From the NASA Deep Space Communications Educator guide [1]: > Deep space begins at approximately 42,000 km (26,098 mi) from Earth [1] https://www.nasa.gov/sit

From the NASA Deep Space Communications Educator guide [1]: > Deep space begins at approximately 42,000 km (26,098 mi) from Earth [1] https://www.nasa.gov/sites/default/files/atoms/files/ps-03435_deepspacecomm-508.pdf https://www.nasa.gov/sites/default/files/atoms/files/ps-0343...