Oct 8, 2024 6 min read ESA

European Mission Studies Aftermath of NASA's Asteroid Impact

Photo: ©ESA

A Journey Beyond Earth

In a new milestone for space exploration, a European mission has embarked on an intriguing journey to investigate an asteroid recently struck by NASA. The mission's goal is to analyze the impact of NASA's DART (Double Asteroid Redirection Test) that, in September 2022, deliberately collided with the asteroid Dimorphos. This joint international effort marks an important chapter in understanding both asteroid dynamics and potential planetary defense techniques. Let's dive into the details and explore the mission's significance.

Revisiting NASA's Asteroid Collision: The Context

NASA's DART mission was a groundbreaking experiment designed to test whether humanity could potentially prevent a hazardous asteroid from impacting Earth. By crashing into Dimorphos, the smaller satellite of the Didymos binary asteroid system, DART sought to alter its trajectory, providing crucial data on asteroid deflection capabilities. The mission not only succeeded in changing the orbit of Dimorphos but also generated substantial amounts of debris, effectively turning the asteroid into a scientific specimen for further study.

Now, the European Space Agency (ESA) is sending a follow-up mission called Hera to learn more about the aftermath of this cosmic collision. Hera aims to provide detailed insights into the structural consequences of the impact and investigate the properties of both Didymos and Dimorphos in depth. This collaborative effort between NASA and ESA is an exciting step forward in our ability to protect Earth from asteroid threats.

Key Objectives of the Hera Mission

The Hera mission, which launched on October 7, 2024, is a two-and-a-half-year journey to reach the asteroid system and commence its studies. The mission has several key goals:

Investigating Dimorphos' Crater: After DART's collision, Dimorphos was left with a significant crater, and Hera aims to analyze its structure. By examining this crater closely, scientists hope to understand how the collision redistributed material across the asteroid and how much energy was transferred during impact.
Detailed Mapping: Hera will perform a detailed mapping of the surface of Dimorphos, focusing on changes to its terrain and composition. High-resolution imagery will be key to identifying the extent of the impact and any changes in surface morphology. Hera will utilize a suite of instruments, including a lidar and a thermal infrared imager, to achieve this.
Measuring the Mass: One major question is the mass of Dimorphos after the collision. Hera will use sophisticated instruments to determine the asteroid's mass, providing data crucial for accurately understanding the effect of the DART impact.
Binary Asteroid Dynamics: The Hera mission also intends to study the dynamics of the binary system formed by Didymos and Dimorphos. Understanding how the two bodies interact gravitationally will contribute to our broader understanding of binary asteroids, which are relatively common in our solar system.
Subsurface Exploration: Hera will deploy two CubeSats, Juventas and Milani, which will conduct close-up investigations, including using radar to probe beneath the surface of Dimorphos and gather data on its internal structure and gravitational field.

A New Frontier for Planetary Defense

The Hera mission represents a vital leap in planetary defense. DART's success demonstrated that kinetic impactors could effectively change an asteroid's orbit, but there is much we still do not know about the mechanics behind such a collision. Hera's measurements will provide empirical data to refine our models, enabling scientists to better predict how different kinds of asteroids might respond to impact attempts, especially those suspected to be "rubble piles" like Dimorphos.

The collaboration between NASA and ESA also demonstrates the power of international partnerships in space exploration. Tackling the challenge of asteroid defense is a global issue, and missions like Hera highlight the importance of working together to ensure planetary safety. These missions can also pave the way for better coordination in future space projects that require extensive cooperation and shared expertise.

Why Studying Asteroids Matters

Asteroids, often viewed as relics of the early solar system, offer a wealth of information about the conditions that led to the formation of planets. By studying asteroids like Didymos and Dimorphos, we can gain insights into the building blocks of our own world. The Hera mission will collect data on the physical properties of these asteroids, including their structure, density, and internal makeup.

Understanding how asteroids are composed helps scientists develop better strategies for dealing with potential Earth-bound threats. Not all asteroids are created equal—some are solid rock, while others are more like loosely bound collections of debris, often described as "rubble piles," which is what Dimorphos is suspected to be. Knowing what kind of asteroid we might be dealing with makes a significant difference in terms of how to mitigate the danger it could pose.

The Future of Asteroid Exploration

Hera's investigation into the aftermath of the DART impact will not be the last word on asteroid research. Instead, it is expected to lay the groundwork for future missions, perhaps even manned missions to near-Earth objects. As space exploration technology continues to advance, the insights gathered from the Didymos-Dimorphos system will undoubtedly influence how we approach not only planetary defense but also the utilization of asteroid resources.

For instance, some asteroids contain precious metals and materials that could be valuable for space industry. Understanding the physical properties and dynamics of these celestial bodies is essential if we hope to ever utilize them as part of our expansion into the solar system.

A Collaborative Step Towards a Safer Future

The Hera mission, as a follow-up to NASA's DART project, is a testament to humanity's determination to better understand the cosmos and safeguard our planet. By venturing out to study the impact site, the European Space Agency is helping to answer crucial questions about our ability to protect Earth from asteroid threats. The mission underscores the importance of collaboration, the value of scientific inquiry, and the potential of technology to mitigate existential risks.

As we watch Hera's progress over the next few years, it serves as a reminder that space exploration is not only about satisfying curiosity—it's also about ensuring the long-term survival of life on Earth. This international effort to explore a distant asteroid system is both a fascinating scientific endeavor and a critical mission for planetary defense.