MISTRAL (AIR-LAUNCHEABLE MICRO-SATELLITE WITH REENTRY CAPABILITY) A small spacecraft to carry out several missions in LEO

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1 IAC-13,A2,3,4,x18907 MISTRAL (AIR-LAUNCHEABLE MICRO-SATELLITE WITH REENTRY CAPABILITY) A small spacecraft to carry out several missions in LEO Dr. Raimondo Fortezza Telespazio, Italy, raimondo.fortezza@telespazio.com Prof. Raffaele Savino 1, Dr. Gennaro Russo 2 1 University of Naples Federico II, Dept. of Industrial Engineering, Naples, rasavino@unina.it 2 Aerospace District of Campania Region DAC, Innovation & Technology, Naples, rino_russo@katamail.com The program called MISTRAL (Air-launcheable Micro-Satellite with Reentry Capability), conceived in the context of the new founded Aerospace District of Campania Region DAC, is here presented. The primary objective of the MISTRAL project is to develop a kg class spacecraft provided with a deployable flexible aero-brake able to return it to Earth in the recovery area. The spacecraft is equipped with a payload compartment able to accommodate a variety of instrument to allow the project to satisfy a large number of missions ranging from Radiation measurement to Exobiology to Atmospheric mapping to Earth observation. The payload should be the order or 3 Kg and will be located into a pressurized canister able to ensure the ambient temperature and 1 bar pressure to allow also the return of Life Science samples The Spacecraft does not have any propulsion system and therefore its operation could be considered extremely safe, opening the possibility to be used onboard ISS as Space Mail for the return of sample to Earth. The control of the Satellite along its orbit is achieved with the modulation of the opening of the shield. An onboard orbital propagator software together with a GPS providing the real-time position of the spacecraft, are linked to the GNC to implement the autonomous control law for the orbital change needed for the satellite to enter into the final re-entry trajectory in the requested position. The aero-brake system is also used as reentry shield to protect the satellite from the heavy thermal load. The paper presents the concept of the spacecraft and its specific ground segment requested to track the satellite and to monitor & control its descend phase. The project plan and the programmatic aspects are also illustrated together with the main components, their characteristics and key technologies associated. I. INTRODUCTION MISTRAL fits into the broader range of space reentry systems for recovery and return on Earth of samples and others materials from space that may become of great importance in the future. In fact, with the recent end of the NASA Space Transportation System program (Space Shuttle), this activity depends nowadays only on the Russian Soyuz TMA and on the new Dragon capsules, thus putting limits and economic constraints to the development of space activities. In this scenario the development of a low cost, easy to use, small capsule could demonstrate to be a convenient alternative to perform different types of scientific and technological missions. In addition it is important to say that once the concept is demonstrated the spacecraft could be easily scaled up to carry large and heavy payload.. The primary objective of the MISTRAL project is to develop a multi-purpose air-launchable 30 kg class micro-platform with re-entry capability. This approach decouples the use of the platform from the availability and intrinsic limitations of any ground launch base, providing to the system high flexibility with respect to a specific mission and guaranteeing short time to use. As an R&D project, MISTRAL will develop a full prototype ready to execute a demonstration mission in which the payload will be essentially focused on monitoring and eventually managing the functional and health status of the capsule during its first flight. The design choices stem from economic and practical reasons given the need and opportunity to develop in the medium term a reliable system with cost levels capable of enabling wide applicability. The project aims to develop research and experimental development to reach the prototype demonstration phase for a small space re-entry capsule, able to return limited mass and volume payloads back to Earth from Low Earth Orbit. The main characteristic of the capsule is a deployable front structure that will be used as both an aerobraking device to slow down the capsule and produce the orbit decay, and a heat shield during the most demanding re-entry phase. During the orbital phase, the deployable structure will be used to control the duration of the orbital decay phase in order to assure the right approach to the defined aerocapture point, where the re-entry phase starts. The deployable "umbrella-like" structure can also be integrated with other functional elements, such as solar panels, antennas, payloads, etc. IAC-13,A2,3,4,x18907 Page 1 of 11

2 Aero-braking and aero-capture, and aero-maneuvers (aero-assisted orbital transfer) in general have been considered as a way to reduce the need of propulsion technologies by NASA in their roadmaps [1,2]. Thermal and structural limitations have hindered their use in scientific missions in the absence of dedicated protective shields. Deployable shields can provide an effective mean of performing such maneuvers in a shorter time, with a lower risk and with larger mass gains avoiding any propulsive boost. Magellan and various Mars missions have used or planned mild aerobraking, in spite of the absence of a shield. For Magellan, the solar panel temperature needed to be kept below 100 degrees C at the cost of a 70 day-long aerobraking maneuver [1]. Along the same idea, for Clean Space applications, a light decelerator, deployed at high altitude, can reduce the lifetime of spacecraft s in orbit and allow their more rapid disposal. The technology can be offered as a low mass kit, adaptable to a number of configurations, and should compare favorably with propulsive maneuvers. There are several missions planned. The standard one could be the sample return from ISS and it could be deployed though the existing satellite jettison device installed on the JEM external platform. The Small spacecraft will be transported into the ISS, it will be loaded with the sample to be returned to earth and will be loaded into the jettison device passing though the onboard airlock. Other mission could be as a stand alone spacecraft launched in a Low Earth Orbit mission and equipped with a small autonomous payload able to exploit the capability to return back to earth both the payload and the related samples. Typical research are that could need such as capabilities are, Life Science, Material Science and Exobiology Despite the domestic industry has in the past participated in activities aimed at developing re-entry spacecraft, also in the frame of European programs, so far a capsule with similar characteristics has been neither in Italy nor in Europe designed. The project will be developed in the frame of the Campania Region Aerospace District (DAC), by a cluster including large industries, Small and Medium Enterprises - SMEs, research organizations and universities with the aim of acquiring the necessary know-how to plan the industrialization phase of the product, qualified and suitable for different commercial applications II. MISTRAL MAIN OBJECTIVES As said, the MISTRAL project has the goal to develop a prototype of an innovative platform for missions in LEO orbit with a capacity of recovery and re-entry into the atmosphere. It is characterized by a highly innovative structure deployable in space. In the initial stages of the project the air launch problem will be studied, taking into reference all the configuration assumptions already made during study of possible air launched missiles carried out in Italy, as part of other industrial projects. The ultimate goal is to identify the geometrical and loads requirements the micro -satellite must meet in order to be launched by the future aerial platform. The studies taken into consideration are based on a missile class 4 tons, launched by heavy fighter with a launch capability of kg in LEO. A critical part of the project will be the deployment system of umbrella-type aero-brake able to perform the function of deorbiting and thermal protection of the payload during reentry; it shall be compatible with other functional elements, such as solar cells, antennas and sensors for navigation. The system shall use classical mechanical systems for opening and closing the umbrella structure (by using electric and/or mechanical energy). The MISTRAL project is expected to develop a proto-flight model of the satellite (even though for critical element is expected also the manufacturing of a qualification model), as well as the EGSE and MGSE required for testing and qualification processes. The ground segment will also be fully developed and all the necessary systems prepared. The flight model will therefore be ready for launch by using one of the flight opportunities offered by commercial launchers whose analysis and selection is also part of the study. It is in fact expected that the first experimental launch will make use of standard launcher, probably ad piggy-bag payload, because even though tailored for air launcher such a vehicle will not be available in due time. At the end of the research/industrial team will have models, methodologies, collaborative design infrastructure, ability to design and manufacture satellite platforms and systems re-entry from space, software for virtual testing, state of the art simulation methods. in the MISTRAL Program design methodologies will be developed to manufacture, after the conclusion of the program, systems of the same type but also with different mission and system requirements, dictated by other possible applications. The launch and operational phases of the demonstrator are outside the scope of this MISTRAL Project. III. REENTRY VEHICLE - STATE OF ART Up to now, at national level, several studies have been conducted on reentry vehicles (e.g. CARINA), but none has proceeded to the stage of development. Currently, the only relevant national program is the USV (Unmanned Space Vehicle) developed by CIRA (Italian Aerospace Research Centre) which aims primarily to the realization of space platforms for the flight testing of the technologies to be used for future IAC-13,A2,3,4,x18907 Page 2 of 11

3 systems space transportation systems; therefore it should be considered of large complexity and long development time. Considering it as a complete reentry system, it is very different from a capsule and it was designed primarily as a "laboratory" for technology and science development, more than as an industrial product itself. One of the first small reentry spacecraft aimed to be used to recovery small payload from Space Station without using propulsion system and based on an inflatable structure was analyzed in the PhD Thesis of one of the author. It was based on a tethered platform used to de-orbit the spacecraft from its initial ISS orbit [3,4]. deployment can be done either by means of pneumatic systems and inflatable structures (IRVE and IRDT) or by mechanical means "umbrella like" (BREM-SAT). IRVE consists of a cylindrical structure containing the electronics, the inflation system and the inflatable shield. The diameter of the shield once deployed is 3m and the vehicle height is about 1.6m. Fig. 2: Inflatable Reentry Demonstrator Technology (IRDT) [7] Fig. 3: BREM-SAT 2 with Folded Parashield [8] Fig. 1: IRVE System [6] Structures with variable configuration capable of addressing the critical stage of an atmospheric re-entry have been studied and in some cases successfully tested in U.S. (Parashield [5] and IRVE, see Fig. 1 [6]), Europe (ESA IRDT [7] and BREM-SAT, see Figs. 2-3 [8]) and Japan (Flare-type Membrane Aeroshell for Atmospheric Entry Vehicle, see Fig. 4, [9]). The change in configuration is achieved through the deployment of heat shield in the early stages of reentry. The Fig. 4: Flare-type Membrane Aeroshell for Atmospheric Entry Vehicle Although setting very different in size and characteristics of the system, it should be noted the Reentry Demonstrator QubeSat that Von Karman Institute (VKI) is developing with European funds in the frame of QB50 project (Fig. 5 [10]). IAC-13,A2,3,4,x18907 Page 3 of 11

4 (a) (b) Fig. 5: Reentry Demonstrator QubeSat [10] a) system with heat shield, b) during reentry Cubesats are increasingly popular, and numerous studies have been performed on the use of deployable shields on these micro satellites. This may offer the opportunity of a low cost entry vehicle, allowing recurrent flights, for technology development. Examples of deployable aerobraking reentry systems for Cubesat recovery have been recently proposed in [11, 12]. At the national level, a group of SMEs of Campania region has recently studied the capsule concept IRENE (Fig. 6), under ASI funding [13]. The heat shield is based on a deployable "umbrella" structure concept. Even though the concept is similar to MISTRAL project, IRENE was based on a much larger spacecraft (150 kg) equipped with propulsion system able to inject the capsule on a reentry trajectory during the final phase of the mission. MISTRAL is based on a consistent heritage starting from the old CARINA project (Fig. 7) developed in the 90 by Alenia-Napoli [14, 15] up to the flight of the capsule SHARK (Fig. 8) that carried out in March 2010 a return suborbital experiment reaching Mach 10 after being jettisoned from the sounding rocket MAXUS-8 of ESA [16, 17]. a) closed configuration b) shield deployed Fig. 6: Drawings of Reentry Capsule IRENE [13] Fig. 7: Capsule CARINA [14, 15] Fig. 8: Capsule SHARK [16, 17] IV. MISTRAL PROJECT DESCRIPTION IV.I Flight Segment The MISTRAL project plans to develop a microplatform multi-use space, equipped with a small re-entry capsule, able to adapt to a wide panorama of use. It falls within the framework of the role that Italy has long been pursuing the atmospheric re-entry. Already involved in the ESA project ARD, over 10 years ago, Italy today has a strong leadership role for the involvement in all reentry projects; the most significant, as mentioned, are the USV EXPERT programs and ESA IXV today in progress. More specifically, MISTRAL is placed even closer to the development of re-entry capsules, the capsule CARINA designed around the 90s, the capsule SHARK designed and developed by CIRA and more recently the capsule IRENE conceived precisely in Campania by a consortium of SME now also involved in MISTRAL.. In the design stage, considering the large number of companies involved in the district, and the broad spectrum of requirements that the platform shall meet, we will develop a system of collaborative concurrent design facility used for the design and development phases. The platform will be characterized by a small mass, class kg, which makes it suitable to the use of a system of aviation-launch. This approach releases the platform on the availability and limitations of a fixed launch base and makes it much more flexible in the mission and suitable for rapid use. These characteristics may also protect an interest in areas not IAC-13,A2,3,4,x18907 Page 4 of 11

5 directly related to space exploration and scientific use, such as civil protection, where earlier satellite services used were generic type and not based on specific orbits dedicated to the purpose. In addition, the platform will be equipped with electronic bus multifunctional characterized by a capacity to elaborate the orbital control, thanks to the considerable computing power available obtained, despite the small size, with the adoption of latest generation processors. The heat dissipation of electronic components could require the development of thermal control systems based on advanced heat-pipe biphasic. For future missions that require additional electrical power on board the design shall include the installation of additional deployable flexible solar panels in orbit. For the type of mission analyzed here, will have to research and develop strategies for unconventional guidance, navigation and control. The solution adopted uses onboard orbital propagators and algorithms for guidance, navigation and control using the predictor-corrector approach able to reprocess independently predictive models based on real-time measurements of the dynamics of the platform, GPS data, and measures of predictions of the aerodynamic resistance in the remaining phase of the trajectory, by properly selecting the output control with non-linear effects. Extensive research activities will be performed on possible sphere-cone configurations for the TPS in order to characterize the different solutions from an aerodynamic point of view. Preliminary analyses involve both the evaluation of thermal and aerodynamic loads and the assessment of the capsules longitudinal stability [18-20]. The aero-thermo-dynamic analyses are performed in transitional and continuum regimes, while the longitudinal stability is analyzed in free molecular, transitional and continuum regimes, also taking into consideration the heat shield deployment sequence at high altitudes. The geometry under study and the related opening scheme are illustrated in Figure 9, 10 and 11. Examples of preliminary calculations made on these geometries are illustrated in Figures 12, 13 and 14. When the flow field around the capsule is rarefied or in free molecular flow, the Direct Simulation Monte Carlo (DSMC) method is the only possible tool for the solution of the aerodynamic and aero-thermo-dynamic problems. Due to the limited communication capacity of the microsatellite, on-board electronics, through the knowledge of the orbital parameters of the satellite's position and that of the landing site, will be required to independently control system deorbiting to get to the target or to the set point of atmospheric entry interface (return). From this point the re-entry module will continue its controlled descent through the modulation of aerodynamic resistance with a low ballistic coefficient, which will allow the descent through the atmosphere with moderate total heat flux values, which may be managed by using materials resistant to high temperatures of a commercial nature. The capsule consists of a cylindrical structure containing all the subsystems necessary for the on-orbit mission and for the re-entry phase, umbrella-like frameworks, off-the-shelf ceramic fabrics for the conical deployable heat shield and available ceramic materials (e.g. silica, alumina or zirconia) for the rigid hemispherical nose. The necessary subsystems will Fig. 9: characteristics of the capsule configurations (dimensions are mm):(a) TPS-45 and (b)tps-60. Fig. 10. Sketch of the deployment process for TPS- 45: (a) Step1, φ=7.50 ; (b) Step2, φ=18.5 ; (c) Step3, φ=35.0 ; and (d) Step4, φ=45.0 [20]. include parachute, beacon, OBDH, AOCS, IMU, GPS receiver, batteries and sensors. A total re-entry mass of 15 kg has been assumed as first attempt. As discussed before, half-cone angles (φ) of 45 and 60 are considered for the TPS. The radius of curvature of the nose for each of the two configurations is such that the conical umbrella is tangent to the nose-cap when the deployment process is complete. Fig. 9 shows the geometrical configurations under investigation. When the TPS is completely deployed the base diameter of the two configurations is 1.08 m, while the cylindrical IAC-13,A2,3,4,x18907 Page 5 of 11

6 structure has a diameter of 30 cm and a total length of 60cm. Figs. 2 and 3 show the configurations of TPS-45 and TPS-60 at three stages during the opening phase up to the final configurations. The structure will be characterized by the use of new ultra-light alloys and "health monitoring" thanks to sensors placed inside the sensitive structures like the deployable umbrella. Such applications are also key elements of other concurrent programs in the DAC in the aviation sector. The flexible solar panels are such as their natural application in the next generation of electric aircraft as manned and unmanned vehicles (UAVs). The attitude control will be assured by the development of micro-actuators and sensors products within the DAC or with COTS components ITAR-free. The modular approach will allow to equip the platform on future missions with different electro-optical sensors and multispectral visible as rooms, and also SAR and LIDAR systems, magnetometers, radiometers, interferometers and can meet a wide panorama of use, however, compatible with the limitations of volume, mass and power typical of this category of satellites. Fig. 11. Sketch of the deployment process for TPS-60: (a) Step1, φ=16.0 ; (b) Step2, φ=36.0 ; (c) Step3, φ=50.0 ; and (d) Step4, φ=60.0 [20] (a) (a) (b) Fig.12: Bridging functions for the capsules drag coefficient profiles, as functions of the free stream Knudsen number (a). Examples of computed temperature distributions (b). The aeroshell is a sphere cones with half angles of 45 [20] (b) Fig. 13: Longitudinal moment coefficient (CMz) profiles of the reentry capsule as functions of the angle of attack (α) at different deployment steps in nominal (a) and reverse (b) attitudes. The altitude is 150 km [20] The micro-platform will be equipped with a telemetry system in band-s (or L or X) for control of the bus and receiving the telemetry of the payload. The microsatellite with recovery capabilities will consist essentially of a service module and a module to return; IAC-13,A2,3,4,x18907 Page 6 of 11

7 the first to contain the on board computer (OBDH) and all major subsystems, namely power, thermal control, guidance and navigation, determination and attitude and orbit control, telecommunications, etc. The second module will consist of all the mechanisms and actuators capable of deploying the flexible surface, which is necessary to perform the mission of deorbiting and at the same time to protect the module from aerodynamic heating during atmospheric re-entry. Inside the module will present the payload and subsystems for landing and recovery (eg parachutes, flotation systems, radiolocalization systems). A typical sketch showing the concept of the microsatellite in the two configurations, the launch and in orbit after the deployment of flexible heat shield, is shown in Fig. 11. Figures 15 shows the predictions of the satellite orbital decay from an initial altitude of 270 km [19]. The results shown in Figure 15(a) are obtained implementing two different models: the direct solution of the dynamic equations of motion and the reduction in orbital period due to atmospheric drag. In both cases calculations have been carried out for an Average Solar Activity. The results agreement appears satisfactory. It is possible to see that for a relatively light satellite the aerobrake is very efficient and the total reentry duration is about 30 hours. because most of the deceleration occurs at higher altitudes (i.e. in the most rarefied part of the atmosphere). On the other hand, the satellite bus with larger ballistic coefficient would re-enter the atmosphere with a steep trajectory to be destroyed by the relatively high aerothermal and mechanical loads [19]. The ballistic coefficients of the capsule with deployed heat shield and of the bus, in Figure 16, are 5 and 240 Kg/m 2, respectively. The existence of such a re-entry capsule offers the unique opportunity of "physical" recovery of scientific data that complements to the real-time capability offered by ground stations. To keep costs low and acceptable in spite of complexity of the system, the reentry capsule is provided with an "umbrella"-like airbrake the modulated opening of which can change the ballistic coefficient of the system and securing its return to the expected landing site. a) b) c) (a) d) e) Fig.14: Hypotesis of Configuration for the platform MISTRAL Figure 15 (b) shows how the modulation of the opening of the "Umbrella" shield permits the tracking of the descending trajectory from 270 to 180 km altitude orbit, neutralizing the effects of an increase of 2% of the solar radiative flux and a decrease in 10% of the air density compared to the corresponding nominal values [19]. Figure 16 shows the case in which the spacecraft is spit into two parts prior the reentry: the capsule and the bus. The relatively low ballistic parameter allows the capsule with large aerobraking to re-enter in a longer time, gradually dissipating its initial kinetic energy, (b) Fig. 15: Satellite orbital decay (considering the umbrella-like heat shield deployed) for an average solar activity (a). Effect of modulation of the opening of the "Umbrella" on tracking the trajectory of descent orbital (b) [19] The dissemination of real-time data to the control center and end users through networking of land will be improved and facilitated during the mission. The nature and complexity of the mission in fact require multidisciplinary expertise distributed network that will be used for the effective control of the platform in all IAC-13,A2,3,4,x18907 Page 7 of 11

8 phases of the mission. The same board transponders will be used in the critical phase of the last connection before deorbiting and used to receive commands specific to the platform to inject the capsule into the path of return. In addition to traditional telemetry system, it will need to attach additional low data rate with a large number of ground stations to ensure monitoring during the critical phase of aero-braking and the insertion of the capsule in the hallway of the nominal return, where finally some subsystems that include satellite links and tracking beacon will ensure and coordinate the recovery of the capsule. The realization of a space system to return from LEO poses a series of design and technological challenges. It is, in fact, a very complex system to achieve that must integrate research and experimental developments in various disciplines, from system design, to aerodynamics and guidance, navigation and control. Fig.16: Effect of the aero-braking on final reentry leg and on aerodynamic heat flux [19] Among the issues that have particularly innovative contents this program will have to address the following points: systems for deployment of umbrella of limited dimensions requiring very low power and therefore with high complexity; methodologies of design and assembly of thermal protection systems based on flexible materials; specific elements for the connection of the heatshielding material with the structure; systems for the mechanical and electrical connection of flexible structures (e.g. solar panels and antennas); cooling system for electronics; simulation and evaluation of thermal and mechanical stress conditions in aero-thermodynamic variables. guidance systems, navigation and control innovative, involving a system deployable in a dynamic way during the flight deorbiting aerodynamic systems based on aero-braking systems for health monitoring and management IV.II Ground Segment The Ground Segment is the component of the MISTRAL project that realizes the functionality of the control center, reception center and High Rate Data Flight Dynamics System. The Satellite Control Centre (CCS) is the system that has the task of managing the satellite in terms of sending and receiving remote telemetry. It has the task of transforming into commands all the instructions laid down by the various centers of the ground segment of the Mission, such as flight dynamics commands or commands related to the planning of activities on board, and to receive and manage all the telemetry satellite will send to the ground. The Satellite Control Centre for the mission MISTRAL arises in the context illustrated in Figure 17. Satellite telemetry generated is sent to the ground through two modes: low transfer rate and high transfer rate. The transmission to the ground via low rate is based on a network of micro-receiving stations capable of receiving a 'Space Twitter' telemetry, i.e. a short message TM encapsulated in an interface that allows the micro-station to sort the data pertaining to the CCS and CCS to log on twitter before inserting the data into the processing chain. The transfer High Rate is dedicated to download high rate telemetry generated on board and sampled for sending to earth. The link with the station at High Rate is also dedicated to the commanding of the satellite. V. POSSIBLE MISSIONS & APPLICATION MISTRAL Spacecraft could satisfy a large variety of missions compatible with a low earth orbit; the analysis of the possible mission represent a specific task of the program however a preliminary not exhaustive list is here presented: Return of payloads from the ISS: MISTRAL could offer frequent services, regular and low cost for the recovery of small payloads (mass of the order of a few kilograms and volume of the order of a few liters) from IAC-13,A2,3,4,x18907 Page 8 of 11

9 Fig. 17- MISTRAL Satellite Ground Segment the International Space Station (ISS). The standard utilization could be sample return from ISS, using existing satellite jettison devices available in the JAXA experimental module (JEM Small Satellite orbital Deployer, JSSOD). The s mall MISTRAL spacecraft (volume in the order of 30x30x40cm and kg mass) will be transported into the ISS with the HTV, the ATV or the Dragon; it will be loaded with the sample to be returned to earth, installed in J-SSOD by crewmembers and passed with a Multi-Purpose Experiment Platform through the JEM airlock for retrieval by a small arm that supports capture, orientation and deployment operations. This kind of missions poses stringent requirements in terms of safety, for which the most interesting scenario provides, for example, the storage of small payloads thermoregulated, the expulsion of the micro-platform from the ISS through an airlock, a long phase of controlled deorbiting based only on aerodynamic forces and then the aero-capture phase in the denser layers of the atmosphere, the return phase and the final recovery. In this case the departure trajectory is that of ISS ( Km) and the goal is to return the sample to the ground in the shortest possible time and the achievement of the recovery point to the ground. Robotic missions allowing the recovery of a payload from the space station for example, have been studied in the frame of ESA s PARES program [21] with a deployable concept different from MISTRAL, and demonstrated to bring significant benefits. Scientific Space missions: for example it could be possible to take small payloads aimed at studying the effects of microgravity environment where it is needed to recover the samples such as those in the fields of physical and life sciences (exobiology, life science, human physiology, biotechnology, materials, etc..). It is also possible to meet requirements coming from research in the field of analysis of solar and cosmic radiation through the development of specific telescopes operating in the corresponding wavelengths (silicon detectors) coupled to passive systems for the evaluation of the total dose of which is required recovery for their development and analysis of results. Probe missions: in order to analyze the upper atmosphere at altitudes above 40 km, have been developed different families of sounding rockets, named to allow you to "sound out" the Earth's atmosphere. The limit of such platforms is linked to the fact that the analysis is limited to the atmosphere on the basis of vertical launch. The microsatellite Mistral would have the disadvantage to operate mainly on altitudes above 120 km, but the huge advantage of being able to acquire data over a very large area, even on a global scale in the case of a polar orbit. Obviously, the analysis would be carried through the sampling and analysis of the elements of the same through the development of specific payloads. Earth Observation Mission at very low altitudes ( ) km: it is possible to think to unconventional missions to minimize size, mass and cost of optical equipment, optimize the spatial resolution on the ground, bridging the gap between platforms (from UAV to balloons, generally operating between 10 and 50 km) and traditional satellites for Earth observation (generally in low orbits above 400 km). A possible scenario, in this case, could be a mission with one or more IAC-13,A2,3,4,x18907 Page 9 of 11

10 microsatellites in parking elliptical orbits, able to reach the selected target in the shortest possible time. The same system of aero-braking might be able to perform, once the mission is completed, an aerodynamic de-orbit maneuver, a controlled re-entry into the atmosphere and a soft landing / splash down to allow later retrieval of the data recorded on board. In this case we start from a parking orbit at an average altitude (600 km) and the mission based on two phases. The first is to reach the target (location, time of day), with the possibility of delaying the arrival in case of bad weather conditions. At that point the satellite starts its mission that could be the acquisition of a strip of the target zone. It should also be able to repeat the observation during successive orbits. Once the mission is completed, the spacecraft on its own would begin the return phase to the recovery point on the ground. Atmospheric Measurement Mapping: this could be the first mission of the demonstrator. The mission includes the departure from the mission in which the satellite is released by the launcher. The acceleration measurements correlated with the exposed surface (= position shield) allows you to scan the high atmosphere and to map the density of the atmosphere in the range by the inclination of the orbit from the initial one until at very low (taking into account that the stay in low altitudes, however, will be limited due to the rapid orbital decay there. Data acceleration on three axes (also to understand the behavior of the satellite of AOCS) could be acquired at a high data rate in order to understand the behavior of the satellite with high frequency in order to analyze also its vibration. On a 30- day mission by recording only the data set to 1 Hz (high-frequency data are erased once analyzed the frequency spectrum) is to acquire about 3x10e6 data set. The map data could be used to improve the system of satellite navigation in later missions. This is mission planned for the maiden flight of the demonstrator: Catch Debris Mission: The spacecraft should be placed on the orbital plane of the debris to be captured, at a higher altitude. The satellite would operate to chase the target debris and to reach its proximity. The payload in this case should contain: 1) an optical system to allow the search and identification of debris, 2) a very low trust propulsion system to allow the satellite to gently approach the target, and 3) a simple system of grasping to capture the debris. Once the debris is captured the satellite would activate the shield to take the right path to return in the chosen location for the destruction of debris. The satellite could possibly release the debris before entering the atmosphere to be recovered and potentially to be re-used. Martian Mission (futuristic). MISTRAL could be used in the future to transfer pieces of equipment on the Martian surface. The capsule should be released from a Martian orbiter and propelled through a phase entered along a long trajectory of return. Due to the completely different characteristic of the Martian atmosphere with respect the Earth one it is likely that will be requested changes in the dimensions of the shield and also changes in the part of landing, where the parachute (not very effective at relatively low speed in the low density atmosphere, should be replaced by retrorockets. In the case of sample return missions from asteroids or other planets instead, the Earth entry velocity, heat fluxes and structural loads increase dramatically, and the application of MISTRAL concept is not demonstrated yet. These types of applications require specific or dedicated studies. Future developments may aim at developing lifting or re-configurable deployable decelerators, that could be steered and allow accurate landing. This feature could present advantages for Mars landing, but also on Earth, for large maneuvers or even for collision avoidance. Finally, deployment of equipment such as antennas, flexible solar arrays, but also solar sails and closely related de-orbit sails have been studied at ESA, JAXA and NASA. Synergies with deployable decelerators are clear VI. CONCLUDING REMARKS The MISTRAL Program will be focused on innovative technologies for small space satellites, promoting developments and demonstrating new capabilities on small spacecraft for science, exploration and space operations. With a synergistic efforts between Small, Medium and Large Enterprises, Universities and Research Centers of the Aerospace District of Campania Region, scientific and engineering results and technological innovations will make it possible to fulfill unique mission and system requirements and challenging flight and ground segments. While the present project foresees the development of a full prototype of the micro-platform, ready to execute a demonstration mission based on its innovative deployable and modulating aerobraking system, the authors believe that extensive utilization of such kind of system may offer cheaper capabilities to the space community. For the maiden flight it is possible the spacecraft will use hitchhiker capabilities made available on existing classic launcher (Vega represent the first option), while the program shall wait same year to have the opportunity to use air-launcher (may be will be the same MISTRAL program to push for the development of this new launcher). The application of deployable aerobraking autonomous guidance and thermal protection systems for the atmospheric reentry of small satellites has not been proven yet, but no obvious showstoppers emerge today against its future implementation. The development of a dedicated distributed ground segment will create new opportunity to re-use it for future generation of micro-satellites as for instance the Cubesat family. IAC-13,A2,3,4,x18907 Page 10 of 11

11 AKNOWLEDGEMENTS The authors acknowledge the relevant contribution of the entire team set up to develop the project proposal submitted to the Campania Region Aerospace District (DAC). A special thank goes to the companies (Telespazio, Vitrociset), consortia (ALI, ANTARES, SAM), Universities (Univ. Naples Federico II, Second Univ. Naples, Univ. Parthenope) and Research Centres (CIRA, CNR, ENEA) that decided to co-fund the project. REFERENCES [1] Adler, M., Wright, M., Campbell, C. and I. Clark. DRAFT Entry, Descent, and Landing Road map Technology Area 09, NASA, DRAFT-Nov2010-A.pdf (2010) [2] D. J. Anderson, M. M. Munk, J. Dankanich, E. Pencil and L. Liou. Status and Mission Applicability of NASA's In-Space Propulsion Technology Project, IEEE Aerospace Conference, _ pdf (2011) [3] R. Fortezza. Tethered Space Mail: Definizione di una capsula di rientro di nuova concezione definition of a new concept of re-entry capsule. PhD Thesis, University of Naples (1989). [4] R. Monti, R. Fortezza. Tether Space Mail, 2nd Intern. Conference on Tethers in Space,Venezia (1987) [5] D. L. Akin. The Parashield Entry Vehicle Concept: Basic Theory and Flight Test Developments, 4 th Annual AIAA/Utah State University Conference on Small Satellites, Logan, UT, August (1990). [6] M.C. Lindell, S.J. Hughes, M. Dixon, C.E. Wiley. Structural Analysis and Testing of the Inflatable Re-entry Vehicle Experiment (IRVE), 47th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference, Newport, RI, May 1-4 (2006), AIAA [7] D. Wilde, S. Walther. Inflatable Re-entry and Descent Technology (IRDT) - Further Developments, 2nd International Symposium of Atmospheric Re-entry Vehicles and Systems, Arcachon, France (2001). [8] M. Wiegand, H.J. Königsmann. A Small Reentry Capsule BREMSAT 2, 10th AIAA/USU Small Satellite Conference, Logan, UT, September (1996) [9] K. Yamada, T. Abe, K. Suzuki, D. Akita, O. Imamura, Y. Nagata, N. Honma. Reentry Demonstration of deployable and flexible aeroshell for future atmospheric entry vehicle using sounding rockets, 64 th International Astronautical Conference, Naples (Italy) 1-5 October (2012) [10] J. Muylaert et al. QB50: An International Network of 50 CubeSats for Multi-Point, In-Situ Measurements in the Lower Thermosphere and for Re- Entry Research, ESA Atmospheric Science Conference, Barcelona, Spain (2009) [11] J. Andrews, K. Watry, K. Brown. Nanosat Deorbit and Recovery System to Enable New Missions, 25th Annual AIAA/USU Conference on Small Satellites, August 8-11 (2011) [12] V. Carandente, G. Elia, R. Savino. Conceptual design of de-orbit and re-entry modules for standard CubeSats, 2nd IAA Conference on University Satellite Missions and Cubesat, Rome, February 4-7 (2013). [13] E. Bassano, R. Savino, R. Lo Forti, A. Ferrarotti, C. Richiello, G. Russo et al.. IRENE: Italian re-entry Nacelle for microgravity experiments, 62nd International Astronautical Congress, Cape Town (South Africa) (2011) [14] G. Borriello, A. Sansone, A. Ricciardi. CARINA: a space vehicle with re-entry capabilities for microgravity experiments. 43rd Intern. Astronautical Congress; Washington, Aug. 28-Sept. 5 (1992). [15] R. Fortezza, P. Dell'Aversana, G. Desiderio, A. Sansone. The retrievable capsule Carina. Analysis of the microgravity payload selection, 42nd Int. Astronautical Congress, Montreal, Canada, Oct (1991). [16] R. Gardi, A. Del Vecchio, G. Russo et al.. SHARK MAXUS 8 Experiment. A Technology Demonstrator for Re-entry Drop Capsule, 5th IAASS Conference "A Safer Space for a Safer World", Versailles (France) (2011) [17] R. Gardi, A. Del Vecchio, G. Russo. SHARK: Flight Results of an UHTC-based Nose related to USV Hot Structures, 7th European Aerothermodynamics Symposium, Bruge (Belgium) ESA SP-692, (2011) [18] R. Fortezza, R. Savino, G.Russo. A recordable Nano Satellite for Frequent and Low Cost Space Service, 64 th International Astronautical Congress, Beijing, September (2013) [19] R. Savino, V. Carandente, Aerothermodynamic and feasibility study of a deployable aerobraking reentry capsule, Fluid Dynamics and Material Processing 8(4) pp (2012). [20] V. Carandente, G. Zuppardi, R. Savino. Aerothermo-dynamic and stability analyses of a deployable re-entry capsule, accepted for publication on Acta Astronautica Volume 93, January 2014, pp [21] W. Fischer, P. Noeding, U. Trabandt, S. Voegt, T. Walloschek. TPS Concept of the PARES Re-entry Capsule, 5th European Workshop on Thermal Protection Systems and Hot Structures; May (2006) Edited by K. Fletcher. ESA SP-631. IAC-13,A2,3,4,x18907 Page 11 of 11