The Hera mission is part of the European Space Agency’s (ESA) planetary defense initiative, designed to test and refine our ability to prevent asteroids from colliding with Earth. Launched under the ESA’s Space Safety Program, Hera is named after the Greek goddess of marriage, as it forms part of a larger international effort alongside NASA’s Double Asteroid Redirection Test (DART) mission. Together, these missions represent humanity’s first attempt at actively deflecting a celestial object.

Overview

Hera will travel to a binary asteroid system, consisting of the 780-meter-wide asteroid Didymos and its smaller, 160-meter-wide moonlet, Dimorphos.

The choice of this binary system is strategic because it allows scientists to study the effects of asteroid deflection on both a larger and a smaller body. While Didymos itself poses no threat to Earth, it serves as an ideal testbed for the study of asteroid dynamics and deflection strategies.

Hera will arrive at the asteroid system in 2026, following NASA’s DART mission, which has already impacted Dimorphos to alter its trajectory. DART’s mission, which took place in September 2022, was designed to crash a spacecraft into Dimorphos, changing its orbital period around Didymos. Hera’s role is to investigate the aftermath of this impact and provide critical data that will inform future planetary defense efforts.

Objectives

Hera’s primary objective is to gather precise data on the aftermath of the DART impact. While NASA’s DART mission was a kinetic impactor designed to physically alter the trajectory of Dimorphos, Hera will carry out a detailed post-impact survey. This includes measuring the size and shape of the crater left by DART, analyzing Dimorphos’ mass and internal structure, and determining whether the impact caused any significant changes to the asteroid’s orbit or spin state.

Hera will also deploy two CubeSats — small companion satellites — named Milani and Juventas, to assist in its scientific goals. These CubeSats will perform close-up measurements of the asteroid system, focusing on their physical and compositional properties. The Juventas CubeSat, equipped with a radar instrument, will probe the interior structure of Dimorphos, providing unprecedented insight into the makeup of the asteroid. Meanwhile, Milani will conduct surface and spectral imaging to analyze the asteroid’s composition and detect potential water-rich minerals.

One of the key reasons for Hera’s involvement is that DART alone cannot gather detailed information about its own impact. Ground-based observations can only measure changes in Dimorphos’ orbit from afar, but Hera will provide close-up, high-resolution data that can only be collected by an in-situ mission. This synergy between DART and Hera is essential to fully understanding the kinetic impact technique and refining our planetary defense strategies for the future.

Technology

The Hera mission incorporates several technological innovations. Among the most significant is its use of autonomous navigation systems. Given the small size of Dimorphos and Didymos, navigating a spacecraft in close proximity to the binary asteroid system poses considerable challenges. To address this, Hera is equipped with an advanced guidance system that allows the spacecraft to autonomously navigate around the asteroid system without requiring constant commands from ground control. This capability will be critical for future missions to similarly small celestial bodies, where precise navigation is crucial.

Another technological milestone is the deployment of the CubeSats. Although small in size, Milani and Juventas are packed with cutting-edge instruments that will provide critical data on the asteroid’s surface composition and internal structure. The Juventas radar, for example, is the first of its kind to be used on an asteroid, marking a significant leap forward in our ability to probe the interiors of such bodies.

Science

Hera’s mission will yield critical insights into the behavior of asteroids, contributing to our understanding of their composition, structure, and dynamics. By studying the effects of DART’s impact, scientists will be able to refine models of asteroid deflection, improving the accuracy of predictions about how future deflection efforts will unfold. Understanding the internal structure of asteroids, in particular, is crucial for planetary defense, as different compositions will react differently to deflection attempts. An asteroid made primarily of solid rock, for example, will behave differently than a loose “rubble pile” asteroid when struck by a kinetic impactor.

Furthermore, Hera will contribute to the broader field of asteroid science. Asteroids are considered to be remnants of the early solar system, and studying them offers a window into the conditions that existed during its formation. The data collected by Hera and its CubeSats will help scientists better understand the composition of asteroids, which could, in turn, inform future missions aimed at mining asteroids for resources such as water or precious metals.

Planetary Defense

The Hera mission is a key part of the international effort to develop a robust planetary defense strategy. By testing the kinetic impactor technique on Dimorphos, Hera and DART are providing invaluable data that could one day be used to prevent a catastrophic asteroid collision with Earth. While the chances of a large asteroid impacting Earth in the near future are slim, the consequences of such an event could be devastating. Missions like Hera and DART are vital for ensuring that humanity has the tools and knowledge necessary to defend the planet from such threats.

Falcon 9 is a reusable, two-stage rocket designed and manufactured by SpaceX for the reliable and safe transport of people and payloads into Earth orbit and beyond.

Falcon 9 is the world’s first orbital-class reusable rocket.

Stats

Total launches: 406

Total landings: 362

Total reflights: 336

The Falcon 9 has launched 52 humans into orbit since May 2020

Specs

Height: 70 m / 229.6 ft

Diameter: 3.7 m / 12 ft

Mass: 549,054 kg / 1,207,920 lb

Payload to Low Earth Orbit (LEO): 22,800 kg / 50,265 lb

Payload to Geostationary Transfer Orbit (GTO): 8,300 kg / 18,300 lb

Payload to Mars: 4,020 kg / 8,860 lb

On January 24, 2021, Falcon 9 launched the first ride-share mission to Sun Synchronous Orbit. It was delivering a record-setting 143 satellites to space. And while this was an important mission for SpaceX in itself, it was also the moment Falcon 9 overtook United Launch Alliance’s Atlas V for the total number of consecutive successful launches.

SpaceX’s Falcon 9 had become America’s workhorse rocket, launching 31 times in 2021. It has already beaten that record this year, launching almost an average of once a week. While most of the launches deliver Starlink satellites to orbit, the company is still launching the most commercial payloads to orbit, too.

Falcon 9 is a medium-lift launch vehicle, with the capability to launch over 22.8 metric tonnes to low earth orbit. Unlike any other rocket, its first stage lands back on Earth after separating from its second stage. In part, this allows SpaceX to offer the cheapest option for most customers with payloads that need to reach orbit.

Under its ride-share program, a kilogram can be placed in a sun-synchronous orbit for a mere 1.1 million dollars, far cheaper than all other currently operating small satellite launch vehicles.

The reusability and fast booster turnaround times have made Falcon 9 the preferred choice for private companies and government agencies. This has allowed SpaceX to capture a huge portion of the launch market.

Photo courtesy of Jenny Hautmann for Supercluster.

Space Launch Complex 40 (SLC-40) is one of two launch sites leased by SpaceX at Cape Canaveral Space Force Station (CCSFS) in Florida, specifically designed for preparing and launching Falcon 9 rockets. Constructed in the early 1960s, SLC-40 was initially used for 55 Titan III and Titan IV rocket launches, including the Cassini-Huygens mission to Saturn. The pad was active from June 18, 1965, to April 30, 2005.

SpaceX began leasing SLC-40 in 2007, converting it to support Falcon 9 rockets. The pad was first upgraded to accommodate the original version of Falcon 9 and later received another upgrade in 2013 to handle the larger, reusable Falcon 9 rocket. On September 1, 2016, an explosion during a Falcon 9 fueling test caused severe damage to the pad. It was rebuilt rapidly, with construction completed in just 10 months, from mid-February to late November 2017. SLC-40 resumed operations with the successful launch of a Dragon capsule to the International Space Station on December 15, 2017.

After adding a crew access arm to the launch tower, SpaceX launched their first crewed mission from SLC-40 on Saturday, September 28th 2024 for NASA's Crew-9 mission to the International Space Station.

Under SpaceX’s management, SLC-40 has been the site of numerous significant missions. Notable launches include the first all-commercial Dragon mission to the International Space Station, NASA’s DSCOVR mission, the Transiting Exoplanet Survey Satellite (TESS) for NASA and MIT, the first satellite for Turkmenistan, the classified Zuma mission for Northrop Grumman and the U.S. government, the first GPS-III satellite, and the Beresheet lunar lander for Israel. Additionally, in September 2024, SLC-40 will host its first crewed launch with SpaceX’s Crew-9 mission, marking a new milestone for the pad.

Cape Canaveral is a major launch site with four currently active launch pads for Atlas V, Delta IV Heavy, Falcon 9, and Minotaur rockets. Located on Florida’s east coast, it offers extensive access to space for a variety of missions, including those targeting the Space Station, Geostationary Earth Orbit, the Moon, interplanetary destinations, and polar trajectories. The site’s location ensures that launches occur over the open Atlantic Ocean, minimizing risks to populated areas.

Cape Canaveral is often confused with or referred to alongside NASA’s Kennedy Space Center on Merritt Island. While they are separate installations, both play pivotal roles in the U.S. space program. Cape Canaveral has a storied history of significant space missions, including the launch of the first U.S. Earth satellite, Explorer 1, in 1958; the first U.S. astronaut, Alan Shepard, in 1961; the first U.S. astronaut in orbit, John Glenn, in 1962; the launch of the first two-person U.S. spacecraft, Gemini 3, in 1965; and the first U.S. uncrewed lunar landing mission, Surveyor 1, in 1966.

SLC-40 and Cape Canaveral continue to be integral to SpaceX’s ambitious launch schedule and the broader U.S. space program, supporting a wide range of missions and contributing to advancements in space exploration.

Photo courtesy of Jenny Hautmann for Supercluster

Hera will travel to the Didymos pair of near-Earth asteroids for a rendezvous in December of 2026.

The 780 m-diameter mountain-sized main body is orbited by a 160 m moon, formally christened 'Dimorphos' in June 2020, which is about the same size as the Great Pyramid of Giza.

By actually venturing to Dimorphos, measuring its mass as well as its shifted orbit from up close and performing its own ‘crash scene investigation’ of the asteroid moon’s impact crater and surrounding surface in great detail, Hera will hone our understanding of the impact process at asteroid scale.

Hera will carry two CubeSats – Juventas and Milani. These are Europe’s first deep-space CubeSats; they will get closer to Didymos’s companion, Dimorphos, gathering additional data on the asteroid whilst testing new intersatellite link technology. Each companion spacecraft will be small enough to fit inside a briefcase, as compared to the desk-sized Hera.