Near-ultraviolet emission spectroscopy of the Hayabusa reentry

Quantitative time-resolved irradiance measurements were obtained of the Hayabusa Sample Return Capsule's entry on 13 June 2010, as measured from a 12.6 km altitude with the Australian Ultraviolet Spectrograph instrument on board the NASA DC-8 Airborne Science Laboratory, jointly managed by the NASA Airborne Science Program and the National Suborbital Education and Research Center. The NASA DC-8 Airborne Science Laboratory was stationed just outside of the landing site at the Woomera Test Range in Australia. The measurements were calibrated against National Institute of Standards and Technology traceable standard calibration lamps on the tarmac at NASA Dryden Aircraft Operations Facility, operated by NASA Dryden Flight Research Center, and at NASA Ames Research Center. The recorded spectra cover the wavelength range from 300 to 470 nm over the duration from 13:52:02.5 until 13:52:33.5 coordinated universal time. The spectra show shock emission from singly ionised molecular nitrogen (N + 2 2 ), as well as several ablation products from the heat shield material: cyanogen radical, calcium, and aluminium. In addition, the high-temperature tail of gray-body emission is observed to enter the wavelength range after 13:52:13 coordinated universal time. These data were evaluated in terms of the temporal evolution of the capsule's stagnation temperature and emissions within the cyanogen radical and N+ 2 2 manifolds. A peak in the irradiance within the wavelength band from 365 to 392 nm was registered at approximately 13:52:07 coordinated universal time and elevated levels of irradiance within the combined cyanogen radical andN+ 2 2 manifolds were subsequently registered at about 13:52:20 coordinated universal time. An apparent maximum capsule temperature close to 3050 K was found at around 13:52:23 coordinated universal time, consistent with apparent capsule temperature values deduced using other instruments