Catching 3I/ATLAS Using a Solar Oberth

TL;DR

This study investigates a Solar Oberth Maneuver (SOM) as a viable indirect, chemically propelled option to intercept the interstellar object 3I/ATLAS using Optimum Interplanetary Trajectory Software (OITS). By integrating a Jupiter gravity assist with a low-perihelion SOM at $R_p=3.2\,\mathrm{SR}$ and optimizing encounter timings and an Intermediate Point, the authors quantify the minimum required $\Delta V$ and mission durations, identifying 2035 as the best launch year with an intercept possible after $35$–$50$ years and a SOM $\Delta V$ of about $8.36\,\mathrm{km\,s^{-1}}$. The analysis suggests that two to three solid boosters plus a fully refuelled Starship Block 3 in LEO could deliver the SOM and support payloads on the order of $\sim$500 kg, though a heat shield is needed to withstand solar flux at $3.2$ AU. Overall, while technically feasible in principle, the SOM approach to 3I/ATLAS faces substantial practical challenges, including propulsion staging, thermal protection, and long mission durations, which temper its real-world viability.

Abstract

The third interstellar object to be discovered, 3I/ATLAS, has a unique and continually unfolding story to tell about its nature and origin as it is monitored by telescopes on Earth, orbiting Earth and around the Solar System. Previous research into missions using chemical propulsion have only really addressed the direct case, where the opportunity to launch already expired before 3I/ATLAS's discovery. In contrast, investigations herein exploit 'Optimum Interplanetary Trajectory Software' to simulate an alternative indirect option for chemical propulsion, namely the Solar Oberth Manoeuvre (SOM). For a SOM, a low perihelion burn provides maximum benefit from the Oberth Effect, and accelerates the spacecraft rapidly towards the receding 3I/ATLAS. Though in principle feasible, results indicate this option presents significant challenges. For possible launch years between 2031 and 2037 inclusive, a 2035 launch permits the most efficient transfer to 3I/ATLAS. The reference mission requires a SOM at 3.2 Solar Radii from the Sun's centre, with an intercept after 35-50 years. It is found the SOM can leverage spacecraft masses up to $\sim{500}$ kg. Two or three solid propellant boosters could deliver the required SOM $Δ$V, and furthermore a refuelled Starship Block 3 in LEO has sufficient performance for such a mission. As inevitable with a SOM, some of the payload mass would be needed for a heat shield to protect against the high solar flux at low perihelion.

Figures (5)

• Figure 1: $\Delta$V needed at SOM against perihelion distance for missions with E-J-SOM-3I sequence and assuming no $\Delta$V at Jupiter.
• Figure 2: Earth hyperbolic excess speed, $V_{\infty}$ against perihelion distance needed for missions with the E-J-SOM-3I sequence and assuming no $\Delta$V at Jupiter.
• Figure 3: Sum of Figures \ref{['fig:SOMDELTAV']} and \ref{['fig:SOMVINF']}
• Figure 4: Perijove altitudes on a logarithmic scale for launch years 2031-2037 and for different Solar Oberth perihelia.
• Figure 5: Performance capability of a Starship Block 3 fully refuelled and in LEO in terms of total payload mass (including additional SOM stages) against Characteristic Energy, $C_3$