Early Apollo Scientific
Experiment Package (EASEP)
Passive Seismic Experiment
Package (PSEP)
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A real nice shot of the Apollo 11 PSEP. Note the
details on the top of the cylinder and at the base.
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Apollo 11 PSEP: Left - folded configuration/Right
- deployed
Apollo Experiment Number: S 031
Weight: 47.7 kg
Apollo missions: 11
As part of the Apollo 11 Early
Apollo Scientific Experiment Package (EASEP), the Passive Seismic Experiment
was a self-contained instrument with its' own power source (solar panels)
and command/communications system. Hence, it was called a "package".
The base was actually a mini Central Station as used on later ALSEPs.
Buzz Aldrin experienced several
difficulties deploying the PSEP. One of the solar panels did not open correctly
and the "BB" device used to level it did not function as predicted. Later
modifications to the ALSEP PSE corrected the
leveling problem and of course those instruments did not include solar
panels as they drew their power from the RTGs.
The Apollo 11 PSEP proved exceptionally
sensitive to the lunar surface vibrations it was designed to detect. It
recorded the crew members' foot falls as they moved about during their
single EVA, as well as the post-EVA equipment jettison, the LM RCS hotfire
and ascent stage liftoff, and some "outgassings" from the descent stage
after the crew left the site. The equipment functioned for only 21 days
after deployment.
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