High-Speed Spectrographic Photometry of the Stardust Sample Return Capsule Around Peak Deceleration

The descent of the Stardust Sample Return Capsule on 15 January 2006 was observed with an intensified highframe-rate slitless spectrograph, which was operated in staring mode. Spectra were recorded at 300 frames per second from 09:57:47 to 09:57:57 UTC (Coordinated Universal Time), around the time of peak deceleration of the capsule. At this time, the spectra contained continuum emission from the hot surface and appeared to be featureless otherwise, with the exception of the telluric absorption caused by molecular oxygen in the atmosphere between the capsule and the observer. By averaging all spectra together, however, it was possible to bring outweak emission lines of oxygen and potassium over the time frame 09:57:51–54 UTC and sodium emission during 09:57:48–51 UTC. The spectral sequence was analyzed for signs of variation in the total emission from a possible wobbling of the capsule at periods higher than the spin rate. No such variationwas observed above the detection threshold of 5 amplitude in the line of sight.