This idea was later shelved, and design of Phase 3D (on-orbit name: AO-40) was undertaken under direction of the project team based in Germany, involving amateur radio payloads from many countries in Europe.
[citation needed] This error occurred because of a difference between the venting mechanism of the 400N motor used in AO-13 and the one in AO-40, complicated by a misunderstanding between the propulsion team and the engine manufacturer.
During June 2001, gas from the arcjet thruster was vented during apogee to raise perigee and stabilize the orbit of the satellite.
On 25 January 2004, telemetry from the main battery was observed to go to an extremely low voltage by Stacey Mills (amateur radio call sign W4SM), a member of the Command Team.
This caused the onboard Internal Housekeeping Unit (IHU) computer to cut power to the transponder payloads.
This exposed the underlying batteries to major fluctuations in temperature and the explosion itself may have caused physical damage to the cells.
Assuming AO-40 had a mass of 400 kg, this change required approximately 160,000 joules of energy directed along the velocity vector of the orbit.