Descent Module Research Articles

Методика экспресс-оценки массовых и объемных характеристик спускаемых аппаратов

The article considers the method of determining the mass and volume characteristics of descent vehicles (DV) based on statistical data on various types of similar vehicles, as well as on using analytical dependencies obtained on the basis of a statistical analysis. Descent module of “Soyuz” class was adopted as the basic version of the device-analog. The dependences allow performing mass analysis of aerospace vehicles in a fairly wide range of overall dimensions, where the requirements for uniformity of the power circuit are maintained and traditional methods of designing a thermal protection system are used. To calculate the masses and volumes of the systems and units, dependencies on the characteristic dimensions of the DV are mainly used, which, as a first approximation, makes it easy to determine the DV volume-mass characteristics when refining the aerodynamic shape and ergonomic factors which require device reconfiguration. This analysis is convenient to use when determining the mass and volume characteristics of an DV at the stage of preliminary design, and the presented material, in perspective, can be used as an additional element for a software package for choosing optimal forms of DV

Boguslawsky Crater on the Moon: Landing Site Selection for the Luna–Glob Mission Descent Module

The article reviews the results of photo geological study of the lunar surface in terms of selection of most favorable landing sites from the point of view of science merit and safety for the Luna—Glob mission descent module.

Software Package for the Development of Thermal Protection Systems for Spacecraft Descent into the Atmospheres of Planets

The paper presents a mathematical model and a computational algorithm and describes a programming and computing suite (PCS) for the development of thermal protection systems for spacecraft designed to descend into the atmospheres of planets. The mathematical model and the PCS are implemented based on the development of thermal protection for the descent module of the EXOMARS 2020 surface platform.

Mission Design of Multipurpose Flights to Venus

The results of applying the efficient methods developed by the authors of this paper for designing interplanetary flight missions to Venus in the near future with the purpose of either executing gravity assist maneuvers (GAMs) around it or being injected into an orbit of Venus and descending onto its surface are presented. The focus is on calculating the launch times and methods for constructing and calculating the reachability regions of the descent module on the surface of Venus.

Spectral Emissivity of a Reentry Orbital Space Vehicle

The problem of the spectral emissivity of the Soyuz-TM descent module during its entry into the dense layers of the atmosphere at altitudes of 90–45 km with an orbital velocity has been solved. The results of three-dimensional numerical simulations are compared with experimental data.

Calibration OGSEs for multichannel radiometers for Mars atmosphere studies

This work describes several Optical Ground Support Equipment (OGSEs) developed by INTA (Spanish Institute of Aerospace Technology—Instituto Nacional de Tecnica Aeroespacial) for the calibration and characterization of their self-manufactured multichannel radiometers (solar irradiance sensors—SIS) developed for working on the surface of Mars and studying the atmosphere of that planet. Nowadays, INTA is developing two SIS for the ESA ExoMars 2020 and for the JPL/NASA Mars 2020 missions. These calibration OGSEs have been improved since the first model in 2011 developed for Mars MetNet Precursor mission. This work describes the currently used OGSE. Calibration tests provide an objective evidence of the SIS performance, allowing the conversion of the electrical sensor output into accurate physical measurements (irradiance) with uncertainty bounds. Calibration results of the SIS on board of the Dust characterisation, Risk assessment, and Environment Analyzer on the Martian Surface (DREAMS) on board the ExoMars 2016 Schiaparelli module (EDM—entry and descent module) are also presented, as well as their error propagation. Theoretical precision and accuracy of the instrument are determined by these results. Two types of OGSE are used as a function of the pursued aim: calibration OGSEs and Optical Fast Verification (OFV) GSE. Calibration OGSEs consist of three setups which characterize with the highest possible accuracy, the responsivity, the angular response and the thermal behavior; OFV OGSE verify that the performance of the sensor is close to nominal after every environmental and qualification test. Results show that the accuracy of the calibrated sensors is a function of the accuracy of the optical detectors and of the light conditions. For normal direct incidence and diffuse light, the accuracy is in the same order of uncertainty as that of the reference cell used for fixing the irradiance, which is about 1%.

Heat-Flux Sensors Integrated Into the Structure of Thermal Protection Coatings

In designing heat-loaded structural elements of descent modules, information on heat loads (heat fluxes and surface temperatures) throughout the active stage of flight in the atmosphere is primary. When a spacecraft moves with hypersonic velocities, the level of temperature and processes occurring on the thermal-protection surface does not necessarily make it possible to use traditional tools to measure heat loads. In this case an alternative to direct measurements is provided by determining heat loads from the data of temperature measurements at several internal points of the structural elements of the thermal protection. The objective of the present work is to develop and evaluate sensors for measurement of the heat loading of thermal protection coatings of today′s descent modules. In the paper, consideration is given to heat-flux sensors for two classes of thermal protection materials: nondestructible fibrous materials and thermally destructible polymers.

MarsTEM sensor simulations in Martian dust environment

A wind tunnel test campaign has been conducted prior to the landing of the Exomars2016 EDM module on the Meridiani Planum on the 19th of October 2016. Test were performed in the Mars wind tunnel facility at Aahrus University (DK) under the 2015 Europlanet Call. The facility was available for a 5 days campaign where different environmental configurations were tested and both a full scale DREAMS (Dust Characterisation, Risk Assessment, and Environment Analyser on the Martian Surface) Metmast model and a Descent Module mockup were studied. In particular the MarsTEM (Mars TEMperature sensor), the temperature sensor of the DREAMS package onboard Exomars2016, was studied for different wind velocities and directions, effect of light sources and presence of dust. The test showed that the sensor response is dependent on wind direction but only slightly on wind velocities. It also seems that the presence of the dust in the wind and the consequent dust deposit on the Metmast and the sensor itself uniforms the response for different wind velocities and directions. Light is also affecting the measurements but it is still not so clear what will be the effect on Mars due to the particular light sources used for the test.

How Particles in the Martian Atmosphere Influence the Thermal Protection Structure of the Descent Module EXOMARS-2

Methods for calculating heat and erosion impact caused by particles in the Martian atmosphere on the heat protection of the descent module EXOMARS-2 during descent in the atmosphere are presented. Atmosphere models corresponding to climatic conditions when landing on the Martian surface are investigated for the landing site Oxita Planum.

Simulation of an on-the-fly measuring system of a descent module under uncertainty of the lunar-surface composition

The measurement method for determining the motion parameters of the module de-orbiting upon the lunar surface has been suggested. The surface-scattered gammas emitted by a radioactive source are detected using four receptors under uncertainty of the lunar soil's elemental composition. The radar-tracking system in the module allows adapting the gamma-ray altimeter to the lunar-soil composition. A mathematical model of the measuring system has been put forward, and dependences of the gamma flux level on the module altitude and the angle of the slanted surface were obtained. The model makes it possible to analyze the relative position of the radioactive source and the receptors and the composition effect of the substrate. The measurement algorithm uses a recursive neural network, which is proposed to be trained in advance and adapted during the module landing.

MISSION PROFILE AND DESIGN CHALLENGES FOR MARS LANDING EXPLORATION

Abstract. An orbiter and a descent module will be delivered to Mars in the Chinese first Mars exploration mission. The descent module is composed of a landing platform and a rover. The module will be released into the atmosphere by the orbiter and make a controlled landing on Martian surface. After landing, the rover will egress from the platform to start its science mission. The rover payloads mainly include the subsurface radar, terrain camera, multispectral camera, magnetometer, anemometer to achieve the scientific investigation of the terrain, soil characteristics, material composition, magnetic field, atmosphere, etc. The landing process is divided into three phases (entry phase, parachute descent phase and powered descent phase), which are full of risks. There exit lots of indefinite parameters and design constrain to affect the selection of the landing sites and phase switch (mortaring the parachute, separating the heat shield and cutting off the parachute). A number of new technologies (disk-gap-band parachute, guidance and navigation, etc.) need to be developed. Mars and Earth have gravity and atmosphere conditions that are significantly different from one another. Meaningful environmental conditions cannot be recreated terrestrially on earth. A full-scale flight validation on earth is difficult. Therefore the end-to-end simulation and some critical subsystem test must be considered instead. The challenges above and the corresponding design solutions are introduced in this paper, which can provide reference for the Mars exploration mission.

DREAMS-SIS: The Solar Irradiance Sensor on-board the ExoMars 2016 lander

The Solar Irradiance Sensor (SIS) was part of the DREAMS (Dust characterization, Risk assessment, and Environment Analyzer on the Martian Surface) payload package on board the ExoMars 2016 Entry and Descent Module (EDM), “Schiaparelli”. DREAMS was a meteorological station aimed at the measurement of several atmospheric parameters, as well as the presence of electric fields, during the surface operations of EDM. DREAMS-SIS is a highly miniaturized lightweight sensor designed for small meteorological stations, capable of estimating the aerosol optical depth (AOD) several times per sol, as well as performing a direct measurement of the global (direct plus scattered) irradiance on the Martian surface in the spectral range between 200 and 1100nm. AOD is estimated from the irradiance measurements at two different spectral bands – Ultraviolet (UV) and near infrared (NIR) – which also enables color index (CI) analysis for the detection of clouds. Despite the failure in the landing of Schiaparelli, DREAMS-SIS is a valuable precursor for new developments being carried-on at present. The concept and design of DREAMS-SIS are here presented and its operating principles, supported by preliminary results from a short validation test, are described. Lessons learnt and future work towards a new generation of Sun irradiance sensors is also outlined.

Computational and theoretical investigation of Mars’s atmospheric impact on the descent module “Exomars-2018” under aerodynamic deceleration

Methods for calculating the aerodynamic impact of the Martian atmosphere on the descent module “Exomars-2018” intended for solving the problem of heat protection of the descent module during aerodynamic deceleration are presented. The results of the investigation are also given. The flow field and radiative and convective heat exchange are calculated along the trajectory of the descent module until parachute system activation.

SUBSURFACE CHARACTERIZATION OF 67P/CHURYUMOV–GERASIMENKO’S ABYDOS SITE

ABSTRACT On 2014 November 12, the ESA/Rosetta descent module Philae landed on the Abydos site of comet 67P/Churyumov–Gerasimenko. Aboard this module, the Ptolemy mass spectrometer measured a CO/CO2 ratio of 0.07 ± 0.04, which differs substantially from the value obtained in the coma by the Rosetta/ROSINA instrument, suggesting a heterogeneity in the comet nucleus. To understand this difference, we investigated the physicochemical properties of the Abydos subsurface, leading to CO/CO2 ratios close to that observed by Ptolemy at the surface of this region. We used a comet nucleus model that takes into account different water ice phase changes (amorphous ice, crystalline ice, and clathrates) as well as diffusion of molecules throughout the pores of the matrix. The input parameters of the model were optimized for the Abydos site, and the ROSINA CO/CO2 measured ratio is assumed to correspond to the bulk value in the nucleus. We find that all considered structures of water ice are able to reproduce the Ptolemy observation with a time difference not exceeding ∼50 days, i.e., lower than ∼2% on 67P/Churyumov–Gerasimenko’s orbital period. The suspected heterogeneity of 67P/Churyumov–Gerasimenko’s nucleus is also found possible only if it is constituted of crystalline ices. If the icy phase is made of amorphous ice or clathrates, the difference between Ptolemy and ROSINA’s measurements would rather originate from the spatial variations in illumination on the nucleus surface. An eventual new measurement of the CO/CO2 ratio at Abydos by Ptolemy could be decisive to distinguish between the three water ice structures.

Rough-Wall Heat Flux Augmentation Analysis Within the ExoMars Project

Surface roughness, especially if enhanced due to ablative form change, increases skin friction drag and convective heat transfer over reentry vehicles. Although the corresponding heat flux augmentation is usually lower compared to increased friction, careful consideration in the prediction of the resulting heat load levels is required. Within the European Mars mission ExoMars, the potential roughness impact on the thermal protection system of the descent module has been analyzed based on analytical predictions, numerical calculations, and dedicated experimental campaigns. This paper describes the experimental efforts in the compressible flow regime to study the impact of roughness at representative conditions. The data are discussed based on comparisons with prediction methods and results of other investigators. Based on these data, the numerical predictive capabilities within the ExoMars program are characterized and validated.

Conceptual design of “Exomars-2018” Descent Module developed by federal enterprise “Lavochkin Association”

Goals and tasks for “ExoMars-2018” mission and share of responsibilities between European partners and p]Russia are presented. The main design requirements for a Descent Module (DM) that define its design concept as well as design specific features are given. The structure of the descent module, thermal control, means for securing systems interaction onboard the spacecraft “ExoMars-2018”, and radio communication with the descent module are examined.

ExoMars 2016, Orbiter module bus a GNC development update

ExoMars programme is part of a cooperation between ESA and Roscosmos. It foresees two missions to Mars that aim to searching for signs of past and present life on Mars, investigating the Martian atmosphere and surface and demonstrating the technologies needed to land on Mars and perform robotic exploration. The first spacecraft launched in early 2016 is composed of an Orbiter module (the Trace Gas Orbiter, TGO) carrying an entry descent and landing demonstration module (EDM) The Orbiter GNC design shall allow the spacecraft composite to cruise towards Mars, to accurately release the EDM, to make orbit insertion in Mars orbit with chemical propulsion system, to circularise the orbit by aerobraking and perform atmosphere observation with the four payloads instruments while relaying communication from assets on Mars surface. After a brief presentation of the ExoMars mission and constraints, the paper first provides an overview of the TGO GNC design (in term of mode and sensor/actuator), then an updated status of development is given. A special emphasis is given to the GNC level implementation of the aerobraking strategies and on specific FDIR features.

Landing a descent module on the Vostochnyi launch site after returning from the moon

Results of the boundary value problem solution for determining the trajectory of returning from the lunar orbit and landing on the Vostochnyi launch site are presented. The solution includes the calculation of the required expenditure of the characteristic velocity for forming the return trajectory and an estimate of the correction impulses for ensuring the required condition of the atmosphere entry. As the descent module moves in the atmosphere, the terminal guidance algorithm developed earlier is used; this algorithm realizes a skip entry trajectory. Results of the statistical simulation of descent trajectories in the disturbed atmosphere for the real-life condition of returning from the Moon are presented. It is shown that, in the case of perfect navigation and load factors of about five, the accuracy of the descent module guidance to the Vostochnyi landing site within 2 km can be achieved.

A concept of the terminal descent control algorithm at reentry into the earth atmosphere with near-parabolic velocity

A concept of the terminal descent control algorithm of the descent module at reentry into the Earth atmosphere with near-parabolic velocity is proposed. Trajectories with one and two (skip reentry) reentries are considered. Simultaneously, downrange and crossrange misses are eliminated by controlling the bank angle and time of bank angle reversal at each phase of the trajectory. The designed control meets the specified load factor constraint.

Construction of the reachability region with regard to the attitude motion of a descent module at reentry with near-circular velocity

A model of the general motion of the descent module that includes the motion of its center of mass and the attitude motion is constructed. An improved estimate of the reachability region in the case of descent in the disturbed Earth atmosphere is obtained. A terminal descent control algorithm with three bank angle reversals for the simultaneous elimination of predicted downrange and cross-range errors with regard to the constraint on the tolerable load factor n tol ≤ 3 is used.