Down to Earth Limits on Unidentified Aerial Phenomena in Ukraine

Brief

Abraham Loeb applies basic atmospheric friction physics to the Zhilyaev et al. (2022) Ukrainian UAP report, which described dark 3–12 m 'Phantom' objects moving at up to 15 km/s at 10–12 km range with no optical emission. Using meteor-derived luminosity efficiency (~10% of kinetic power radiated in the optical band), Loeb computes that a 10 m² object at 10 km/s would generate ~150 GW optical luminosity, trivially detectable and inconsistent with the reported darkness. Reducing the inferred distance by a factor of ten brings speed down to ~1.5 km/s and transverse size down to ~0.3–1.2 m, consistent with artillery shells at ~1 km. A separate luminous object detected via two-site parallax at ~1,170 km altitude is attributed to a satellite.

Metadata

Category

Phenomenon

Venue

preprint (arXiv astro-ph)

Type

Preprint

Year

2022

Authors

Abraham Loeb

arXiv

2210.01972

Access

Open access

Length

87.4 K

Programs

Galileo Project, Breakthrough Prize Foundation

Data sources

Zhilyaev et al. 2022 (arXiv:2208.11215), Brown et al. 2002 meteor optical efficiency data

Tags

UAP-physics, atmospheric-optics, SETI, technosignature, propulsion

Key points

• The Ukrainian report (Zhilyaev et al. 2022) attributed speeds up to 15 km/s and sizes of 3–12 m to 'Phantom' objects at 10–12 km distance with no optical emission, which Loeb argues exceeds the capabilities of human-made aircraft or rockets.p.2
• Bow-shock mechanical power for a 10 m² object at 10 km/s in air at 0.3 kg/m³ (10 km elevation): P ≈ 1.5 TW, per equation (1).p.3
• Applying 10% optical efficiency from meteor data (Brown et al. 2002), implied optical luminosity is L_opt ≈ 150 GW for the stated parameters, rendering the objects unambiguously bright, not dark.p.4
• Fireball luminosity scales with inferred distance to the 5th power (L_opt ∝ A × v³, combined with angular size distance dependence), so a 10x distance error reduces luminosity by five orders of magnitude.p.4
• At the corrected distance of ~1 km, inferred size drops to 0.3–1.2 m and speed to ~1.5 km/s, both characteristic of artillery shells in an active war zone.p.4
• An artillery shell with 10 cm frontal diameter yields L_opt ~10 kW, which at ~1 km would be 'extremely faint' and consistent with dark appearance.p.4
• The luminous, variable object at ~1,170 km detected via two-site observations is identified as a satellite.p.4

Verbatim

• “I show that the distance of these dark objects must have been incor- rectly overestimated by an order of magnitude, or else their bow shock in the Earth's atmosphere would have generated a bright fireball with an easily detectable optical luminosity.”

  p.2

• “I conclude that the reported speeds and sizes of the "Phantom" ob- jects (Zhilyaev et al. 2022), would have generated fireballs of detectable optical lu- minosity at their suggested distances, and so these objects could not have appeared dark.”

  p.4

• “if the Phantom objects are ten times closer than suggested, then their angular motion on the sky corresponds to a physical velocity that is ten times smaller, v ∼ 1 . 5 km s − 1 , and their inferred transverse size would be ∼ 0 . 3–1.2 meters, both characteristic of artillery shells.”

  p.4

• “It is likely that any functional devices embedded in the Earth's atmosphere are not carrying biological entities because these would not survive the long journey through interstellar space and its harsh conditions, including bombardment by ener- getic cosmic-rays, X-rays and gamma-rays”

  p.2

Most interesting

• Loeb's luminosity formula scales with the 5th power of inferred distance: a 10x range overestimate inflates apparent luminosity by 100,000x, turning an artillery shell into a numerically implausible 150 GW fireball.
• The paper was funded jointly by the Galileo Project at Harvard and the Breakthrough Prize Foundation, two distinct UAP/SETI initiatives co-supporting the same mundane-explanation result.
• Loeb invokes the Tsiolkovsky rocket equation to show chemical propulsion caps human spacecraft near tens of km/s (~10⁻⁴ c), incidentally placing the Phantom objects' reported 15 km/s within the range of conventional rockets rather than anomalous technology.
• Self-replicating probes launched at ~10⁻⁴ c could, Loeb calculates, visit ~10¹⁰ habitable planets around Sun-like stars in under one billion years, framing the Ukraine analysis within a broader SETI context.
• The Ukrainian report covered two phenomenological categories, 'bright' and 'dark' objects, but only the dark 'Phantoms' produce the physics contradiction Loeb addresses; the luminous category is separately explained as a satellite via parallax.