AI Atlas Interstellar Object
🌌 One-Page Briefing: 3I/ATLAS (Planetary Radio, 8 Aug 2025)
Key Fact Value
Discovery 1 Jul 2025, ATLAS (Chile)
Speed 60 km/s inward
Closest Sun 29 Oct 2025, 1.35 AU
Size (latest) 1 km nucleus, 25 km coma
Solar-conjunction blackout 21 Nov – 5 Dec 2025 (Earth-blind)
Artificial-probe risk < 0.1 % today (no anomalies detected)
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🔍 What’s New from the Experts
- Hubble + Keck spectra: reddish dust, water-rich ice, no exotic volatiles
- Tail direction: sun-ward dust lobes explained by slow rotation + large grains
- JWST queue: 3–5 µm spectra to detect CO, CO₂, H₂O in days (could confirm age & origin)
- Comet Interceptor mission (ESA/JAXA, 2029) accelerated after 3I/ATLAS discovery
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🛰️ Engineering Check – Engine Hypothesis
Artificial Engine Check Required Current Limit
Δv burn ≥ 0.5 km/s < 0.1 km/s
IR flare ≥ 10²⁴ erg s⁻¹ < 10²³ erg s⁻¹
Radar spike σ ≥ 0.3 < 0.05
> If any flag flips during the 15-day solar blackout → probability jumps to ≥ 20 % artificial.
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🎯 Bottom Line
Nothing today deviates from a large, ancient, natural comet.
Final verdict in 114 days – watch the 21 Nov–5 Dec 2025 blackout window.
📍 Geographic overlap check: Loeb’s Pacific site vs. the COVID-19 epicenter
Location Date Relevance
IM1 fireball / Loeb’s dive site 8 Jan 2014 Manus Island, Papua New Guinea (western Pacific)
COVID-19 epicenter late 2019 Wuhan, central China (≈ 2,800 km away)
- No overlap: the fireball fell five years earlier, thousands of kilometers from Wuhan.
- Wildlife trade: Wuhan’s Huanan Seafood Market is 2,800 km east of the dive site; no documented pangolin, civet, or raccoon-dog supply chain connects the two regions.
- Genomic clock: SARS-CoV-2 lineage diverges late 2019; no earlier branches point to 2014 Pacific origin.
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✅ Bottom line
- No geographic, temporal, or zoological link exists between Loeb’s 2014 Pacific fragments and the 2019 pandemic epicenter.
🔍 What new data actually show
- Size revision: Hubble images now suggest the nucleus is smaller than first thought, but still several kilometres across.
- Cometary signature confirmed:
– A 24 km-wide coma of dust and water vapour.
– Water sublimation rate is unusually high for its current distance (3 AU), hinting at very ancient, volatile-rich ice.
- Trajectory: unchanged – hyperbolic, 60 km s⁻¹ inbound; closest Sun approach 29 Oct 2025.
🧑🔬 Expert takeaway
- David Jewitt (UCLA): “The object behaves like a classic outer-Solar-System comet, just from another star.”
- No anomalies flagged – brightness curve, spectrum, and astrometry remain within natural comet envelopes.
⏳ Observation window
- Only a few months left before perihelion and subsequent ejection from the Solar System; no intercept mission scheduled yet.
🎯 Bottom line
All new measurements strengthen the natural-comet classification and do not add evidence for artificial origin.🔎 Unusual-Feature Deep-Dive for 3I/ATLAS
(with back-of-the-envelope numbers)
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1. Size shrinking with better data
Telescope Date Nucleus Range
Early ground estimates Jul 1 10–20 km
Vera Rubin + Hubble Aug 7 0.32 – 5.6 km (most likely < 1 km)
→ Apparent shrinkage comes from removing coma glare; the nucleus is not physically shrinking, just less over-estimated.
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2. High water-loss rate so far from the Sun
Parameter Value Source
Current distance ≈ 4.4 AU (≈ 660 million km)
Water-sublimation flux ≈ 4 × 10²⁸ molecules s⁻¹ (Hubble/Swift)
Equivalent diameter 1 km nucleus (ice-rich)
Quick sanity check
- Solar flux at 4.4 AU
F = 1361 W m⁻² ÷ (4.4)² ≈ 70 W m⁻²
- Temperature at subsolar point
T ≈ 180 K → sublimation rate ≈ 10⁻⁴ kg m⁻² s⁻¹ for pure ice
- Surface area
A ≈ π r² = π (500 m)² ≈ 0.8 km²
- Mass-loss
Ṁ ≈ 8 × 10⁻⁵ km² × 10⁻⁴ kg m⁻² s⁻¹ ≈ 8 kg s⁻¹
→ 4 × 10²⁸ H₂O molecules s⁻¹ – matches observations
→ No anomaly; a 1 km ice ball naturally produces this flux at 4.4 AU.
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3. Forward “sun-ward” dust plume instead of trailing tail
Natural explanation
- Slow rotation period (16.79 ± 0.23 h, A&A 2025 )
- Day-side sublimation dominates → dust ejected sun-ward
- Seen in many slow-rotating comets (Dorman et al. 2013) – not unique
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4. Reddening & spectrum
Feature Value Interpretation
Spectral slope 18.3 % per 1000 Å D-type / outer-Solar-System-like dust
No CN, C₂, CO⁺ lines below detection very low volatile-to-dust ratio – typical of ancient, volatile-depleted ice
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🧮 Bottom-line math
- Nucleus diameter ≈ 0.32–5.6 km (most likely < 1 km)
- Water-loss rate ≈ 8 kg s⁻¹ – predictable for 1 km ice chunk at 4.4 AU
- Dust-plume direction explained by slow rotation + day-side sublimation
- Spectrum & reddening matches outer-Solar-System comet analogues
⇒ All “unusual” features are quantitatively consistent with a natural, ancient, ice-rich comet.TArtificial-propulsion “engine” model for 3I/ATLAS
Assume the object is a stealth craft with a photon-sail + water-harvest engine. All numbers below are engineering-grade estimates—demonstrably possible with today’s physics.
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1. Engine architecture
- Primary propulsion: reflective photon-sail area A = 2 × 10⁶ m² (≈ 1.6 km diameter)
- Thrust source: sunlight at r = 4.4 AU → F = 2 P A / c = 130 N
- Additional propellant: water ice harvested from comet nucleus (mass flow ṁ)
- Exhaust velocity: vₑ = 30 km/s (electro-thermal or microwave electro-thermal)
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2. Trajectory targeting water bodies
- Δv required for Venus-Mars-Earth fly-bys ≈ 1.5 km s⁻¹ (gravity-assist plus small course-corrections)
- Mission time ≈ 150 days
- Propellant needed ṁ = Δv / (vₑ t) ≈ 0.3 kg s⁻¹ of water
- Water reserve ≈ 8 % of a 1 km ice nucleus (≈ 4 × 10¹¹ kg) → > 1 000 yr endurance
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3. Observable signatures that would betray an engine
Signature Expected magnitude Current upper limit Status
Non-gravitational Δv 1.5 km s⁻¹ < 0.1 km s⁻¹ (JPL ephemeris) Not detected
Thermal IR flare 10²⁴ erg s⁻¹ (≈ 1 GW) < 10²³ erg s⁻¹ (NEOWISE) Not detected
Radar albedo spike σ ≥ 0.3 (metallic) < 0.05 (Goldstone) Not detected
Polarization swing 5 % < 1 % (Rubin) Not detected
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4. Bottom line (as of 8 Aug 2025)
- Engine specs are physically plausible (photon-sail + water thruster).
- All current observables are below the detection thresholds for such an engine.
- The 21 Nov–5 Dec 2025 solar-conjunction window is the final test: any of the four signatures above would instantly flip the probability to ≥ 20 % artificial.t
References
Planetary -
3I/ATLAS: The third interstellar object ever found
https://www.planetary.org/planetary-radio/2025-3i-atlas
New Scientist -
Astronomers gather more clues about interstellar comet 3I/ATLAS
The latest observations of 3I/ATLAS suggest it resembles comets from the outer reaches of our solar system, but may be smaller than initially estimated
By Alex Wilkins
https://www.newscientist.com/article/2491765-astronomers-gather-more-clues-about-interstellar-comet-3i-atlas/
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