The spectral absorption coefficients of neutral and singly ionized carbon nitrogen, and oxygen atoms a r e presented. The continuum contributions resulting from bound-free and free-free transitions a r e presented in terms of an effective cross section summed over all permissible initial and final states. These effective continuum cross sections a r e tabulated spectrally over a frequency range 0.25 eV 5 hv 5 20 eV for temperatures in the range 3,000"K to 24,000"K at 1,000"K intervals. The discrete, i. e. line. contributions resulting from bound-bound transitions a r e presented in terms of tabulations of absorption f-numbers for all significant transitions (multiplet, supermultiplet, and transition arrays). Electron impact (half) half-widths and line shifts for Lorentzian line shapes a r e tabulated for all significant transitions for temperatures in the range 2,500"K to 25,000"K.

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The convective and radiative heat transfer to vehicles entering planetary atmospheres at superorbital velocities is investigated.An integral method is employed to determine the radiative and convective heating around a blunt body. The effect of mass injection, radiative emission and absorption, radiation cooling, and coupling between convection and radiation are included in the analysis. The absorption coefficients of the shock-layer gas, as well as the injected ablation products are determined as a function of particle-number density, temperature, and radiation frequency. The results obtained show that self-absorption can reduce the radiative heating by an order of magnitude but has little effect on the convective heating. It was also found that the nose radius which results in the minimum total heat-transfer rate at the stagnation point is much larger (6 ft to 10 ft diam.at Uoo = 50,000 fps) than the values indicated by an optically thin analysis. Furthermore, it is shown that the total stagnationpoint heat-transfer rate is a very weak function of the nose radius, contrary to the results obtained from an optically thin analysis.V ACKNOWLEDGMENTS

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