Illustration of photonic laser thruster infrastructure for in-space transportation in cislunar space. Credits: Young K. Bae
Y.K. Bae Corp is on the verge of testing a revolutionary photonic laser thruster (PLT) that could be a game changer for in space propulsion and interplanetary travel. Founder and Chief Scientist Young K. Bae Ph.D described the technology in a recent Future In-Space Operations (FISO) Telecon presentation. The secret is generating thrust through photon pressure of a recycled laser beam enabling high energy to thrust efficiency without onboard propellant. Y.K. Bae Corp’s Continuous-Operation laser thruster or PLT-C is capable of delivering continuous thrust for long periods of time (e.g. days – years). The crew/payload section of the craft contains no power supplies, fuel or rocket engines. A power source is needed at the destination to generate a velocity reversal and stopping beam.
Dr. Bae believes an in-space “photonic railway” using this technology could open the solar system to commercialization and laid out a timeline for development of the photonic laser thruster. He believes that a 1 Newton (N) thrust PLT demonstration on the ISS could be accomplished within 3 years, a 50-N thrust PLT suborbital lunar launch is possible within 10 years, transits to the Moon can be done within 20 years and trips to Mars/Asteroids are projected to be in the 30 – 40 year timeframe.
When scaled up, super high ∆v can be achieved using the PLT. With a total electric laser power of 1000MW, travel times from the Earth to Mars could be achieved in less then 20 days for a 1-ton ship with 50% payload. From Mars out to Jupiter, a trip would take about 45 days for a craft with the same mass. The PLT spacecraft could be the main mode of rapid in-space transportation for humans and high price or lighter commodities after conventional thrusters (e.g. chemical rockets) establish the initial infrastructure and continue as the transportation choice for low cost or heavier payloads.
Illustration of a photonic railway using PLT infrastructure for in-space propulsion established at (from right to left, not to scale) Earth, Mars, Jupiter, Pluto and beyond. Credits: Young K. Bae.
Y.K. Bae Corp has demonstrated the photonic laser thruster technology in the lab. Check out their cubesat demo video.
Artist renderings of an autonomous pneumatic handling system using SHEPHERD technology. An asteroid is first carefully enclosed in a touchless manner within a sealed fabric envelope, de-spun and de-tumbled through friction with an introduced controlling gas, then driven by continuous gas flow to introduce delta-V and deliver the asteroid to a target destination. Chemical and thermal interaction between the introduced atmosphere and the asteroid will permit fuel and water extraction, 3D electroforming of parts from metal sources and the creation of in-space biospheres to feed large habitats. Concept depicted by: Bruce Damer and Ryan Norkus with key design partnership from Peter Jenniskens and Julian Nott. Note: all of the illustrations in this post are credited as above unless otherwise indicated
The SHEPHERD concept for gentle asteroid retrieval with a gas-filled enclosure, an SSP favorite open source technology, has been covered in a previous post. Dr. Bruce Damer, one of the coinventors of the system, recently appeared on SpaceWatch.Global’s Space Café podcast where he revisited this promising technology for capturing asteroids, mobilizing them and extracting key materials to support space settlement (which can be found near the end of the recording). SHEPHERD could solve the three main sourcing problems of sustainable spaceflight and habitation: harvesting volatiles, building materials, and sources of food. Dr. Damer has also been busy with his (and UCSC Prof. David Deamer’s) Hot Spring Hypothesis, a testable theory regarding the place and mechanism of the life’s origins on the Earth, which was the main focus of the podcast. In fact, the arc of his career has tied these two endeavors together in interesting ways. SSP reached out to Dr. Damer for an exclusive interview via email on these groundbreaking topics.
SSP: Dr. Damer, thank you so much for taking the time to answer my questions about SHEPHERD. I’ve been excited and intrigued with the technology ever since I saw the initial paper and your 2015 TEDx talk. Can you give our readers an overview of the concept?
Damer: The goal for SHEPHERD is to provide a universal technology to open the solar system to sustainable spaceflight and beyond that, to large scale human colonization (see figures and explanations for Fuel, Miner and Bio variants below). Enclosing an asteroid (or Near-Earth Object-NEO) within a fabric membrane and introducing a controlling gas would turn that asteroid into a “small world”. The temperature of the gas, its chemical composition and gas pressure forces set up within it can enable multiple in-situ resource utilization (ISRU) scenarios. Initially, the extraction of water and other volatiles from icy NEOs could provide fueling stations with deliveries throughout the solar system. Next, the use of the Mond-process carbonyl gas extraction from high-metallic NEOs can provide electroform 3D printing of large parts in space for construction of habitats. Lastly, melting the ice content of a NEO to a liquid phase surrounding its rocky core enables the introduction of microbes, algae and even some aquatic animals into a biosphere, a mini-Earth terrarium sustained in space. This one invention could provide many of the elements necessary for sustainable spaceflight but also for the construction and support of in-space and surface-located planetary and lunar habitats for thousands or millions of inhabitants. Co-inventor of the design, Dr. Peter Jenniskens at the SETI Institute, calls this the “sailing ship for space” harkening back to how his Dutch ancestors helped open the Earth to commerce centuries ago.
SHEPHERD-Fuel variant with volatiles such as water ice sublimating from the NEO into a warming gas, the resulting water vapor pumped down and condensed into liquids in storage tanks and then separated into hydrogen and oxygen. These tanks become the fuel source for a self-propelling tanker block which can be delivered to a refueling rendezvous point such as Earth cislunar space or Mars orbitSHEPHERD-Miner version with an introduced carbonyl gas and an electric field dipole drawing off ions from a metallic NEO and layering them on a mandrel (shown on the left) to create a precision 3D part such as blocks, beams or tanks for space habitat constructionSHEPHERD-Bio variant sustaining a liquid biosphere around the rocky core of a NEO, with a lit interior and boom to introduce and extract organic materials. A balance of microbes, algae, and even small aquatic animals could maintain this small world, a “terrarium in space” to support large populations in habitats and at surface coloniesSHEPHERD-Fuel variant in Mars orbit or at some distance away showing the delivery of re-fillable tanker block sections to a Mars mission, the nearly empty block propelling itself for refilling. In this way ample fuel is provided in-situ prior to the craft arriving at Mars, with mission lander fuels, water for human consumption, shielding and return propellant provided in orbit in advance without having to extract volatiles from the Mars atmosphere or regolithVision of SHEPHERD Miner and Bio variants supporting a large habitat in LEO with the mantra of: “built in space, and fed in space”
SSP: Have there been any developments or updates to the concept since the initial TEDx talk and NewSpace Journal paper which both came out in 2015?
Damer: Back then we thought that no company or government had the will or capability to invest in such an opportunity, but this is now changing. The roaring success of NewSpace ventures such as SpaceX and their dual award of NASA’s Artemis Program returning humans to the moon based on reusable crewed launches and their recent successful low altitude testing rounds for Starship, has totally changed the space landscape of the near future. Jeff Bezos’ vision for megastructures in space based on the O’Neill colonies of the 1970s would require substantial asteroid resourcing. Elon Musk’s vision for large surface colonies on Mars would be equally well supported by simple, automated space based ISRU which overcomes substantial mining and manufacturing hazards attempting to process bulk materials on the surface of Mars or the moon. In addition, Bigelow’s success with inflatables, China’s surging space program with a new crewed station and rovers on the moon and Mars, all point to much more traffic and demand, especially for fueling depots, as early as the mid-2030s. Reducing the cost of lifting heavy and bulky materials from Earth may never be competitive to extraction, electroforming and farming in space with low-cost delivery directly to points of demand.
Earlier this year I determined that the time was right to place our invention out into the field again and seek partners to join in a development roadmap that will provide a solid financial and technical ladder for SHEPHERD’s maturation.
At a NASA/SETI meeting in January 2019 I was discussing SHEPHERD with members of the Luxembourg Space Agency and was overheard by space entrepreneur Carlos Calva. He approached me and offered that he would work with me to make SHEPHERD into a business. Subsequent meetings at SETI with my co-designer Peter Jenniskens (Julian Nott had died tragically in a ballooning accident) gave us early insights into SHEPHERD’s developmental timeline.
In that spring of 2019 Carlos and I engaged in a rapid-fire series of meetings developing a short-term cash business model for SHEPHERD which would provide a financial lever for the technology. Capturing, moving, and extracting resources from asteroids is a longer-term (15+ years) play, with no immediately apparent buyer for the first potential products: volatiles for propulsive fuel, air, water, and other crew consumables. Elon Musk and SpaceX might reach a point in this decade when they would buy a futures contract for hundreds, or thousands of tons of water and fuel delivered into Earth and Mars orbits sometime in the 2030s. Jeff Bezos may also want to finance the development of SHEPHERD as a technology for delivery of resources to build space habitats much as he has with Amazon’s funding of drone and other robotic fulfillment innovations.
But how to prove SHEPHERD as a technology and then sustain it as a business for long enough to be ready for either of these clients? We settled on two emerging market opportunities: 1) satellite servicing and decommissioning, and 2) hazardous debris removal and deorbiting. Both are potential cash businesses that could provide us achievable milestones to support the multiple investment rounds required. Satellite servicing and debris removal or de-risking is an urgent unmet market need for both governments and commercial operators worldwide. Along with the CubeSat revolution, SpaceX’s reusable launch platform and Bigelow Aerospace’s success with the inflatable Genesis and BEAM module on the ISS, many core technologies were maturing.
Making SHEPHERD into a viable sailing ship for space will not be without its challenges. Designing and flying a fabric enclosure which can open, admit an object (a satellite, a chunk of debris, or a space rock) and then closing it tight, sealing it well enough to fill it with a controlling gas was a major technical challenge which NASA identified in their review of our 2014 Broad Agency Announcement proposal for the asteroid redirect program (since cancelled). The tried-and-true way to make a new space system work reliably is to build scale models, test them to failure, and test them again.
SSP: You mentioned that some of the capabilities of the system could be tested in LEO with CubeSats. Since the technology is open source, has anyone reached out to you to develop hardware for such an experiment? What would be tested and how?
Damer: Carlos and I made a bee-line for the world-renowned annual CubeSat Developer Conference meeting at Cal State San Luis Obispo in April of 2019 where we were able to interact with many of the leading thinkers and solution providers in the CubeSat industry. We devised a back-of-an-envelope LEO test vehicle flight series and made some key contacts. For a small investment (2-4 million USD), an effective six test flight series with a 4U CubeSat would first deploy a gas filled bag into which we could release a target object (such as a real meteorite which would be returned to space). The images below depict this scenario. Later flights in the series could have the target released to space and then the CubeSat would match orbits, track, enclose and seal the object into the enclosure. Key for any test is the ability to manage the object within the enclosure such that it does not contact the fabric. This would not be an issue for our small CubeSat, but it would be a potentially catastrophic encounter for a satellite or NEO. The key to safety (SHEPHERD stands for Secure Handling through Enclosure of Planetesimals Headed for Earth-Moon Retrograde Delivery) is that the system is touchless. In the image below we see gas jets firing to move the object toward and hold it in the center of the enclosure.
SHEP Cube test vehicleInflation of bag enclosure using controlling gas, introduced target object (perhaps a meteorite returned to space)Management of target object position with gas jetsLit interior showing target centered safely in the enclosure
All of this early effort to build and fly the CubeSat missions would mature our IP including: tracking, gas fluid dynamics for handling and enclosure deployment and sealing. We could then value the company and seek a round of investment from governmental or commercial partners in the satellite servicing and debris removal markets.
SSP: How do you foresee these two potential near term commercial applications generating sufficient revenue to “pay the way” for SHEPHERD to achieve its long-term goals?
A much larger SHEPHERD version with an enclosure for capture and servicing of a high value large satellite. Servicing could either be carried out with a robotic bay or by astronaut mechanics flying on SpaceX Dragon, who enter through an airlock and can breathe a low-pressure Earth atmosphere negating the need for bulky EVA/space suits
Damer: Paying the way for SHEPHERD could come from a mixture of satellite servicing (expensive “big birds” for the US DOD or communication satellite operators), orbit graveyarding (for GEO, or de-orbiting from LEO), and of course mitigation of dangerous space debris to head off Humanity’s disastrous encounter with the “Kessler syndrome” as depicted in the movie Gravity. In-space satellite servicing via robotic spacecraft is problematic, requiring very high-risk grappling procedures between vehicles which have no built-in standard grappling mechanism. SHEPHERD provides a gas-based “pneumatic” way to safely envelop and control spacecraft without hard contact. Early computational studies at the SETI institute in 2014 established that a shape model of multi-ton asteroid 2008 TC3 could be de-tumbled and de-spun in less than 24 hours if the object was interacting within a gas at 10% Earth atmosphere pressure. The friction of the satellite or chunk of debris with the gas will bring it to a standstill, then gas jets can be used to rotate and position the enclosed spacecraft for servicing. Imparting a continuous driving force onto the craft using these same jets can create sufficient delta-V to change its orbit. Such safe handling and mobilization of objects in space is key to a whole range of future space operations. The irregularity of satellite shapes (including long booms or antennae) presents fewer challenges to SHEPHERD’s scale and size-independent gas handling system than they would to a robotic or crewed “jet pack” style EVA servicing as we saw with the Space Shuttle’s Hubble servicing missions.
If a satellite servicing, extension of life, or safe decommissioning capability were clearly on the horizon, supporters of international treaties and reinsurance companies could create guaranties, service contracts and insurance instruments which would finance a first generation of SHEPHERD vehicles.
SSP: What do you see as the full vision for the sustainable space architecture which SHEPHERD could enable?
A full vision of the architecture enabled by SHPHERD supporting near-Earth habitats, interplanetary missions, and a class of continuously cycling robotic and crewed spacecraft. Cycling visits of SHEPHERD ISRU supply depots could capture, relocate and extract from asteroids of all sizes and compositions. Eventually a mature SHEPHERD architecture could scale up enclosure sizes to provide the Earth a comprehensive planetary protection shield from larger NEO impact hazards
Damer: The image above depicts the enabling of SHEPHERD-derived spacecraft and processing facilities to support both near Earth space stations and larger megastructure colonies, robotic and human exploration of the inner solar system and beyond. I envision the SHEPHERD business being most akin to the mining industry I was raised around in British Columbia and as depicted in the Sci Fi series The Expanse. Some companies would fly prospecting (and orbit determination) missions to NEO targets, file claims and then sell them on to development companies. Those companies would license or build SHEPHERD-class spacecraft financed through contracts for future deliveries of commodities to companies and governments. Buyers would eventually acquire the risk-taking development companies and leverage them to support much larger projects such as space settlement megastructures or to supply Mars surface colony operations. Over time, scaling of the SHEPHERD system enclosure sizes would permit the safe handling and redirection of Earth-threatening asteroids giving us all a planetary protection shield. A great deal of Astrobiology science could also be supported such as the delivery of a pristine carbonaceous asteroid to Lunar orbit (see below) for astronaut geologists to sample. These samples might give us clues as to how life began on the Earth through the delivery of abundant organics from asteroids like this.
Release of pristine asteroid into Lunar orbit to support sampling by Astrobiologists looking for clues to life’s origins on the Earth, four billion years ago
SSP: What are the next steps for SHEPHERD?
Damer: The COVID-19 pandemic caused a pause on SHEPHERD’s development both as an engineering concept and a business. When I was invited to appear on the Space Café podcast in April (of 2021), I decided to bring it up again to gauge public interest and bring it to leaders in New Space. This interview with you is the next step in developing that interest, calling forward a development team. What I am also seeking is critical input from the community on the concept, leadership in research, and the formation of a company or university research program with financial support for the early on-ground computational and test-article studies leading up to CubeSat flights.
I specifically “open sourced” the basic concept of SHEPHERD on behalf of the three co-inventors in my 2015 TEDx talk, but IP developed by one or more implementers of this core concept can provide them and their investors with protectable value. The seal closure will be one key patentable innovation. Together with a team of keen and willing supporters including myself and Carlos, we produced a pitch deck which was first premiered at the Space Resources Roundtable held at the Colorado School of Mines in May of 2019. This deck concisely lays out the initial cash business in satellite servicing and debris removal and the engineering we have done around the CubeSat and larger variants. Carlos is back at work on the key steps of recruiting engineering leadership and funding for the ground-based development. I am open to inquiries from qualified contacts who wish to discuss their involvement seriously.
SSP: As you described above, of the three key applications of SHEPHERD, one could be food production for space settlements by creating a fully self-contained biosphere out of an asteroid, a mini-Earth if you will. This complements your Hot Springs Hypothesis for life’s beginnings in its method for seeding space with life beyond Earth. Is there an underlying principle linking the origin of life and humanity’s role in extending it beyond the cradle of the Earth?
Series of three images showing cellular mitosis beginning with fission of the nucleus, mitosis underway and completion of the process with daughter cells separatedSHEPHERD Bio with image of Earth overlain on its 500m diameter terrarium worldMitosis of the Earth into “daughter worlds” represented by the arising of SHEPHERD-Bio in the solar system
Damer: Thank you for asking this question! A couple of years ago I literally sat bolt upright in bed having had a dream of a future vision of the solar system, possibly from the year 2100. A ring of asteroids had become enclosed with SHEPHERD craft or some derivative thereof, and thousands to millions of “new worlds” were orbiting the sun. In nearby orbits were the sharply geometric and tubular shapes of space settlements under construction, housing billions of humans and the organisms with which they cohabitate. Evolution had a future path, moving off our birth world by first creating many new ones. Like the first living cells, the Earth had undergone a spectacular mitosis! I realized in a flash that this future solar system was a huge scale evolution of the ancient hot spring pool cycling with membrane-enclosed protocells which Dave Deamer and I have proposed for life’s beginning. The principal of membranous encapsulation enabling chemical activity and resource sharing acted out four billion years ago in hot spring pools would return to enable life to emerge from the womb of the Earth into a long evolutionary future in the cosmos. It was truly gratifying. You can see how I then wove together these stunning parallel visions in my two TEDx talks below.
The SHEPHERD project is dedicated to the memory and genius of Julian Nott (right) at home in Santa Barbara during my 2014 visit
Artist rendering of a Direct Fusion Drive nuclear rocket. Credits: Princeton Satellite Systems
A small New Jersey company called Princeton Fusion Systems (PFS) is close to developing a nuclear rocket using an innovative reactor that could also have applications that are down to Earth. Called the Princeton Field Reversed Configuration (PFRC) reactor, the system is based on over 15 years of research at the Princeton Plasma Physics Laboratory (PPPL), with funding primarily by the U.S. DOE and NASA. PFS, a subsidiary of Princeton Satellite Systems, could have a space based system by the end of this decade which could significantly reduces trip times to the outer solar system and increase payload capability while ensuring a robust power source at the designation. The second iteration of the research reactor, PFRC-2, is currently undergoing testing at PPPL.
Second generation Princeton Field Reversed Configuration (PFRC-2) undergoing testing at Princeton Plasma Physics Laboratory. Credits: Princeton Plasma Physics Laboratory
The PFRC reactor is simple, small and produces very little radiation through the fusion of deuterium and helium-3. This makes it uniquely suited for space-based applications. The field-reversed configuration is a magnetic-field geometry in which a toroidal electric current is induced in a cylindrical plasma by radio frequency (RF) heating. The plasma is confined in a “magnetic bottle” composed of a linear array of coaxial magnets. The design is compact (about the size of a minivan) as compared to some of the more complex fusion devices currently under development such as the ITER donut shaped tokamak. A Princeton Satellite Systems video explains how the PFRC reactor is used in a DFD for space applications by exhausting fusion byproducts out one end of the device through a rocket nozzle:
In May of 2019, Stephanie Thomas, a VP at Princeton Satellite Systems made a presentation at the Future In-Space Operations working group on the DFD technology. Of particular note was the slide on the product development roadmap on technology readiness for flight hardware. If all goes according to plan, fusion could be achieved in the fourth generation research reactor PFRC-4 within 5 years and a flight ready payload could be launched before this decade is out.
DFD notional roadmap to flight. Credits: Stephanie Thomas, Princeton Satellite Systems
Travel time for a 1-2 MW fusion engine and 10,000 Kg payload would be 1 year to Jupiter, 2 years to Saturn and 5 years to Pluto, a significant reduction over chemical rockets using gravity assists. Many other missions to the outer solar system and beyond have been scoped by Princeton Satellite Systems using this technology. In his thesis for a Master Degree in Aerospace Marco Gajeri used the DFD architecture to design a trajectory for a mission to Titan. This blog covered a trip to Saturn using the DFD back in 2019. An interstellar mission to Alpha Centuari has also been considered.
The PFRC reactor has a multitude of clean energy applications on Earth as well:
A new YouTube channel has just been launched called Space Matters. Hosted by Rhonda Stevenson, President/CEO of the Tau Zero Foundation, the show is a weekly digest covering a wide array of current space activities, challenges and accomplishments which aims to show how our success in space will improve life on Earth. This could become an influential forum for discussion among industry leaders on how to steer humanities course toward becoming a spacefaring civilization. The first episode, a panel discussion with pillars of the space industry, aired on March 20th and featured Jeff Greason of Tau Zero and Electric Sky, Justin Kugler of Redwire Space, Grant Anderson of Paragon Space Development Corporation, Andy Aldrin of the ISU Center for Space Entrepreneurship, at FIT and Rod Pyle, editor of Ad Astra and author of Space 2.0. The group had a lively discussion on each of their contributions to space development as well as current trends in the New Space economy. Subscribe to get an update every week on why Space Matters.
Artist’s concept of an Alcubierre warp drive starship. Credits: NASA via Phys.org
New research is bringing us closer to understanding the physics of two modes of interstellar travel popularized in science fiction. The first is a paper by Alexey Bobrick and Gianni Martire at the Advanced Propulsion Laboratory at Applied Physics in New York on physical warp drives. Readers may remember the initial excitement of the Alcubierre warp drive and then subsequent disappointment when the devil came out of the details, namely that “negative energy” (what ever that is) and lots of it were needed to make the concept work. Even Dr. Miguel Alcubierre had doubts about the feasibility of this “unphysical” approach and moved on to different areas of research in theoretical physics such as gravitational waves and black holes, as he explained at the Starship Congress 2017 and later on The Space Show.
In this new paper the authors show that it is theoretically possible to construct a class of subluminal warp drives based on physical principles known today. Even Sabine Hossnefelder, a theoretical physicist at the Frankfurt Institute for Advanced Studies, was impressed by this paper and gives a good overview in this short video.
A second line of investigation involves wormholes as shortcut conduits through spacetime. In a paper in Physical Review D, researchers Juan Maldacena and Alexey Milekhin show that with accelerations less than 20 g, a human-traversable wormhole is theoretically possible making a journey across the galaxy in less than a second! Of course the practical engineering details, not to mention discovery of an actual worm hole, remains to be realized.
Artist impression of a human traversable worm hole. Credits: Tomáš Müller via Quanta Magazine
Understanding the physics of interstellar space travel is the first step toward practical engineering solutions for the methods of transportation humanity will use in our spacefaring future. Skeptics may need reminding that there were doubters that considered the possibility of space ships carrying humans to the Moon a fantasy over 100 years ago when Tsiolkovsky and others first worked out the physics of the rocket equation.
Image of an interstellar Worldship. Credits: Michel Lamontagne / Principium, Issue 32, February 2021
The feasibility of Worldships has been covered previously on SSP by The Initiative and Institute for Interstellar Studies via Principium. A new article by Michel Lamontagne on page 29 of the most recent issue examines the concept from a perspective of an interplanetary society which has harnessed fusion energy and life support systems for space settlements, while reducing costs through self replicating factories.
Such a starship is envisioned to use a deutrium/He3 fusion drive to accelerate to 1% of the speed of light completing a journey to Alpha Centauri in about 430 years. The author envisions a fleet of 3 or 4 (or more) Worldships housing about 1000 passengers each in rotating torus habitats 1,200m in diameter with artificial gravity.
Image of the interior of a worldship habitat. Credits: Michel Lamontagne / Principium, Issue 32, February 2021
Self replication is the key to this architecture. Lamontage explains: “If fully self replicating systems exist at the departure of the mission, Sprinter starships carrying self replicating machines can be sent at the same time as the Worldship flotilla departs. The Sprinters will arrive centuries before the Worldships, and the self replicating machines will have ample time to create multiple habitats, and perhaps begin to seed them with simple life forms.”
Lamontage cautions that the needed AI technology and practical self replicating machines may be more difficult to develop than predicted. The Worldship habitat ecosystems may encounter instabilities over centuries-long journeys leading to eventual breakdown of life support systems. Finally, rapid technological advances may lead to advanced propulsion schemes or other opportunities that would make a Worldship obsolete before getting started.
Artist’s depiction of propulsion concept using Directed Energy. At left, Directed Energy Launch Technology Array (DELTA) beams power to laser powered electrical propulsion (LEP) spacecraft for rapid travel to the outer solar system or for laser sailing to the stars. At right, a sub-module from a close packed array of laser emitters within DELTA. Credits: Todd F. Sheerin / International Astronautical Federation
A concept for fast transit to the outer solar system and beyond has just been published by Todd F. Sheerin et al.* in Acta Astronautica. Since the article is behind a paywall, SSP has obtained permission by one of the coauthors, Professor Philip Lubin at the University of California, Santa Barbara to link to an earlier version of the paper presented at the 70th International Astronautical Congress held in Washington D.C. back in October 2019. Professor Lubin is Director of the Experimental Cosmology Laboratory at UCSB where he oversees research on several interesting directed energy projects.
The concept makes use of an Earth-based Directed Energy Launch Technology Array (DELTA) to beam laser energy to photovoltaic cells on an electric propulsion vehicle for travel within the solar system, or for photon reflection via a laser sail on gram-scale spacecraft accelerated to relativistic speeds for interstellar missions. In the former case, this method leverages existing solar electric propulsion technology which converts optical energy to propulsive jet power like what was used on NASA’s Dawn mission. An existing NASA Innovative Advanced Concepts (NIAC) program at UCSB has demonstrated proof of concept for elements of the array.
The DELTA architecture development can be terraced in progressive stages starting with small one meter arrays building up to large 10 km systems. The concept could support a range of missions, from swarms of gram-scale robots all the way up to human-rated spacecraft greater than 100 tons.
The authors believe this approach “… enables a scalable, cost effective roadmap to rapid solar system transportation for robotic and human missions alike, including robotic and human Mars-in-a-Month missions, with transit times of 30 days, as well as the first robotic relativistic interstellar flight within our lifetime.”
* Authors: Todd F. Sheerin, Elaine Petro, Kelley Winters, Paulo Lozano, Philip Lubin
Illustration of a nuclear thermal rocket in low earth orbit. Credits: NASA
Two U.S. companies are partnering with NASA to develop new fuel sources and reactor designs for future nuclear-fueled crewed space missions. Nuclear thermal and fusion powered rockets could significantly reduce the travel time to the Red Planet, lowering the risk of radiation exposure and the cost of life support consumables.
In an article in IEEE Spectrum, freelance journalist Prachi Patel describes the challenges of designing space nuclear reactors that are safe and lightweight, which will be needed to propel exploratory missions to Mars. These type of space reactors have the added benefit of being able to switch from propulsion to a power source at their destination.
Seattle based Ultra Safe Nuclear Corporation has a reactor design that uses a grade of nuclear fuel enriched to less then 20% uranium classifying it below the limit of highly enriched uranium, thus reducing proliferation risks by nefarious actors. The company coats its microscopic uranium fuel pellets with ceramics in a zirconium carbide matrix. This design approach ensures that the fuel can withstand the extremely high temperatures and volatile conditions inside a nuclear thermal reactor.
BWX Technologies Corporation located in Lynchburg, Virginia has extensive space nuclear reactor experience and has been working under contract to NASA since 2017 to explore designs also using a temperature resistant ceramic composite fuel with low enriched (< 20%) uranium.
Both companies may benefit from the recent Trump Administration Space Policy Directive-6 released December 16 which aims to limit the use of highly enriched uranium in space nuclear reactors unless absolutely necessary. The Memorandum on the National Strategy for Space Nuclear Power and Propulsion specifies that “The use of highly enriched uranium (HEU) in SNPP [space nuclear power and propulsion] systems should be limited to applications for which the mission would not be viable with other nuclear fuels or non‑nuclear power sources.” Although Space Policy Directives can be negated or modified by new administrations this particular directive should have bipartisan appeal.
The article also mentions the Princeton Plasma Physics Laboratory’s Direct Fusion Drive that SSP covered last year. Fusion rockets, although further behind in technology readiness levels, hold promise to outperform fission-based propulsion as fusion reactions release up to four times as much energy.
The Space Show – the nation’s first talk radio show focusing on increasing space commerce, advancing space science and economic development, facilitating our move to a space-faring economy which will benefit everyone on Earth – needs your help. The Space Show is hosted by Dr. David Livingston, who completed his doctoral dissertation in 2001 on the commercialization and expansion of space development. Take a moment to visit The Space Show website and read Dr. Livingston’s end of year message. Please give generously to ensure this valuable resource continues to promote, encourage, and support future global economic opportunities, scientific discoveries, and medical advances for all humankind through peaceful and cooperative ventures in outer space.
Space is Open for Business by Robert Jacobson is a must-read for all potential “astropreneurs” (entrepreneurs involved the NewSpace economy), space advocates, investors or anyone who wants to keep current on space commerce and its impact on the future of humanity. This book is a refreshingly positive view of our future in space, a welcome alternative outlook in stark contrast to many dystopian and negative predictions of where we’re headed in today’s media.
Jacobson covers all aspects of the nascent space economy which has already begun to grow in leaps and bounds, and is headed for explosive growth in the near future. No stone is left unturned by his deep research of all aspects of space commerce, with scores of interviews of executives from both established and small startup space companies.
I especially liked the Sci-Fi and Society chapter in which Jacobson talks about science fiction “illuminating the possibility of the space frontier”. Much of what is now happening in space was predicted in science fiction in the last century. Many CEOs and executives of NewSpace companies were inspired to pursue careers in science or engineering through science fiction books, televisions shows and movies.
Eventually, humanity will evolve to migrate off Earth and establish space settlements throughout the solar system and eventually among the stars. Development of the technologies and commercial activities for space settlement have the potential to create vast wealth, bring billions of people out of poverty and preserve Earth’s natural environment. Jacobson has provided a hopeful glimpse of how the space businesses supporting this effort will manifest this destiny.
