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This paper explores the wide-ranging topography of micro-propulsion systems that have been flown in different small satellite missions. CubeSats, known for their compact size and affordability, have gained popularity in the realm of space exploration. However, their limited propulsion capabilities have often been a constraint in achieving certain mission objectives. In response to this challenge, space propulsion experts have developed a wide spectrum of miniaturized propulsion systems tailored to CubeSats, each offering distinct advantages. This literature review provides a comprehensive analysis of these micro-propulsion systems, categorizing them into distinct families based on their primary energy sources. The review provides informative graphs illustrating propulsion performance metrics, serving as beneficial resources for mission planners and satellite designers when selecting the most suitable propulsion system for a particular mission requirement. [ABSTRACT FROM AUTHOR]

• Triglyme with a Cu(II)-based additive is proposed as a low-toxicity hypergolic fuel. • Hypergolic ignition was experimentally investigated using ≥ 70 wt% H 2 O 2. • The ignition delay time of triglyme-based fuels was improved by blending with an ionic liquid. • Theoretical performance of the proposed propellant is comparable to MMH/NTO. Low-toxicity hypergolic propellants have been a demanding research area in recent years for space propulsion, with the aim of replacing conventional toxic propellants. Therefore, the current research was focused on the development of low-toxicity hypergolic propellants for safe, cost-effective, and sustainable space exploration. In this study, triglyme was selected as a fuel component for the low-toxicity hypergolic propellant. Hypergolic performance of various concentrations (3 to 13 wt%) of monocyanotrihydroborate tetrakis(imidazole) copper(II) cyanotrihydroborate additive (Cu-P1) in triglyme fuel was experimentally investigated with 70, 90 and 95 wt% hydrogen peroxide (H 2 O 2). The new fuels, 13Cu-TriG and 13Cu-TriGIL, containing 13 wt% of Cu-P1 in triglyme and triglyme:1-ethyl-3-methyl imidazolium cyanoborohydride ([EMIM][BH 3 CN]) blend, respectively, were investigated. The hypergolic performance and properties of triglyme were improved by using [EMIM][BH 3 CN]. For example, 13Cu-TriG was not ignited with 70 wt% H 2 O 2 ; however, 13Cu-TriGIL exhibited an IDT of 16.5 ms. Furthermore, 13Cu-TriG and 13Cu-TriGIL revealed an IDT of 18.7 and 8.0 ms, respectively, with 95 wt% H 2 O 2. The physicochemical properties, such as density, viscosity, decomposition temperature, and freezing/melting temperature, of 13Cu-TriG and 13Cu-TriGIL, were also measured. 13Cu-TriGIL showed a density of 1.017 g/cm3 and a viscosity of 26.42 mPa·s. Additionally, 13Cu-TriG exhibited a freezing point of −45 °C. However, with the addition of [EMIM][BH 3 CN] in the fuel, the freezing temperature drops below −80 °C (13Cu-TriGIL). Furthermore, 13Cu-TriGIL with 95 wt% H 2 O 2 demonstrated theoretical specific impulse and density specific impulse of 2.1 % lower and 9.7 % higher than MMH/NTO, respectively. Overall, the use of ionic liquid to improve the hypergolic performance and physicochemical properties of triglyme-based fuels was the advantage of our research. [ABSTRACT FROM AUTHOR]

The renewed interest in space exploration has led to the growth in research efforts pertaining to advanced space propulsion systems, including highly efficient electric propulsion systems. Although already tested in space many decades ago and being currently employed on various space platforms and thousands of satellites, these systems are yet to reach their full potential for applications on orbit and in deep space. One specific feature of space electric propulsion is the large diversity of physical processes used in this technology, which is not typical for many other types of propulsion systems used in transport, such as those used by airplanes or automobiles. Various physical processes and mechanisms underpin different electric propulsion technologies and should be integrated to drive the future science and technology of space electric propulsion systems. This opinion article briefly highlights this feature of space electric propulsion and outlines some challenges and opportunities that follow from this diversity. [ABSTRACT FROM AUTHOR]

This paper describes the latest advances in electric propulsion systems prepared for the new space exploration activity. Missions to the Moon and Mars will require these new thrusters to convey the huge amounts of provisions that would be expected to help changeless bases on other universes. The new advancements are likewise being utilized for unmanned investigation missions that will go to the furthest reaches of the nearby planetary group. This paper is expected to provide some insight into some ideas for electric propulsion - standards and work skills, as well as a diagram of mission applications that would benefit from these frame drives and their use with state-of-the-art control systems. [ABSTRACT FROM AUTHOR]

To develop a spacefaring civilization, humankind must develop technologies which enable safe, affordable and repeatable mobility through the solar system. One such technology is nuclear fusion propulsion which is at present under study mostly as a breakthrough toward the first interstellar probes. The aim of the present paper is to show that direct fusion drive is even more important in human planetary exploration and constitutes the natural solution to the problem of exploring and colonizing the solar system. • Direct Fusion Drive (DFD) allows revolutionary breakthrough in space propulsion. • DFD based on the aneutronic D-3He fusion requires a moderate radiation screening. • A spacecraft with DFD makes it an ideal choice for human planetary missions. • A 120 days Earth-Mars and a 250 days Earth – 16 Psyche transfers are studied. • It is demonstrated that DFD is the key to fast planetary missions. [ABSTRACT FROM AUTHOR]

The electric sail is an innovative concept for spacecraft propulsion, which can generate continuous thrust without propellant by reflecting solar wind ions. In previous studies, the thrust of an electric sail is described by a classical model that neglects the effects of the electric sail attitude on the propulsive thrust modulus and direction. This paper reappraised the performance of the electric sail in the Vesta and Ceres exploration mission with an advanced thrust model that considers the effect of the spacecraft attitude on both the thrust modulus and direction. By using a hybrid optimization method, the trajectory optimization of the electric-sail-based spacecraft from earth to Vesta and Ceres is implemented in an optimization framework. Numerical results show that the minimal flight time with the advanced thrust model is longer than that with the classical model. The difference in performance between the classical and advanced models is attributable to overestimation of the maximum thrust cone angle and the thrust modulus by the classical model. [ABSTRACT FROM AUTHOR]

The article provides information on the propulsion systems of space vehicles which are used in space exploration. According to the author, the extent of space exploration in the future will depend upon the sizes and efficiencies of the propulsion systems which will be developed. Most types of rockets are based on the principles of action and reaction, where the motion depends upon expelling some material from the vehicle. There are several types of propulsion which include solid propellants, liquid propellant rockets, and other chemical systems. The author adds that nuclear energy can also be a very compact type of almost limitless energy and it is natural to seek some way of utilizing it for space exploration.

Rapid advances in small satellite (often referred to as CubeSats) technology are providing opportunities for space exploration to a wide range of users (in particular universities) at substantially reduced costs. Many of the capabilities provided by larger satellites and spacecraft (>2000 kg) are now available through small satellite technologies. Ongoing improvements in attitude control, propulsion, advanced communications, and scientific instrumentation continue to enhance their benefits, even within such strict volume and mass constraints. With such advances in CubeSat technologies, the power and energy demands have also increased dramatically, necessitating the need for larger deployable solar arrays, lower power electronics, efficient energy storage systems, and even energy transfer/harvesting systems. In terms of energy storage, more advanced battery chemistries with higher energy densities and higher power capabilities over a wider operating temperature range are also a fundamental need. There already exist today numerous commercially available energy storage options suitable for CubeSat applications, although many missions rely on custom designs. Similar to standard satellite design, the selection of an appropriate energy storage system is driven by mission requirements related to power, energy, and lifetime. This paper will provide a general review of performance capabilities of state-of-the-art lithium-ion battery technologies, as well as other advanced energy storage systems for small satellite applications. [ABSTRACT FROM PUBLISHER]

• Evaluated the diffusion behavior of uranium mononitride and zirconium carbide. • The resultant phase of the diffusion is a uranium-zirconium carbonitride phase. • The composite samples were manufactured using field-assisted sintering. The next generation of space exploration will require extensive developments in rocket technology. Space nuclear propulsion is of interest due to its high fuel density and power; however, it also has high temperature and stability demands. This study examines a uranium mononitride (UN) and zirconium carbide (ZrC) ceramic-ceramic particle composite as a potential fuel for these missions. Based on the constituent properties, this fuel composite is expected to be thermally efficient and resistant to the hot hydrogen propellant. One of the main concerns with this composite is the unknown diffusion behavior between UN and ZrC over time. Diffusion couple experiments and isothermal furnace tests of composites were two experimental techniques used to determine how these constituents will behave when left in contact at high temperatures. UN and ZrC were found to have limited but observable diffusion at the phase boundary. The resulting phase is a UZr(CN) quaternary phase. UZr(CN) has been examined for other high temperature and gas nuclear reactors with preliminary success; however, there lacks sufficient data to fully understand this phase. Based on the limited information available, the resultant quaternary phase could be deemed acceptable and even provide better adhesion for the fuel particles (UN) to the matrix (ZrC). [ABSTRACT FROM AUTHOR]

The results of updating the parameters of motion of the Spektr-R spacecraft at the end of 2016 have shown that, in January 2018, with a probability close to unity, the condition that a spacecraft stay in the Earth's shadow is violated; however, in May of the same year, the ballistic life of the spacecraft will be terminated. Thus, in 2017, the question arose of how to design the correction of flight of this spacecraft using its onboard propulsion system. The correction was designed with allowance for the fact that, for the first time since it was launched, the spacecraft in the course of several years, beginning with 2017, repeatedly approaches the Moon, deeply immersing into its sphere of influence. This paper presents the technologically and organizationally convenient, allowable versions of upcoming correction of the Spektr-R spacecraft trajectory and justifies the particular scheme of its implementation. [ABSTRACT FROM AUTHOR]

A space propulsion system is important for the normal mission operations of a spacecraft by adjusting its attitude and maneuver. Generally, a mono- and a bipropellant thruster have been mainly used for low thrust liquid rocket engines. But as the plume gas expelled from these small thrusters diffuses freely in a vacuum space along all directions, unwanted effects due to the plume collision onto the spacecraft surfaces can dramatically cause a deterioration of the function and performance of a spacecraft. Thus, aim of the present study is to investigate and compare the major differences of the plume gas impingement effects quantitatively between the small mono- and bipropellant thrusters using the computational fluid dynamics (CFD). For an efficiency of the numerical calculations, the whole calculation domain is divided into two different flow regimes depending on the flow characteristics, and then Navier-Stokes equations and parallelized Direct Simulation Monte Carlo (DSMC) method are adopted for each flow regime. From the present analysis, thermal and mass influences of the plume gas impingements on the spacecraft were analyzed for the mono- and the bipropellant thrusters. As a result, it is concluded that a careful understanding on the plume impingement effects depending on the chemical characteristics of different propellants are necessary for the efficient design of the spacecraft. [ABSTRACT FROM AUTHOR]

Advanced liquid rocket engines (LREs) are being created by Yuzhnoye Design Office of Ukraine based on the fifty-year experience of rocket engines' and propulsion systems' development. These LREs use both hypergolic (NTO+UDMH) and cryogenic (liquid oxygen+kerosene) propellants. First stage engines have a range of thrust from 40 to 250 t, while the upper stage (used in space) engines - from several kilograms to 50 t and a re-ignition feature. The engines are intended for both Ukraine”s independent access to space and international market. [ABSTRACT FROM AUTHOR]

A particular highlight is Gray's deep dive into the diesel-powered hydraulic motors used by the Amish, who generally eschew electricity but still need to produce furniture on an industrial scale: They retrofit commercial electric devices to use compressed-air motors. I A Traveler's Guide to the Stars i , Les Johnson, Princeton U. Press, 2022, $27.95 Although people have been dreaming of space exploration for decades, visiting and settling other worlds is still the stuff of science fiction. - rd Engines: The Inner Workings of Machines That Move the World I Engines: The Inner Workings of Machines That Move the World i , Theodore Gray; photographs by Nick Mann, Black Dog & Leventhal, 2022, $32.00 This new large-format book by Theodore Gray, an author and chemistry enthusiast, is a tinkerer's dream. [Extracted from the article]

With the maturity of nuclear reactor miniaturization technology and the increasing demand of human space exploration, nuclear powered spacecraft is expected to become a reality. With the continuous exploration of the deep universe by mankind, the capacity of the heat dissipation of the space radiators is required continuously be improved, which leads to the increasing weight and economical decline of the spacecraft. The heat pipe radiator has advantage that other radiators cannot compare with. In this paper, the finite difference method and the iterative method are used to study the influence of fin width, inlet temperature, length of the heat pipe condensing section, and coolant mass flow rate on the weight and the heat dissipation area of the heat pipe radiator. Taking the weight and the heat dissipation area of the radiator as the optimization goals, the whale optimization algorithm is used to optimize the design parameters of the heat pipe radiator with a given heat dissipation. ANSYS fluent is used to simulate and analyze the heat pipe-fin unit with the best design parameters. [ABSTRACT FROM AUTHOR]

Abstract: NASA has created a plan to implement the Flexible Path strategy, which utilizes a heavy lift launch vehicle to deliver crew and cargo to orbit. In this plan, NASA would develop much of the transportation architecture (launch vehicle, crew capsule, and in-space propulsion), leaving the other in-space elements open to commercial and international partnerships. This paper presents a space exploration strategy that reverses that philosophy, where commercial and international launch vehicles provide launch services. Utilizing a propellant depot to aggregate propellant on orbit, smaller launch vehicles are capable of delivering all of the mass necessary for space exploration. This strategy has benefits to the architecture in terms of cost, schedule, and reliability. [Copyright &y& Elsevier]

The solar sail is a new type of spacecraft for deep space exploration that is propelled by solar radiation pressure. The solar sail is large, has a large moment of inertia, and is highly flexible, and its motion involves a coupling of the orbit, the attitude, and structural vibration. With the coupling effect of the orbit and the attitude included, a non-Keplarian displaced solar orbit is designed. In the rotating frame, the solar sail has a stable equilibrium point, and an attitude controller is employed for coupled attitude-orbit control. With control, the time required for eliminating the orbital deflection is much larger than that required for the attitude deflection. Including the additional influence of the flexibility of the solar sail, the structure shows a sustained, high-frequency vibration, which also leads to sustained and high-frequency likewise small vibrations of the orbit and attitude. This work demonstrates the importance of including the structural flexibility into the coupling effect of the solar sail for long-term missions in space. [ABSTRACT FROM AUTHOR]

Purpose – The purpose of this paper is to present a solution space searching method to study the initial design of interplanetary low thrust gravity assist trajectory. Design/methodology/approach – For reducing the complexity and nonlinearity of the initial design problem, a sixth degree inverse polynomial shape based approach is brought. Then some improvements are provided for solving the parameters in the shape function and a quasi-lambert solver is brought through the shape based method, the thrust profile can be generated under the given time of flight, boundary states including positions and velocities for low thrust phase. Combining gravity assist model, the problem is summarized and an improved pruning technique is used for searching the feasible solution space for low thrust gravity assist trajectory. Findings – Using the solution space searching method, the feasible solution region would be generated under the given mission condition. The treatment about gravity assist demonstrates more accurate than previous method. Also another advantage is that the searching method can be used to design different types of mission trajectory, including flyby and rendezvous trajectories. Practical implications – The method can be used as an efficient approach to search the feasible region for the complex low thrust gravity assist trajectory, and it can provide appropriate initial guesses for the low thrust gravity assist trajectory in mission design phase. Originality/value – Feasible solution space would be obtained through the searching method. The quasi-Lambert solver in the paper is found under the shape-based method and relative improvement, and it shows its availability during the searching process. Through mission trajectory design, the effectiveness of the method is shown. [ABSTRACT FROM AUTHOR]

Abstract: The status and the main results achieved by Project 242 are presented. Project 242 is a programme (funded by ASI—1999/2002 from an idea of Carlo Rubbia) that studied a new concept of space propulsion motor by using direct conversion of the kinetic energy of fission fragments into increasing of enthalpy of a propellant gas. Project 242 studied the application of this propulsion system to a manned mission to Mars. Preliminary results were very satisfactory and it has been observed that a propulsion system with these characteristics could make the mission feasible. Results for other unmanned missions to the outer solar system are also presented. [Copyright &y& Elsevier]

Dawn's ion propulsion system (IPS) is the most advanced propulsion system ever built for a deep-space mission. Aside from the Mars gravity assist it provides all of the post-launch Δ V required for the mission including the heliocentric transfer to Vesta, orbit capture at Vesta, transfer to various Vesta science orbits, escape from Vesta, the heliocentric transfer to Ceres, orbit capture at Ceres, and transfer to the different Ceres science orbits. The ion propulsion system provides a total Δ V of nearly 11 km/s, comparable to the ΔV provided by the 3-stage launch vehicle, and a total impulse of 1.2×10 N s. [ABSTRACT FROM AUTHOR]

Abstract: In the early 2000s, NASA made substantial progress in the development of solar sail propulsion systems for use in robotic science and exploration of the solar system. Two different 20-m solar sail systems were produced. NASA has successfully completed functional vacuum testing in their Glenn Research Center’s Space Power Facility at Plum Brook Station, Ohio. The sails were designed and developed by Alliant Techsystems Space Systems and L’Garde, respectively. The sail systems consist of a central structure with four deployable booms that support each sail. These sail designs are robust enough for deployment in a one-atmosphere, one-gravity environment and are scalable to much larger solar sails – perhaps as large as 150m on a side. Computation modeling and analytical simulations were performed in order to assess the scalability of the technology to the larger sizes that are required to implement the first generation of missions using solar sails. Furthermore, life and space environmental effects testing of sail and component materials was also conducted. NASA terminated funding for solar sails and other advanced space propulsion technologies shortly after these ground demonstrations were completed. In order to capitalize on the $30M investment made in solar sail technology to that point, NASA Marshall Space Flight Center funded the NanoSail-D, a subscale solar sail system designed for possible small spacecraft applications. The NanoSail-D mission flew on board a Falcon-1 rocket, launched August 2, 2008. As a result of the failure of that rocket, the NanoSail-D was never successfully given the opportunity to achieve orbit. The NanoSail-D flight spare was flown in the Fall of 2010. This review paper summarizes NASA’s investment in solar sail technology to date and discusses future opportunities. [Copyright &y& Elsevier]

Abstract: As we enter the 21st century, the lack of a space propulsion science discipline – involving the development of new emerging physical theories and models – within the bounds of Rocket Science forbids any rapid development of ideas and concepts toward new frontiers in spaceflight and implies a stagnate death in the advancement of Rocket Science as a whole. Specifically, the conventional disciplines in Rocket Science lacks foresight into the physics of acceleration to include the nature of gravity and inertia, which is foremost needed for the progression of spaceflight. In this paper is discussed various topics toward the understanding that space propulsion science is not a major player in Rocket Science, but must become so, if Rocket Science is to evolve the necessary new frontiers needed for future space exploration. [Copyright &y& Elsevier]

Abstract: The versatility of solar sail propulsion can be utilized in the exploration of Earth’s magnetotail. An inclined periodic orbit with respect to ecliptic is possible for a solar sail with its orbital plane in synchronous rotation with the sun. Solar sail evolving on such an inclined orbit is free of Earth shadow. Formation flying of a cluster of sails around such an inclined periodic orbit is investigated in this paper. The solution of the first-order approximation to the linear relative motion is used to qualitatively analyze the configurations of relative orbits. Since the relative motion is unstable, active control is necessary to keep a periodic relative motion. A typical LQR method is employed to stabilize the relative motion. The design method is validated by numerical examples. [ABSTRACT FROM AUTHOR]

Abstract: The invention of gravity-propelled interplanetary space travel (also known as “gravity-assist trajectories”) in the early 1960s broke the high-energy barrier of classical space travel based on reaction propulsion, and made possible the exploration of the entire solar system with instrumented spacecraft. In this concept, a free-fall spacecraft is launched from a launch planet P1 to a nearby planet P2 such that its gravitational field (superimposed on the gravitational field of the Sun) catapults the vehicle to another planet P3, which in turn is used to repeat the process. Thus, through a series of planetary encounters, a gravity-propelled trajectory P1-P2-P3-P4-…-P N is generated. This paper describes how the invention was conceived and how the difficult mathematical problem of computing the trajectories was solved in order to numerically investigate and use the invention in actual missions. The crucial roles played by the UCLA Computing Facility and the Departments of Mathematics and Physics are also described. [Copyright &y& Elsevier]

Abstract: Missions towards potentially hazardous asteroids require considerable propellant-mass consumption and complex flybys maneuvers with conventional propulsion systems. A very promising option is offered by an electric sail, an innovative propulsion concept, that uses the solar-wind dynamic pressure for generating a continuous and nearly radial thrust without the need for reaction mass. The aim of this paper is to investigate the performance of such a propulsion system for performing rendezvous missions towards all the currently known potentially hazardous asteroids, a total of 1025 missions. The problem is studied in an optimal framework by minimizing the total flight time. Assuming a canonical value of sail characteristic acceleration, we show that about 67% of the potentially hazardous asteroids may be reached within one year of mission time, with 137 rendezvous in the first six months. A detailed study towards asteroid 99942 Apophis is reported, and a comparison with the corresponding performance achievable with a flat solar sail is discussed. [Copyright &y& Elsevier]

Abstract: For the last 50 years solid propulsion has successfully created a multitude of small launchers and many first stages or boosters for heavy launchers with low risk, high performance, competitive cost, superb storability, and “instant” readiness in many countries. Technical support for these successes arose from simple designs, very high thrust levels, and low development and operation costs/risks. The first solid propulsion roadmap based on these foundations and rational projections was published in 2000 [A. Davenas, D. Boury, M. Calabro, B. D’Andrea, A. McDonald, Solid propulsion for space applications: a roadmap, in: 51st International Astronautical Congress, paper IAA-00-IAA.3.3.02, October 2000]. Moreover, subsequent information supports its enabling technologies (high strength composite cases, energetic material processing based on continuous mixing, low density insulation, reduced actuator energy requirements, and advanced detailed simulations) and applications (first stages, strap-on, add-ons, small launchers, and niche space applications). Missions currently devoted to solid propulsion and plans for present and future launchers and exploration mission developments in the USA, Japan, and Europe are sketched and targeted improvements, and potential breakthroughs are discussed. [Copyright &y& Elsevier]

Solar sails are currently being studied and developed as alternate propulsion vehicles that can provide high velocities. Their ability to reflect photons coming from the sun on a large lightweight reflective surface enables many unique space science missions. One such mission is the GeoSail mission, for which the aim is the study of Earth's magnetotail. Recent advances in solar sail technologies, satellite bus miniaturization, and attitude control motivate the present study of an alternate systems design approach for GeoSail. This paper details a practical systems approach toward the design of a 40 x 40 m sail, focusing on the design and use of niche enabling technologies with applications to the proposed GeoSail mission. The study is based on mission and system design requirements from ESA's technology reference studies, which focus on the development of strategically important technologies in preparation of future scientific missions: in this case, for the 2015-2025 time frame. [ABSTRACT FROM AUTHOR]

Abstract: We present a concept for a challenging in situ science mission to a primitive, binary near-Earth asteroid. A sub-400-kg spacecraft would use solar electric propulsion to rendezvous with the C-class binary asteroid (175706) 1996 FG3. A campaign of remote observations of both worlds would be followed by landing on the ∼1km diameter primary to perform in situ measurements. The total available payload mass would be around 34kg, allowing a wide range of measurement objectives to be addressed. This mission arose during 2004 from the activities of the ad-hoc Small Bodies Group of the DLR-led Planetary Lander Initiative. Although the particular mission scenario proposed here was not studied further per se, the experience was carried over to subsequent European asteroid mission studies, including first LEONARD and now the Marco Polo near-Earth asteroid sample return proposal for ESA’s Cosmic Vision programme. This paper may thus be of interest as much for insight into the life cycle of mission proposals as for the concept itself. [Copyright &y& Elsevier]

The employment of low-thrust propulsion systems is an attractive option for space missions requiring large changes in orbital energy. Therefore in this paper, we investigate the performance of a hybrid low-thrust propulsion system, constituted by a solar electric thruster coupled with a solar sail. Loosely speaking, the solar sail may be seen as a propellantless auxiliary system capable of reducing the gravitational force acting on the spacecraft in such a way that the propellant expense for a given mission may be decreased. To quantify this effect, we analyze the problem in terms of optimization of a scalar performance index that takes into account both the mission time and the propellant mass required to reach the target orbit. A weighting parameter is used to trade between these two conflicting requirements. The problem is solved using an indirect approach and the resulting optimal control law is applied to a circle-to-circle rendezvous transfer. Key features of the paper are the use of realistic models for both the solar electric thruster and the solar sail. [ABSTRACT FROM AUTHOR]

Solar sails have been studied in the past as an alternative means of propulsion for spacecraft. Recent advances in solar sail technology and the miniaturization of technology can drive these systems much smaller (<5 kg mass, <10 m sail diameter) than existing sails, while still having a high A V and acceleration capability. With these unique capabilities of miniature solar sails, called solar kites, some very unique space science missions can be achieved which are difficult to implement using conventional propulsion techniques. One such unique candidate mission is to study the Earth's magnetotail. The paper describes the main design features and technologies of a solar kite mission/platform and demonstrates that a cluster of solar kites with science payloads can provide multiple, in situ measurements of the dynamic evolution of energetic particle distributions of the rotating geomagnetic tail of Earth. With a unique design, a solar kite proves to be an efficient, affordable, and versatile solution for the mission analyzed with a significant science return. [ABSTRACT FROM AUTHOR]

Abstract: One very cost-effective route into orbit is as an Auxiliary Microsatellite on the ASAP-5 structure. All planned flights of the ASAP-5 structure are into GTO. The Advanced Microsatellite Mission study carried out within the ESA General Studies Programme addressed the feasibility of a deep space mission starting from this point. One of the major configuration drivers in the ASAP-5 launch envelope is the available volume. Low-density nondeployable equipment (tanks, star sensor baffles, etc.) becomes design drivers. Optimisation for power and volume has led to an Attitude Control System architecture which is gyro-based (using the latest high-performance MEMS devices) making use of opportunistic calibration by minimally baffled star sensors. Solar electric propulsion appears the leading candidate for missions requiring large . There has historically been a quest for ever higher values of for SEP thrusters, but it is shown that a full mission-level trade-off taking into account the restricted power availability on this class of spacecraft often leads to a lower value of in order to minimise operations costs and improve the timeliness of scientific observations. It is concluded that useful deep space missions can be performed by a spacecraft complying with the ASAP-5 constraints. [Copyright &y& Elsevier]

Abstract: Variable-specific-impulse electric propulsion systems can provide important advantages and cost reductions to any scale of planetary mission. The first part of this paper describes their potential benefits, with special emphasis on mission analysis aspects. The second part identifies the physical limitations of traditional electric propulsion technologies and presents some preliminary development results achieved within the frame of ongoing European activities. [Copyright &y& Elsevier]