YES2 rattling to DIMAC, and other advanced confirmations

This colorful picture shows a fit of YES2 rate date (dark blue, loops per second vs. deployment time in the second stage, peaking at 65 Hz at deployment completion), as derived previously, vs. a recent spectrograph from RedShift's DIMAC accelerometers (green, yellow, red). Amazingly, the rattling of the tether (with a mass density of only 0.2 gram per meter) as it unwinds inside FLOYD [those who have been at the deployment tests know the sound of it!] is visible as accelerations on the 7000 kg Foton spacecraft, and shows up as a curve of high intensity in this plot of frequency vs. time . The match of the two independently determined curves provides direct evidence of the correctness of the deployment reconstruction by the YES2 team, as the overlay is near perfect, and confirms once more the full deployment of 31.7 km tether.

From DIMAC also the deployment angle could be determined (with about 5 degrees accuracy), and compared to the YES2 reconstruction. A clear confirmation was obtained from phase and amplitude of the swing during the hold phase (between first and second stage), as well as the angle during most of the second stage. Amazingly, the complex lateral (sideways) waves in the tether during the swing back to the vertical could be resolved as oscillations on the tether angle at Foton, both in DIMAC data as in YES2 simulations of the mission that were meant to match the flight data. The match is uncanning and shows how the YES2 mission data is already providing a yet unseen understanding of tether behavior in space. The data confirms the YES2 reconstruction, namely that the Fotino was released nearly exactly at the vertical, which would have sent it towards the Uzbeki-Kazakhi border (see earlier story on this site).