Continued Analysis and Restoration of Apollo DTREM Instrument Data

During the years of 1969 to 1972, NASA sent 12 men to walk on the surface of the Moon. On each mission, on the first lunar extra vehicular activity, the astronauts deployed the Early Apollo Surface Experiments Package (EASEP) (Apollo 11) or the Apollo Lunar Surface Experiments Package (ALSEP) (Apollo 12 - 17). The EASEP was a short-lived package that operated for a few months while the ALSEP contained scientific instruments to collect data on the lunar environment long after the astronauts had left the lunar surface. Part of the package on Apollo 11, 12, 14 and 15 was the Dust, Radiation, Thermal, Engineering Measurement (DTREM), also known as the Lunar Dust Detector. The DTREM was a small fiberglass box that had 3 thermometers and 3 solar cells. The output from the solar cells was used to determine the degradation of the cells from dust, temperature, and radiation on the lunar surface. Over a period of 5-7 years, the DTREM instruments collected data and returned them to Earth through the ALSEP central station housekeeping (Word 33) telemetry stream. The data were in the form of raw digitized telemetry files. The only translated and calibrated data from the instrument that existed were 38 reels of computer printout images archived at the National Space Science Data Center. As part of the lunar data restoration effort, the raw telemetry files from the communications stream have been translated and recalibrated, using the archived microfilm record to determine the correct values in terms of temperature and voltage output. Once they have been properly archived by the Lunar Data Node of the Planetary Data System (PDS) the data sets will be released to the scientific community. The DTREM instrument collected data every 54 seconds for 6 years on the Apollo 14 and 15 missions. The immense size of the data set required that a process be created to convert the raw telemetry fires autonomously. Therefore, we have recreated a digital version of the data from Apollo 14 and 15 that includes time, temperature, and uncalibrated and calibrated solar cell output. The digital version of the data allows modern analytical techniques to be performed with computers which were unavailable in the 1970's. We have also extended the available data to the turn-off in 1977. This makes it easier to determine solar cell degradation and to study the effects of dust and temperature vs. radiation. In the future, we plan to examine effects of the August, 1972 solar-proton event on the solar cells, and to look at other sources of solar cell degradation.