Powering missions to the outer solar system is a significant challenge. These missions are typically powered by a Radioisotope Thermoelectric Generator (RTG). Though these sources provide stable power regardless of location in space, they are expensive to produce, difficult to integrate, and have both safety concerns as well as negative sociopolitical connotations. Perhaps most importantly, the availability of their fuel, plutonium -238, is scarce. Solar power is often considered a more attractive option. However, photovoltaic generation falls off at the distance from the sun squared. This drives the size of traditional solar generators to infeasible levels for deep space and their utilization at locations deeper than Jupiter is currently non-existent. Herein, a hypothetical solution, the PowerSail, and its application to a non-nuclear Uranus mission is presented. The PowerSail is a marriage of solar sails and thin-film solar cell assemblies. Herein the application of PowerSail spacecraft to a high priority science mission, the Applied Physics Laboratory's Uranus Probe and Explorer, is studied. The overall mission design along with key subsystems design changes are discussed, ultimately showing that a PowerSail could be utilized as a non-nuclear option to reach destinations very deep in our solar system. Key needed technology developments to make the PowerSail and such a mission a reality are given.

The NASA George C. Marshall Space Flight Center (MSFC) and Glenn Research Center (GRC) are evaluating the use of space-based solar power (SBSP) to enable lunar night survival, with stretch goals of enabling continued science, exploration, and manufacturing during the lunar night within permanently shadowed regions (PSRs) or outside of settled areas with permanent power generators. Current designs integrate either optical or RF-based power sources into a constellation of satellites intended for lunar orbit. This effort will focus specifically on laser- based power beaming; however, the team is also investigating radiofrequency ( RF)-based power beaming systems. These satellites are equipped with a photovoltaic (PV) array to provide charging power to the craft's batteries, which are then used to power the laser. Power is received on the ground via dual-use PV receiver. Heat generation on the craft is mitigated by radiators sized by measuring the power conversion efficiencies of the PV, battery, and laser. Conceptually, no additional heat mitigation is required for the surface asset, as the power density (defined as irradiance in W/m(2)) delivered in most cases is no more than the power/heat delivered by the sun.

Continuous, in-situ, multi-point observations along the Sun-Earth line at and inside the Lagrange point L1 (subL1) will enable a better understanding of the three-dimensional structure and temporal evolution of heliospheric structures that drive terrestrial space weather. The proposed SWIFT (Space Weather Investigation Frontier) mission will use a new solar sail propulsion system developed by NASA to enable a suite of science instruments onboard a smallsat to maintain observations along the Sun-Earth line, sub-L1, for extended periods. Three identically instrumented small spacecraft at L1 will fly in concert with the sailcraft at sub-L1 in an optimized tetrahedron constellation, covering scales between 10 and 100s of Earth radii. This viewing geometry will enable scientists to distinguish between local and global processes driving space weather by revealing the spatial characteristics, temporal evolution, and geo-effectiveness of small-to meso-scale solar wind structures and substructures of macro-scale structures, such as interplanetary coronal mass ejections (ICMEs) and stream interaction regions (SIRs). In addition, real time measurements of earth-bound heliospheric structures from sub-L1 will improve our current forecasting lead-times by up to 35 percent. This paper will provide an overview of the proposed SWIFT science and mission concept.

Reflectivity control devices (RCDs) based on polymer dispersed liquid crystals were fabricated for Solar Cruiser, a SmallSat NASA Pathfinder Mission consisting of a 1653 square meter solar sail that would establish an artificial orbit sunward of the L1 Lagrange point for heliophysics observations. Here we describe the optical characterization of these birefringent electro-optic devices including thin film measurements and analysis, hyperspectral bidirectional reflectance distribution function measurements, and radiometric analysis. These measurements demonstrate the promise of RCDs for roll control and momentum management of solar sails.

This paper describes the design and space environments testing of a power generation and commutation array referred to as the Lightweight Integrated Solar Array and AnTenna (LISA-T). LISA-T is the first fully thin-film array for small spacecraft. Inherently, small spacecraft are extremely resource limited. Restricted mass, volume, and surface area choke capability. This drives the need to do more from less, especially for power generation and communications. Herein, a solution, LISA-T, is presented. LISA-T is formed by coupling recent advancements in thin-film solar cell and antenna elements with new solar sail propulsion technologies. Cell and antenna elements are directly embedded into a solar sail-based polyimide substrate and coated with a protective thin-film top layer. The elements are electrically interconnected via welded ribbon and backed by a multifunctional structural deployment system. Both power generation and antenna emission have been achieved from this array. Benchtop deployments have also been successfully completed. A comprehensive space environments test campaign, including ascent vent, thermal deployments, thermal cycling, particulate radiation, ultraviolet radiation, and atomic oxygen, has been conducted to characterize and predict the array performance and survivability in space. The array is shown to be currently suitable for space missions with a >300% improvement in power performance metrics compared to state-of-the-art arrays.

NOAA has a research priority to acquire observations of solar wind parameters at sub-L1 points along the Sun-Earth line.Operational measurements at sub-L1 would improve geomagnetic storm alert lead times.We present a proposed mission based on the Solar Cruiser mission architecture that can meet the first step of these research observations using solar sail propulsion technology.The higher characteristic acceleration available from using a solar sail overcomes the difficult duty station requirement at sub-L1.The mission will also fly a science payload to observe the solar wind density, velocity, temperature and the interplanetary magnetic field at sub-L1.The primary mission objective is to demonstrate that a spacecraft using solar sail propulsion technology with a science payload enables in-situ plasma and magnetic field observations at sub-L1.

Solar sails enable missions to observe the solar environment from unique vantage points, such as sustained observations away from the Sun-Earth line; sub-L1 station keeping; high inclination solar orbits; Earth polar-sitting and polar-viewing observatories; fast transit missions to study heliosphere to interstellar medium transition, as well as missions of interest across a broad user community. Recent and planned demonstration missions make this technology ready for use on near-term science missions.

A near-term possibility for utilization of Breakthrough Initiatives Project Starshot technology is application of the sun diving maneuver as a replacement for laser acceleration of highly miniaturized photon sails to interstellar velocities. This possibility was discussed during the June 2022 Breakthrough Discuss meeting in Santa Cruz California. Here, we consider application of statite-type photon sail probes to achieve rectilinear trajectories to explore outer solar system and near-interstellar destinations. Statite-Type solar photon sails are sufficiently thin and reflective that solar radiation pressure force on the sail exactly balances the solar gravitational force. In such a force-free environment, the spacecraft exits the solar system at its pre-sail-deployment solar-orbital velocity. Here we consider departures from a circular 1 AU solar orbit, the perihelion of a 0.7-1 AU elliptical solar orbit and the perihelion of a 0.3-1 AU solar orbit. Possible outer-solar system destinations of possible interest to Breakthrough Initiatives extraterrestrial-life/artifact -search researchers include Europa, Titan, Enceladus, Methone, and Arrokoth. More distant possible objectives are ‘Oumuamua and the Sun’s inner gravitational focus. To achieve a rectilinear trajectory, the sail must be oriented normal to the Sun and spacecraft areal mass thickness is 1.46 × 10-3 kg/m2. Current sail technology is reviewed to determine whether it can achieve the required areal mass thickness.

A brief guide to the real science of interstellar travel With known exoplanets now numbering in the thousands and initiatives like 100 Year Starship and Breakthrough Starshot advancing the idea of interstellar travel, the age-old dream of venturing forth into the cosmos and perhaps even colonizing distant worlds may one day become a reality. A Traveler’s Guide to the Stars reveals how. Les Johnson takes you on a thrilling tour of the physics and technologies that may enable us to reach the stars. He discusses the latest exoplanet discoveries, promising interstellar missions on the not-so-distant horizon, and exciting new developments in space propulsion, power, robotics, communications, and more. But interstellar travel will not be easy, and it is not for the faint of heart. Johnson describes the harsh and forbidding expanse of space that awaits us, and addresses the daunting challenges—both human and technological—that we will need to overcome in order to realize tomorrow’s possibilities. A Traveler’s Guide to the Stars is your passport to the next great frontier of human discovery, providing a rare inside look at the remarkable breakthroughs in science and technology that will help tomorrow’s space travelers chart a course for the stars.

Low areal density and tailored functionality are key attributes making diffractive films attractive for radiation pressure space applications. This talk will describe recent experimental and theoretical work, and a roadmap for the flat optics community.

Solar sails are of great promise for space exploration, affording missions that push the limits of the possible. They enable a variety of novel science missions ranging from ultrafast interstellar travel to imaging the poles of the sun—missions that are beyond the reach of current propulsion technology. Here, we describe requirements and challenges associated with optical materials and photonic designs facing the next generation of solar sails. A technology development roadmap is outlined to guide researchers in pioneering the space faring future.

This investigation outlines preliminary trajectory design for NASA’s sail-based Solar Cruiser spacecraft, selected on December 3, 2020, to be a secondary payload launched with the Interstellar Mapping and Acceleration Probe (IMAP) in 2025. Trajectory optimization is carried out to ensure that Solar Cruiser can successfully reach a halo orbit about a Sun–Earth sub-L1 Lagrange point in under one year using only solar sail propulsion. Trade studies are performed to identify optimal trajectories subject to restrictions on sail incidence angles and deployment times, and off nominal initial-conditions are examined to determine the feasibility of the baseline mission profile. Results, thus far, show that Solar Cruiser can be incorporated as a secondary payload on IMAP while satisfying tight operational restrictions. However, additional work must be done to mitigate risks from large launch vehicle injection errors.

Selected by NASA as an ESPA-class rideshare technology demonstration mission to launch with the Interstellar Mapping and Acceleration Probe (IMAP) mission in 2025, the NASA MSFC Solar Cruiser mission will mature solar sail technology for use in future Heliophysics missions, as well as missions of interest across a broad user community including NOAA, Earth, and Planetary Sciences. Solar sails, which use reflected sunlight to derive thrust, can be used to create artificial equilibria and near-indefinite station-keeping at locations sunward of L1 along the Sun Earth Line (SEL), or at any desired offset from the SEL leading or trailing the Earth in its orbit. They can change the heliocentric inclination of a spacecraft from the ecliptic to as high as solar polar, stopping and remaining at any intermediate inclination orbit in between or can be used around a range of solar system bodies. The Solar Cruiser mission will fly a small spacecraft (~100 kg) with a large (>1600 square meter) solar sail containing embedded reflectivity control devices (RCDs) and photovoltaic cells, attaining a characteristic acceleration of >0.12 mm/s2. The mission concept includes successful deployment of the solar sail, validation of all sail subsystems, controlled station-keeping inside of the Sun-Earth L1 point, demonstration of pointing performance for science imaging, and finally an increase in heliocentric inclination (out of the ecliptic plane). Solar Cruiser would serve as a pathfinder for missions that observe the solar environment from unique vantage points such as a high inclination solar mission, opening a fundamentally new range of observational capabilities for the Heliophysics Program and for space weather monitoring. Observations away from the Sun-Earth line (SEL) present unique opportunities for answering the outstanding science questions of Heliophysics, for improving space-weather monitoring and prediction, and for revealing new discoveries about our Sun and solar system. High solar inclinations are particularly compelling. Investment in, and demonstration of, the technology needed to enable polar missions is essential to making this unique vantage point a reality in the next decade.

As one of the secondary payloads on the space launch systems vehicle, the Near-Earth Asteroid (NEA) Scout will demonstrate a low-cost and innovative approach to deep space reconnaissance missions. The main objective is to image and characterize a Near-Earth asteroid. The spacecraft packages a full deep space mission into the volume of a 6U CubeSat. To enable long-term sustained propulsion to the target, a solar sail is utilized as the main propulsion system. The spacecraft bus is single string, with compact avionics. Guidance and control performance meets science requirements with margin, but limited power impacts the amount of science data that can be returned, an aspect that is in part mitigated by the introduction of novel on-board data analysis software. Following in the recent footsteps of the Mars Cube One (MarCO) mission, the first deep space CubeSat demonstration, which included the infusion of the Iris radio; the NEA Scout will continue to blaze the trail for small CubeSats for interplanetary science and reconnaissance missions. This article will provide an overview of the mission, flight system design, and unique features needed for science and propulsion.

The High Inclination Solar Mission (HISM) is a concept for an out-of-the-ecliptic mission for observing the Sun and the heliosphere. The mission profile is largely based on the Solar Polar Imager concept: initially spiraling in to a 0.48 AU ecliptic orbit, then increasing the orbital inclination at a rate of $\sim 10$ degrees per year, ultimately reaching a heliographic inclination of $>$75 degrees. The orbital profile is achieved using solar sails derived from the technology currently being developed for the Solar Cruiser mission, currently under development. HISM remote sensing instruments comprise an imaging spectropolarimeter (Doppler imager / magnetograph) and a visible light coronagraph. The in-situ instruments include a Faraday cup, an ion composition spectrometer, and magnetometers. Plasma wave measurements are made with electrical antennas and high speed magnetometers. The $7,000\,\mathrm{m}^2$ sail used in the mission assessment is a direct extension of the 4-quadrant $1,666\,\mathrm{m}^2$ Solar Cruiser design and employs the same type of high strength composite boom, deployment mechanism, and membrane technology. The sail system modelled is spun (~1 rpm) to assure required boom characteristics with margin. The spacecraft bus features a fine-pointing 3-axis stabilized instrument platform that allows full science observations as soon as the spacecraft reaches a solar distance of 0.48 AU.

Space can be used as a tool by decision and policy makers in developing, implementing and monitoring various policy areas including resource management, environment, transport, security and energy. This paper focuses on the role of space for the energy policy. Firstly, the paper summarizes the European Union's (EU) main objectives in energy policy enclosed in the Energy Strategy 2020–2030–2050 and demonstrates how space assets can contribute to achieving those objectives. Secondly, the paper addresses how the European Space Agency (ESA) has established multiple initiatives and programs that directly finance the development of space assets, technology and applications that deliver services in support of the EU energy policy and sector. These efforts should be continued and strengthened in order to overcome identified technological challenges. The use of space assets, technology and applications, can help achieve the energy policy objectives for the next decades.