Spin state evolution of asteroid (367943) Duende during its 2013 earth flyby

Observational investigation of the 2013 near-Earth encounter by asteroid (367943) Duende

“…The key question that remains is whether these differences, including the different best-fit periods in our RMS analysis, are due to noise in the pre-flyby data, are due to changes in observing geometry pre-and post-flyby, and/or indicate a change in rotation state due to tidal effects during the encounter. We address this question in the following section, noting that the more comprehensive analysis of the solid body dynamics presented in Benson et al (2019) provides results that complement arguments presented here. We note here an important point that generalized models for bodies in NPA rotation find that viewing geometry changes can modify the strength of FFT peaks, but typically do not cause a shift of the peaks in frequency space (Samarasinha & Mueller, 2015).…”

“…The global minimum is indicated with the white star. The white box centered around P 2 = 23.7 encloses a set of low RMS solutions that represent our preferred interpretation based on dynamical arguments (Benson et al, 2019).…”

“…A brief overview of short-axis non-principal axis rotation facilitates the following discussion (Figure 11). More detailed descriptions of the SAM coordinate system, rotation mode, and justification for its relevance to Duende, are provided in Benson et al (2019). A SAM state can be described by rotation about several axes.…”

“…The rotation periods associated with these two axes are P ψ and Pφ respectively. Based on constraints from the radar observations and the solid body analysis in Benson et al (2019), the nutation angle θ is expected to be large, ∼ 70 − 85 • . For axis convention shown here, the nodding rate P θ = P ψ .…”

“…Our preferred interpretation of the available data is that the precession rate increased from 8.4 hours prior to the flyby to 8.7 hours afterwards. A companion paper by Benson et al (2019) provides a more detailed dynamical analysis of this event and compares the data to synthetic lightcurves computed from a simple shape model of Duende. The interpretation and results presented in these two works are consistent with one another.…”