DARPA is funding a nuclear thermal orbital flight demonstration by 2025. The Demonstration Rocket for Agile Cislunar Operations (DRACO) program is to demonstrate a nuclear thermal propulsion (NTP) system on orbit. NTP uses a nuclear reactor to heat propellant to extreme temperatures before expelling the hot propellant through a nozzle to produce thrust. Compared to conventional space propulsion technologies, NTP offers a high thrust-to-weight ratio around 10,000 times greater than electric propulsion and two-to-five times greater specific impulse (i.e. propellant efficiency) than chemical propulsion.
The DRACO program will have two tracks. Track A will include the baseline design of a NTP reactor and culminate in a baseline design review. Track B will include development of an operational system concept to meet operational mission objectives and a demonstration system design that is traceable to the operational system but focuses on demonstrating the propulsion subsystem. Track B is anticipated to culminate in a technology maturation plan review for the demonstration system.
The three prime contractors are General Atomics, Blue Origin, and Lockheed Martin.
Rapid maneuver is a core tenet of modern Department of Defense (DoD) operations on land, at sea, and in the air. However, rapid maneuver in the space domain has traditionally been challenging because current electric and chemical space propulsion systems have drawbacks in thrust-to-weight and propellent efficiency, respectively. DRACO’s NTP system has the potential to achieve high thrust-to-weight ratios similar to in-space chemical propulsion and approach the high propellent efficiency of electric systems. This combination would give a DRACO spacecraft greater agility to implement DoD’s core tenet of rapid maneuver in cislunar space (between the Earth and moon).
Phase 1 of the program will last 18 months and consist of two tracks. Track A will entail the preliminary design of an NTP reactor and propulsion subsystem concept. Track B will produce an Operational System (OS) spacecraft concept to meet mission objectives and design a Demonstration System (DS) spacecraft concept. The DS will be traceable to the OS concept, but specifically focus on demonstrating an NTP propulsion subsystem.
“This first phase of the DRACO program is a risk reduction effort that will enable us to sprint toward an on-orbit demonstration in later phases,” added Greiner.
General Atomics will perform the Track A reactor development work. Blue Origin and Lockheed Martin will independently perform the Track B work to develop OS and DS spacecraft concept designs. DRACO’s Phase 1 is expected to inform follow-on phases for detailed design, fabrication, and on-orbit demonstration. Any follow-on phases will be solicited by DARPA in a future announcement.
The General Atomics SNAP-10A reactor has been the only U.S. nuclear power reactor launched into space, for which General Atomics was directly involved in nuclear fuel testing and characterization.
In 2021, the Demonstration Rocket for Agile Cislunar Operations (DRACO), formerly known as “Reactor on a Rocket (ROAR)” had $21 million in funding. This is up from an initial $10 million in 2020. DRACO “will develop and demonstrate a High-Assay LowEnriched Uranium (HALEU) nuclear thermal propulsion (NTP) system.” NASA is working on similar nuclear thermal propulsion rockets, which use low-enriched — between 5 and 20 percent — uranium-235 (U-235). U-235 is the basic nuclear fuel for commercial light-water reactors when enriched to between 3 and 5 percent; the Navy’s nuclear reactors use U-235 fuel enriched to 90 percent.
There have been decades of ground tests for nuclear thermal propulsion. This will be a far smaller system that will not launch from ground to orbit. The goal is for better orbital operations.
SOURCES- General Atomics, DARPA, Breaking Defense, CNET
Written By Brian Wang, Nextbigfuture.com
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