Explorer 35, (IMP-E, AIMP-2, Anchored IMP-2, Interplanetary Monitoring Platform-E), was a spin-stabilized spacecraft built by NASA as part of the Explorer program. Designed for the study of the interplanetary plasma, magnetic field, energetic particles, and solar X-rays, from lunar orbit. Spacecraft Explorer 35 was similar to the earlier Explorer 33. The spacecraft mass was . The main body of the spacecraft was an octagonal prism, across and high. Four arrays containing 6144 n/p solar cells, providing an average of 70 watts power, extended from the main bus, along with two magnetometer booms. Four whip antennas are mounted on top of the spacecraft. A retrorocket was mounted on top of the bus. Power was stored in silver–cadmium batteries (Ag-Cd). Communication (PFM telemetry) was via a 7-watts transmitter and a digital data processor. The science payload had a mass of and included two 3-axis magnetometers, low energy protons and alpha energy analyzer, low energy protons and electrons detector, energetic particle detector, plasma probe, a micrometeorite detector, a solar cell damage experiment, and gravity field and bistatic radar experiments. Mission Part of the Interplanetary Monitoring Platform program, it was of a design similar to Explorer 33 (IMP-D / AIMP-1), which launched in 1966. However, Explorer 34 (IMP-F), with a different design and mission objectives, was launched about two months prior to IMP-E. Explorer 41 (IMP-G) was the next IMP spacecraft to fly after Explorer 35, in 1969. It was also designed to study the Moon's gravity field, ionosphere and micrometeorite and dust distribution. The spin axis direction was nearly perpendicular to the ecliptic plane, and the spin rate was 25.6 rpm. Launch Explorer 35 was launched on 19 July 1967 from the Eastern Test Range of Cape Kennedy on a Thor-Delta E1 (Thrust Augmented Delta - TAD). It went on a direct ascent trajectory, reaching the Moon on 22 July 1967. It entered an initial altitude elliptical lunar orbit at 147° inclination after a 23-seconds retrorocket burn. The main engine separated 2 hours later. Explorer 35 operated normally in lunar orbit for 6 years until shut off on 24 June 1973. Experiments AMES Magnetic Fields The Ames magnetometer experiment consisted of a boom-mounted triaxial fluxgate magnetometer and an electronics package. The sensors were orthogonally mounted, with one sensor oriented along the spin axis of the spacecraft. A motor interchanged a sensor in the spin plane with the sensor along the spin axis every