Alenia Spazio Research Articles

Lunar Astrobiology: A Review and Suggested Laboratory Equipment

In October of 2005, the European Space Agency (ESA) and Alcatel Alenia Spazio released a "call to academia for innovative concepts and technologies for lunar exploration." In recent years, interest in lunar exploration has increased in numerous space programs around the globe, and the purpose of our study, in response to the ESA call, was to draw on the expertise of researchers and university students to examine science questions and technologies that could support human astrobiology activity on the Moon. In this mini review, we discuss astrobiology science questions of importance for a human presence on the surface of the Moon and we provide a summary of key instrumentation requirements to support a lunar astrobiology laboratory.

EXPERT: An atmospheric re-entry test-bed

In recognition of the importance of an independent European access to the International Space Station (ISS) and in preparation for the future needs of exploration missions, ESA is conducting parallel activities to generate flight data using atmospheric re-entry test-beds and to identify vehicle design solutions for human and cargo transportation vehicles serving the ISS and beyond. The EXPERT (European eXPErimental Re-entry Test-bed) vehicle represents the major on-going development in the first class of activities. Its results may also benefit in due time scientific missions to planets with an atmosphere and future reusable launcher programmes. The objective of EXPERT is to provide a test-bed for the validation of aerothermodynamics models, codes and ground test facilities in a representative flight environment, to improve the understanding of issues related to analysis, testing and extrapolation to flight. The vehicle will be launched on a sub-orbital trajectory using a Volna missile. The EXPERT concept is based on a symmetrical re-entry capsule whose shape is composed of simple geometrical elements. The suborbital trajectory will reach 120 km altitude and a re-entry velocity of 5–6 km / s . The dimensions of the capsule are 1.6 m high and 1.3 m diameter; the overall mass is in the range of 250–350 kg , depending upon the mission parameters and the payload/instrumentation complement. A consistent number of scientific experiments are foreseen on-board, from innovative air data system to shock wave/boundary layer interaction, from sharp hot structures characterisation to natural and induced regime transition. Currently the project is approaching completion of the phase B, with Alenia Spazio leading the industrial team and CIRA coordinating the scientific payload development under ESA contract.

A novel simulation model for ring type ultrasonic motor

In this paper, a novel mathematical model for a traveling wave ultrasonic motor, developed by Alenia Spazio, now Alcatel Alenia Space Italia S.p.A. (Roma, Italy), within an Italian Space Agency (ASI) program, is described. The dynamic equations for the stator and the rotors of the ultrasonic motor are assembled into a differential system, whose equations are coupled by terms which represent interface generalized forces. Neglecting transient conditions, the complete mathematic model of the system is solved and an iterative process is developed, in order to obtain the motor’s running curves for different operation parameters, geometric dimensions and physical features of the system. The algorithm is implemented in Matlab\({^{\circledR}}\) environment and a graphical user interface is constructed for user-friendly managing. The model, also validated by means of experimental tests, can be used for parametric analyses with respect to different parameters, in order to optimize motor’s configuration. It represents a simple but powerful aid to determine final motor design that can satisfy specifications or to predict motor’s behavior under different working conditions.

National Workshop on Astrobiology: The Life Science Involvement of AAS–I Laben

The search for traces of past and present life is a complex and multidisciplinary research activity involving several scientific heritages and a specific industrial ability for planetary exploration. Laben was established in 1958 to design and manufacture electronic instruments for research in nuclear physics. In the mid 2004 the company was merged with Alenia Spazio. It is now part of Alcatel Alenia Space, a French Italian joint venture. Alcatel Alenia Space Italia SpA is a Finmeccanica Company. Currently the plant of Vimodrone provides a wide heritage in life science oriented to space application. The experience in Space Life Science is consolidated in the following research areas: (1) Physiology: Mouse models related to studies on human physiology Human neuroscience research and dosimetry (2) Animal Adaptation and Behaviour: mice behaviour related to stabling stress (3) Developmental Biology: aquatic microorganisms cultivation (4) Cell culture & Biotechnology: Protein crystal growth General purpose Multiwell Next Biotechnology studies and development: Bio reactor, mainly oriented to tissue engineering Microsensor for tissue control (organ replacement) Multiwell for adherent cell culture or for automated biosensor based on cell culture Experiment Container for organic systems Experiment Container for small animals Instrumentation based on fluorescent Biosensors Sensors for Life science experiments for Biopan capsule and Space Vehicle Ray Shielding Materials Random Positioning Machine specialisation (Support ground equipment) The biological features of this heritage is at disposal for the exobiology multi science. The involvement of industries, from the beginning of the exobiology projects, allows a cost effective technologies closed loop development between Research Centres, Principal Investigators and industry.

Selecting enhanced space debris shields for manned spacecraft

A research program was funded by the European space agency (ESA) to improve and optimize the shields used to protect the manned elements of the international space station (ISS) against impacts of micro-meteoroids and orbital debris. After a review of existing shielding systems and after a series of light gas gun (LGG) experiments to screen interesting new materials and configurations, the research focused on shields with a metallic outer bumper, an intermediate stuffing and an inner metallic wall (representing the pressure shell of a manned spacecraft). Additional LGG experiments were performed on several configurations, with bumpers containing aluminum foam or made from titanium and aluminum super-alloys and with several combinations of stuffing materials. The comparison of the test results showed that ceramic cloth (Nextel) plus aramid fabric (both 2D and 2.5D Kevlar weaving) used as intermediate bumper gave a good protection compared to the overall area density requested. Configurations with by-layered aluminum foam bumpers (sandwich panels with asymmetric Al face sheets and a core made from Al foam) and Kevlar stuffing showed excellent resistance to normal impacts at about 6.5 km/s. However, the influence of material properties varying from batch to batch and threshold phenomena made ranking among the tested options rather difficult. The test campaign showed that it was rather difficult to improve over the already good ballistic performances of the debris shields developed by Alenia Spazio for the ISS manned elements. The by-layered Al-foam bumper and Kevlar stuffing configuration was selected for additional tests, including low velocity and oblique impacts, to develop ballistic limit curves.

Evaluation of the effect of preload force on resonance frequencies for a traveling wave ultrasonic motor

In this paper, a novel method of numerical computation of the natural frequencies, depending on the most important running parameters for an ultrasonic motor, is described. The analyzed configuration by the Space Division of Alenia Spazio, Rome, within an Italian Space Agency (ASI) development program, is the flexural traveling wave one. The dynamic equations for the stator and the rotors of the ultrasonic motor are assumed into a differential system, whose equations are coupled by terms that represent interface generalized forces. In order to calculate natural frequencies of the motor-coupled terms of the equations are worked out with respect to the variables of the degrees of freedom. Hence, the mass, damping, and stiffness matrix for the whole system are obtained, then resonance frequencies, depending on the most important running parameters such as axial preload of the motor, are calculated. The results are compared with numerical ones, obtained by a finite element modeling (FEM) model, showing a good agreement.

Monitoring and surveillance potentialities obtained by splitting the antenna of the COSMO-SkyMed SAR into multiple sub-apertures

The authors discuss the potentialities obtained by splitting the antenna of the COSMO-SkyMed synthetic aperture radar (SAR), developed by Alenia Spazio under contract to the Italian Space Agency and Italian Ministry of Defence, into multiple sub-apertures. The modified sensor has the capability to detect slowly moving ground targets that compete with the clutter Doppler spectrum. Special attention is devoted to a preliminary analysis of the signal processing techniques to be used. Moreover their capabilities for surveillance purposes are characterised based on theoretical and simulated results. Moreover the modified sensor is shown to allow sea current/wave monitoring by along-track SAR interferometry, relocation of moving targets in high resolution SAR images, and fully polarimetric imaging. Some practical implementation issues related to the possible modification are also briefly discussed.

An Integrated Medium Access Control and Traffic Management Architecture for DVB-RCS SkyplexNet Satellite Systems

The growing development of standard Internet services and the emerging exploitation of several broadband multimedia contents disclosing in the last years, significantly promoted scenarios where Satellite Networks can play key roles. Several satellite networks are currently implemented according to the Digital Video Broadcasting-Return Channel via Satellite (DVB-RCS) standard, assuming to operate with a transparent satellite and an hub-centric (star) network topology. The present work addresses the SkyplexNet (SKN) system: an advanced Broadband Satellite Network for meshed connectivity developed by Alenia Spazio, within the framework of ESA Artes 3 --- Line 1 Program, according to the DVB-RCS standard with duly extensions for the on-Board multiplexing capability of the Skyplex Units currently embarked on HotBird VI and W3A satellites. In this paper an architecture design study aiming at integrating the Medium Access Control (MAC) and Traffic Management (TM) functionality in a DVB-RCS like Network is presented. The envisaged Traffic Management schemes shall enable the SKN System to guarantee an adequate support of various Quality of Service (QoS) requirements and their application according to pre-defined Traffic Profiles established at connection set up phase with the support of physical medium access management functions. The functional architectures studied for the SKN Inter-Working Layer, from Internet protocols to SkyplexNet ones, and the SKN MAC layer have been also analysed on the interoperability level of these layers in order to deploy such functions as SKN connection mapping, packet scheduling and Bandwidth on Demand (BoD) policies. In this paper two different schemes of Traffic Management and MAC are presented reporting a detailed analysis of advantages and drawbacks of both approaches to be taken into account for future SkyplexNet system implementations.

An Intelligent Data Integration Approach for Collaborative Project Management in Virtual Enterprises

The increasing globalization and flexibility required by companies has generated new issues in the last decade related to the managing of large scale projects and to the cooperation of enterprises within geographically distributed networks. ICT support systems are required to help enterprises share information, guarantee data-consistency and establish synchronized and collaborative processes. In this paper we present a collaborative project management system that integrates data coming from aerospace industries with a main goal: to facilitate the activity of assembling, integration and the verification of a multi-enterprise project. The main achievement of the system from a data management perspective is to avoid inconsistencies generated by updates at the sources' level and minimizes data replications. The developed system is composed of a collaborative project management component supported by a web interface, a multi-agent data integration system, which supports information sharing and querying, and web-services that ensure the interoperability of the software components. The system was developed by the University of Modena and Reggio Emilia, Gruppo Formula S.p.A. and tested by Alenia Spazio S.p.A. within the EU WINK Project (Web-linked Integration of Network based Knowledge--IST-2000-28221).

ARTEMIS orbit raising inflight experience with ion propulsion

To demonstrate and promote North/South station keeping (inclination control) using ion propulsion, ESA on July 12, 2001 onboard Ariane 510 launched its most advanced telecommunication satellite: ARTEMIS. Due to a launcher failure the satellite was injected into a useless too low elliptic orbit. The ARTEMIS mission was salvaged by an Alenia Spazio / Astrium / ESA team at Telespazio (Fucino) using in novel modes to operate the on-board chemical and ion propulsion systems provided by Astrium. Using the chemical propulsion_ system provided by Astrium GmbH - Lampoldshausen - the inital orbit, having an apogee of half the targeted altitude. was quickly upgraded to a safe circular parking orbit at 31000 km altitude. The Liquid Apogee Engine was fired in total 8 times to achieve apogee as well as perigee raising. The final orbit raising to geostationary altitude is being performed by means of the ion propulsion system (IPP) applied in a newly designed spacecraft attitude control mode. Alenia Spazio and Astrium, in close cooperation, quickly redesigned all control and data handling software modules affected since the original spacecraft configuration was designed for inclination control only and not to generate thrust with the ion engines in a direction tangential to the orbit. The flexibility of the IPP system consisting of 4 thruster assemblies, provided in its totality by Astrium including the 2 alignment mechanisms for precision thrust direction control, had proven invaluable. To demonstrate the technologies available in Europe and to enhanced reliability, Astrium implemented two different technologies: a Kaufmann type system (EITA) provided by Astrium Ltd. - Portsmouth; and a Radiofrequency Ion Thruster Assembly (RITA) provided by Astrium GmbH - Ottobrunn. Two ion engines of different technology were mounted side by side on one ITAM (Ion Thruster Alignment Mechanism) provided by Austrian Aerospace. Artemis, after EURECA launched on 31 July 1992 and retrieved on 1 July 1993, is the second European satellite equipped with electric propulsion. This paper, after a brief description of the ion propulsion system and the results of the qualification life testing will summarize as well the special testing to support the orbit rising. The core part however will address the IPP performance on ARTEMIS in orbit during activation, inclination control and orbit raising operations. In a prominent chapter the 3-axis attitude control used during the orbit raising phase with the ion thrusters is described. In addition a principle maneuver strategy of the ARTEMIS Salvage Mission is shown.

Integral model for the description of the debris cloud structure and impact

The purpose of the present paper is to introduce a new integral model capable to describe the evolution of the debris clouds originated after normal-impacts of orbital debris over a Whipple shield. This work had been developed at Alenia Spazio in the context of a degree thesis. Several numerical SPH simulations of debris impacts on a Whipple shield configuration were performed to determine the ballistic limit and to compare it with semi-empirical damage equations. In the present paper, the numerical simulations were used to investigate the typical behaviour of experimental debris clouds ([6] and [9]) and to support the development of the integral model. With respect to previous papers ([1], [2], [3], [10]) in which a spherical shell-wise debris cloud was considered, here we try to introduce more realistic assumptions. We approximate the cloud's shape also introducing ejecta veil effects, which produce a multiplication of the deposited momentum upon the underneath wall. In the present model, the most peculiar hypothesis is a cinematic self-similar behaviour that is, whatever the shape is, the debris cloud evolves keeping unchanged its shape. Then, the material is opportunely distributed inside a volume and the choice of that distribution is described taking into account the results of the numerical simulations. Knowing the spatial material distribution and treating the cloud as a fluid, we can estimate the load time history and the drag-unitary force induced by the cloud impacting upon the rear wall. Of course, such a method uncouples the dynamic response of the rear wall from the evolution of the debris cloud. The balances of mass, momentum and energy allow three global and unknown parameters to be determined. The one-dimensional theory of impact ([10]) is used to take into account the conversion of part of the initial kinetic energy into internal thermal energy. No integration of differential equations is performed since complex propagation phenomena are taken into account through the effects they globally produce. The model still presents some free parameters related to the integral formulation. These parameters cannot be calculated through any balance condition, but they must be imposed to get a good, global reproduction of the debris cloud. The choice of these parameters is still the weak aspect of the method, and it depends on the consideration of the results obtained with more sophisticated tools, as, for instance, SPH simulations. The spatially defined load time history obtained with the debris cloud integral model can be used for further analysis on the back up plate.

Development of a parallel molecular dynamics code on SIMD computers: Algorithm for use of pair list criterion

In recent years several implementations of molecular dynamics (MD) codes have been reported on multiple instruction multiple data (MIMD) machines. However, very few implementations of MD codes on single instruction multiple data (SIMD) machines have been reported. The difficulty in using pair lists of nonbonded interactions is the major problem with MD codes for SIMD machines, such that, generally, the full connectivity computation has been used. We present an algorithm, the global cut-off algorithm (GCA), which permits the use of pair lists on SIMD machines. GCA is based on a probabilistic approach and requires the cut-off condition to be simultaneously verified on all nodes of the machine. The MD code used was taken from the GROMOS package; only the routines involved in the pair lists and in the computation of nonbonded interactions were rewritten for a parallel architecture. The remaining calculations were performed on the host computer. The algorithm has been tested on Quadrics computers for configurations of 32, 128, and 512 processors and for systems of 4000, 8000, 15,000, and 30,000 particles. Quadrics was developed by Istituto Nazionale di Fisica Nucleare (INFN) and marketed by Alenia Spazio. © 1998 John Wiley & Sons, Inc. J Comput Chem 19: 685–694, 1998

New Satellite Testing Strategy for Commercial Programs

The commercial space industry is required by current and future programs to be always more competitive in terms of cost and schedule. In this context it is mandatory to establish suitable testing approaches that can be a reasonable compromise among the conflicting needs of cost/schedule reduction, technical risk and test effectiveness. The participation of Alenia Spazio in the Globalstar program, having the responsibility of integrating and testing one qualification model and 56 flight models satellites in less than 2 years, with a production rate of four satellites per month, gave the opportunity to investigate suitable test strategies that can achieve such a goal. This paper will describe the various aspects analyzed by Alenia Spazio to identify some aspects and areas related to testing strategy for medium/small size class satellites. The first part of the paper will examine the importance of the “Concurrent Engineering” approach—in place of traditional project environment—aiming to involve test engineers in the satellite project cycle, besides design engineers, from the early program phase. Then the model philosophy and derived test programs will be discussed, outlining the difference between the “design verification oriented” test approach, for satellite qualification purposes and the “workmanship check oriented” test sequence conceived only for recurring flight models. Further discussions will deal with the “island production” approach applicable when a high production rate of satellites is required to deploy in orbit a constellation of small/medium size spacecrafts in short time.

A comparison between several satellite constellations for GNSS2

The paper describes the characteristics of new satellite constellations identified and studied by Alenia Spazio for future Global Navigation Satellite Systems (GNSS2) services. The optimization work makes use of advanced software tools, developed in house, based on iterative and exhaustive variations of the orbital parameters and using mission specific performance objectives as driving criteria. More in particular, the following methods have been used: 1. a) Walker method: to find constellations of satellites in circular orbits (LEO, ICO) 2. b) GRACE (Generalized Rules for Advanced Constellations Evaluation) method: to find constellations of satellites in High Elliptical Orbits (HEO). Two different service areas have been considered: 1. a) regional coverage: which can include all Europe+Africa, or America, or Asia+Australia 2. b) global coverage: which includes all the Earth surface. The driving criteria to compare the constellations are expressed in terms of availability, continuity, integrity and accuracy at system level.

STEP mission and system design

STEP (satellite test of the equivalence principle) is a candidate mission, in the discipline area of `fundamental physics', for the third medium-size project (M3) of ESA's long-term science programme `Horizon 2000'. A phase A study of the spacecraft and mission has been carried out by an industrial consortium led by Alenia Spazio, with Matra Marconi Space and Dornier Satellitensysteme as subcontractors. The concept that was studied was for an autonomous ESA mission with a payload provided by principal investigators. The model payload includes four equivalence principle accelerometers, a spin-coupling accelerometer and a gradiometer. A helium cryostat provides the required cryogenic temperatures for the payload. Spacecraft and warm payload equipment are accommodated on two platforms surrounding the cryostat. STEP will be launched with a Lockheed Martin LMLV-2 launch vehicle directly into its Sun-synchronous operational orbit at 400 km.

Mini pressurized logistics module (MPLM)

The MPLM Program was initiated through a Memorandum of Understanding (MOU) between the United States' National Aeronautics and Space Administration (NASA) and Italy's ASI, the Italian Space Agency, that was signed on 6 December 1991. The MPLM is a pressurized logistics module that will be used to transport supplies and materials (up to 20,000 lb), including user experiments, between Earth and International Space Station Alpha (ISSA) using the Shuttle, to support active and passive storage, and to provide a habitable environment for two people when docked to the Station. The Italian Space Agency has selected Alenia Spazio to develop MPLM modules that have always been considered a key element for the new International Space Station taking benefit from its design flexibility and consequent possible cost saving based on the maximum utilization of the Shuttle launch capability for any mission. In the frame of the very recent agreement between the U.S. and Russia for cooperation in space, that foresees the utilization of MIR 1 hardware, the Italian MPLM will remain an important element of the logistics system, being the only pressurized module designed for re-entry. Within the new scenario of anticipated Shuttle flights to MIR 1 during Space Station phase 1, MPLM remains a candidate for one or more missions to provide MIR 1 resupply capabilities and advanced ISSA hardware/procedures verification. Based on the concept of Flexible Carriers, Alenia Spazio is providing NASA with three MPLM flight units that can be configured according to the requirements of the Human-Tended Capability (HTC) and Permanent Human Capability (PHC) of the Space Station. Configurability will allow transportation of passive cargo only, or a combination of passive and cold cargo accommodated in R/F racks. Having developed and qualified the baseline configuration with respect to the worst enveloping condition, each unit could be easily configured to the passive or active version depending upon the ISSA logistics requirements and their optimized fulfillment.

Analysis and Control of Microvibrations on ARTEMIS Satellite

The need for a very high pointing accuracy and an extremely quiet on-board environment (micro-dynamic) has become an increasingly important issue in the most advanced space missions, such as the ARTEMIS telecommunication satellite. In the first part, this paper presents the activities carried out by Alenia Spazio (ALS) to analyze the effects of microvibrations on the satellite. In the second part, a feasibility study based on a smart structure is proposed to suppress the structural microvibrations. A numerical simulation of an intelligent structure based on piezo sensors and actuators connected in a closed-loop architecture with PD feedback is performed; the effects of feedback gain, sensor/actuators location and thicknesses are investigated to show the capability to reduce the dynamic environment transmitted to the satellite.

RA-2 radar altimeter: instrument operation concept and system performance

The European Space Agency (ESA) has awared a contract to DAIMLER-BENZ Aerospace, Dornier to fly on ENVISAT-1 mission the Radar Altimeter RA-2 developed by Alenia Spazio SpA. RA-2 is a nadir pointing pulse limited radar altimeter operating at two frequencies: 13.575 Ghz (Ku-band) and 3.2 Ghz (S-band). Its key feature is represented by a new on board signal processing algorithm (Model Free Tracker-MFT) able to autonomously detect, acquire, lock-on and track the earliest part of the radar echoes at Ku band from ocean, ice and land surfaces without interruption, irrespective of sudden changes in surface characteristics and elevation. The radar echo samples collected at Ku-band are processed by the MFT algorithm to adjust the radar resolution and receiver gain to values which allow the proper sampling of the earliest part of the radar echo. Four resolutions are available corresponding to the transmitted pulse bandwidth of 320, 80, 20 MHz and CW pulse. The radar echo samples at S-band are collected at fixed resolution corresponding to a transmitted pulse bandwidth of 160 Mhz. They are processed on ground to remove from the height measurement performed at Ku-band the bias error introduced by the propagation through the ionosphere. Point Target Responce (PTR) measurements are also collected at every transmission without interrupting the tracking to monitor the variation of the parameters which have been calibrated on ground. To assess validity of the design, a series of simulation runs over a variety of simulated test scenarios, representing typical operative conditions as tracking over mountains, ice regions, wet lands, have been performed.

Mini-pressurized logistics module for space station freedom

The Italian Government, acting through Agenzia Spaziale Italiana, has selected Alenia Spazio to develop a small logistics module, the Mini-Pressurized Logistics Module (MPLM). This module is to be the only carrier for pressurized cargo during the Man Tended Phase of Space Station Freedom. Once permanent manned capability is achieved, the MPLM will continue to be used to supplement the capability of the other Freedom logistics elements. This paper describes the development of MPLM requirements. Design implementation is discussed including the structure, the subsystems, the major trade studies and the operational strategy for use of the module. Unique aspects of the program such as the management structure, hardware commonality, accommodation of national priorities, verification and integration and support of the hardware are presented. Due to late authorization of this program, schedule has become a prime program driver. Methods to accommodate and meet these requirements are discussed. Boeing, the National Aeronautics and Space Administration Work Package One contractor, has been designated by Marshall Space Flight Center to serve as NASA's representative in providing requirements for MPLM design and oversight of its development and utilization. This unique management arrangement has been implemented and is working effectively.

A Re-Entry Capsule Control System Design for Microgravity Experiments

Abstract CARINA is a new retrievable unmanned capsule designed by ALENIA SPAZIO under ASI (Agenzia Spaziale Italiana) contract. This paper deals with the operative attitude acquisition phase and the operative phase of its life cycle. In the operative phase the control system must assure microgravity requirements. Two different type of actuators are used for the two different phases: 20N hydrazine thrusters for the first, magnetic coils and a reaction wheel for the second, and, consequently, two control systems techniques are used. The former is based on a new discrete time modeling of the system due to the PWM-like behaviour of the thrusters and results in a discrete controller able to guarantee robustness against parameter uncertainties. The latter is a scheduling technique based on a LOR approach and guarantees the fulfilling of microgravity requirements. All the simulations, performed on the ESA-MIDAS dynamics simulator, take into account atmospheric drag, solar pressure and gravity gradient disturbances, and show the effectiveness of the adopted approach.