During the Spacelab 1 shuttle mission (November 28 to December 7, 1983) spectral measurements were made in the ultraviolet which resolve the N+(5S) doublet at 2143 ¿ from the NO (1-0) gamma band at 2148 ¿ in the upper thermosphere. The measured slant path surface brightness profile of the N+ feature is well explained by photodissociative ionization of N2 with a yield of 0.2. The intensity of the N+ feature relative to the NO (1-0) gamma band is dependent on the conditions prevailing at the time and location of the measurement. For the near-twilight mid-latitude measurements made here, in the upper thermosphere the N+(5S) feature would contribute 20% to 75% of a low spectral resolution NO measurement.