Prediction of the Near-UV spectrum of the reentry capsule

Shinsuke Abe, Kobe University, Kobe, Japan
From near-ultraviolet spectrum, we identified N2+(1-) in a bright Leonid fireball which also could be observed in a shock layer of arc plasma heated by the reflected shock and by reentry spacecraft such as the Space Shuttle orbiter. The flow in the head and wake regions of a hypersonic object, such as a reentry capsule, tends to be in a thermochemical nonequilibrium state. The most likely scenario of the induced N2+(1-) in the meteoroid will result in the effect of large dimensions of high-temperature regions just ahead and behind the meteoroid caused by the large meteoroids' vapor cloud. The reentry speed from interplanetary space is more than 12 km/s at the altitude of 100 km, which is enough velocity for producing N2+(1-) suggested from laboratory experiments. Therefore, the reentry capsules (meter-size meteoroids) of Stardust (cometary dust sample return), and Hayabusa (asteroidal material sample return) directly from interplanetary space, which will return to the Earth in 2006 January, and 2007 June, respectively, will provide us with good opportunities to conduct artificial fireball spectroscopy.