From 27 July 2004 to 10 August 2004, TC-1 and TC-2 satellites suffered flux gate magnetometer resets, remote terminal stops, and a few other instrument anomalies more than 30 times during the short period. Convincing evidence is presented that internal discharges due to the enhancement of penetrating electron flux during this period led to the anomalies for both spacecraft. Although their orbits are much different, with the former being equatorial and the latter being polar, both of their various anomalies coincide with the enhancement of penetrating electron flux and are densely populated in the outer radiation belt. Integrated flux of electrons greater than 2 MeV experienced in orbit are in good agreement with the pattern of event occurrence. Although direct evidence is only available by identification of the breakdown sites and ground reproduction of the anomalies, the correlation of anomalies with space environment still provides evidence that internal discharges are probably to be blamed for the anomalies, which implies that the hazard is underestimated and that the protection is inadequate. I. Introduction S ATELLITES TC-1 and TC-2, known together as Double Star, were designed, developed, and launched by the Chinese National Space Administration, with the mission of studying the solar effect on the Earth’s environment in concert with ESA’s cluster mission. The equatorial spacecraft TC-1 was launched 29 December 2003, running in an elliptical orbit of 555 × 78,051 km, inclined at 28 deg to the equator. This enables it to investigate the Earth’s huge magnetic tail, the region where particles are accelerated toward the planet’s magnetic pole by reconnection. The polar satellite TC-2 was launched 25 July 2004 into a 681 × 38,278 km polar orbit, concentrating on the physical processes taking place over the magnetic poles and the development of auroras. Shortly after the launch of TC-2 satellite, both TC-1 and TC2 suffered dense anomalies, which exhibited as a majority of flux gate magnetometer (FGM) resets and remote terminal (RT) stops accompanied by a few other instrument malfunctions. In general, the operational anomalies of spacecraft can be attributed to two factors: hardware and the space environment. Because the TC-1 satellite had been in normal operation since its launch before these anomalies occurred, the cause of hardware malfunctions can be eliminated. What is more important is that the two satellites with such different orbits encounter like problems simultaneously, for which the only reasonable explanation is that their anomalies are caused by a common factor, the space environment. Most environment-induced spacecraft anomalies are related to single-event upsets, differential surface discharges, and internal discharges. Single-event upsets occur when a proton or heavy ion generates enough free carriers in a sensitive volume of a microelectronic device to cause the circuit to change state. Single-event upsets generally cause soft errors such that the circuit can be re