I4is Science Fiction Book Club – Next meeting 19th October
The i4is SF Book Club members are considering again ‘The Road to Science Fiction Volume 3: From Heinlein to Here’ edited by James Gunn, a collection of selected short stories from the ‘Heinlein to Here’ era. We will be reading and discussing stories 12, Critical Factor by Hal Clement, and 13, Fondly Fahrenheit by Alfred Bester but also open to more discussion/debate.
The meeting will be on Zoom, Thursday 19th October at 1900 UK time. Mark the date in your calendar! To join the club, please email firstname.lastname@example.org for the link.
I4is recently started this science fiction book club for readers and writers. We read and discuss stories that take the eyes above and beyond the horizon, tales that inspire minds and hearts to leap from here and now to tomorrow and elsewhere. We examine stories for both their readability and for what we can learn from them as writers. Due to the worldwide nature of the i4is membership, this book club will be held once a month on Zoom.
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.” To ensure a level playing field, submissions must be in Shunn’s Modern Manuscript format, the widespread standard for fiction submissions. https://www.shunn.net/format/story/ (Make sure you click the Modern tab.) Further information is available – or just send submissions as email attachments – to the editors email@example.com and firstname.lastname@example.org
"Project Icarus meeting – 30th September at the British Interplanetary Society HQ (Vauxhall, London) and available online
Many of you will know that a number of the i4is members were part of the BIS Project Icarus – a study to design a fusion-powered interstellar space probe. There is a special symposium to be held at the BIS HQ on Saturday 30th September which will be a ‘hybrid’ meeting ie can also be watched online or in-person (note: watch out with travel plans, a rail drivers strike has been called for that day). If interested in finding out more information or signing up, go to: https://www.bis-space.com/event/project-icarus-the-latest-on-an-interstellar-design/
Our team at i4is has been working with using SOHO's SWAN instrument to look at potential water outgassing from Oumuamua. The data had so far been overlooked. Their preliminary results indicate that no hydrogen-containing outgassing that would explain the acceleration was detected. If this is true, it rules out the hydrogen/water iceberg hypothesis. The nitrogen hypothesis remains possible, although it makes 1I very unusual. Using a simple force equation with mass flow x exhaust velocity x collimation degree which shows that to explain the acceleration by lower outgassing levels, 1I would have to be much lighter than existing comets. Hence no matter how you turn things, you end up with a highly unusual – and likely interstellar – object. Exciting news for sure! If interested in finding out more information or signing up, go to: https://www.bis-space.com/event/project-icarus-the-latest-on-an-interstellar-design/.
An Interstellar Discovery or Not?
A research team headed by Harvard astrophysicist Avi Loeb made headlines a few weeks ago when it claimed to have scooped up from the sea floor fragments of a meteorite that came from beyond our Solar System. Finding such an interstellar sample on Earth would be incredibly exciting because it might shed light on how planets and stars beyond our own form. Loeb’s team had found small metallic spherules off the coast of Papua New Guinea’s islands. The unique spherules show an excess of Be, La, and U, by up to three orders of magnitude relative to the solar system standard. Loeb’s report was published on Cornell’s preprint server ARXIV on August 29th, 2023, and can be found here: https://arxiv.org/abs/2308.15623.
However, several scientists say that the evidence that the material came from another planetary system is not convincing so far. Some claim that an analysis of the oxygen isotopes in the spherules is necessary, as an analysis of the atomic composition is rather unreliable. These isotopes are very similar in objects from the Solar System but different in those from other planetary systems. Moreover, Loeb asserts that the spheres came from a meteorite that hit Earth in 2014, which they say arrived from interstellar space. But many specialists disagree saying the characteristics of the meteor do not suggest an interstellar origin. More can be found here: https://www.nature.com/articles/d41586-023-02823-y.
Swarming Proxima Centauri
On September 12th, 2023, a paper titled “Swarming Proxima Centauri: Optical Communications Over Interstellar Distances” was published on the preprint server ResearchGate. Authors of this paper include i4is’s own Adam Hibberd and Robert G. Kennedy. The paper discusses the challenges associated with spacecraft communication over interstellar distances and proposes using a swarm of 100s–1000s of “operationally coherent” spacecraft to simultaneously and feasibly transmit a reasonable number of signal photons to Earth. These probes would be similar, but not identical copies of each other as each would be intended for a particular purpose. The velocity of these probes would have to be modulated by the launch laser to ensure none of them fall behind. The swarm would communicate with each other through optical means, to then create a signaling array to communicate back with Earth.
The paper also discusses additional advancements and resources needed for such a mission, namely a highly powerful clock, reliable down to the picosecond, to enable a swarm of widely separated small spacecraft or small flotillas of such to behave as a single distributed entity. There is also the need for a powerful laser and accurate predictions of the location of the bodies in the Proxima Centauri system over the next 40 years. The paper also includes additional mission concept details such as a step-by-step of the fly-by and a discussion of power sources. The full paper can be found here: https://www.researchgate.net/publication/373833951_Swarming_Proxima_Centauri_Optical_Communications_Over_Interstellar_Distances
An Interstellar Precursor Mission
Cornell’s preprint server ARXIV published a paper by Julius Karlapp et al titled “Ultrafast transfer of low-mass payloads to Mars and beyond using aero graphite solar sails” on August 31, 2023. With interstellar mission concepts now being under study by various space agencies and institutions, a feasible and worthy interstellar precursor mission concept will be key to the success of the long shot. Hence this paper investigates interstellar-bound trajectories of solar sails made of the ultra-lightweight material aerographite. Due to its extremely low density and high absorptivity, a thin shell can pick up an enormous acceleration from solar irradiation. Payloads of up to 1 kg can be transported rapidly throughout the solar system.
This paper focuses on the potential of solar lightsails to carry small payloads to Mars in short times, that is, weeks to months. Considering NASA’s interest in putting humans on Mars, the paper believes that such a precursor mission would serve two purposes and hence be the most likely to be accepted and actually executed. The paper uses simulations to consider various launch scenarios from a polar orbit around Earth including direct outbound launches as well as Sun diver launches towards the Sun with subsequent outward acceleration. The paper also includes a trajectory analysis of such a spacecraft, and it could then easily be adapted to reach interstellar space in just 5.3 years. The full paper can be found here: https://arxiv.org/abs/2308.16698
On September 8th, 2023, the Journal of Spacecraft and Rockets published a paper by Larry Silverberg and Jeffrey W. Eischen titled “Trajectory of a Spacecraft When It Passes by a Gravitational Body During Interstellar Travel.” As we all know, interstellar missions that reach their destinations within a generation will require spacecraft that navigate across the cosmos at relativistic speeds. The planning for these missions will therefore be heavily based on simulation software that performs mission design tradeoff studies, energy and cost budgeting, astronavigation optimization, etc. In terms of the underlying physics, these codes will have to predict a spacecraft’s relativistic trajectory as it passes by a gravitational source. This paper applies a new relativistic formulation of mechanics that can greatly simplify these predictions.
The paper first outlines the mechanics of such an interstellar mission, including how relativistic velocity and acceleration would be achieved. To this end, it develops geometric models of acceleration and velocity and derives a few governing equations. From these findings, the paper analyzes various relativistic orbital trajectories, including various interactions with a multitude of different gravitational bodies. It then discusses the various precautions and modifications that would have to be made to an interstellar probe to allow it to accomplish its mission despite some gravitational interaction. The full paper can be found here: https://www.mae.ncsu.edu/eischen/wp-content/uploads/sites/17/2023/09/LMS-JWE-JournalSpacecraftRocketsSept2023.pdf.
Diffractive Light and Solar Sails
On August 21st, 2023, Rochester Institute of Technology published a thesis by Prateek Ranjan Srivastava titled “Diffractive Light and Solar Sails.” The thesis proposes using an elementary space variant diffractive film to design passively stable light sails propelled by laser radiation. It also explores the application of this concept to solar sails, enabling spiral trajectories and high orbital inclination angles at close solar orbits. It details the challenges of both approaches and provides a material analysis describing what composition would serve as the ideal light sail material.
The main focus of the thesis focus is on a ’bi-grating’ light sail, designed for stable ’beam-riding’ on a Gaussian laser beam. This concept aligns with the Breakthrough Starshot program, which aims to propel an ultra-lightweight sail to a nearby star at relativistic speeds. The paper also presents alternative light-sail designs – such as a conical mirror sail and spherical sail – but then explains why such designs are inferior to the bi-grating light sail. The paper analyzes stability conditions and evaluates 2D and 3D configurations of different light sail situations and designs. Leveraging advanced multi-objective optimization techniques, the thesis presents a solar sail with the highest force and lowest mass for maximum acceleration with a detailed mission concept and analysis. The full thesis can be found here: https://scholarworks.rit.edu/theses/11547/.