If an interstellar visitor like Oumuamua arrives in the solar system, humanity is already prepared for it

Comets are spectacular but hard-to-find wanderers of the Solar System, and obtaining close-up data on them is a complicated task, although not impossible. Astronomers have studied many such objects in space throughout history, one of their most famous representatives, Halley’s Comet, was mapped up close in the 1980s during the Giotto and Vega missions, and then Borrelly’s Comet during Deep Space 1 in 1998, Comet Wild-2 was visited by the Stardust mission in 2004, Churyumov-Gerasimenko in 2004, Temple 1 and Hartley 2 in 2005, but most of the observations were made with ground-based instruments.

The common feature of the missions is that the subjects of their investigation were comets that appear regularly, every few years, in the vicinity of the Sun,

then, passing by the star, continuing their elliptical orbit, they move away from it for a while, only to return again. Since these short-period comets often come close to the Sun and are also affected by the proximity of the planets of the inner Solar System, their shape, surface and composition change significantly over time, so it is no longer possible to obtain data on their original, untouched structure.

In order to be able to examine an ancient visitor free of similar effects more thoroughly, researchers need to capture a long-period comet, whose orbital period is more than 200 years, but can even be as long as a thousand or a million years. Among them, the most promising version would be a so-called dynamically-new comet (DNC), i.e. a dynamically new comet, which enters the inner part of the Solar System for the first time, and therefore offers much more opportunities to assess the ancient conditions. Of course, the DNCs have also changed somewhat since their birth, they were exposed to potential collisions and traveled a long way before reaching their current residence, for example the Oort Cloud located at the edge of the Solar System, from where they may one day visit the inner Solar System, but still these objects held them their most original, least modified form among comets. With their help, astronomers can get a much deeper insight into the conditions that existed during the formation of the Solar System, when the set of planets and other space objects had just begun to form from the protosolar nebula.

The ancient comet may have largely retained the constituents and surface features that tell of these ancient times.

in addition, the interaction of a comet approaching the Sun for the first time with its environment and the solar wind may also hold interesting information for scientists.

Comet NDC, however, has a potentially even more exciting observational target: an interstellar visitor entering not just the inner Solar System, but the entire star system for the first time. So far, researchers have had the opportunity to detect few similar celestial bodies, specifically two, Oumuamua and 2I/Borisov, the former in 2017 and the latter in 2019. Mapping the wanderer ejected from other star systems could answer many of the questions raised by the appearance of its famous predecessors. But how can you examine such a distant visitor or a long-period comet up close, when spacecraft launched from Earth need a long preparation time and also a long journey to get close to the celestial bodies?

The Comet Interceptor program

The solution is an advanced garrison, a “hunter” in space, which waits in ambush for the passing stranger and quickly crosses his path at the right time. The European Space Agency (ESA) is preparing to deploy such a spacecraft in cooperation with the Japanese Space Agency (JAXA) within the framework of the Comet Interceptor program. The program was officially accepted by ESA in 2022, and according to current plans, the probes will start their journey in 2028 or 2029, and the further fate of the mission will depend on when and what kind of observation subject is found during the wait. The main probe provided by ESA (Spacecraft A) and the two sub-units traveling with it (Spacecraft B1 and B2), one of which is made by JAXA and the other by ESA and their partners, will be stationed at the second Lagrangian point of the Sun-Earth system, here they wait in orbit for the moment when, through ground observations, the ideal subject for testing is identified. As Ákos Kereszturi, senior scientific associate of the HUN-REN Astronomy and Earth Science Research Center, said at the current H-SPACE space research conference in Budapest, it is not yet possible to know whether this will end up being a long-period comet or an interstellar object, essentially nothing can be concretely determined in advance celestial body, but what is certain is that it will be searched for in the sky within the framework of the LSST (Legacy Survey of Space and Time) project of the Vera Rubin Observatory. LSST will be a large-scale sky observation program, collecting 500 petabytes of images and data to map the Milky Way and learn more about the celestial bodies of the Solar System.

For a few years, the probe will be able to correct its position sufficiently to stay on a suitable orbit, but it cannot orbit around the Lagrange point indefinitely, so if the astronomers do not find the object they are looking for within five years of its “parking”, then a it will visit a different type of short-period comet. After selecting the target, upon reaching the comet, the main probe remains at a distance of 1,000 kilometers from the celestial body, while the two smaller units released fly closer to the comet’s nucleus in order to obtain even more data during the measurements. During the tests, the instruments will measure the structure, shape, composition of the core, the gases released by it, the characteristics of the plume, the magnetic field surrounding the object, the dust cloud, heat emission and its interaction with the solar wind, including equipment built with Hungarian cooperation.

The Digital Processing Unit (DPU) of the CoCa (Comet Camera) camera of the main probe is developed by the Hungarian company REMRED and SGF, Admatis produces the passive and active thermal control hardware for the probe, the staff of the Miklós Thege Konkoly Institute of Astronomy are also involved in the development of the CoCa camera part and the researchers of the Wigner Physics Research Center contribute to the preparation of the plasma tests. The CoCa camera provides high-resolution imaging using four filters that measure at different wavelengths from approximately 400 nm to 1000 nm. In order to be cost-effective, the two main elements of the equipment were created based on the design of instruments that already existed and performed well on other missions, and the “leftover” instruments used for these were used: one of them is the CaSSIS telescope of the ExoMars Trace Gas Orbiter orbiter, the other is the Janus telescope used in the JUICE program detector system.

The devices can be used to produce images of the unknown object that are orders of magnitude better than the images of Giotto, who observed Halley’s Comet, even though Giotto was only 596 kilometers away from Halley. The minimum exposure time of the camera is 220 μs, so you won’t have to expect blurry shots even at the fastest flight speed. CoCa works with a resolution of 8 meters per pixel and can take one picture per second. The spacecraft will send a total of 2,500 images to Earth during the part of the entire observation period as it passes by the comet.

The most unusual part of the Comet Interceptor mission promises to be that, for the time being, the participants planning the mission can only visualize a phantom comet during the preparation, but in fact they do not know the future target at all, in fact, the spacecraft will leave for its station even before they know where it will come from. the object. According to Kereszturi, even in the future, they will not be able to be sure whether the selected comet really started from the edge of the Solar System or from interstellar space, but the curve of the celestial body’s trajectory can be a telling clue. If the arc of the orbit is highly elliptical, parabolic or hyperbolic, there is a high chance that the detected celestial body has not been close to the Sun before. Studies regarding the selection of possible targets have already been published in recent years, but the identity of the real candidate can only be revealed by future observations.

(Photo: Maciej Frolow/Getty Images)

What does Earth’s twin hide, is there life in the clouds of Venus?
We talked with a planetary scientist about, among other things, whether there were oceans on Venus, or whether there could be life in the clouds 50-60 km high on the planet.