Cernan's Three Unexplained Events, Apollo 17, December 1972
NASA-UAP-D2, Apollo 17 Transcript, 1972
A declassified excerpt of the Apollo 17 air-to-ground voice transcript documenting three mission-day intervals in which crew members reported unexplained luminous phenomena: a tumbling fragment field at spacecraft separation, a rhythmically flashing distant rotating object in cislunar space, and a brief surface flash north of Grimaldi crater on the Moon.
Brief
Over three days of the December 1972 lunar mission, Apollo 17 CDR Eugene Cernan, CMP Ronald Evans, and LMP Harrison Schmitt reported distinct categories of unexplained observations. On day one, a field of bright tumbling fragments surrounded the spacecraft post-maneuver; crew tentatively attributed them to the S-IVB stage but called that assessment 'a wild guess.' On day two, Cernan described a singular intense light that struck between his eyes during sleep and later identified a distant, rhythmically flashing object with alternating bright-and-dull flashes, assessed it as physically real and rotating, and Houston attempted real-time triangulation using spacecraft attitude data. On day three, Schmitt reported a brief flash on the lunar surface north of Grimaldi, prompting Houston to check seismometers for a corresponding impact signature.
Metadata
- Agency
- NASA
- Release
- 5/8/26
- Incident
- 1972
- Location
- Moon
- Type
- PDF • .pdf
- Length
- 16 pages
- Classification
- UNCLASSIFIED
- Programs
- Apollo 17, Saturn V, S-IVB, ALFMED, SLA panels
- Tags
- luminous tumbling fragments, rotating dual-flash object, cislunar space, lunar orbit, lunar surface flash, Grimaldi crater, 1972, Apollo 17
Key points
- CMP Evans reports 'very bright particles or fragments' tumbling near the spacecraft during the S-IVB separation maneuver; attribution to the rocket stage is characterized as 'a wild guess.'p.1
- LMP Schmitt describes the Day 00 fragment field as looking 'like the Fourth of July out of Ron's window.'p.1
- CDR Cernan describes the fragments as 'flat, flakelike particles' up to 6 inches across, twinkling and apparently moving away from the craft; once the maneuver ends the field is co-static with the spacecraft.p.3
- Cernan reports that on his first night he saw peripheral streaks and a singular intense light that 'flashed right between my eyes like a very bright headlight - like a train coming at you, only with a flash,' experienced while in a sleep-hazy state.p.5
- Cernan states definitively regarding the Day 02 streak observations: 'no question in my mind but that they're there,' adding that he had never observed the phenomenon on any prior mission.p.6
- Cernan identifies a distant bright object viewed through the hatch window at approximately 45 degrees pitch-up, located roughly 10-12 Earth diameters from Earth, 'obviously rotating' in 'very rhythmic fashion' with alternating bright and dull flashes.p.7
- Cernan explicitly rules the object out as a nearby particle: 'it's something physical in the distance.' Houston responds: 'We don't doubt it, Gene.'p.8
- Houston attempts real-time triangulation by requesting NOUN 20 spacecraft attitude data and a mark when the object crosses the XX axis, with stated intent to 'start locating this object.'p.8
- At 02:20:55:22, Cernan reports two additional distant flashers — widely separated, showing identical bright-and-dim patterns — provisionally attributing them to SLA panels.p.11
- At 03:15:38:09, Schmitt observes 'a bright little flash' described as 'a thin streak of light' on the lunar surface north of Grimaldi crater; Houston immediately checks seismometers and asks Schmitt to mark the map location.p.16
Verbatim
Most interesting
- Cernan's most intense observation — the train-headlight flash between his eyes — occurred during his first night's sleep and went unreported to Houston until Day 02, meaning the sighting aged roughly 24 hours before entering the official record.
- Houston's triangulation attempt was methodical and engineering-grade: flight controllers requested spacecraft attitude figures (NOUN 20) and a timed mark as the object crossed the XX axis, explicitly aiming to resolve the object's inertial position.
- The rotating object exhibited a reproducible two-flash signature — one bright flash followed by one dull flash per rotation — which Schmitt attributed to the S-IVB's cylindrical body and engine bell presenting different reflective faces; Cernan rejected that explanation.
- The ALFMED (Apollo Light Flash Moving Emulsion Detector), a cosmic-ray experiment visible in pages 6-7, was active during this period; Houston's remark 'we were just trying to make the data fit the curve; you know the old trick' suggests ground teams had a standing hypothesis linking the crew's flash reports to cosmic-ray retinal stimulation.
- The fragment field on Day 00 became 'essentially static' once the S-IVB maneuver ended, exhibiting 'no apparent relative motion between fragments' — behavior consistent with debris co-moving with the spacecraft rather than dispersing into free drift.
- Ground control confirmed it had been tracking what appeared to be the Day 02 distant flasher for approximately 24 hours before Cernan raised the subject, but had not yet committed to identifying it as the S-IVB.
- Houston's response to the Grimaldi surface flash — 'a small impact probably would give a fair amount of visible light' — treats the event as a possible meteorite strike observable from lunar orbit, a phenomenon that has since been confirmed by dedicated lunar impact monitoring programs.