Editing Openai/67c4e193-e008-8008-8d82-c239519e3d5a (section)

==== Apollo 15 – First Extended Scientific Mission (J-Mission) ====

Mission Data: Apollo 15 (July–Aug 1971) inaugurated the J-missions with longer stays on the Moon (three days, multiple EVAs) and a strong focus on science. The mission data volume increased accordingly. Apollo 15 carried a color TV camera on the Lunar Roving Vehicle, providing live television from the Moon’s surface as the astronauts drove (this was transmitted via the Lunar Module’s antenna to Earth). Those broadcasts were recorded on standard video tapes and are preserved (Apollo 15’s TV – like Scott’s hammer-feather drop demonstration – is widely available). Additionally, Apollo 15’s Command Module had a suite of orbital science instruments (the Scientific Instrument Module, or SIM bay) that operated while the CMP circled the Moon. These included a panoramic camera (on film), gamma-ray and X-ray spectrometers, a laser altimeter, etc., which streamed data to Earth in real time. All of this telemetry (surface and orbital) was recorded on the MSFN (Manned Space Flight Network) data tapes during the mission. By the early 1970s, NASA had started archiving some processed results of these experiments (e.g., the gamma-ray spectrometer data might be saved in binary form on 9-track tapes at the science center). However, the raw 14-track telemetry recordings were still treated as temporary backups. As with prior missions, Apollo 15’s original telemetry tapes were not permanently archived and almost certainly fell victim to the 1980s tape reuse. None of the Apollo 15 real-time telemetry reels are documented as surviving todaynasa.gov<ref>{{cite web|title=nasa.gov|url=https://www.nasa.gov/wp-content/uploads/static/history/alsj/a11/Apollo_11_TV_Tapes_Report.pdf#:~:text=searchers%20never%20found%20what%20they,Apollo%2011%20moon%20landing%20and|publisher=nasa.gov|access-date=2025-12-06}}</ref>.

One small example: Apollo 15’s Lunar Module decent and ascent data were recorded and later used in training simulations; but the tapes themselves were reused. The only reason we have insight into such data now is because astronauts or engineers might have written down values or printed strips at the time. For instance, Apollo 15’s mission report and ALSJ (Apollo Lunar Surface Journal) contain details of engine performance and trajectory from telemetry, but the source tapes are gone.

Surface Science Telemetry: Apollo 15 deployed a comprehensive ALSEP at Hadley Rille, including a heat flow experiment, active seismic experiment, lunar surface magnetometer, and more (in addition to the common seismometer and ion detector). Apollo 15’s ALSEP transmitted huge amounts of data until it was turned off in 1977. The archiving situation for Apollo 15’s ALSEP is similar to Apollo 14’s. Many raw data tapes were lost, but some were recovered. Notably, Apollo 15’s heat flow experiment suffered a malfunction (one probe’s cable was broken), but the other probe’s data was recorded. The restoration project managed to gather all available Apollo 15 heat flow data and publish it in corrected form in PDSpds-geosciences.wustl.edu<ref>{{cite web|title=pds-geosciences.wustl.edu|url=https://pds-geosciences.wustl.edu/missions/apollo/index.htm#:~:text=works%20as%20well%20as%20new,analyses|publisher=pds-geosciences.wustl.edu|access-date=2025-12-06}}</ref>. Likewise, Apollo 15’s Suprathermal Ion Detector data and other datasets have been restored (PDS released Apollo 15 ALSEP data alongside Apollo 12’s in 2019)pds-geosciences.wustl.edu<ref>{{cite web|title=pds-geosciences.wustl.edu|url=https://pds-geosciences.wustl.edu/missions/apollo/index.htm#:~:text=October%2015%2C%202019,data%20are%20now%20available%20online|publisher=pds-geosciences.wustl.edu|access-date=2025-12-06}}</ref>. In 2010, when ~440 tapes were recovered, they included Apollo 15 ALSEP data from mid-1975poikiloblastic.wordpress.com<ref>{{cite web|title=poikiloblastic.wordpress.com|url=https://poikiloblastic.wordpress.com/2013/02/22/the-long-road-to-alsep-data-recovery/#:~:text=,data%20tapes%2C%20and%20reprocessed%20tapes|publisher=poikiloblastic.wordpress.com|date=2013-02-22|access-date=2025-12-06}}</ref>. These yielded raw readings (e.g., from the magnetometer, seismic, etc.) that were then processed. On the orbital science side, Apollo 15’s gamma-ray spectrometer data was actually archived in the 1970s in the NSSDC, so that was never truly lost. The same goes for the mapping camera photography (on film) and laser altimeter data (which might have been stored in NASA archives). So, for Apollo 15’s unique science experiments, the data is mostly safe in some form; what was at risk were the ALSEP telemetry streams, now largely saved by the recovery team.

Spacesuit Telemetry: A unique subset of Apollo 15 telemetry that has been made accessible involves the astronauts’ Portable Life Support System (PLSS) data. During EVAs, the biomedical and suit status data (oxygen pressure, water, battery levels, etc.) were telemetered and also recorded in Mission Control on strip charts. Recently, NASA scanned some of these analog charts. For instance, an NTRS report titled “Apollo 15 PLSS Telemetry” contains raw images of strip charts for each EVA, showing suit pressures, temperatures, etc.space.stackexchange.com<ref>{{cite web|title=space.stackexchange.com|url=https://space.stackexchange.com/questions/22731/what-documentation-remains-from-apollo#:~:text=Mission%20Telemetry|publisher=space.stackexchange.com|access-date=2025-12-06}}</ref>. These scans mean that even without the original digital telemetry tape, we have the analog record of that telemetry. It’s a form of preservation: the charts were generated in real time from the telemetry and then kept. Now digitized, they allow analysis of the astronauts’ life support performance.

space.stackexchange.com<ref>{{cite web|title=space.stackexchange.com|url=https://space.stackexchange.com/questions/22731/what-documentation-remains-from-apollo#:~:text=Mission%20Telemetry|publisher=space.stackexchange.com|access-date=2025-12-06}}</ref>Those Apollo 15 PLSS strip charts illustrate how NASA can retrieve telemetry information from paper records. It’s a reminder that a lot of Apollo data was also recorded in human-readable formats at the time (either on paper or film), which serves as a backup when tapes are missing.

Current Status: Mission Telemetry Tapes: No original Apollo 15 mission tapes are known to exist in any archive. Apollo 15 is included in the blanket statement that Apollo-era telemetry reels (aside from Apollo 9’s few) don’t exist anymorenasa.gov<ref>{{cite web|title=nasa.gov|url=https://www.nasa.gov/wp-content/uploads/static/history/alsj/a11/Apollo_11_TV_Tapes_Report.pdf#:~:text=searchers%20never%20found%20what%20they,Apollo%2011%20moon%20landing%20and|publisher=nasa.gov|access-date=2025-12-06}}</ref>. The National Archives and NASA have not reported any Apollo 15-specific tapes in storage. Therefore, all the raw telemetry (spacecraft state vectors, etc.) is gone as magnetic media. In practice, however, Apollo 15’s mission is richly documented. The Apollo 15 Mission Report (hundreds of pages) includes tables and plots derived from telemetry. The voice and video recordings were preserved: Apollo 15’s mission control audio tapes were stored and have been partially digitized (for example, audio of the landing phase is available on the Apollo 15 Flight Journal site). All the 16mm films and 70mm photos taken during Apollo 15 are archived and accessible, providing visual telemetry of sorts (e.g. a film camera captured the LM liftoff from the Moon, which helps analyze the ascent trajectory).

Science Data Tapes: Apollo 15’s ALSEP and orbital science data are now largely secure in digital archives. The physical tapes that still existed (like those recovered ARCSAV tapes from 1975) were read and then presumably archived or discarded after digitization. The condition of those tapes varied, but evidently at least some Apollo 15 ARCSAV tapes were readable enough to extract datantrs.nasa.gov<ref>{{cite web|title=ntrs.nasa.gov|url=https://ntrs.nasa.gov/api/citations/20190032593/downloads/20190032593.pdf#:~:text=System%20%28PDS%29,These%20newly|publisher=ntrs.nasa.gov|access-date=2025-12-06}}</ref>. Many more Apollo 15 ALSEP tapes (from earlier in the mission) are still missing, but because Apollo 15’s experiments had a lot of redundancy and continuous streams, later data plus other records have filled most gaps. The Apollo 15 subsatellite (a small satellite left in lunar orbit) transmitted data on lunar gravity and charged particles; those data were received by tracking stations until the subsatellite’s eventual decay in 1972. It’s likely that information was stored on separate science tapes and later published; the raw subsatellite telemetry tapes likely got recycled too. However, NASA did archive processed subsatellite results (for example, Apollo 15’s subsatellite provided gravity mapping that was documented).

One highlight of preservation is the Apollo 15 mission audio: As of 2022, the Apollo mission control audio project has Apollo 15 on its roadmap (Apollo 16 and 17 audio are being processed, and Apollo 15 would follow). So within a short time, we may have all Apollo 15 audio publicly accessible, drawn from the surviving tapes at JSC.

To sum up, Apollo 15’s telemetry tapes are officially listed as missing, but the mission’s legacy data (scientific and operational) is robustly preserved in alternate forms. No Apollo 15 raw tape reels are on display anywhere; if any remain, they would quietly sit in a NASA facility, but none have been reported. Researchers interested in Apollo 15 can obtain the full set of experiment results from NASA’s databasespds-geosciences.wustl.edu<ref>{{cite web|title=pds-geosciences.wustl.edu|url=https://pds-geosciences.wustl.edu/missions/apollo/index.htm#:~:text=Apollo%20Data%20from%20Individual%20Investigators,SEED%20and%20ASCII%20table%20format|publisher=pds-geosciences.wustl.edu|access-date=2025-12-06}}</ref> and can utilize transcripts, audio, and film to reconstruct events that were originally recorded on now-missing telemetry tapes.