Abstract: A method of determining payload potential may include the steps of receiving data on a first bias voltage and a resulting first collected current of a first needle of a multi-needle Langmuir probe, receiving data on a second bias voltage and a resulting second collected current of a second needle of the multi-needle Langmuir probe, assigning a value for the electron temperature in which the multi-needle Langmuir probe was operating, and using the current and voltage data, the assigned electron temperature value and Langmuir probe theory to calculate the platform potential of the multi-needle Langmuir probe.