A team of scientists has outlined a bold mission concept to intercept the interstellar comet 3I/ATLAS, which is currently speeding away from our solar system. The plan involves a high-risk maneuver that would send a spacecraft closer to the Sun than any probe has gone before to gain unprecedented speed.
The proposed mission would use a technique known as a Solar Oberth Maneuver, leveraging the Sun's immense gravity to slingshot a probe towards its distant target. If launched by 2035, the spacecraft could catch up to the comet in as little as 30 years, traveling farther and faster than any human-made object in history.
Key Takeaways
- Scientists have detailed a mission to intercept interstellar comet 3I/ATLAS, which has already left our inner solar system.
- The plan relies on a Solar Oberth Maneuver, involving a rocket engine burn extremely close to the Sun.
- A proposed 2035 launch could lead to an intercept by 2085, reaching a distance of over 68 billion miles from the Sun.
- The mission would require advanced heat shielding to survive temperatures exceeding 2,500 degrees Fahrenheit.
The Oberth Effect in Action
The core of the proposed mission is the Solar Oberth Maneuver (SOM), a concept first described by rocket pioneer Hermann Oberth in 1929. The principle is that a rocket engine is most efficient when the spacecraft is moving at its highest velocity. By firing its thrusters at its closest approach to a massive body like the Sun, a spacecraft can achieve a much greater change in speed, or delta-V, than it could anywhere else.
"Pretty much every launch uses the Oberth effect," explained T. Marshall Eubanks, chief scientist at Space Initiatives Inc. and a co-author of the research paper. He noted that missions to the Moon perform their injection burns at the closest point in their Earth orbit. "However, I cannot find a record of a straight-out Oberth maneuver of the type we propose, which is a major rocket burn at closest approach in a flyby."
To execute this maneuver, the spacecraft would need to get perilously close to the Sun—just 3.2 solar radii from its center. This is deep within the Sun's outer atmosphere, the corona, and closer than the current record-holder, NASA's Parker Solar Probe.
A Journey of Extremes
- Closest Solar Approach: 3.2 solar radii from the Sun's center.
- Expected Temperature: Up to 2,600°F (1,400°C).
- Target Intercept Distance: 732 AU (68 billion miles) from the Sun.
- Comparison: Voyager 1, our most distant probe, is currently at 170 AU after nearly 50 years of travel.
A Complex Trajectory to Gain Speed
The mission's flight path is counterintuitive. Instead of heading directly toward the Sun after launch, the spacecraft would first travel outward to Jupiter. This journey, taking about a year, is a crucial first step.
Any object launched from Earth carries our planet's orbital velocity of roughly 18.6 miles per second (30 km/s). To fall close enough to the Sun for the Oberth maneuver, the spacecraft must first shed some of this speed. The probe would use Jupiter's immense gravity to brake, altering its trajectory to send it plunging back toward the inner solar system.
After rounding Jupiter, the spacecraft would fall toward the Sun, accelerating to incredible speeds. At its closest point, or perihelion, it would fire its onboard solid-rocket boosters. This powerful thrust, amplified by the Oberth effect, would catapult the probe onto an escape trajectory, making it the fastest spacecraft ever launched by a significant margin.
Surviving the Sun's Fury
Getting that close to the Sun presents a monumental engineering challenge. Temperatures are expected to reach up to 2,600 degrees Fahrenheit (1,400 degrees Celsius). Protecting the 1,100-pound (500 kg) spacecraft would require a highly advanced heat shield.
"In principle, a similar heat shield could be used for the mission to 3I/ATLAS," lead author Adam Hibberd told Space.com, referencing the design of NASA's Parker Solar Probe.
The design would likely involve a carbon-composite shield, similar to Parker's, but reinforced with additional layers of aerogel for enhanced insulation against the searing heat. The mass of this shield, estimated to be around 160 pounds (73 kg), would be a significant portion of the spacecraft's total payload.
Is Chasing 3I/ATLAS Worth the Risk?
With 3I/ATLAS already racing away at 38 miles per second (61 km/s), the mission would be a flyby, not an orbital insertion. This raises the question of whether this specific comet is the right target, especially with new interstellar visitors being discovered more frequently.
The Rise of Interstellar Visitors
To date, astronomers have confirmed three objects from outside our solar system: 1I/'Oumuamua, 2I/Borisov, and 3I/ATLAS. With new observatories like the Vera C. Rubin Observatory coming online, scientists expect to find, on average, one new interstellar comet every year. This could provide future missions with easier targets that can be intercepted before they leave our system.
Some researchers suggest that more conventional mission profiles might be better for future discoveries. The European Space Agency's Comet Interceptor mission, scheduled for launch around 2029, is designed for this purpose. It will wait in a stable orbit until a promising long-period or interstellar comet is identified, then travel to meet it.
"For future interstellar objects, a solar Oberth maneuver should be avoided if possible, since it is designed to catch a specific interstellar object 'after the bird has flown,'" Hibberd noted.
A Gateway to the Outer Solar System
Even if a mission to 3I/ATLAS never materializes, the development of Solar Oberth Maneuver trajectories could revolutionize exploration of our own solar system. This high-speed technique could open up previously inaccessible regions.
Potential targets for such missions include:
- Trans-Neptunian Objects: Exploring the icy bodies in the Kuiper Belt and beyond.
- Planet Nine: If the theorized distant planet is discovered, a SOM would be essential to reach it in a reasonable timeframe, with its orbit estimated between 290 and 800 AU.
- The Solar Gravitational Lens: Sending a telescope to a distance of 550 AU, where the Sun's gravity bends light, could create a telescope far more powerful than any built today.
While the chase for 3I/ATLAS remains a concept, the ambitious plan highlights a powerful new tool for space exploration. Mastering the Sun-diving maneuver could dramatically shorten travel times across the vast distances of space, bringing the most remote corners of our solar system within reach.