Power budget and performance analysis of X-ray communication during the Earth re-entry of spacecraft

X-ray communication (XCOM) is a novel method that exploits X-rays as a carrier for data transmission. The high penetration of X-rays enables XCOM to avoid radio blackout during the atmospheric re-entry into Earth. To guarantee stable and robust XCOM, this study provides a power budget for XCOM. The Monte Carlo method was used to evaluate the transmission properties of X-ray beams in near-earth space, and a link model in the re-entry blackout region were established. Moreover, we established a noise model for the X-ray detector and evaluated the mathematical relationship between the transmitting power, and the bit-error-rate (BER). Results indicated that the X-rays with energies of 30–50 keV are highly suitable at an altitude of 35 km, and that robust communication performance could be obtained by using soft X-rays in the upper atmosphere. Adopting optimal X-ray energies according to different altitudes of spacecraft re-entry is, thus, of great significance. We calculated the minimum transmitting power of the X-ray source for a targeted BER and found that, when the link distance is 295 km and the X-ray energy is 50 keV, the power consumption of the X-ray source must be 140 W to achieve BER of less than 10−6 level.