Effect of the solar activity variation on the Global Ionosphere Thermosphere Model (GITM)

in Annales Geophysicae (2016), 34(9), 725--736

The accuracy of global atmospheric models used to predict the middle/lower thermosphere characteristics is still an open topic. Uncertainties in the prediction of the gas properties in the thermosphere ... [more ▼]

The accuracy of global atmospheric models used to predict the middle/lower thermosphere characteristics is still an open topic. Uncertainties in the prediction of the gas properties in the thermosphere lead to inaccurate computations of the drag force on space objects (i.e. satellites or debris). Currently the lifetime of space objects and therefore the population of debris in low Earth orbit (LEO) cannot be quantified with a satisfactory degree of accuracy. In this paper, the Global Ionosphere Thermosphere Model (GITM) developed at the University of Michigan has been validated in order to provide detailed simulations of the thermosphere. First, a sensitivity analysis has been performed to investigate the effect of the boundary conditions on the final simulations results. Then, results of simulations have been compared with flight measurements from the CHallenging Minisatellite Payload (CHAMP) and Gravity Recovery and Climate Experiment (GRACE) satellites and with existing semi-empirical atmospheric models (IRI and MSIS). The comparison shows a linear dependency of the neutral density values with respect to the solar activity. In particular, GITM shows an over-predicting or under-predicting behaviour under high or low solar activity respectively. The reasons for such behaviour can be attributed to a wrong implementation of the chemical processes or the gas transport properties in the model. [less ▲]

Status of the QB50 cubesat constellation mission

in Proceedings of the International Astronautical Congress, IAC (2014)

Cubesats have emerged as powerful tools for a new class of space missions that is recognized by academia and the space industry. They have served many objectives but are mainly used to educate young space ... [more ▼]

Cubesats have emerged as powerful tools for a new class of space missions that is recognized by academia and the space industry. They have served many objectives but are mainly used to educate young space engineers through hands-on design and manufacturing experience. The QB50 project aims to use the cubesat concept to further facilitate access to space for future generations, to carry out unprecedented science, to demonstrate new space technologies, and train young engineers. To this end, the Project, coordinated by the von Karman Institute for Fluid Dynamics in Belgium, has invited universities from all over the world to submit proposals for cubesats to be embarked on the mission. The QB50 Consortium is managing the mission. In particular, it is developing the deployment system and the common sensors that will be placed on all scientific satellites, and procures the launch service. In addition, it provides a number of key technologies and services such as an attitude control system and satellite control software for the teams participating in the project. This article introduces the project, describes the technologies develope, the management approach taken and summarizes the current status. [less ▲]

Aerothermal Assment of the Expert Flap in the Scirocco Wind

in Proceedings of the 7th European Symposium on Aerothermodynamics for Space Vehicles (ESA SP-692) (2011)

EXPERT: The ESA Experimental Re-entry Test-bed

Scientific Conference (2010)

Review of surface properties of thermal protection materials for the design of IXV thermal protection system

in Proceedings of the 6th European Symposium on Aerothermodynamics for Space Vehicles (2009)

In the framework of the creation of an aerothermodynamic database for the design the Intermediate Experimental Vehicle, surface properties of heat shield materials that represent the boundary conditions ... [more ▼]

In the framework of the creation of an aerothermodynamic database for the design the Intermediate Experimental Vehicle, surface properties of heat shield materials that represent the boundary conditions are reviewed. Catalytic and radiative characteristics available in the literature are critically analyzed and summarized. It turns out that large uncertainties on the parameters exist. Finally, simple and conservative values are proposed. [less ▲]

EXPERT- The ESA Experimental Re-Entry Vehicle: Overview of the Experiments and Payloads qualified and accepted for the flight

in Proceedings of the International Astronautical Congress, IAC (2009)

Design of a Catalysis In-Flight Experiment

in Proceedings of the 46 th AIAA Aerospace Sciences Meeting and Exhibit (2008)

Aspects of Advanced Catalysis Modelling for Hypersonic Flows

in Proceedings of the 2008 CTR Summer Program (2008)

A multiscale approach for building a mechanism based catalysis model for high enthalpy CO2 flow

in Collection of Technical Papers - 39th AIAA Thermophysics Conference (2007)

The principles of the gas-surface-interaction taking place in the chemically reacting flow around an atmospheric re-entry vehicle are investigated. It turns out that the currently very often used approach ... [more ▼]

The principles of the gas-surface-interaction taking place in the chemically reacting flow around an atmospheric re-entry vehicle are investigated. It turns out that the currently very often used approach employing a recombination coefficient has a limited applicability. Serious concerns arise when the interaction model is extrapolated from ground to flight tests. A mechanism based approach taking into account every interaction step is therefore proposed for the carbon dioxide interaction with platinum. The necessary reaction rates are determined using a microscopic model, which are then used in a continuum viscous flow simulation. The dependence of the catalysis on the outer flow conditions and also on the wall temperature is demonstrated. [less ▲]

Sensitivity analysis of the local heat transfer simulation for the application to thermal protection systems

in Collection of Technical Papers - 9th AIAA/ASME Joint Thermophysics and Heat Transfer Conference Proceedings (2006)

A methodology that determines chemical surface properties is presented. It has been developed by Russian scientists in order to test Thermal Protection Systems for re-entering vehicles. It is based on ... [more ▼]

A methodology that determines chemical surface properties is presented. It has been developed by Russian scientists in order to test Thermal Protection Systems for re-entering vehicles. It is based on experimental measurements and numerical simulations. Its reliability has been investigated and it was found that the source of the largest uncertainty is the heat flux measurement compared with the error that comes from the other measurements and modeling constraints. [less ▲]