Hayabusa 1 – The Japanese Mission that Expanded the Frontiers of Space Exploration

Often, what sparks our interest and arouses our desire is not within our reach. But who has never crossed the city to eat that market pastry at the Japanese stall, or traveled to the United States to buy back that watch that you sold by mistake? Well, when it comes to Science, JAXA, the Japanese Space Agency, traveled more than 2 billion kilometers to search for fragments of space rock on the asteroid Itokawa that would help us learn a little more about the history of the Solar System.

This feat accomplished by the Hayabusa probe was an epic story of overcoming technological challenges in a true saga that redefined the limits of space exploration and culminated in the triumphant return of Hayabusa to our planet, bringing with it secrets from the distant past of this little corner of the Galaxy.

At the end of the 20th century, the Japanese space program was experiencing a period of expansion, with the development of satellites, rockets and scientific missions that consolidated the country as a space powerhouse. All of this laid the groundwork for an unprecedented and much more ambitious mission: traveling to the asteroid Itokawa, collecting samples from its surface and bringing them back to Earth for analysis by scientists.

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The mission, named Hayabusa, which in Japanese means “Peregrine Falcon”, was complex, full of challenges and required the development of innovative technologies, such as an autonomous navigation system and an ion engine for space propulsion.

After years of development and rigorous testing, Hayabusa was launched in May 2003 aboard an MV rocket from the Kagoshima Space Center in Japan. The probe carried with it the hopes of an entire nation and the promise of revolutionizing our understanding of the origins of the Solar System. But what made the asteroid Itokawa so special to science?

When the Hayabusa mission was first planned in 1996, its target was the asteroid Nereus. But two years later, Itokawa was discovered and turned out to be a more suitable option. Studies based on ground-based observations suggested that it was an S-type asteroid, composed mainly of silicates, rocky materials similar to those found in the Earth's crust. Asteroids like Itokawa hold within themselves the clues to unraveling the mysteries of the formation of the Solar System, since they have not undergone geological transformations like those that occur on Earth, remaining practically intact, as if they were cosmic fossils preserved in time.

In the year of the mission's launch, the asteroid was named Itokawa, in honor of rocket engineer Hideo Itokawa, considered the father of the Japanese space program.

Hayabusa's journey was a true space marathon, with obstacles. A two-and-a-half-year journey, in which the Japanese probe successfully debuted its ion propulsion system, an innovative technology that uses a beam of ions to generate thrust. However, this journey was far from smooth. JAXA controllers faced and overcame several technical challenges, such as communication failures, problems with the attitude control system and the loss of one of the probe's four ion engines.

In September 2005, after a journey of 2 billion kilometers, Hayabusa arrived at its destination and immediately revealed that Itokawa was not the uniform and monotonous celestial body that had been imagined. The asteroid was about 535 meters long, weighed 35 million tons and had a peculiar peanut shape, with curious relief features, full of gigantic rocks and flat regions covered by regolith. And with Hayabusa in orbit around Itokawa, it was time to put into practice the most daring part of the mission.

Other missions, such as Galileo and NEAR Shoemaker, had visited asteroids before, but the Hayabusa mission in 2005 was the first space probe to collect samples from the surface of an asteroid. This feat was accomplished with the help of an ingenious device that fired projectiles into the ground to collect the regolith and fragments ejected from the surface.

After two years of studying the asteroid in orbit and with the collected material carefully stored in the return capsule, Hayabusa began its long journey back to Earth. The problem is that the return trip was even more troubled than the outward one. The probe faced problems with its communication system, fuel leaks and the loss of two of its three gyroscopes, responsible for stability during the flight. But while you were sleeping, the Japanese at JAXA worked hard, and they managed to bring Hayabusa back home.

I am only sorry to say that Hayabusa, the probe that took Japan on this epic journey through the Cosmos, turned into vapor and disintegrated in a spectacular re-entry into our atmosphere. But this was not just another failure of that pioneering mission. This was expected. The only part that needed to survive the re-entry was the small capsule containing the samples. And it, protected by a heat shield and with its descent cushioned by a parachute, landed safely in the Australian desert on June 13, 2010.

The samples collected by Hayabusa from the asteroid confirmed that Itokawa was indeed an S-type asteroid, composed of silicates rich in olivine and pyroxene, minerals common in meteorites found on Earth. The analyses also revealed that Itokawa is a contact binary, that is, formed by the debris of two other asteroids that collided in the past. This is the same accretion process that all large bodies in the Solar System have undergone, but this was the first time that we were getting a close look at a contact binary. The discovery reinforced the theory that asteroids are true fossils, preserving the history of the formation of the Solar System!

Despite all the challenges faced, the Hayabusa mission was a milestone in the history of space exploration. The mission's success inspired JAXA to develop Hayabusa-2, an even more audacious mission that, in 2020, collected samples from another asteroid, Ryugu. The samples from Ryugu have already arrived on Earth and are being analyzed by scientists around the world, and they provide clues, including about the origin of life here on Earth.

(Artist's conception of the Hayabusa probe next to the asteroid Itokawa – Credits: JAXA)

All this, thanks to the boldness, determination and competence of Japanese engineers, who would make Hideo Itokawa himself proud, demonstrating that, driven by science, humanity is capable of flying even further and expanding the frontiers of space exploration!