Mystery of interstellar comet 3I/ATLAS may be solved with new scientific studies

There is a proposal for a mission whose goal is to reach Halley's Comet and accompany it during its next solar passage. Halley's Comet does not approach Earth frequently; its next visit to the solar system is scheduled for 2061. The proposed mission aims to achieve what the probes that visited it in 1986 could not—namely, observing the comet over an extended period.

The main difficulty lies not just in reaching Halley (which is difficult in itself), but in the ability to track its movement. The comet's orbit is retrograde, meaning it moves in the direction opposite to the movement of most planets in the solar system, and has an inclination of about 162 degrees, which significantly complicates placing a spacecraft on the same trajectory and speed as the object.

Researchers from Khalifa University and their colleagues have presented a possible solution. Instead of relying on a single gravitational maneuver, the proposal combines flybys of Jupiter and Saturn using a low-thrust propulsion system. The calculated launch windows are August 2036 and September 2037.

Halley's orbital characteristics explain the difficulty of observing the comet. When the comet was studied in detail in 1986, various spacecraft made flybys, including the European Space Agency's 'Giotto' and Soviet 'Vega' probes. Since the trajectories of these probes did not allow them to follow the comet, observations were limited to a few hours.

The new proposal is based precisely on this limitation. The goal is not just to cross Halley's path, but to reach it along a trajectory that allows staying close while the object approaches the Sun. This is important because the comet's activity changes as it receives more heat. A mission remaining nearby at this stage could record these changes.

Studies of comet exploration missions also demonstrate how different observations can be used to study characteristics such as composition, shape, and interaction with space travel factors. To reach Halley, the spacecraft will not fly directly to it. The idea is to use the gravity of Jupiter and Saturn to assist in changing the trajectory during the flight.

The spacecraft will weigh about 2 thousand kilograms, including instruments and fuel, and will use a type of engine called a Hall effect thruster. It does not provide a large impulse immediately but gradually accelerates the spacecraft over a long period. The first important planet on the way will be Jupiter. By flying past it, the craft uses the planet's gravitational force to gain speed and be directed toward Saturn.

A further significant change will occur at Saturn. The gravity of this planet will help tilt the spacecraft's trajectory, making its path more similar to Halley's. This is necessary because the comet follows a very inclined orbit relative to the orbits of the planets. Thus, Jupiter will help the craft gain speed, and Saturn will change its trajectory direction. Thanks to these two maneuvers and continuous engine acceleration, the proposal suggests that the spacecraft could reach Halley in 2060, about a year before the comet reaches its closest point to the Sun.

Reaching Halley before its maximum solar approach would allow observation of an important phase of the comet's journey. The craft would arrive when the comet is still beyond Mars' orbit and could observe it as the Sun's heat increases the activity of its nucleus. However, at present, all of this remains only a mission concept described in the paper, not an approved space project. If advanced, the mission may have two possible windows: August 2036 or September 2037.

A research recently published in the Monthly Notices of the Royal Astronomical Society brought new information about the formation and origin of the interstellar comet 3I/ATLAS. This celestial body, which was the third external visitor to the Solar System detected by science, revealed secrets about its remote origin.

As it approached the Sun and began its journey away from planetary neighborhood, the comet underwent an intense process of material release. This event allowed scientists to meticulously examine the internal chemical composition of this celestial object, uncovering secrets preserved since its birth in a distant part of the Universe.

To analyze the expelled material, researchers from the University of Northumbria, located in the United Kingdom, used a modern spectrograph installed on the William Herschel Telescope, situated in Spain. This high-precision instrument captured the light emitted by the gases in the comet's tail, allowing for the identification of five chemical substances released simultaneously during the eruptions of the space visitor.

Among the components identified by the equipment were molecules of nitrogen, carbon monoxide, carbon dioxide, water, and hydrocarbons. By accurately mediating the proportion between nitrogen and carbon monoxide, the scientific team was able to estimate the approximate temperature at which the object was originally synthesized in its system of origin.

The findings indicated that 3I/ATLAS originated under conditions of extreme cold, with temperatures below minus 240 degrees Celsius. This data suggests that the comet developed in the coldest and most peripheral areas of its native stellar system, in a region analogous to the Oort Cloud or the Kuiper Belt around our Sun.

The large amount of gaseous nitrogen corroborates this hypothesis, since this element can only remain stable in environments where the heat from the central star is almost nonexistent. Scientists emphasize that studying these interstellar fragments offers a unique chance to understand the raw material of other worlds without the need to send probes to unreachable distances.

The investigation also progressed technically by mapping the chemical changes along the comet's tail as it interacted with solar winds. The precision achieved demonstrates how new optical instruments are expanding the capacity to study small celestial bodies that traverse space at high speed, quickly and unexpectedly.

However, despite the advances in the study of 3I/ATLAS, science faces a statistical limitation due to the small amount of comparative data. As explained by amateur astronomer Cristóvão Jacques, founder of the SONEAR Observatory, in an interview with Olhar Digital News some months ago: 'We have observed this type of object only three times. It is too little to draw broader conclusions.'

This limited sample makes it difficult to precisely determine the trajectory and origin of the space visitor. Although the chemistry of 3I/ATLAS provides a profile of its formation environment, it does not point to its exact location in the galaxy. For Jacques, identifying the natal star 'would allow us to better understand the environment in which it formed and compare it with what we observe today, based on analyses made on Earth.' However, he believes this information will probably never be determined with accuracy, stating: 'Knowing which specific star gave rise to this object is extremely difficult, perhaps impossible.'

This scenario of data scarcity should change drastically with the commissioning of the Vera C. Rubin Observatory in Chile, expected at the end of June. There is an expectation among astronomers that, driven by the scanning power of this new astronomical complex, the detection rate will increase considerably, making it possible to discover at least one new interstellar visitor annually and significantly expanding the catalog of objects available for study.

Equipped with an 8.4-meter diameter mirror and the largest digital camera ever created for astronomy, boasting an impressive 3.2 gigapixels, the observatory will conduct the Legacy Survey of Space and Time (LSST). Every few nights, the system will map the entire visible sky of the southern hemisphere with great sensitivity, capable of identifying faint and fast-moving celestial bodies that previously went unnoticed.

For Bruno Quint, a doctor in astronomy from the University of São Paulo (USP) and operations scientist at the observatory, the new complex will be 'a machine for discoveries' and will revolutionize the way science studies the Cosmos. In his participation in the Olhar Digital News program, during the launch of the first test images of Vera Rubin, the astronomer pointed out that even in the commissioning phase, the telescope registered 1,000 asteroids in a single night, illustrating the impact of the initiative over its planned 10 years of operation.

This massive detection capability will also bring a new methodological model. According to Quint, previously scientists examined only small parts of the sky looking for specific targets, comparable to looking for a needle in a haystack. He compares: 'What Rubin will do is take that haystack, shake it, throw a bunch of needles on the ground, and we will have to think about what to do with them.'

In practice, this unprecedented volume of data will function integrated into a real-time automated alert system. A statement informs that upon detecting any object with a hyperbolic trajectory typical of an external visitor to the Solar System, the observatory will issue immediate warnings to the global astronomical community. This agility will allow instruments focused on spectroscopic analysis, such as the William Herschel Telescope, to be instantly directed to the target, ensuring the detailed investigation of its internal chemistry before the object moves away from the Sun and disappears into deep space.