NASA generally uses 15 decimal places of pi. Including the '3' before the decimal, this makes a total of 16 digits.
While pi has infinitely many digits, for most calculations, especially in space exploration, only a relatively small number of digits are needed for incredibly precise results.
NASA's Marc Rayman, former chief engineer for the Dawn mission, explained that using far more digits than 15 is unnecessary. Even for interplanetary missions requiring extreme accuracy, the increase in precision from using more digits of pi is negligible compared to other sources of error.
To illustrate, Rayman provided a hypothetical calculation: imagine calculating the circumference of the observable universe (estimated at 93 billion light-years in diameter) using only 39 digits of pi. The error in the calculation would be smaller than the size of a hydrogen atom!
Therefore, NASA focuses on using a practical and manageable number of digits (16), balancing computational efficiency with the required precision for its missions.
