Hera Visits the Injured Didymos

The European Space Agency (ESA) has launched the Hera mission, part of its planetary defense program, to assess the effectiveness of NASA's mission to alter the trajectory of an asteroid. Last week, on October 7, the ESA began its new space mission named Hera, which was launched aboard a SpaceX Falcon 9 rocket to visit a binary asteroid system. The asteroid, named Didymos, has a smaller moonlet called Dimorphos in its orbit, forming a binary asteroid system. Didymos is approximately 780 meters in diameter, while its moonlet Dimorphos is about 160 meters in diameter. The United States space agency, NASA, initiated a mission in 2021 to test the effectiveness of a defensive method against asteroid threats that occasionally approach Earth. The risk of near-Earth asteroid impacts is a serious threat that can cause significant destruction in a specific area and, if the impacting object is large enough, could lead to global devastation and even threaten human life. To date, over 31,000 near-Earth asteroids have been identified, of which 2,300 are classified as potentially hazardous to Earth. Estimates suggest that there are still over 15,000 near-Earth objects larger than 140 meters that remain unidentified. Contrary to the portrayal in commercial films, defending Earth against such objects is not a simple task. Our best hope for defense is early detection and the use of methods that can change the trajectory of these objects over time. One such method involves using the kinetic energy of a projectile. When we identify an asteroid at a distant location, we may be able to send a projectile to slightly alter its path, and this small change could be sufficient to divert it enough by the time it reaches Earth to save us from danger. The DART mission was initiated for this purpose and targeted the binary asteroid system Didymos and its moonlet. The reason for this choice was that first, the targeted asteroid would not pose a threat to Earth if its trajectory were altered, and second, due to its binary structure, precise calculations of the impact effects could be made. The mission was successfully executed, and the change observed in the orbits of these asteroids appears to be acceptable. For more information about the risks of space impacts on Earth, you can listen to episode 35 of Chistara. Hera began its mission on October 7 with the SpaceX Falcon 9 rocket. Now, four years after that impact, the European Space Agency (ESA) has sent a mission to the same asteroid system as part of its planetary defense project. This mission, which began its journey last week aboard the SpaceX Falcon 9, is tasked in its first phase with using a set of visible light imaging tools, spectrometry, altimetry, and small satellites (cubesats) to investigate the effects of the DART impact on this asteroid system four years later. However, this is not all that Hera will accomplish on its journey. This mission will also conduct a more detailed examination of the structure of this asteroid system. Along with the instruments installed on this mission, Hera carries two cubesats. One of these small explorers, named Milani, will attempt to create a spectral map of the asteroids using advanced spectrometry tools to identify the surface compositions and minerals constituting the asteroid Dimorphos. This information is crucial not only for understanding the nature of the asteroid but also for helping researchers gain a more accurate picture of the impact effects of the DART mission. This cubesat will also analyze and separate the dust remnants surrounding this asteroid. The other cubesat, named Juventas, aims to investigate the subsurface structures of the asteroid Dimorphos. Most of this research will be conducted using radar tools installed on this explorer. Asteroids are, in a sense, fossils of the solar system. Their formation dates back to the early days of the solar system, but unlike large planets and moons, they have not been affected by erosion and have preserved the initial conditions of our solar system like a souvenir photo. There are hypotheses that suggest Earth's water resources may have been brought to our planet through asteroid impacts in its early days; however, these ancient relics can also play a role in ending life as we know it on the planet. Just as one of them ended the age of dinosaurs about 60 million years ago and initiated the era of mammal dominance.