I4iS March 2024 Newsletter

I4is Science Fiction Anthology

You will have seen from earlier Newsletters that we are still looking for short stories for the upcoming “The i4is Science Fiction Anthology.” Further information is available – from the editors [email protected] and [email protected]

Advances in Spacecraft Engineering

On February 20th, 2024, Jamell Ivor Samuels of the Imperial College London released a preprint on ResearchGate titled “Advances in Spacecraft Engineering: A Comprehensive Plan for Future Missions.”

As the name implies, the paper presents a comprehensive overview of advancements in spacecraft engineering, focusing on key areas such as propulsion systems and autonomy and how they support more complex future missions, such as interstellar travel.

The explores the latest developments in materials science, additive manufacturing, and computational modeling for improving spacecraft design and performance. Additionally, the paper analyzes advancements in propulsion technologies, namely electric propulsion, nuclear thermal propulsion, and solar sails. It compares their potential for enabling ambitious space exploration missions and their relative feasibility. Furthermore, it examines the integration of advanced sensors, artificial intelligence, and robotics for enhancing spacecraft autonomy, enabling tasks such as maintenance, repair, and autonomous navigation, and the many benefits this could bring. Moreover, the paper explores emerging communication technologies, such as optical communication and quantum communication, and their role in enabling high-speed data transmission and secure communications in space. The paper concludes by noting areas for further research and innovation in spacecraft engineering.

The full paper can be found here: https://www.researchgate.net/publication/378313874_Advances_in_Spacecraft_Engineering_A_Comprehensive_Plan_for_Future_Missions

Light Sails Under Complex Conditions

University of Colorado’s publication Dean & Francis published a paper by Chenxi Wang on February 19th, 2024, titled “Analysis of Using the Light Pressure Effect to Drive Spacecraft under Complex Conditions.”

Under the current theoretical framework, a small-scale light pressure-driven spacecraft with suitable light sail materials is a highly competitive alternative for interstellar navigation.

This article commences with a thorough overview of the operating principles of light sails – namely the light pressure effect – and how it is different under complex environments. It then simulates the process of light pressure-driven spacecraft accelerating to sub-light speed through laser irradiation on the Earth’s surface and decelerating the returning spacecraft in a complex environment. The article comprehensively considers factors such as laser frequency, sail size, and spacecraft mass during the simulation process and provides simulation results under appropriate conditions. Due to the significant relativistic effect of this process, this paper also considers the red shift and blue shift effects of relativistic light in the simulation process. The paper concludes by noting the additional research and refinement necessary for light-sail missions to become truly feasible.

The full paper can be found here: https://www.deanfrancispress.com/index.php/te/article/view/459

The Ethical Side of Interstellar Travel

Cornell’s preprint server ARXIV published a preprint by Florian Neukart on February 23rd, 2024, titled “Toward the Stars: Technological, Ethical, and Sociopolitical Dimensions of Interstellar Exploration.”

Although the technological side of interstellar travel tends to get the most attention, it is important to recognize that the endeavor of interstellar exploration is a convergence of technical innovation and profound ethical inquiry, challenging humanity to extend its reach beyond the confines of our solar system while contemplating the moral implications of such a leap.

This paper explores the multifaceted aspects of interstellar travel with a unique structure that reflects this integrative approach. Following the introduction, it reviews the current technology state and theoretical frameworks underpinning interstellar travel in the Technical Foundations section. It then proceeds to the section on Ethical Considerations, examining the moral dilemmas posed by extending human presence beyond Earth or interacting with alien life forms. The Sociopolitical Implications section explores the governance and societal impacts of space colonization – including robotic colonization. In contrast, Philosophical and Evolutionary Perspectives elaborates on the existential questions and potential evolutionary trajectories for space exploration. Finally, the paper discusses the challenges and opportunities that lie ahead, asserting the importance of ethical stewardship and innovative thinking in navigating humanity’s future among the stars.

The full paper can be found here: https://arxiv.org/abs/2402.15536

Direct Radiation Pressure Measurements for Lightsail Membranes

On February 29th, 2024, Cornell’s preprint server ARXIV published a paper titled “Direct Radiation Pressure Measurements for Lightsail Membranes” by Lior Michaeli et al. of CalTECH.

Ultrathin lightsails propelled by laser radiation pressure to relativistic speeds are currently the most promising route for flyby-based exoplanet exploration. However, there has been a notable lack of experimental characterization of key parameters essential for lightsail propulsion. Therefore, a model platform for optomechanical characterization of lightsail prototypes made from realistic materials is needed – which this paper works to fulfill.

The paper’s model simultaneously measures the optical forces and driving powers, which capitalizes on the multiphysics dynamics induced by the driving laser beam. By modeling the lightsail with a 50-nm thick silicon nitride membrane suspended by compliant micromechanical springs, the paper quantifies force from off-resonantly driven displacement and power from heating-induced mechanical mode softening. As lightsails will inevitably experience non-normal forces, the paper also quantifies the effects of incidence angle and spot size on the optical force and explains the nonintuitive trend discovered by edge scattering. The paper’s findings stress the need for a self-stabilizing mechanism to support the sail during flight.

The full paper can be found here: https://arxiv.org/abs/2403.00117

Cable Actuated Solar Sails

On February 28th, 2024, Soojeong Lee and Ryan J. Caverly of the University of Minnesota published a paper on preprint server ResearchGate titled “Robust Cable-Actuated Shape Control of a Flexible Solar Sail Boom for the Cablessail Concept.”

Solar sails are one of the most promising technologies for interstellar travel, but they have attitude control challenges due to the significant disturbance torques that they encounter as a result of imperfections in the sail and its supporting structure, as well as limited actuation capabilities. The Cable-Actuated Bio-inspired Lightweight Elastic Solar Sail (CABLESSail) concept – which is explored in this paper – has thus been proposed to overcome these challenges by controlling the shape of the sail through cable actuation. The structural flexibility of CABLESSail introduces control challenges, which necessitate the design of a robust feedback controller for this system.

This paper aims to design a robust controller to ensure precise and reliable control of CABLESSail’s boom. Taking into account the dynamic properties of the CABLESSail concept, the paper designs a passivity-based PD controller for a single boom on the CABLESSail system and assesses it in numerical simulations. The simulation results show that this PD control is robust when applied to the linearized system but suffers from robustness issues when applied to the nonlinear system. The paper hence introduces a time-varying feedforward control input to mitigate this robustness issue, simulating with this addition.

The full paper can be found here: https://www.researchgate.net/publication/378678660_Robust_Cable-Actuated_Shape_Control_of_a_Flexible_Solar_Sail_Boom_for_the_CABLESSail_Concept

Raman Spectroscopy for Deep Space Applications

Open access publication MDPI published a paper on February 27th, 2024, by Yiheng Liu et al. titled “A Signal-Based Auto-Focusing Method Available for Raman Spectroscopy Acquisitions in Deep Space Exploration.”

With the development of technology and methodologies, Raman spectrometers are becoming efficient candidate payloads for planetary materials characterizations in deep space exploration missions. Ground testing with this equipment has revealed issues with the spectrometer focus and axial offset, which would obviously affect the acquired data.

To eliminate this error and, more importantly, simplify the application of Raman instruments in deep space exploration missions, this paper proposes an automatic focusing method wherein Raman signals are optimized during spectrum collection. It put forward a novel method that is realized by evaluating focus conditions numerically and searching for the extremum point as the final focal point. To verify the effectiveness of this method, it developed an Auto-focus Raman Probe (SDU-ARP) and performed various tests and simulations, which are included in the paper.

The full article can be found here: https://mdpi.com/2072-4292/16/5/820