Introduction: The Lunar Frontier and the Strategic Significance of Cislunar Space
In the contemporary global space race, nations and private entities are fervently vying to establish Moon bases and tap into the Moon’s resources, including valuable helium-3 for potential nuclear fusion power. Notably, China has made substantial strides in lunar exploration, including a historic landing on the Moon’s far side.
There is global space race among countries to build Moon bases, harness it’s mineral resources and helium-3, fuel for future nuclear fusion power plants. Space agencies in China, Japan, Europe, Russia, Iran, Canada and a few private companies all hope to send people to the moon by as early as 2025. They’re talking about building bases, mining for natural resources, and studying the moon in unprecedented detail. A key figure at the European Space Agency says we must look at how we exploit the moon’s resources before it is too late, as missions begin surface mapping. China has taken global lead in this moon race.
For detailed knowledge on Moon exploration, Mining and technologies please visit: Lunar Horizons: The New Era of Moon Exploration, Mining, Moon Colonization, and Sustainable Space Presence
As we witness this growing lunar exploration fervor, it becomes increasingly evident that cislunar space, the vast region extending from Earth to the Moon, holds strategic importance. It has become a focal point for military operations, space exploration endeavors, and commercial activities.
Challenges of Cislunar Space and the Propulsion Imperative
The space domain is essential to modern commerce, scientific discovery, and national defense. As entities around the world have increasingly sought to develop space capabilities that benefit their individual interest, the space domain is becoming congested, competitive, and
complex. Cislunar space is an important region for the United States as it provides a strategic location for military operations, exploration, and commercial activities. However, it is also a challenging environment that requires advanced technologies to operate effectively. Maintaining U.S. interests in cislunar space will require leap-ahead propulsion technology.
Operating effectively in cislunar space is a multifaceted challenge. The traditional propulsion methods, especially chemical rockets, have inherent limitations when it comes to efficiency and speed. Electric propulsion systems have high efficiency (i.e., specific impulse) but low thrust-to-weight. Chemical propulsion systems have comparatively low efficiency but high thrust-to-weight. Beyond a certain point in the solar system, traditional solar energy ceases to be viable, leaving spacecraft to rely on alternative energy sources.
A study by the National Academies, sponsored by NASA, said nuclear thermal propulsion and nuclear electric propulsion approaches could reduce the travel time of expeditions to Mars but must overcome significant technical hurdles.
To address these limitations and navigate the complexities of cislunar space, propulsion technology must leap forward. Programs such as the Defense Advanced Research Projects Agency’s (DARPA) Demonstration Rocket for Agile Cislunar Operations (DRACO) are at the forefront of developing advanced propulsion technologies.
Nuclear Thermal Propulsion (NTP): A Game-Changer for Space Travel
Many spacecraft already use nuclear propulsion. They use radioactive material to heat one junction of a thermocouple and so generate electricity by the thermoelectric or Seebeck effect. This is then used to power the electrical systems of the spacecraft, rather than to provide propulsion. The amount of power generated this way though is quite low; nothing higher than around 600 W has ever been flown. In comparison, ESA’s Smart 1 used solar cells to generate the 1.2 kW necessary to power the ion thrusters that carried it to the Moon.
One of the most promising technologies within the DRACO program is Nuclear Thermal Propulsion (NTP). This revolutionary propulsion system leverages nuclear reactors to heat a propellant, often liquid hydrogen, to extremely high temperatures, resulting in powerful thrust. NTP offers numerous advantages over traditional chemical propulsion, including significantly higher efficiency and greater thrust.
Unlike propulsion technologies in use today, NTP can achieve high thrust-to-weights similar to chemical propulsion but with two to five times the efficiency. By harnessing the power of nuclear thermal propulsion, spacecraft can achieve higher speeds, travel more efficiently, and embark on missions that were previously beyond the reach of traditional propulsion systems.
DRACO’s Vision: Developing Advanced Propulsion Technology
DRACO sets its sights on a momentous goal: the development of a functional nuclear thermal propulsion system ready for live demonstration by 2025. This ambitious initiative encompasses multiple phases, each aimed at pushing the boundaries of propulsion technology.
At its core, DRACO seeks to empower agile and responsive military operations within cislunar space, emphasizing the critical need for advanced propulsion systems in this challenging environment.
DARPA’s decision to push forward with development of nuclear thermal propulsion comes as critical enabling technologies are maturing, said Jonathan Cirtain, president of advanced programs at BWX Technologies. Cirtain’s company, which makes most of the nuclear reactors found on US Navy submarines and aircraft carriers, is working with NASA on the design of a reactor to enable Mars missions.
One advancement has come in the ability to manufacture refractory metals, which are extraordinarily resistant to heating. To operate efficiently, Cirtain said, an engine must be able to withstand huge temperature and pressure changes across just two meters in length. Hydrogen fuel is stored at just 19 Kelvin and heated to 2,500 Kelvin or higher. At the same time, engineers designing nuclear reactor cores have access to computational power that allows them to iterate new designs—calculating such variables as neutron flux and fluid dynamics—quickly. “Now, with supercomputers on your desk, you can go from years’ worth of calculation time to days, and iterate to a design solution much faster than you could previously,” he said.
For deeper understanding of Nuclear propulsion and its applications please visit: Nuclear Propulsion: Powering the Future Across Land, Sea, Air, and Space
The DRACO program is focused on developing advanced space propulsion technologies to enable agile and responsive military operations in cislunar space. Some of the key technologies being developed as part of the program include:
- Nuclear Thermal Propulsion (NTP): NTP is a type of rocket propulsion technology that uses nuclear reactors to heat a propellant, such as liquid hydrogen, to extremely high temperatures, generating thrust. NTP offers several advantages over traditional chemical rocket propulsion, including higher efficiency and greater thrust.
- Solar Electric Propulsion (SEP): SEP is a type of rocket propulsion technology that uses solar panels to generate electricity, which is then used to ionize a propellant, generating thrust. SEP offers several advantages over traditional chemical rocket propulsion, including higher efficiency and greater endurance. This technology is well-suited for long-duration missions in cislunar space, such as the establishment of a cislunar outpost.
- In-Space Manufacturing: In-space manufacturing is a technique that involves manufacturing components and systems in space using 3D printing and other advanced manufacturing techniques. In-space manufacturing offers several advantages over traditional manufacturing methods, including reduced launch costs and greater flexibility in design.
- Autonomous Operations: Autonomous operations are a set of technologies and techniques that enable spacecraft to operate and make decisions without human intervention. Autonomous operations offer several advantages over traditional spacecraft operations, including greater efficiency and flexibility.
The Crucial Role of the Experimental Nuclear Thermal Reactor Vehicle (X-NTRV)
Central to DRACO’s mission is the creation of the Experimental Nuclear Thermal Reactor Vehicle (X-NTRV) and its associated engine. Lockheed Martin, in collaboration with BWX Technologies, has been awarded a contract to spearhead this pivotal phase of the program.
NASA and DARPA released an interagency agreement outlining the roles and responsibilities of each agency; the agreement grants NASA final authority over the nuclear thermal rocket engine’s development and fabrication. However, the agreement grants DARPA authority over the “experimental NTR vehicle (X-NTRV),” the spacecraft that will be powered by the planned nuclear rocket engine, and DARPA will be responsible for operating and disposing of the X-NTRV in orbit.
Sending humans to Mars has become one of the primary spaceflight goals of government space agencies and private spaceflight firms alike. NASA’s Artemis program is part of the agency’s “Moon to Mars” vision that will leverage what NASA will learn from its planned lunar exploration to work toward establishing a human presence on the Red Planet. “Our intent is to lead and develop a blueprint for human exploration and sustained presence throughout the solar system. That is a very important goal. And we think that these advanced technologies will be a critical part of it.”
The successful development of the X-NTRV marks a monumental achievement in advancing nuclear thermal propulsion technology. It unlocks the potential for future missions that rely on this groundbreaking propulsion system to explore not only our Solar System but also the vast expanse of space beyond.
In “Phase 1” of its solicitation, DARPA has asked industry for the designs of both a nuclear thermal reactor and an operational spacecraft upon which to demonstrate it. This initial phase of the program will last 18 months. Subsequent phases will lead to detailed design, fabrication, ground tests, and an in-space demonstration.
The objectives of Phase 1 are to develop the maturity of an NTP reactor to reduce risk early in the program and develop a technology maturation plan to achieve an on-orbit demo in 2025.
Phase 1 proposals were accepted through two tracks: Track A: Baseline Reactor Design, and Track B: Operational System (OS) and Demonstration System (DS) Concept Design. The period of performance for each track is expected to be 18 months.
Phase 1 is expected to inform Phases 2 and 3 of the DRACO program.
The objectives of Phase 2 are to complete detailed design of the DS, fabricate the nuclear reactor, execute a zero-power-critical test of the reactor, and acquire long-lead materials for the DS. The objectives of Phase 3 are to complete fabrication, assembly, launch, and on-orbit demonstration of the DS.
DRACO’s Phase 1 Awards and Ambitious Vision
In April 2021, DARPA initiated the first phase of the Demonstration Rocket for Agile Cislunar Operations (DRACO) program, marking a pivotal moment in advanced space propulsion technology. The Phase 1 awards were distributed as follows:
- General Atomics was entrusted with the preliminary design of the nuclear thermal reactor.
- Blue Origin and Lockheed Martin were tasked with conceptualizing the in-orbit demonstration system.
This initial 18-month phase aimed to lay the foundation for subsequent advancements. The primary objective was to push the boundaries of propulsion technology and set the stage for a transformative leap in space exploration.
General Atomics’ and Blue Origin’s Crucial Roles
Christina Back, Vice President of Nuclear Technologies and Materials at General Atomics Electromagnetic Systems, highlighted the groundbreaking nature of nuclear thermal propulsion. NTP represents a leap ahead of conventional propulsion technology, offering spacecraft the capability to traverse vast distances swiftly. Agile spacecraft, a result of NTP, are vital for maintaining space domain awareness and reducing transit times within the expansive cislunar region. For missions like human expeditions to Mars, NTP’s versatility opens up new launch windows and enables extended stays on the Red Planet.
A Vision for the Future: Phase 1 and Beyond
The DRACO program’s Phase 1, with its diverse array of participants, was completed by October 2022. However, it was just the beginning of an ambitious journey. DARPA promptly issued a solicitation on May 4 for Phases 2 and 3, signaling the program’s intent to take propulsion technology to new heights.
Phases 2 and 3: Towards a Nuclear Thermal Propulsion Milestone
The Defense Advanced Research Projects Agency (DARPA) announced its quest for Phases 2 and 3 in May 2022. These phases are integral to the development and assembly of a nuclear thermal rocket engine, with a groundbreaking flight demonstration anticipated in Earth orbit by 2026.
The key highlights of Phases 2 and 3 include:
- A single award for the initiative, open to a wider pool of participants.
- Evaluation criteria, emphasizing scientific and technical merit, relevance to DARPA’s mission, cost realism, and proposer capabilities and experience.
The Power of Phase 2 and 3: Design, Fabrication, and Flight
Phase 2, spanning 24 months, encompasses the comprehensive preliminary and detailed design of the demonstration, including the nuclear reactor, nozzle, controllers, and associated equipment. This phase also involves the crucial task of validating the flight engine through construction and experimental trials.
Phase 3 swiftly follows Phase 2, with an estimated duration of approximately 15 months. During this phase, the hydrogen tank will undergo full fabrication and rigorous performance tests, even while fully loaded. The ultimate culmination of Phase 3 is the launch and in-orbit demonstration of the nuclear thermal propulsion (NTP) engine at full power and full thrust.
Lockheed Martin’s Crucial Role and the Path Forward
In a monumental step towards realizing DRACO’s vision, NASA and DARPA jointly selected Lockheed Martin to lead the assembly of the experimental nuclear thermal reactor vehicle (X-NTRV) and its associated engine. The contract for this endeavor is valued at $499 million. Additionally, BWX Technologies will partner with Lockheed Martin to develop the nuclear reactor and fabricate the high-assay low-enriched uranium fuel essential for powering the reactor.
Lockheed Martin has secured a contract from DARPA (Defense Advanced Research Projects Agency) to develop and showcase a nuclear-powered spacecraft as part of the Demonstration Rocket for Agile Cislunar Operations (DRACO) project. This initiative represents a significant advancement in propulsion technology aimed at benefiting both space exploration and national defense. DARPA has collaborated with NASA’s Space Technology Mission Directorate on this project, which includes an in-space flight demonstration of a nuclear thermal rocket engine vehicle scheduled for no later than 2027.
Nuclear thermal propulsion systems function by utilizing a nuclear reactor to rapidly heat hydrogen propellant to extremely high temperatures, generating potent thrust when the heated gas is expelled through the engine nozzle. The reactor uses a special high-assay low-enriched uranium (HALEU) to convert cryogenic hydrogen into a hot and pressurized gas. Importantly, the reactor is only activated once the spacecraft reaches a safe orbit, ensuring the system’s safety.
Lockheed Martin has partnered with BWX Technologies to develop the nuclear reactor and produce the HALEU fuel necessary for this project. Their collaboration aims to expand the use of nuclear products and capabilities in space.
Lockheed Martin’s extensive experience in nuclear controls, coupled with its history of building radioisotope thermoelectric generators for NASA missions, positions the company well in this emerging field. Additionally, Lockheed Martin’s investments in cryogenic hydrogen storage and transfer technology are expected to play a crucial role in both nuclear and conventional propulsion systems for deep space exploration. Overall, the DRACO project represents a significant step forward in space propulsion technology with potential applications in space exploration and national security.
Unlocking a New Era of Space Exploration and Dominance
As cislunar space activity is poised to surge in the coming years, nuclear thermal propulsion will play a pivotal role in maintaining space domain awareness and advancing the interests of the United States in this evolving space frontier. It lays the groundwork for future missions that will harness the potential of NTP to explore not only our Solar System but also the vast expanse beyond. The propulsive capabilities achieved through DRACO are poised to bolster the United States’ interests in space and revolutionize NASA’s long-duration human spaceflight missions.
Through this Demonstration Rocket for Agile Cislunar Operations or DRACO program, the defense agency seeks technology that will allow for more responsive control of spacecraft in Earth orbit, lunar orbit, and everywhere in between, giving the military greater operational freedom in these domains.
In tandem with NASA and DARPA, Lockheed Martin and BWX Technologies are positioned to lead the charge in developing this transformative technology, ushering in a new era of space exploration and asserting dominance in cislunar space.
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