The purpose of the S-55 series were to test vehicle performance and guidance and to investigate the nature and effects of micrometeoroids on the spacecraft systems. The Explorer 23 or S 55C micrometeoroid satellite was the third in the series of S 55 micrometeoroid satellites orbited by NASA.

Its purpose was to obtain data on the near-earth meteoroid environment, thus providing an accurate estimate of the probability of penetration in spacecraft structures by meteoroids and allowing a more confident definition of the penetration flux-material thickness relation to be derived.