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Solar sails can play a critical role in enabling solar and heliophysics missions. Solar sail technology within NASA is currently at 80% of TRL-6, suitable for an in-flight technology demonstration. It is conceivable that an initial demonstration could carry scientific payloads that, depending on the type of mission, are commensurate with the goals of the three study panels of the 2010 Heliophysics Survey. Follow-on solar sail missions, leveraging advances in solar sail technology to support Heliophysics Survey goals, would then be feasible. This white paper reports on a sampling of missions enabled by solar sails, the current state of the technology, and what funding is required to advance the current state of technology such that solar sails can enable these missions.
We critically review our recent claims that it is possible to obtain a propellantless propulsion device similar to electrodynamic tethers by means of a closed wire partially shielded by a superconductor from the outer magnetic field. We find that such a device is not possible as it violates basic physical laws. Furthermore, we show what is the correct local picture for the currents distribution within the superconductor.
Challenging space missions include those at very low altitudes, where the atmosphere is source of aerodynamic drag on the spacecraft. To extend the lifetime of such missions, an efficient propulsion system is required. One solution is Atmosphere-Breathing Electric Propulsion (ABEP) that collects atmospheric particles to be used as propellant for an electric thruster. The system would minimize the requirement of limited propellant availability and can also be applied to any planetary body with atmosphere, enabling new missions at low altitude ranges for longer times. IRS is developing, within the H2020 DISCOVERER project, an intake and a thruster for an ABEP system. The article describes the design and simulation of the intake, optimized to feed the radio frequency (RF) Helicon-based plasma thruster developed at IRS. The article deals in particular with the design of intakes based on diffuse and specular reflecting materials, which are analysed by the PICLas DSMC-PIC tool. Orbital altitudes $h=150-250$ km and the respective species based on the NRLMSISE-00 model (O, $N_2$, $O_2$, He, Ar, H, N) are investigated for several concepts based on fully diffuse and specular scattering, including hybrid designs. The major focus has been on the intake efficiency defined as $eta_c=dot{N}_{out}/dot{N}_{in}$, with $dot{N}_{in}$ the incoming particle flux, and $dot{N}_{out}$ the one collected by the intake. Finally, two concepts are selected and presented providing the best expected performance for the operation with the selected thruster. The first one is based on fully diffuse accommodation yielding to $eta_c<0.46$ and the second one based un fully specular accommodation yielding to $eta_c<0.94$. Finally, also the influence of misalignment with the flow is analysed, highlighting a strong dependence of $eta_c$ in the diffuse-based intake while, ...
Background: A solar sail presents a large sheet of low areal density membrane and is the most elegant propellant-less propulsion system for the future exploration of the Solar System and beyond. By today the study on sail membrane deployment strategies has attracted considerable attention. Goal: In this work we present an idea of the deployment and stretching of the circular solar sail. We consider the superconducting current loop attached to the thin membrane %to develop a new (method) approach of deployment of a solar sail and and predict that a superconducting current loop can deploy and stretch the circular solar sail membrane. Method: In the framework of a strict mathematical approach based on the classical electrodynamics and theory of elasticity the magnetic field induced by the superconducting current loop and elastic properties of a circular solar sail membrane and wire loop are analyzed. The formulas for the wire and sail membrane stresses and strains caused by the current in the superconducting wire are derived. Results: The obtained analytical expressions can be applied to a wide range of solar sail sizes. Numerical calculations for the sail of radius of 5 m to 150 m made of CP1 membrane of the thickness of 3.5 $mu m$ attached to Bi$-$2212 superconducting wire with the cross-section radius of 0.5 mm to 10 mm are presented. Calculations are performed for the engineering current densities of 100 A/mm$^{2}$ to 1000 A/mm$^{2}$. Conclusion: Our calculations demonstrate the feasibility of the proposed idea for the solar sail deployment for the future exploration of the deep space by means of the light pressure propellant.
In this paper, we detail the scientific objectives and outline a strawman payload of the SOLAR sail Investigation of the Sun (SOLARIS). The science objectives are to study the 3D structure of the solar magnetic and velocity field, the variation of total solar irradiance with latitude, and the structure of the corona. We show how we can meet these science objective using solar-sail technologies currently under development. We provide a tentative mission profile considering several trade-off approaches. We also provide a tentative mass budget breakdown and a perspective for a programmatic implementation.
The immense volume of data generated by the suite of instruments on SDO requires new tools for efficient identifying and accessing data that is most relevant to research investigations. We have developed the Heliophysics Events Knowledgebase (HEK) to fill this need. The HEK system combines automated data mining using feature-detection methods and high-performance visualization systems for data markup. In addition, web services and clients are provided for searching the resulting metadata, reviewing results, and efficiently accessing the data. We review these components and present examples of their use with SDO data.