Meet EASEP
I am the Early Apollo Scientific Experiments Package (EASEP). Armstrong and Aldrin deployed me approximately 17 metres south of the Lunar Module. I had a total mass of about 48 kg and was a forerunner of the more extensive ALSEP packages used on later Apollo missions.
My instruments
- Passive Seismic Experiment: a seismometer that measured seismic activity and helped scientists investigate the lunar crust and interior.
- Lunar Dust Detector: monitored dust accumulation and radiation damage to solar cells.
- Two solar panels: supplied electrical power. I could operate only during lunar daytime.
- Antenna and communications system: received commands from Earth and transmitted scientific telemetry to ground stations.
- Isotope heater and supporting structure: formed part of the package's thermal and instrument-support arrangement.
My mirror companion
About five metres NNW of EASEP, the astronauts deployed a Laser Ranging Retroreflector (LRRR). It was not attached to the EASEP unit and needed no electricity. Its reflectors return laser light towards its source. Timing laser pulses sent from Earth and returned from the Moon allows scientists to measure the Earth–Moon distance very precisely.
My working life
Mission Control activated me at 04:40:39 UTC on 21 July 1969, while the astronauts were still on the surface. Despite operating temperatures about 30°C above the planned maximum, I functioned normally.
On 3 August 1969 at 10:58:46 UTC, about five hours before local lunar sunset, ground controllers stopped my transmissions as my power began to fall. I was switched on again during the next lunar day. On 27 August 1969, near lunar noon, I stopped accepting commands and the experiment was terminated.
Mission details are based on the NASA/NSSDCA Apollo 11 Lunar Module / EASEP record supplied for this project.