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Novel Methods for Deep Ice Access on Planetary Bodies
Published in Yoseph Bar-Cohen, Kris Zacny, Advances in Extraterrestrial Drilling, 2020
William Stone, Vickie Siegel, Bart Hogan, Kristof Richmond, Corey Hackley, John Harman, Chris Flesher, Alberto Lopez, Scott Lelievre, Krista Myers, Nathan Wright
On Earth, in polar regions, hot water drills have proven to currently be the most efficient means of penetrating deep ice (Benson et al. 2014, Rack 2016) and they are robust in the face of substantial insoluble debris (Thorsteinsson et al. 2008). The laser-powered VALKYRIE probe (Stone et al. 2014, 2018) was an effort to take the best aspects of hot water drills and create an efficient closed-cycle hot water drill (CCHWD) that could be encapsulated into a self-contained cryobot. The power levels used—5 kW—were sufficient to prove out, in field tests, theoretical models of descent rates as well as to validate the significant advantage of CCHWD over a passive melt probe, based on the previously described metric of watt-hours per centimeter of descent. For planetary penetration of ultra-cold ice, a much larger power source is needed to ensure downward progress. For a viable flight vehicle—in the 25–35 cm diameter range to enable inclusion of ice penetration machinery, power plant, science payload, and communications links—a power source on the order of 50 kW is required (Stone et al. 2018). The successfully hot-fired “Kilopower” micro fission reactor developed by NASA Glenn (NASA 2018) provides a nominal 43 kW of thermal power and 1 kW of electrical power and is a template for a viable flight cryobot power source. Using this as a design requirement, Stone Aerospace designed and fabricated a full scale CCHWD cryobot called THOR.
Foreword Special issue on the Kilopower Project, Kilowatt Reactor Using Stirling TechnologY (KRUSTY) Test
Published in Nuclear Technology, 2020
In this issue, the introduction paper presents the goals of the Kilopower Project and the potential missions this reactor concept could serve in NASA. Kilopower was intended to serve both human exploration needs on planetary surfaces as well as science needs for deep-space exploration. The design work for the experiment by Poston and the power conversion development by Gibson present the pre-work required to perform the eventual KRUSTY test. A paper on regulatory analysis follows, to show the path used to gain approval of the proposed experiment. Then, the early zero-power critical experiments are presented by Sanchez and Grove. These experiments were essential data used to enhance model predictions prior to the high-temperature test. Next, Poston presents the three experiments (warm criticals) that increase the temperature in an incremental fashion prior to the final experiment. These experiments were used to achieve final regulatory approval of the final high-temperature experiment. The last paper by Poston presents the results of the steady-state and transient testing of the reactor at full power and at the design temperature. These results show that the reactor design and as-built experiment met all of the requirements that NASA had developed for the system.
Heat Transport and Power Conversion of the Kilopower Reactor Test
Published in Nuclear Technology, 2020
Marc A. Gibson, David I. Poston, Patrick R. McClure, James L. Sanzi, Thomas J. Godfroy, Maxwell H. Briggs, Scott D. Wilson, Nicholas A. Schifer, Max F. Chaiken, Nissim Lugasy
In 2015, the convertors were repurposed to undergo testing as part of the new nuclear fission project named Kilopower. The Kilopower generator concepts included system architectures that utilized several smaller Stirling convertors and heat pipes in an array to provide additional layers of redundancy and power scaling. In order to fit the convertors into a tight vertical array, the CSAFs were cut down to a smaller diameter and fitted with gas coolers for the tests. The heat-collector interface was not modified for the Kilopower tests and was directly bolted to the flat interface of the heat pipe condenser. The convertor array architecture also required a balancer to be used with each convertor in order to cancel out the inertia forces from the piston and displacer during operation. This was the first time that a single Stirling convertor was configured with a heat pipe and balancer and required a respectful amount of testing to characterize control and performance.
KRUSTY Reactor Design
Published in Nuclear Technology, 2020
David I. Poston, Marc A. Gibson, Thomas Godfroy, Patrick R. McClure
The Kilowatt Reactor Using Stirling TechnologY (KRUSTY) was envisioned as the next step toward successful deployment of a space reactor. KRUSTY was a prototypic nuclear-powered test of a 5-kW(thermal) Kilopower space reactor.2 Kilopower reactor concepts utilize heat pipes to transfer fission energy from a solid block of fuel and are intended for simple, low-power [1- to 10 -kW(electric)] space and surface power systems. KRUSTY was designed to be as prototypic as possible within the cost constraints of a 3-year, <$20 million program.