FIGURE 2 - uploaded by Sini Merikallio
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Illustration of a two-chamber unit that can be used in situ to extract water from asteroid regolith. Asteroid material is heated in the first chamber (left) so that water in the material vaporizes. Pressure gradient drives the water vapor into the second chamber (right), where it cools and condenses.
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The electric solar wind sail (E-sail) is a novel propulsion concept that enables fast and economic space travel in the solar system. For propulsion it utilizes a continuous particle stream from the Sun (i.e., solar wind) by deploying long, electrically conductive charged tethers, which through electric force interaction are pushed by the charged so...
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The Psyche mission is planned to travel to the main belt asteroid (16) Psyche, and will use Hall Effect thrusters for all deterministic thrusting. We present a substantive update to the navigation uncertainty model for the mission's electric propulsion thrusting, greatly refining error models presented in a previous publication. The new models are...
Citations
... where τ ∈ {0, 1} is a switching (dimensionless) parameter that models the thruster operating mode: either on (when τ = 1) or off (i.e., τ = 0). These two modes are obtained by switching on or off the onboard electron gun powered by the solar panels [24,25]. In Equation (1), a c is the characteristic acceleration [26], which is defined as the maximum propulsive acceleration magnitude a at a solar distance r = r ⊕ , andn is the unit vector normal to the sail nominal plane (the plane that ideally contains the charged tethers) in the direction opposite to the Sun. ...
The aim of this paper is to investigate the performance of a robotic spacecraft, whose primary propulsion system is an electric solar wind sail (E-sail), in a mission to a heliostationary point (HP)—that is, a static equilibrium point in a heliocentric and inertial reference frame. A spacecraft placed at a given HP with zero inertial velocity maintains that heliocentric position provided the on-board thrust is able to counterbalance the Sun’s gravitational force. Due to the finite amount of storable propellant mass, a prolonged mission toward an HP may be considered as a typical application of a propellantless propulsion system. In this respect, previous research has been concentrated on the capability of high-performance (photonic) solar sails to reach and maintain such a static equilibrium condition. However, in the case of a solar-sail-based spacecraft, an HP mission requires a sail design with propulsive characteristics that are well beyond the capability of current or near-future technology. This paper shows that a medium-performance E-sail is able to offer a viable alternative to the use of photonic solar sails. To that end, we discuss a typical HP mission from an optimal viewpoint, by looking for the minimum time trajectory necessary for a spacecraft to reach a given HP. In particular, both two- and three-dimensional scenarios are considered, and the time-optimal mission performance is analyzed parametrically as a function of the HP heliocentric position. The paper also illustrates a potential mission application involving the observation of the Sun’s poles from such a static inertial position.
... The Electric Solar Wind Sail (E-sail) is a propellantless propulsion system that exploits the interaction of the charged particles in the solar wind with a spinning grid of tethers, kept at high potential by an electron gun and stretched by the centrifugal force [1,2,3]. The peculiarity of an E-sail allows innovative and exotic mission scenarios to be feasible, including non-Keplerian orbits and artificial Lagrange points maintenance [4,5,6]. ...
The Electric Solar Wind Sail (E-sail) is a propellantless propulsion system that generates thrust by exploiting the interaction between a grid of tethers, kept at a high electric potential, and the charged particles of the solar wind. Such an advanced propulsion system allows innovative and exotic mission scenarios to be envisaged, including non-Keplerian orbits, artificial Lagrange point maintenance, and heliostationary condition attainment. In the preliminary mission analysis of an E-sail-based spacecraft, the local physical properties of the solar wind are usually specified and kept constant, while the E-sail propulsive acceleration is assumed to vary with the heliocentric distance, the sail attitude, and the grid electric voltage. However, the solar wind physical properties are known to be characterized by a marked variability, which implies a non-negligible uncertainty as to whether or not the solutions obtained with a deterministic approach are representative of the actual E-sail trajectory. The aim of this paper is to propose an effective method to evaluate the impact of solar wind variability on the E-Sail trajectory design, by considering the solar wind dynamic pressure as a random variable with a gamma distribution. In particular, the effects of plasma property fluctuations on E-sail trajectory are calculated with an uncertainty quantification procedure based on the generalized polynomial chaos method. The paper also proposes a possible control strategy that uses suitable adjustments of grid electric voltage. Numerical simulations demonstrate the importance of such a control system for missions that require a precise modulation of the propulsive acceleration magnitude.
