A new paper accepted for publication in the Journal of the British Interplanetary Society by Adam Hibberd (i4is), T. Marshall Eubanks (Space Initiatives Inc.), and Andreas Hein (University of Luxembourg) demonstrates that a chemically propelled spacecraft could intercept 3I/ATLAS — the third interstellar object ever detected — using an E–J–SOM–3I trajectory: Earth launch, passive Jupiter gravity assist, a powered perihelion burn at 3.2 solar radii, then a long cruise to intercept. The 2035 launch window is optimal, requiring a fully refuelled SpaceX Starship Block 3 to deliver ~18,000 kg to the necessary C3. The mission is feasible with existing or near-term propulsion technology, but demands 35–50 years of flight time and extreme thermal protection at close solar approach.1
01 — Context
3I/ATLAS — the third interstellar object ever discovered — was first detected on July 1, 2025, by the NASA-funded ATLAS survey telescope in Chile. It entered our solar system on an extremely hyperbolic trajectory (eccentricity of 6.14) at roughly 60 km/s relative to the Sun, originating from the direction of the Galactic Center in Sagittarius. It reached perihelion on October 29, 2025, at 1.36 AU, and its closest Earth approach of 1.7 AU occurred on December 19, 2025.
An unprecedented multi-platform observation campaign mobilized assets including Hubble, JWST, Parker Solar Probe, Europa Clipper, TESS, ESA's Mars Express, ExoMars TGO, JUICE, SOHO, XMM-Newton, and XRISM. The Breakthrough Listen Initiative also conducted technosignature searches using the Green Bank Telescope, MeerKAT, and others — finding no artificial signals. The comet exhibited wobbling jets, an unusual anti-tail, and anomalously large dust particles, making it a uniquely compelling science target.2
However, direct intercept missions are impossible — 3I/ATLAS was detected too late, its retrograde orbit rules out rendezvous, and the required launch date for a direct trajectory had already passed before discovery. Even ESA's planned Comet Interceptor architecture would have been insufficient.
02 — The Proposed Solution: Solar Oberth Manoeuvre
The study evaluates an indirect intercept using the Solar Oberth Manoeuvre (SOM). The mission architecture follows an E–J–SOM–3I sequence: Earth launch, passive Jupiter gravity assist to shed tangential velocity, a powered perihelion burn at 3.2 solar radii from the Sun's center, then a long cruise toward the receding target.
The Jupiter gravity assist is essential — it effectively nullifies the ~30 km/s tangential velocity inherited from Earth's heliocentric orbit, enabling the spacecraft to achieve the required low solar perihelion without prohibitive ΔV. All onboard propulsion is then dedicated to the SOM burn.
Using the team's proprietary Optimum Interplanetary Trajectory Software (OITS), results across launch years 2031–2037 conclusively identify 2035 as optimal, offering the best alignment of Earth, Jupiter, Sun, and 3I/ATLAS for minimum propulsion and launch vehicle requirements. The reference mission requires a launch characteristic energy (C3) of 130.2 km²/s², a SOM ΔV of 8.36 km/s, and yields a heliocentric escape speed exceeding 350 km/s.1
03 — Reference Mission Parameters
| Flight Duration | Intercept Dist. | C3 | SOM ΔV | Rel. Speed at 3I | Payload |
|---|---|---|---|---|---|
| 50 yr | 732 AU | 130.2 km²/s² | 8.36 km/s | 16 km/s | 546 kg |
| 40 yr | 609 AU | 130.1 km²/s² | 9.29 km/s | 20 km/s | 342 kg |
| 30 yr | 487 AU | 162.1 km²/s² | 10.36 km/s | 25 km/s | N/A |
| 20 yr | 365 AU | 175.4 km²/s² | 14.08 km/s | 39 km/s | N/A |
04 — Launch Vehicle & Propulsion Architecture
The study assumes a fully refuelled SpaceX Starship Block 3 in Low Earth Orbit can deliver approximately 18,000 kg of total payload mass to the required C3 of 130.2 km²/s². Five identified stage combinations using commercially available solid rocket motors (CASTOR 30XL, CASTOR 30B, STAR 75, STAR 63F, STAR 48B) fit within this mass envelope while delivering the 8.36 km/s SOM ΔV. Useful payload masses range from 312–546 kg, comparable to NASA's New Horizons spacecraft (~500 kg).1
A critical engineering challenge is thermal protection. At 3.2 solar radii, the solar flux reaches approximately 6 MW/m² — extreme conditions requiring a dedicated heat shield analogous to but more capable than Parker Solar Probe's Thermal Protection System (which masses ~73 kg). This shield mass directly reduces the available science payload.
05 — Positional Accuracy: A Major Advantage Over 1I/‘Oumuamua
A key finding: 3I/ATLAS's trajectory is known with dramatically higher precision than 1I/‘Oumuamua, making a deep-space flyby far more feasible from a navigation standpoint. At 100 AU, 3I/ATLAS has an estimated transverse positional error of just ~2,000 km versus ~200,000 km for 1I/‘Oumuamua — a 100× improvement. Radial errors are similarly ~50× smaller.1
06 — Investment Implications
The study's reliance on a refuelled Starship Block 3 reinforces Starship's emerging role not just as a LEO workhorse, but as a foundational enabler for planetary science, deep space, and eventually interstellar missions — a long-duration demand signal for SpaceX's architecture and its orbital refuelling capability.
The mission requires 2–3 commercially available solid rocket stages (CASTOR, STAR families). Northrop Grumman, the primary manufacturer, stands to benefit from any serious ISO intercept program. This is additive to existing national security and commercial launch demand.
Extreme close-solar-approach missions drive demand for advanced materials and TPS development — an area where Johns Hopkins APL and commercial materials firms have growing IP portfolios since Parker Solar Probe.
A 35–50 year mission timeline underscores that interstellar object science will increasingly require sustained institutional commitment, favoring agencies and contractors with long-duration mission experience (JPL, APL, ESA).
With three interstellar objects now detected (1I/‘Oumuamua 2017, 2I/Borisov 2019, 3I/ATLAS 2025), the cadence is accelerating. ESA's Comet Interceptor (launching ~2029) and future survey telescopes like Vera C. Rubin Observatory will increase detection rates, creating recurring demand for rapid-response intercept architectures.
- Hibberd, A., Eubanks, T.M., & Hein, A.M. (2026). "Catching 3I/ATLAS Using a Solar Oberth." arXiv:2601.02533v2. Accepted, Journal of the British Interplanetary Society.
- NASA Science, ESA, Breakthrough Listen / SETI Institute. Multi-platform observation campaign summary, 2025–2026.
- Space.com, Universe Today, Live Science. Coverage of 3I/ATLAS trajectory analysis and intercept feasibility, Feb. 2026.
- Initiative for Interstellar Studies (i4is), Space Initiatives Inc., University of Luxembourg. Research consortium disclosure.
- Off Earth Data Comprehensive Database. 3300+ entities, 26 sectors, 110+ subsectors. Internal scoring methodology.
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