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Directed energy propulsion technology for rapid travel to the outer solar system (and the stars)

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

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NASA investing in nuclear propulsion for Mars missions

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.

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UK company aims to turn lunar soil into oxygen

Artist’s depiction of a future lunar base 3D printed from local materials. Credits: ESA/Foster + Partners

A British company called Metalysis as been funded by ESA to study their industrial-scale production of metals and alloys for application in a lunar environment. Metalysis has already demonstrated that they can extract 96% of the total oxygen content from ilmenite, a black iron-titanium oxide with a chemical composition of FeTiO3 found by Apollo astronauts to be abundant in lunar regolith. The process leaves a metallic powder alloy that can be used for in-situ 3D printing on the Moon.

In a press release last month, Metalysis states that “The project will provide an assessment to prepare and de-risk technology developments, focused towards oxygen production for propellants and life support consumables. The ability to extract oxygen on the moon is vital for future exploration and habitation, being essential for sustainable long duration activities in space. In-Situ Resource Utilisation (ISRU) will significantly reduce the payload mass that
would be needed to be launched from Earth.”

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Moonwards demo now on line – the future is for making

Moonwards is a technically realistic simulation of a settlement on the Moon called Moontown. It’s a 3d virtual environment you can explore on your own, or you can interact with others in the online experience. You can chat with other people there via your respective avatars touring the facility. You can learn about how all the structures were built and the machines that maintain the settlement by opening cards attached to objects, playing audio clips, watching slide shows, or activating animated presentations. Right now it is just a demo, but when completed, you will be able to build things, create characters, add 3d models to the library, create presentations, play games inside the town, hold or attend events and much more. Its all open source to encourage collaboration.

Visit Moonwards and click on “download” to get a free demo today. You can help realize this exciting vision of the humanity’s future by visiting and cooperating to build out this virtual settlement on the Moon.

Moonwards creator Kim Holder and I discussed the new demo with Dr. Space himself, David Livingston on The Space Show last Sunday. Checkout a podcast of the show at here.

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Martian in situ manufacturing using chitosan biolith

Illustration of three applications of chitosan derived Martian biolith cast into different geometries including a wrench, freeformed material or an additive manufactured habitat model. Credits: Ng Shiwei, Stylianos Dritsas, Javier G. Fernandez via PLOS ONE

Working with simple chemistry suitable for an early Martian settlement, a team of researchers in Singapore has demonstrated that Martian biolith using chitosan derived from shrimp, with minimal energy requirements, could be used for rapid manufacturing of objects ranging from basic tools to rigid shelters. Ng Shiwei, Stylianos Dritsas, and Javier G. Fernandez publish their results in a paper in PLOS ONE.

Chitosan is chemically derived from chitin, the organic matrix produced by biological organisms incorporating calcium carbonate into rigid structures. Chitin would be a byproduct of food production in a closed-loop life support system on Mars.

Chitosan can form transparent objects similar in appearance and mechanical properties to plastic, which would be lacking in early stage Mars settlements. When processed with Martian regolith, the resulting Chitosan biolith produces a material with good mechanical properties and general utility for manufacturing on Mars.

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Athens: a beacon of liberty on Mars

Illustration of the basic farm/home unit of the Athens settlement, a domestead. Credits: Peter Hague

Peter Hague, an astrophysicist located in the UK has published his entry in the Mars Society City State Design Competition for a settlement of 1 million people on Mars. Although not chosen for presentation at the Mars Society Conference last October, the paper describing the city called Athens is linked on Hague’s blog planetocracy.org.

The site selected for the Athens settlement is Hellas Planitia which is attractive because of its low elevation and therefore higher atmospheric pressure than other locales on Mars providing greater radiation protection. The location also has the added benefits of close proximity to subsurface ice deposits as well as an easier landing site.

The basic residential unit in the colony shown above is called a “domestead” consisting of a steel framed geodesic dome with a shielded habitat at its center. The structure will enclose a self sufficient family farm with sustainable heat and power which will produce a surplus of biological matter and other goods. Each dwelling will be connected to others via network of underground tunnels.

All aspects of the settlement such as city design, construction and materials, economics, IT and governance have been worked out for its settlers to prosper while continuing to expand, producing more with fewer inputs from Earth. Eventually the colony could become fully independent.

Hague concludes his paper with a positive vision: “The story of Athens does not stop at a million people. It is designed to produce surplus material and to continue attracting new settlers. It can grow as a city, or it can support the creation of other cities elsewhere on Mars. From such cities a nation can be built, and that nation will have a space program. Technically adept and burdened by much less gravity than any nation on Earth, the Martian nation can then spearhead the humanisation of the solar system and beyond.”

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Breakthrough: New aluminum alloy for radiation resistant spacecraft

Credits: Advanced Science Open Access / Wiley‐VCH GmbH

In space, conventional aluminum alloys tend to degrade when exposed to stellar-radiation such as solar flares or coronal mass ejections resulting in softening of the material to the point of dissolving over time. This property has ruled out aluminum as a lower mass material suitable for space structures…until now.

A new blend of aluminum has been discovered that may provide light weight radiation hardened material for protective hulls of spacecraft. The new research by Matheus A. Tunes et al.* was published in Advance Science. Using a metallurgical strategy called “crossover alloying,” the researchers combined 5xxx (AlMg) with the 7xxx (AlZn) alloy series obtaining beneficial properties of both such as high formability and high strength. The new amalgam was then age hardened to form a complex crystal structure of Mg32(Zn,Al)49 called a “T-Phase” that when subjected to heavy ion bombardment representative of stellar radiation, achieved a high degree of radiation tolerance. The results of the research show that the alloy is a promising candidate for applications in space.

* Authors of the Advance Science paper: Matheus A. Tunes, Lukas Stemper, Graeme Greaves, Peter J. Uggowitzer, Stefan Pogatscher.

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Enter the NSS Space Settlement Contest

Credits: Bryan Versteeg, Spacehabs.com via NSS

It’s time once again for the National Space Society’s annual Space Settlement Contest open to students from anywhere in the world up to grade 12. If you are a budding space settlement designer or have kids that are excited about creating communities in space, now is your chance to share your family’s vision in friendly competition with other space enthusiasts. Details can be found at the NSS Space Settlement Contest website curated by Al Globus.

Check out the winner from 2019 called ASM Corpris by The Aersospace Meridian. There’s even an ASM Corpris Anthem called “Chosen Among the Stars”!:

Image of ASM Corporis, winner of 2019 NSS Space Settlement Contest. Credits: Aerospace Meridian / Illustration by Austin Pham. Corporis logo by Jayde Whiting / The Aerospace Meridian
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Redwire manufactures the first 3D printed ceramic in space

Image of Ceramics Manufacturing Module (CMM), a commercial manufacturing facility that produces ceramic parts in microgravity for terrestrial use. Credits: Redwire/Made in Space

Made in Space, a recent acquisition of Redwire, has just for the first time successfully manufactured a ceramic part in their Ceramics Manufacturing Module on the ISS using additive manufacturing. The demonstration could stimulate demand in low Earth orbit from terrestrial markets which will be a key driver for space industrialization. Redwire claims that the parts, which included a turbine blisk (bladed disk) and other test pieces, demonstrate that the CMM can produce ceramic parts that exceed the quality of turbine components made on Earth.

According to Redwire’s press release: “CMM aims to demonstrate that ceramic manufacturing in microgravity could enable temperature-resistant, reinforced ceramic parts with better performance, including higher strength and lower residual stress. For high-performance applications such as turbines, nuclear plants, or internal combustion engines, even small strength improvements can yield years-to-decades of superior service life.”

Image of CCM 3D printed part fabricated in LEO. Credits: Redwire
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The Space Show fund raising drive

Credits: The Space Show

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.