Engineering topics
Publications and source records attributed to Timothy Peshek.
PILS (Photovoltaic Investigation on the Lunar Surface) short presentation to the Lunar Reconnaissance Orbiter (LRO) virtual Planetary Science Working Group (PSWG) meeting. The presentation provides a general overview of the PILS project and the current status of the hardware.
One cool October morning in Cleveland I was presented with an interesting opportunity: a call for proposals for commercial lunar payloads was out, the response time frame was rapid, and the solicitation desired hardware that was nearly complete. I took the afternoon off, went for a long hike in a local park and developed an idea, later to be known as the Photovoltaic Investigation on the Lunar Surface (PILS). I will recount the story of how a handful of photovoltaics researchers developed lunar hardware to probe the interaction of solar arrays and the lunar plasma environment, and what this project means for NASA, going forward. My goal is to convey the message that the paperwork was as challenging as the research and development, but made me a better scientist. In this telling I will also present the fundamental physics of plasma interaction science, future directions in our research and also motivate why thin film solar cells may end up being the future of space power – if we can make them somewhere else.
• Announcement of Collaborative Opportunity (ACO) with SSLMaxar • Purpose: • Evaluate blanket solar arrays with mechanical actuation for dust removal • Evaluate vibratory shaking and electrostatic methods for efficacy in simulated lunar environment • Goal is to develop dust mitigation for solar arrays • To maintain solar array operational capability over time • Avoid replacement costs • Extend mission durations
Mitigating dust accumulation on the surface of solar arrays is crucial for maintaining maximum power output. We propose investigating electroluminescence imaging paired with image processing as a means of evaluating various dust mitigation techniques. Image processing was able to clearly differentiate between pristine and dusted solar cells. Paired with traditional analysis techniques, this method proves to be a quick and powerful characterization tool.
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Electroluminescence (EL) imaging can be used as a quantitative characterization method for solar cell performance when combined with image processing, allowing for the impact of dust grain size on electroluminescence imaging characteristics to be investigated. Simulating these results via modelling can help to predict what dust grain sizes, if any, will have a greater impact on performance.
In support of NASA's Artemis program with the goal of a sustained human-lunar presence, there is a need for very large (>100kW) and high-voltage-capable solar arrays, estimated to cost over $150M. Perovskite-based thin-film photovoltaics offer substantial advantages over state-of-the-art solar arrays from the perspective of manufacturing large arrays. Perovskites have also demonstrated some of the lowest temperature coefficients and highest defect tolerance, which make them excellent candidates for aerospace applications. However, MHPs must demonstrate durability in space which presents different challenges than terrestrial operating environments. To decisively test the viability of perovskites being used in space, a perovskite thin film is positioned in low earth orbit for 10 months on the International Space Station, which was the first long-duration study of an MHP in space. Postflight high-resolution ultrafast spectroscopic characterization and comparison with control samples reveal that the flight sample exhibits superior photo-stability, no irreversible radiation damage, and a suppressed structural phase transition temperature by nearly 65 K, broadening the photovoltaic operational range. Further, significant photo-annealing of surface defects is shown following prolonged light-soaking postflight. These results emphasize that methylammonium lead iodide can be packaged adequately for space missions, affirming that space stressors can be managed as theorized.