THRESHOLD COMPLEX EXPLORATION LOG
Designation / Log ID: 39-J36
Apparent Date/Time: 11 September 2026 / 09:17 (local) — secondary stamp reads 03:44 22 November 1983
Entry Method: Double steel door marked “S-29 SURGE TANK GALLERY – CONFINED SPACE”. Exterior door clear aperture measures 1.12 m × 2.11 m. Interior aperture measures 0.97 m × 2.28 m on entry and 1.19 m × 1.94 m on exit.
Environmental Baseline
Lighting: fluorescent tubes, color temperature measured at 4120 K. Intensity constant at 54 lux.
Ambient temperature: 19.4 °C. Humidity: 61 %.
Background sound: continuous low-frequency tank resonance at 31 Hz. Baseline reading 27 dB.
Air movement: none detected. Barometric pressure 1012.8 hPa on entry; 1007.1 hPa after 4.2 m of travel.
Spatial Observations
Gallery estimated 31 m long by 5.1 m wide by 3.6 m high. Laser measurement returns 22.4 m long by 6.3 m wide by 2.9 m high.
Floor: sealed concrete with blue chemical-resistant coating. Coating thickness measures 1.4 mm. Surface remains uniform under repeated contact.
Walls: painted concrete block with four vertical surge tanks. Paint thickness measures 0.6 mm. Surface remains uniform under repeated contact.
Ceiling: exposed structural beams with six recessed lamp fixtures. Fixture count remains six after nine visual inventories.
Repeating motif: every 3.4 m a surge tank is mounted against the north wall. Tank diameter measures 1.85 m. Level gauge arrays are identical across all tanks.
Anomalies
Visual inventory of surge tanks returns 4. Physical inventory returns 4. Measured liquid level equals 0.0 m while calculated residual volume across the same tanks equals 11.7 m³.
Floor remains level under spirit level. Measured dust film on the lower wall panels slopes 2.3° toward the west wall. Slope reverses after 6 minutes of continuous observation without change in physical orientation.
Gallery pressure measures 1012 hPa while the external door indicator reads 1016 hPa. Seal integrity lights remain green.
Sound of residual pressure-relief valve actuation arrives 1.9 seconds after the corresponding surface disturbance is detected. Delay increases by 0.31 s for every additional 1.6 m of distance from the entry door.
Humidity at mid-gallery remains 61 % while condensation forms on the tank exteriors after 5 minutes of observation. Condensation evaporates without measurable change in local humidity.
Local magnetic field strength measures 0.4 gauss at floor level and 2.1 gauss at 1.5 m height. Field direction reverses after 7 minutes without change in gallery state.
Tank level-gauge needle count on the status array decreases by 3 over 11 minutes while measured liquid level at all sight glasses remains 0.0 m.
Surface of residual liquid film on tank floors exhibits capillary rise of 4.8 cm against vertical surfaces. Rise collapses after 40 seconds without change in measured surface tension.
Entity Notes
None observed.
At the 9.1 m mark a localized temperature drop of 4.2 °C occurs across a 1.7 m radius. Drop persists for 6 seconds then collapses. No visible source.
Exit / Continuity Status
Exit achieved through the same double steel door after 24 minutes of continuous observation. Exterior aperture on exit matches the interior measurement recorded on entry.
Residual effect: left boot sole retains a thin film of residual liquid that evaporates over 16 minutes without measurable mass change. Right boot sole remains dry.
Secondary timestamp on the log device advances 47 minutes while local elapsed time measures 24 minutes.