December 25, 2024

Matthew Fang

9th Grade

Williamsville East High School

On November 24, 2021, NASA launched its first venture into asteroid deflection: the DART mission. Although not a threat to Earth’s safety, DART successfully struck the asteroid Dimorphous in September 2022, knocking its orbit around a larger asteroid, Didymos, off course. Now, the spacecraft Hera is going back to the impact site in order to observe and analyze the results.

Launched on October 7th of 2024, Hera intends to return to the two asteroids in order to map out their surfaces, study the structure and composition of the asteroids to determine their masses, as well as inspect the impact crater that DART formed. In doing so, it will allow us to understand the many important factors in asteroid deflection, such as the momentum transfer efficiency, spin, and also the process in which craters form in low gravity.

Hera contains several instruments in order to aid our study of the asteroids. It contains Asteroid Framing Cameras and a Thermal Infrared Imager to allow it to capture images of the asteroids, as well as a Planetary Altimeter, in order to measure the distance to the asteroids using lasers, which will allow us to map the surface topography of the asteroids’ surfaces. Hera will also utilize a Radio Science Experiment, which uses radio waves in order to measure the mass and gravity of the asteroids. Hera also holds two CubeSats, named Milani and Juventas, which each contain multiple instruments that allow us to study the asteroid further. They are used in order to study the asteroid at extremely close proximity and, as such, will not put the main spacecraft, Hera, at risk.

In order to observe the asteroid, Hera will undergo five observation phases. The first phase is the Early Characterization Phase, in which Hera will slowly approach the asteroid, until it is caught in the asteroids’ orbits. From there, Hera will maintain a distance of 20-30 kilometers from the surface of the asteroids and orbit around the asteroids in order to determine their shape, mass, and density.

The next phase is the Payload Development Phase, which is when the CubeSats are first released, where the asteroid will be further studied at a distance. Then, after two weeks, the Detailed Characterization Phase will begin, where they will descend until they reach about 8-20 kilometers from the surface. From there, they will study the asteroids’ thermal, structural, and interior properties.

Then, the CubeSats will continue to descend, until they reach a distance of about four kilometers from the surface, in which they will conduct high-resolution studies of the asteroid and impact crater. Then, they will finally lower down until they are less than a kilometer from its surface to study the asteroids’ geological properties, with the final phase being completed once Hera lands on the surface of Didymos.

Although a seemingly small event, the mission of the Hera spacecraft is one that can have quite a large impact. It can tell us how to prevent any future asteroid impacts, and although there aren’t very many possible threats of an asteroid collision with Earth in the near future, if a dangerous asteroid ever comes to Earth, we’ll be ready to defend our home.