Broadband Array Spectrograph System (BASS) thermal IR observations of NaK droplets in Low Earth Orbit (LEO)
- Paper number
IAC-16,A6,1,5,x31806
- Coauthor
Dr. Mark A. Skinner, Boeing, United States
- Coauthor
Dr. Ray Russell, The Aerospace Corporation, United States
- Coauthor
Dr. Richard Rudy, The Aerospace Corporation, United States
- Coauthor
Mr. Daryl Kim, The Aerospace Corporation, United States
- Year
2016
- Abstract
There exists a population of sodium-potassium (NaK) droplets in 900-950 km altitude orbits. These droplets are the result of former Soviet Union ocean reconnaissance nuclear-powered satellites (“RORSAT”) reactor-core ejections. The droplets come from the NaK that was the liquid metallic coolant for the reactor cores, and the droplets have been measured by radar to have sizes up to ~6 cm diameter. Previously, the droplets had been observed in the visible and radar bands, and droplet formation had been modeled. In this work, we report on the first long-wave thermal IR observations of NaK droplets, taken with the Broadband Array Spectrograph System (BASS), in both the IR (3-13 µm), as well as the visible. Due to their small size (~6 cm), we find the droplets to be at the limits of our ability to characterize, even using a 4-meter class telescope. We have, however, measured the spectra of the droplets, and from the spectra we have estimated the temperature and the emissivity-area product. We find the temperatures to be above freezing for NaK, and if we assume sizes for these objects as published previously from radar observations, we find an emissivity of ≥60%, which may be a result of their oxidation by atomic oxygen. If these were simply pure metallic spheres, we would expect much lower emissivities. We describe our methods, the data collected, our analysis approach and results, and our future plans.
- Abstract document
- Manuscript document
IAC-16,A6,1,5,x31806.pdf (🔒 authorized access only).
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