Aging NASA Spacecraft Could Intercept The Interstellar Comet On The Other Side Of The Sun, Astronomers Suggest

On July 1, 2025, astronomers spotted an object moving through the Solar System at nearly twice the velocity of previous interstellar visitors ‘Oumuamua and Comet Borisov. The object, which was confirmed to be an interstellar comet with its own dusty coma, is far larger than the previous two, with an estimated nucleus (the rocky part of the comet, excluding its coma) of around 5.6 kilometers (3.5 miles).

Early work has shown that it may be of huge interest to scientists, beyond it being the third confirmed interstellar visitor. For a start, it may have come from a different region of our galaxy altogether, and may be far older than any of the known bodies in our Solar System. But there is a problem in studying it close up. At its closest point to the Sun (perihelion), the object will be on the opposite side of the Sun to Earth, making it somewhat difficult to view.

In the new paper, which has not yet been peer reviewed, Loeb, Adam Hibberd, and Adam Crowl discuss the possibility of repurposing NASA’s Juno spacecraft to intercept the object as it makes a close approach to the gas giant.

“This close encounter provides a rare opportunity to shift the spacecraft Juno from its current orbit around Jupiter to intercept the path of 3I/ATLAS at its closest approach to Jupiter,” the team explains in their paper.

“The instruments available on Juno, namely a near-infrared spectrometer, magnetometer, microwave radiometer, gravity science instrument, energetic particle detector, radio and plasma wave sensor, UV spectrograph and visible light camera/telescope, can all be used to probe the nature of 3I/ATLAS from a close distance.”

In order to place Juno in the path of the interstellar comet, an “Oberth Maneuver” would need to be performed by the spacecraft. In this maneuver, a spacecraft drops further into a gravity well (in this case, Jupiter), increasing its speed, before firing its engines. Thrust at this point adds more kinetic energy to the spacecraft’s orbit than it would if it was further away, resulting in a fuel-efficient velocity increase.

“We have found that the application of a thrust of 2.6755 km s⁻¹ on September 9, 2025, can potentially shift the Juno spacecraft from its orbit around Jupiter to intercept the path of 3I/ATLAS on March 14, 2026,” the team concludes. “With Juno’s many instruments, a fly-by can probe the nature of 3I/ATLAS far better than telescopes on Earth.”

While a cool idea, NASA is currently facing vast cuts from the Trump administration. Juno, which first entered orbit around Jupiter in July 2016, is due to end its mission in September 2025, or “until the spacecraft’s end of life”, according to NASA. Though it may be a tempting opportunity to see an interstellar object, with the path of 3I/ATLAS being uncertain as it heats up on its solar approach, NASA also may not want to sacrifice time studying Jupiter for the chance.

Another caveat to add regards claims about the possible nature of the object itself. Earlier this month, in a paper Loeb claims “is an interesting exercise in its own right, and is fun to explore, irrespective of its likely validity”, he suggested the object could be an interstellar probe sent by an intelligent species.

In that paper, which he states is largely a “pedagogical exercise”, he posited that the object could be hostile, as outlined in the “Dark Forest” hypothesis. In short (though you should read the book on which it is based), given the finite resources in the universe, any lifeform may want to pre-emptively attack any other form of life, before it becomes a threat to their own civilizations. According to Loeb’s paper, the object could be here for that purpose.

“3I/ATLAS achieves perihelion on the opposite side of the Sun relative to Earth. This could be intentional to avoid detailed observations from Earth-based telescopes when the object is brightest or when gadgets are sent to Earth from that hidden vantage point,” Loeb writes on his blog.

“The optimal point for a reverse Solar Oberth maneuver to become bound to the Sun is at perihelion,” he added, “it is this optimal breaking point for 3I/ATLAS that is obscured from our view by the Sun.”

The paper goes on to claim that if the comet were a spacecraft, it would be able to make it to Earth using this maneuver by November or December 2025. This isn’t too surprising, as Loeb made similar claims about the previous two interstellar objects, suggesting ‘Oumuamua may be a light sail, and is known for such outlandish speculation. 

Back in reality, we will only learn more about these objects as we see more of them and, hopefully, one day, take a closer look at them using spacecraft. But don’t get your hopes up too much for NASA adopting this plan. With reduced budget and staffing, and instructions to head to Mars, it already has a lot on its hands.

The paper is posted to pre-print server arXiv.