Recent research has shed light on the fascinating potential for various spacecraft to visit Comet 3I/ATLAS, offering scientists an unprecedented opportunity to study this interstellar visitor up close. Discovered on July 1 by the Asteroid Terrestrial-impact Last Alert System (ATLAS), 3I/ATLAS is only the third known object from another star to drift through our solar system, providing a unique chance to analyze material that predates the formation of our solar system.
3I/ATLAS has a remarkable trajectory and an astonishing velocity of approximately 130,000 mph (219,000 km/h). Recent studies suggest that it may originate from a much older region of our galaxy, specifically the Milky Way's thick disk, potentially dating back 7 billion years or more. This makes it significantly older—at least 2.5 billion years—than our sun and the majority of objects within our solar system, including asteroids and comets. Such an age indicates that 3I/ATLAS could provide insights into the conditions of the universe during a period known as cosmic noon, a time characterized by high star formation rates.
As 3I/ATLAS approaches the sun, it sheds material due to the intense solar radiation that heats its icy core, converting ice directly into gas. This process results in the formation of the comet's distinctive tails and comas, offering scientists a glimpse into its chemical composition. However, researchers have identified a significant challenge: during its closest approach to the sun, known as perihelion, 3I/ATLAS will be positioned behind the sun as seen from Earth. Consequently, key telescopes, including the James Webb Space Telescope (JWST) and the Hubble Space Telescope, will be unable to observe the comet during this critical phase.
In light of these challenges, a team of researchers, including lead author T. Marshall Eubanks, Chief Scientist at Space Initiatives Inc., has explored which spacecraft could successfully observe 3I/ATLAS during perihelion. Notably, the comet will pass within the orbit of Mars, allowing several spacecraft, such as the NASA mission Psyche and the European Space Agency's (ESA) Jupiter Icy Moons Explorer (JUICE), to capture data during this pivotal moment. JUICE, benefiting from a gravity assist from Venus, will be well-positioned to gather crucial observations of 3I/ATLAS.
Several spacecraft currently orbiting Mars, including the Mars Reconnaissance Orbiter (MRO), Tianwen-1, and Hope, are also in prime positions to provide valuable data on 3I/ATLAS. These spacecraft will be located closer to the comet than Earth ever will, with distances ranging from 18 million miles (29 million km) to 28 million miles (45 million km). This proximity enhances their ability to gather information as the comet sheds material and develops its tail.
As 3I/ATLAS approaches the sun, it will also pass within the field of view of several solar monitoring spacecraft, including ESA's Solar and Heliospheric Observatory (SOHO), NASA's PUNCH, and the Parker Solar Probe. These instruments will provide scientists with the opportunity to monitor the comet's behavior on a day-to-day basis, albeit from greater distances and lower resolutions.
While some spacecraft may not capture detailed images of 3I/ATLAS, they could still play a pivotal role in studying this interstellar visitor. Spacecraft like the Europa Clipper and Hera may potentially pass through the comet's tail, offering a unique method to analyze its composition through mass spectroscopy. This could yield critical data regarding the origins of 3I/ATLAS and whether it indeed stems from the thick disk of the Milky Way.
Eubanks and Hein emphasize the unparalleled opportunity presented by 3I/ATLAS. If this comet originated from a thick disk star system, it could provide insights into cosmic history without the need for traditional travel beyond our solar system. Given the age of materials in the solar system, which formed around 4.6 billion years ago, studying 3I/ATLAS could unveil the secrets of cosmic dawn and the conditions that existed billions of years before.
The team acknowledges the rarity of this opportunity, as the frequency of interstellar objects passing through our solar system remains uncertain. With advancements in telescope technology, such as the Vera Rubin Observatory, scientists hope to identify more interstellar visitors in the future. However, the unique characteristics of 3I/ATLAS may not be replicated for decades, making it a significant focus for ongoing research.
As 3I/ATLAS continues its journey through our solar system, it may leave behind fragments that could be observed from both Mars and Earth, potentially creating meteor showers as dust particles enter our atmospheres. With the upcoming months promising exciting discoveries, scientists are poised to unlock the mysteries of 3I/ATLAS and the ancient cosmos it represents.
