Two research papers propose extreme gravitational slingshot trajectories that could fling a spacecraft onto a path to catch up with 3I/ATLAS, which NASA and the European Space Agency describe as an interstellar comet and only the third interstellar object ever detected. One concept calls for diving a probe perilously close to the Sun for a speed boost, while a separate proposal explores repurposing an existing NASA spacecraft already orbiting Jupiter. Both ideas carry significant engineering risk and remain unapproved concepts, but the scientific payoff of studying material from beyond our solar system has researchers sketching out possible flight plans before the comet slips away.
An Alien Comet Spotted From Chile
The comet now designated 3I/ATLAS was first spotted on July 1, 2025, by the ATLAS survey operating from Chile. At the time of the announcement, the object was roughly 4.5 astronomical units from the Sun and approaching from the direction of the constellation Sagittarius. Its hyperbolic orbit, too fast for the Sun’s gravity to capture, confirmed it as a visitor from interstellar space. The European Space Agency notes that 3I/ATLAS is only the third such object ever identified, following 1I/’Oumuamua in 2017 and 2I/Borisov in 2019, underscoring how rare it is to catch an interstellar traveler passing through the planetary region of our solar system.
Weeks after the initial detection, the Hubble Space Telescope turned its optics on the comet on July 21, 2025. In NASA’s Hubble update, the comet is described as showing a teardrop-shaped coma surrounding the nucleus, consistent with an active body shedding gas and particles as solar heating intensified. That active outgassing distinguishes 3I/ATLAS from ‘Oumuamua, which showed no detectable coma during its brief solar system pass. For planetary scientists, the dust and gas streaming off the comet represent a direct sample of the chemistry that formed around a distant, unknown star, making 3I/ATLAS an extraordinarily attractive target for a close encounter mission that could compare its ices and dust to those found in native solar system comets.
Diving Past the Sun at 3.2 Solar Radii
The bolder of the two mission concepts relies on a technique called a Solar Oberth Manoeuvre. In this approach, a spacecraft would be sent on a trajectory that brings it extremely close to the Sun, where the star’s intense gravity accelerates the probe to velocities unattainable by conventional chemical rockets alone. A preprint posted to arXiv models a reference mission with a closest solar approach of roughly 3.2 solar radii, equivalent to skimming about 2.2 million kilometers above the Sun’s visible surface. At that distance, the spacecraft would fire its engines at the moment of peak gravitational pull, converting a modest fuel burn into a dramatic velocity gain that could send it hurtling after the departing comet on a hyperbolic escape path of its own.
The study identifies 2035 as the optimal launch year, with a broader feasible window stretching from 2031 to 2037. Even under the best-case scenario, however, the spacecraft would not reach 3I/ATLAS for an estimated 35 to 50 years after launch. That timeline reflects just how fast the comet is fleeing the solar system and how limited current propulsion technologies remain for deep-space chases. Most coverage of the Solar Oberth concept has focused on the speed gains, but the thermal engineering challenge deserves equal attention. At roughly 3.2 solar radii, a spacecraft would face extreme thermal conditions, making heat-shielding and propulsion operations near the Sun a central engineering risk for the concept. No existing heat shield has been qualified for a powered engine burn at such proximity to the Sun, which means a dedicated mission would require new materials, advanced cooling strategies, and rigorous testing before any hardware could be cleared for flight.
Repurposing Juno for a Faster Intercept
A second, more immediate proposal takes a different approach entirely. Rather than building and launching a new probe, a separate preprint on arXiv outlines a plan to redirect Juno, the NASA spacecraft that has been orbiting Jupiter since 2016. The concept calls for Juno to perform a Jupiter Oberth maneuver, using Jupiter’s gravity in much the same way the Solar Oberth uses the Sun’s, but at a far less punishing distance. The proposed burn date was September 9, 2025, with a total velocity change requirement of approximately 2.6755 km/s. If executed as modeled in the preprint, the maneuver could place Juno on a trajectory to intercept 3I/ATLAS as early as March 14, 2026, enabling a rapid-response flyby while the comet was still relatively close to the giant planet’s orbit.
The appeal of the Juno option is speed: a rendezvous within months rather than decades, using a spacecraft that is already in space and fully operational. But the tradeoffs are steep. Juno was designed to study Jupiter’s atmosphere, magnetic field, and interior structure, not to chase comets through deep space, and its instrument suite lacks the dedicated spectrometers and dust analyzers that would extract the most value from an interstellar flyby. The 2.6755 km/s fuel requirement also represents a significant fraction of what Juno’s propulsion system can deliver at this stage of its extended mission. No announcement on NASA’s news feed has confirmed any commitment to retargeting the spacecraft, and the September 2025 burn window passed without a public decision, leaving this concept as a detailed case study rather than an active mission plan.
Why Two Approaches Beat One
Taken together, the two proposals sketch out what could become a phased strategy for studying 3I/ATLAS at different points in its escape trajectory. A fast Juno flyby, had it been feasible, would have captured imaging and basic measurements at relatively close range while the comet was still near Jupiter’s orbit. A follow-on Solar Oberth mission, launching in the 2030s, would then pursue a more distant intercept decades later, when the comet is far from the Sun but still shedding material into space. In this vision, early reconnaissance would guide the design of the later, more capable probe, helping scientists prioritize which instruments and sampling techniques would yield the most insight into the comet’s unusual chemistry.
Even without Juno, the dual-track thinking illustrates how planetary scientists are learning to respond to fleeting interstellar opportunities. Unlike long-period comets native to the solar system, which can sometimes be predicted years in advance, interstellar visitors are discovered only after they have already crossed into the inner regions and are on their way back out. That leaves little time to design, fund, and launch a spacecraft from scratch. By exploring both rapid repurposing of existing assets and longer-term, high-energy missions, researchers are effectively rehearsing a playbook that could be applied when the next interstellar comet is spotted, whether or not 3I/ATLAS ultimately receives a dedicated spacecraft of its own.
Racing Against Physics and Budgets
Behind the technical details, the 3I/ATLAS proposals highlight the institutional realities of space exploration. Any mission must compete for funding, launch opportunities, and engineering talent within agencies that already juggle planetary probes, astrophysics observatories, and human spaceflight programs. On its main portal, NASA emphasizes long-term flagship missions and carefully planned discovery-class projects, and an interstellar comet chaser would need to fit into these existing frameworks. The decades-long flight times envisioned for a Solar Oberth mission might also complicate support, as the spacecraft would outlive multiple budget cycles and potentially several generations of mission managers.
At the same time, agency leaders and scientists are aware that interstellar objects offer a kind of science that no other target can match. Analyses of 3I/ATLAS’s coma could reveal whether the building blocks of planets and organic molecules are broadly similar across stellar systems or whether our solar system’s chemistry is unusual. Those questions resonate across planetary science, astrobiology, and cosmochemistry, making it easier to argue that a bold mission is worth the cost. Policy discussions and workshop summaries, often highlighted in recently published updates, suggest growing interest in missions that can pivot quickly when rare events occur, even if that means accepting higher risk or unconventional trajectories.
For now, 3I/ATLAS continues its silent escape, trailed by a faint veil of dust that carries the imprint of another star’s nursery. The detailed Solar Oberth and Juno concepts show that, in principle, humanity could still catch up to this traveler, but they also expose how close we are to the edge of our current capabilities. Whether or not a probe is ultimately dispatched, the work done to chart these trajectories will inform future mission designs, refine our understanding of what is technically possible, and ensure that the next time an interstellar visitor swings through our skies, we are better prepared to follow it back into the dark.
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*This article was researched with the help of AI, with human editors creating the final content.
