the stability of the orbit of the utilization at a long time interval, and the energy consumptions for transferring the space object from the working orbit to the utilization orbit are estimated. The novelty of the obtained results consists in the development of a clustering technique for the orbits of utilized space debris objects and the development of a technique for selecting a possible orbit for the utilization of space debris in the area of low near-Earth orbits. The results obtained can be used in the planning and organization of the orbital utilization of space debris.

At present, satellite systems, each comprising hundreds of satellites, are, and are to be, deployed in low orbits. In addition, existing satellite systems are replenished. There has appeared a trend towards the development of modular satellites, which will lead to the development of easy-to-maintain spacecraft consisting of many small structural modules with standardized interface mechanisms. To extend the life of all these systems and reduce their maintenance cost, it is advisable to develop a system for their maintenance. Despite the relatively large number of works on the rendezvous problem, this problem is considered in a somewhat simplified formulation, which is not sufficient for spacecraft servicing in low orbits. As a rule, the consideration is limited to coplanar rendezvous problems in an impulse formulation. In real conditions, rendezvous maneuvers in low orbits are nontrivial. As is known, the orbital parameters of low-orbit spacecraft may differ significantly: the difference in the longitude of ascending nodes (LAN) may reach tens and even hundreds of degrees. Because of this, the energy consumption for an orbital plane change becomes unacceptably high for modern service spacecraft. This energy consumption can be reduced by using the precession of the line of nodes due to the non-centrality of the Earth's gravitational field. A waiting maneuver of a service spacecraft in a well-chosen orbit makes it possible to eliminate the mismatch between the LANs of the service spacecraft’s parking and destination orbits, thus significantly reducing the orbital transfer energy consumption. However, the long wait time of the service spacecraft in its parking orbit significantly increases the total orbital transfer time. The aim of this article is to develop a mathematical model of bicriteria optimization of a transfer of a service spacecraft with a low constant thrust engine between low near-circular orbits with significantly different LANs. This problem is solved by averaging the service spacecraft’s dynamics equations over a fast parameter and using a genetic algorithm of global Pareto optimization. The novelty of the results obtained lies in a formulation of a bicriteria optimization problem and the development of a mathematical model for choosing an optimal service spacecraft parking orbit. The mathematical model developed may be used in planning service spacecraft transfers between low near-circular orbits with significantly different LANs.