In a significant step forward for planetary defence, the European Space Agency’s Hera spacecraft has launched an ambitious mission to investigate the aftermath of NASA’s Double Asteroid Redirection Test (DART).
In September 2022, DART made history by intentionally colliding with Dimorphos, the moonlet of a giant asteroid named Didymos, to test the viability of using kinetic impact to deflect potentially hazardous asteroids.
Hera will conduct a detailed post-impact survey to gather crucial data that could transform asteroid deflection into a reliable technique for protecting Earth.
Hera’s Mission Objectives
Hera, a spacecraft roughly the size of a small car, will be the first to explore a binary asteroid system in depth. Its primary target is Dimorphos, which is about 160 meters in diameter—comparable in size to the Great Pyramid of Giza. By studying the asteroid pair, mainly focusing on the changes caused by DART’s impact,
Hera aims to Measure the mass, size, and shape of Dimorphous with unprecedented precision; assess the size, depth, and shape of the crater left by DART; determine the composition and internal structure of Dimorphos (whether it is a solid body or a loose rubble pile); and investigate the orbital changes caused by the impact and compare them to predictions.
Achieving these objectives will require a suite of advanced scientific instruments, including high-resolution cameras, a lidar system for 3D mapping, and a radio science experiment to measure the asteroid’s gravity field. The data collected by Hera will be essential for validating and refining impact-based asteroid deflection models, helping to develop a reliable defence against potential asteroid threats.
One of the significant challenges Hera will face is navigating the complex gravitational environment of the Didymos binary system. The two asteroids orbit each other, creating a constantly changing gravitational field that can make it difficult for a spacecraft to maintain a stable trajectory.
To overcome this challenge, Hera will demonstrate advanced autonomous navigation capabilities. Using onboard cameras and sophisticated algorithms, Hera can identify surface features on the asteroids and use them as reference points for navigation. This will allow the spacecraft to safely manoeuvre around Didymos and Dimorphos, even without constant guidance from ground control. Autonomous navigation will be crucial for enabling close-up observations of Dimorphos’ surface and for coordinating the activities of Hera’s CubeSat companions.
In addition to its autonomous navigation system, Hera will showcase several other innovative technologies that could pave the way for future deep space missions. One of the mission’s most exciting aspects is deploying two shoebox-sized CubeSats, Juventas and Milani, to explore Dimorphos up close. Juventas, developed by GomSpace, will be the first spacecraft to probe an asteroid’s interior using low-frequency radar. By penetrating through the surface layers, this radar will reveal details about Dimorphos’ internal structure and composition, helping to determine whether it is a solid body or a loose rubble pile.
This information is crucial for predicting how the asteroid would respond to future deflection attempts. Milani, built by Tyvak International, carries a multispectral camera capable of imaging beyond the visible light spectrum. By analyzing the spectral signatures of the asteroid’s surface, scientists can identify the minerals present and map their distribution, providing insights into the formation and evolution of the Didymos system.
The Engineering Behind Hera’s CubeSats
Integrating sophisticated scientific instruments into CubeSats is a significant engineering challenge. These miniature spacecraft’s limited size, mass, and power budgets require careful design and miniaturization of components. Advanced materials, such as lightweight composites and highly efficient electronics, are essential to maximize performance within the constraints. For example, Juventas’ low-frequency radar must be powerful enough to penetrate Dimorphos’ surface while still fitting within the CubeSat’s compact frame. This requires innovative antenna designs and advanced signal processing techniques to extract meaningful data from the reflected signals.
Similarly, Milani’s multispectral camera must be able to capture high-quality images across multiple wavelengths while operating within the power and data storage limitations of the CubeSat platform. Another critical technological innovation demonstrated by Hera is the use of inter-satellite links for communication between the main spacecraft and its CubeSat companions. These links allow Hera and the CubeSats to share data and maintain precise positioning relative to each other and the asteroids. Inter-satellite links can enhance the mission’s scientific return by enabling coordinated observations and measurements. The success of Juventas and Milani could demonstrate the potential of CubeSats as capable and cost-effective tools for deep space exploration, paving the way for future missions that deploy swarms of these tiny spacecraft to study distant targets.
The Hera mission is an excellent example of international collaboration in space exploration. While Hera is an ESA-led mission, it builds upon the success of NASA’s DART mission and involves contributions from multiple countries. The CubeSats, Juventas and Milani are provided by consortia led by GomSpace (Denmark) and Tyvak International (Italy), respectively. Additionally, Hera’s scientific instruments are the result of collaboration among research institutions across Europe, including the German Aerospace Center (DLR), the French National Centre for Scientific Research (CNRS), and the Italian National Institute for Astrophysics (INAF). By pooling expertise and resources from different nations, the Hera mission demonstrates the power of international cooperation in tackling complex challenges like planetary defence.
Hera began its journey with a launch on a SpaceX Falcon 9 rocket from NASA’s Kennedy Space Center on October 7, 2024. The spacecraft will now embark on a two-year cruise phase, covering a distance of nearly 500 million kilometres to reach the Didymos system. During this time, Hera will perform several deep space manoeuvres, including a flyby of Mars in 2025, to gain a gravitational assist and adjust its trajectory. The Mars flyby will also serve as an opportunity to test and calibrate Hera’s instruments by observing the planet’s moon, Deimos. Arrival at Didymos is scheduled for late 2026, four years after DART’s impact. Over several months, Hera will conduct a series of close flybys, progressively getting closer to Dimorphos’ surface. The spacecraft and its CubeSats will work together to create detailed maps of the asteroid, characterize its physical properties, and search for signs of DART’s impact. The ultimate goal is to comprehensively understand the collision’s aftermath and its implications for planetary defence.
The data collected by Hera will have far-reaching implications for our understanding of asteroid deflection and planetary defence strategies. By providing detailed post-impact measurements of Dimorphos, Hera will help validate numerical models of kinetic impact deflection and identify any discrepancies between predicted and observed results. This information will be crucial for refining and optimizing future deflection missions. Moreover, Hera’s findings could influence the design of future asteroid missions and the development of new technologies for planetary defence. For example, insights into the composition and internal structure of asteroids could guide the selection of appropriate deflection techniques (kinetic impact, gravity tractor, ion beam deflection, etc.) based on the characteristics of the target body. Similarly, the experience gained from operating CubeSats near an asteroid could inform the development of specialized instruments and spacecraft for future exploration and deflection missions.
The Hera mission represents a significant milestone in humanity’s efforts to protect Earth from the threat of asteroid impacts. By providing a detailed post-impact assessment of DART’s collision with Dimorphos, Hera will help validate and refine kinetic impact as a viable deflection technique. The data collected by Hera will not only inform the development of future missions but also contribute to a global strategy for planetary defence. Beyond its primary objective, Hera will demonstrate innovative technologies that could revolutionize deep space exploration. Autonomous navigation, miniaturized instruments, and inter-satellite communication could enable more efficient and cost-effective missions in the future, opening new frontiers in our exploration of the solar system. As Hera sets sail on its groundbreaking journey, it carries the hopes and aspirations of scientists, engineers, and policymakers worldwide. The mission’s success could mark a turning point in our ability to safeguard Earth from the threat of asteroid impacts while showcasing the power of international collaboration in space exploration. With Hera leading the way, we are taking a crucial step towards a future where planetary defence is not just a concept but a reality.
TLDR
- ESA’s Hera mission was launched to investigate the aftermath of NASA’s DART asteroid impact.
- Hera will study the Didymos binary asteroid system, focusing on changes to Dimorphos.
- Key objectives: precise measurements of Dimorphos’ properties, impact crater assessment, and composition and internal structure determination. Demonstrates innovative technologies like autonomous navigation, CubeSats with radar and multispectral imaging, and inter-satellite links.
- Hera will navigate the complex gravitational environment of the binary asteroid system.
- The mission involves international collaboration, with contributions from multiple countries and institutions. Hera’s data will validate and refine kinetic impact as an asteroid deflection technique, influencing future missions and planetary defence strategies.
