Low-orbit spacecraft for highly detailed observation with a long lifetime in working orbits with an altitude below four hundred kilometers

The paper analyzes mass-dimensional design parameters of the optical-electronic equipment for Earth’s remote sensing from heights in the range of 300...400 km. Within the research, we carried out the synthesis of a mirror-lens telescopic complex with an additional rotary mirror tilted to the optical axis of the main mirror and selected the design parameters from the conditions for ultra-high spatial resolution satellite images. Furthermore, we analyzed the mass-dimensional parameters of the spacecraft as a whole, the parameters allowing for the smaller effect of the Earth’s upper atmosphere on the evolution of the parameters of the working orbit. To maintain the radius of the low working orbit of the spacecraft for seven years, an electric propulsion system is proposed. To compensate for the aerodynamic drag force in the investigated range of heights and in any conditions of the upper atmosphere, a thrust force of no more than 18 milliNewtons is sufficient. The reserves of the mass of the working body for the operation of the electric propulsion system depend on the design-ballistic parameters of the spacecraft and the required lifetime in a given working orbit.

Two-mirror cylindrical antenna system with high efficiency.

A technique for the synthesis of two-mirror cylindrical antenna systems for a given amplitude distribution in the aperture has been developed. At the first stage geometrical-optical synthesis is carried out, at the second stage a refined solution is found using the field of the feed on the secondary mirror found by the numerical method of finite element. As an example, a two-mirror cylindrical antenna system with a horn-lens feed and a uniform field distribution in the main mirror aperture has been synthesized. Using full-wave simulation by the finite element method, the analysis of the radiation characteristics of a synthesized two-mirror antenna system is carried out. The scanning characteristics of the antenna system by turning the main mirror are investigated. The efficiency of a cylindrical two-mirror antenna system with a horn-lens waveguide transition in the E-plane and an H- sectorial horn feed reaches 0.95 i.e. is close to the limiting value. When scanning the main lobe of the pattern in an angular sector of 27 degrees due to the rotation of the main mirror gain exceeds 26 dB, and efficiency exceeds 0.8.

An Integral Field Unit Based on Parabolic Mirror

Recently many modern instruments and systems have been developed to study the Sun. For that, spectral instruments with high spectral resolution are most often used. It is relevant to achieve high spatial resolution along with spectral one for many scientific tasks. In practice, the achievement of both high spectral and spatial resolution can be done by the use of integral field spectroscopy. Current paper is devoted to searching for a system solution for an integral field unit (IFU), which will be implemented to the optical system of solar telescopecoronagraph. The diameter of the main mirror is D = 3 m. Telescope’s working spectral range is ∆λ = 390 − 1600 nm. The integral field unit is based on reflective elements. It divides the input field of a rectangular shape with a size of 0.7500 ×1200(0.145 mm×2.327 mm) into 8 parts with a size of 0.09400×9600(0.018 mm×18.617 mm) each. The possibility of creating an IFU optical system using a parabolic mirror for all (eight) channels is shown. The quality of the optical system was evaluated, as well as the effect of vignetting on the slicing mirrors.

FOUCAULT KNIFE-EDGE METHOD APPLICATION FOR ADAPTATION OF THE MILLIMETRON OBSERVATORY MIRROR SYSTEM

In the process of space telescopes development there is an increase in the diameter of their reflector.In this case, composite reflectors are used more often. So the main mirror of the Millimetron observatory consists of 96 elements, each of which can deviate from the calculated position during the transition to the transport position and back to the working position when the telescope is put into orbit. In this paper, we consider the possibility of using Foucault knife-edgemethod to solve the problem of adapting the mirror system of the Millimetron observatory. An optical scheme for solving the adaptation problem is proposed. It was simulated in the Zemax software package. In the process of modeling, the effects arising from the deviation of all the components of the reflector in 6 degrees of freedom were studied. The advantage in the approach to the digital matrix in the telescope is highlighted.