Near-Infrared Spectroscopy of the Hayabusa Sample Return Capsule Re-Entry

During the 2010 NASA / JAXA Hayabusa re-entry observational campaign, a system of four co-located cameras was deployed by Utah State University on the NASA DC-8 Airborne Laboratory to track and measure the spacecraft fragmentation and sample return capsule descent. These instruments included an intensified video camera for narrow-field tracking, an intensified video camera for visible and near-infrared spectral measurements

from 400 to 900 nm, and a near-infrared InGaAs spectrograph for high resolution measurements from 980 to 1080 nm. The latter was configured to monitor the capsule emissions’ spectral evolution during descent, seeking evidence of possible carbon signatures due to ablation of the heat shield. Data complement previous Stardust capsule observations where distinct 1069 nm emission signatures were measured, likely associated with carbon ablation from the Phenolic Impregnated Carbon Ablator (PICA) heat shield. The Hayabusa capsule spectra also exhibit 1069 nm line emissions, appearing intermittently at ∼13:52:05, persisting from ∼13:52:10-13:52:20 as the capsule approached peak heating, and weakening to undetectable levels after ∼13:52:20. Continuum emission and nitrogen line emissions were detected simultaneously. The evolutions of these signatures over the course of re-entry are investigated, in comparison with model predictions and complementary campaign data.