Conceptual illustration of a planetary sunshade blocking a fraction of sunlight from reaching Earth at the L1 Lagrange point. Credits: Planetary Sunshade Foundation
The Planetary Sunshade Foundation (PSF) would answer “Yes!” to both questions. In a paper presented at the AIAA ASCEND conference in 2020 on the group’s website, the authors* lay out a well researched case on feasibility. The technology needed to build such a megastructure, envisioned to be located at the Earth-Sun L1 Lagrange point, will depend heavily on resource extraction on the Moon and Near Earth Asteroids as well as in-space manufacturing, both of which are anticipated to be mature industries by mid-century.
Building such a megastructure will be a huge undertaking and would require significant funding as well as international cooperation among world governments. PSF and many other groups (including President Joe Biden) take the position that global warming is an existential threat and therefore mitigating its effects are worth the costs. The foundation says on their website that “We have only ten years to dramatically decrease the use of fossil fuels, or be forced to respond to catastrophic global warming.” Other credentialed climate scientists interpret the same data differently disagreeing that if we don’t act now the impact will be catastrophic. They believe that a more gradual transition based on innovation and adaption would make more economic sense.
Dr. Steven Koonin, who served as Undersecretary for Science in the U.S. Department of Energy under President Obama, in his book “Unsettled” uses data from the UN Intergovernmental Panel on Climate Change to show that the impact on the U.S. economy near the end of this century due to the worst scenario of predicted global temperature rise would be minimal. Therefore, in his view the warnings of an “existential threat” are not supported by the data.
Bjorn Lomborg takes the position that rather than making an abrupt change to our economy of reducing carbon emissions to zero by mid century, which is projected to impose significant economic costs and lower standards of living, we need to ramp up our investments in green energy innovation. This would include research and development in renewable energy technology such as solar and wind power, improving battery efficiency, nuclear power and other options to more gradually migrate away from fossil fuels.
The idea of placing a sunshade at L1 to cool the planet is not new, as evidenced by a few examples listed as references in the PSF paper. One of the references published back in 2006 by Roger Angel, Professor of Astronomy and Optical Sciences at the University of Arizona, examines the “Feasibility of cooling the Earth with a cloud of small spacecraft near the inner Lagrange point (L1)”. Angel realized that embarking on such an ambitious endeavor should only be initiated to avert serious climate change “…found to be imminent or in progress.” He concludes that “The same massive level of technology innovation and financial investment needed for the sunshade could, if also applied to renewable energy, surely yield better and permanent solutions.”
Such major undertakings among world governments are by nature political, but if agreement is eventually reached by stakeholders on the urgency to build a planetary sunshade, the option will be available to humanity in the near future should it become necessary. The planetary sunshade is technically possible with future technology advances and has the potential for other benefits. For example, if the structure is made from thin-film photovoltaics, it would be possible to collect enough solar energy to provide hundreds of terawatts of power which is many times the current needs of Earth (currently 17TW). PSF believes the sunshade megastructure “…could generate civilization-transforming energy supplies.” The authors even suggest that a toroidal colony like the one conceived in the NASA 1975 Space Settlement Design Study could be constructed nearby to house workers supporting the manufacture of the sunshade and be “…combined to create banded toroidal settlements as well, scaling linearly, depending upon the population needs of the settlement.”
___________________
* The authors ( A. Jehle, E. Scott, and R. Centers) of the paper “A Planetary Sunshade Built from Space Resources” as of last year were graduate students in the Center for Space Resources at the Colorado School of Mines in Golden, Colorado. Centers and Scott are Director and Systems Engineer, respectively on the PSF Team.
Conceptual illustration of a Virtus Solis satellite array beaming power to central California (not to scale). Credits: Virtus Solis Technologies. NOTE: all images in this post are credited to Virtus Solis Technologies
Ever since I was in high school space solar power has been the holy grail of space advocates. I even wrote a report on the topic based on Peter Glaser’s vision in my high school physics class before Gerard K. O’Neill popularized the concept in The High Frontier leveraging it as the economic engine behind orbiting space settlements. But the technology was far from mature back then, and O’Neill knew back in 1976 the other main reason why after all these years space solar power has not been realized:
“If satellite solar power is an alternative as attractive as this discussion indicates, the question is, why is it not being supported and pushed in vigorous way? The answer can be summarized in one phrase: lift costs.” – Gerard K. O’Neill, The High Frontier
John Bucknell, CEO and Founder of Virtus Solis, the company behind the first design to cost space solar power system (SSPS), believes that recent technological advances, not the least of which are plummeting launch costs, will change all that. He claims that his approach will be able to undercut fossil fuel power plants on price. He recently appeared on The Space Show (TSS) with Dr. David Livingston discussing his new venture. SSP reached out to him for an exclusive interview and a deep dive on his approach, the market for space solar power and its impact on space development.
SSP: Technological advancements of all the elements of a space solar power system have gradually matured over the last few decades such that size, mass and costs have been reduced to the point where there are now experiments in space to demonstrate feasibility. For example, SSP has been following the first test of the Naval Research Laboratory’s Photovoltaic Radio-frequency Antenna Module (PRAM) aboard the Air Force’s X37 Orbital test vehicle. Caltech’s Space-based Solar Power Project (SSPP) has been working on a tile configuration that combines the photovoltaic (PV) solar power collection, conversion to radio frequency power, and transmission through antennas in a compact module. According to your write-up in Next Big Future on a talk given to the Power Satellite Economics Group by the SSPP project manager Dr. Rich Madonna, they plan a flight demonstration of the tile configuration this December. The Air Force Research Laboratory’s Space Solar Power Incremental Demonstrations and Research (SSPIDR) project also plans a flight demonstration later this year with an as yet unannounced configuration. Which configuration of this critical element (PRAM or tile) do you think is the most cost effective and can you say if your system will be using one of these two configurations or some other alternative?
Bucknell: There is a lot of merit to the tile configuration as it shares much of it’s manufacturing process with existing printed circuit board (PCB) construction techniques. The PRAM itself is a version of the tile, but as it was Dr. Paul Jaffe’s doctoral dissertation prototype (from 2013) it did not use PCB techniques and should not be considered an intended SSPS architecture. Details of Caltech’s latest design aren’t released, but it appears they intend to deploy a flexible membrane version of the tile to allow automated deployment. Similar story with SSPIDR. As space solar power is a manufacturing play as much as anything, you would choose known large scale manufacturing techniques as your basis for scaling if you intend earth-based manufacturing – which we do. So yes, we are planning a version of the tile configuration.
SSP: You’ve said that the TRL levels of most of the elements of an SSPS are fairly mature but that the wireless power transmission of a full up phased array antenna from space to Earth is at TRL 5-6. The Air Force Research Laboratory (AFRL) plans a prototype flight as the next phase of the SSPIDR project with demonstration of wireless power transmission from LEO to Earth in 2023. What is your timeline for launching a demo and will it beat the Air Force?
Bucknell: Our timescales are similar for a demonstrator, but I suspect the objectives of a military-focused solution would be different than ours. We would plan a LEO technology demonstrator meeting most of the performance metrics required for a MEO commercial deployment.
SSP: Your solution is composed of mass produced, factory-built components including satellites that will be launched repeatedly as needed to build out orbital arrays. Will multiple satellites be launched in one payload or will each module be launched on its own? What is the mass upper limit of each payload and how many launches are needed for the entire system?
Bucknell: We intend a modular solution, such that very few variants are required for all missions. A good performance metric for a SSP satellite would be W/kg – and we believe we can approach 500 W/kg for our satellites (Caltech has demonstrated over 1000 W/kg for their solution). With known launchers and their payloads a 100MW system would take three launches of a Starship, with less capable launchers requiring many more. Since launch cost is inversely related to payload mass, we expect Starship to be the least expensive option although having a competitive launch landscape will help that aspect of the economics with forthcoming launchers from Relativity Space, Astra and Rocket Lab being possibilities.
SSP: The way you have described the Virtus Solis system, it sounds like once your elements are in orbit, additional steps are needed to coordinate them into a functional collector/phased array. Presumably, this requires some sort of on-orbit assembly or automated in-space maneuvering of the modules into the final configuration. I know you are in stealth mode at this point, but can you reveal any details about how the system all comes together?
Bucknell: An on-orbit robotic assembly step is necessary, although the robotic sophistication required is intentionally very low.
SSP: Your system is composed of a constellation of collection/transmitter units placed in multiple elliptical Molniya sun-synchronous orbits with perigee 800-km, apogee 35,000-km and high inclination (e.g. > 60 degrees). I understand this allows the PV collectors to always face the sun while the microwave array can transmit to the target area without the need for physical steering, which simplifies the design of the spacecraft. Upon launch, will the elements be placed in this orbit right away or will they be “assembled” in LEO and then moved to the destination orbit. Do the individual elements or each system assembly as a whole have on-board propulsion?
Bucknell: The concept of operations is array assembly in final orbit, mostly to avoid debris raising from lower orbits.
Schematic illustration of a three-array Virtus Solis constellation in Molniya orbits serving Earth’s Northern Hemisphere and a two-array constellation serving the Southern Hemisphere of Luna
SSP: The primary objective of the AFRL SSPIDR project is delivery of power to forward deployed expeditionary forces on Earth which would assure energy supply with reduced risk and lower logistical costs. It sounds like your system would not work for this application given the need for 2-km diameter rectenna. Could this potential market be a point of entry for your system if it were scaled down or reconfigured in some way?
Bucknell: Wireless Power Transmission (WPT) at orbital to surface distances suffer from diffraction limits, which is true for optics of all kinds. It is not physically possible to place all the power on a small receiver, and therefore the military will likely accept that constraint. As a commercial enterprise, we could not afford to not collect the expensively-acquired and transmitted energy to the ground station. There are also health and safety considerations for higher intensity WPT systems – ours cannot exceed the intensity of sunlight for example, and therefore is not weaponizable.
SSP: You said on TSS that your strategy would, at least initially, bypass utilities in favor of independent power producers. What criteria is required to qualify your system for adoption by these organizations? You mentioned you have already started discussions with one such group. Can you provide any further details about how they would incorporate an SSPS into their existing assets?
Bucknell: One of the key features of space solar power is on-demand dispatchability. Grid-tied space solar power generation has the benefit of being able to bid into existing grids when generation is needed and task the asset to other sites when demand is low. This all assumes that penetration will be gradual, but some potential customers might desire baseload capacity in which case there is not as much need for dispatchability. Each customer’s optimal generation profile is likely to be unique so it is preferable to attempt to match that with a flexible system.
Conceptual illustration of a 1GW Virtus Solis rectenna array next to Topaz Solar Farm of 550MW capacity in San Luis Obispo County, California
SSP: Other companies have alternative SSPS designs planned for this market. For example, SPS – ALPHA by Solar Space Technologies in Australia and CASSIOPeiA by International Electric Company in theUK. How does Virtus Solis differentiate itself from the competition?
Bucknell: From a product perspective, we are able to provide baseload capacity at far lower cost. Also, we intentionally selected orbits to not only reduce costs but to induce sharing of the orbital assets across the globe such that this is not a solution just for one country or region.
SSP: How big is the likely commercial market for your product/services going to be by the time you are ready to start commercial operations? Can you share some of your assumptions and how they are derived?
Bucknell: Recent data indicates that electrical generation infrastructure worldwide is about $1.5T annually. If you add fossil fuel prospecting, it is $3.5T. Total worldwide generation market size is about $8T. All of this is derived from BP’s “Statistical Review of World Energy – June 2018” and the report from the International Energy Agency “World Energy Investment 2018”
SSP: For your company to start operations, what total funding will be required, and will it come from a combination of government and private sources, or will you be securing funding only from private investors?
Bucknell: As a startup, especially in hardware, funding comes from where you can get it. To date no governmental funding opportunities have matched our technology, but that might change. Our early raise has been from angel investors and venture capital firms. Over the course of the research and development efforts, we expect demand for capital will be below $100M over the next several years but accurately forecasting the future is challenging. We would note this level of required investment is far below our competition.
SSP: For hiring your management team, since this business is not mature, what analogous industries would you be looking at to recruit top talent?
Bucknell: Everything in our systems exist today elsewhere. The wireless data industry (5G for example) has the tools and experience for developing radio frequency antennas and associated broadcast hardware. The automotive industry has extensive experience with manufacturing electronics at low cost in high volumes, including power and control electronics. Controls software engineering is a large field in aerospace and automotive, but in a large distributed system like ours the controls software will extend far beyond guidance, navigation and control (GNC).
SSP: O’Neill envisioned the production of SSPSs as the market driver for space settlements, in addition to replication of more space colonies. This approach seems to have gathered less steam over the years as economics, technological improvements, and safety concerns have taken people out of the equation to build SSPSs in space. In a recent article in the German online publication 1E9 Magazine you talked about SSPSs being useful for settlements on the Moon and Mars. What role do you see them playing in free space settlements and could they still help realize O’Neill’s vision?
Bucknell: We stand at a cross-roads for in-space infrastructure. For the first time access to space costs look to be low enough to make viable commercial reasons to deploy large amounts of infrastructure into cislunar space and beyond. To date the infrastructure beyond earth observation and telecom has been deployed to mostly satisfy nation-state needs for science unable to be performed anywhere else as well as exploration missions (also a form of science). However, there has to be a strong pull/demand to spur the construction of access to space hardware (heavy lift rockets) that consequently lowers the cost further through economies of scale. As I described in my Space Show interview there are only a few commercial in-space businesses that are viable with today’s launch costs. We have had telecom for a long time, followed closely by military and then commercial earth observation. Now we have a large constellation of “internet of space”. Even with those applications, there is not a large pull to scale reusable launch vehicle production – as reusability is counter-productive for economies of scale. A large, self-supporting in-space infrastructure would be needed to bootstrap launch production sufficiently to self-fulfil low cost access to space – Space Solar Power is that infrastructure. Space tourism, asteroid mining and others do not have scale nor potential lofted mass to scale the launch market adequately. In that way, O’Neill’s vision is right – and the follow-on markets can leverage the largely paid-for launch infrastructure to make themselves viable. Space solar power will be the enabler for humanity to live and work off-Earth, and Virtus Solis is leading the way.
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 depiction of a lander descending to the lunar surface carrying a rover housing Masten’s Rocket Mining System. Credits: Masten Space Systems
Called RocketM for Resource Ore Concentrator using Kinetic Energy Targeted Mining, Masten Space Systems has partnered with Honeybee Robotics and Lunar Outpost to design a novel system for blasting ice out of lunar regolith for ISRU under NASA’s Break the Ice Lunar Challenge program.
Lunar Outpost rover decending to the lunar surface down a ramp deployed off a Masten lander. Credits: Masten Space Systems
RocketM equipment would be housed aboard a Lunar Outpost rover delivered to lunar surface via Masten’s lunar lander. After unloading, the rover would be robotically navigated by a geologic team to an excavation site in the Aitken Basin near the Moon’s south pole. Upon arrival over the target area, the RocketM dome is extended down to the surface to create a seal over the regolith. A rocket is then ignited in a series of 1/2 second pulses fluidizing the regolith into icy grains which are conveyed out of the dome via a Honeybee Robotics PlanetVac pneumatic sampling system for processing. Beneficiation of the particles is accomplished using an Aqua Factorem process for separation into purified ice and other useful components. Aqua Factorem has been covered by SSP in a previous post. The whole process would only take 5-10 minutes.
A view of the inner workings of RocketM showing a centrally located pressure dome extending down to form a seal on the lunar surface. Credits: Masten Space SystemsCutaway view showing a 100lb thrust rocket engine firing half-second bursts to heat the regolith to a depth of 2 meters releasing icy grains for processing to extract water. Credits: Masten Space Systems.
The stored water can subsequently be electrolyzed using solar energy into hydrogen and oxygen for lunar operations. What is so exciting about this ISRU system is that the rocket engine can be refueled by the mined products enabling an estimated useful life of 5 years.
Masten has tested the system using simulated lunar regolith providing groundwork toward optimizing conditions within the pressure dome. Further testing is needed at the system level to validate flight readiness.
As stated on Masten’s blog: “Usable as drinking water, rocket fuel, and other vital resources, lunar ice extraction is critical to maintain a sustained presence on the Moon and allow future missions to Mars and beyond. It can also be used in conjunction with other volatiles found in lunar regolith, such as oxygen and methane, to support energy, construction, and manufacturing needs. There’s a lot of promise – water excavation is just step one!”
