Hayabusa 2 is a space probe from JAXA, the Japanese space agency. Launched on December 3, 2014, it achieved the feat of bringing back to Earth samples of an asteroid.
Hayabusa 2 was preceded by the Hayabusa mission, launched in 2003. The objective of this mission was to study the small asteroid Itokawa as well as to carry out several tests of robotic exploration techniques. The Hayabusa space probe had carried several scientific instruments for this purpose. After two years of travel, the Hayabusa space probe eventually reached the asteroid Itokawa in 2005. However and despite several attempts to land on the asteroid, no sampling was successful due to the very low gravity of Itokawa. On its return, a small sample of dust was still collected. The probe’s return trip to Earth did not go as planned, and the Hayabusa probe eventually landed on Earth in 2010, three years after the original arrival date.
The Hayabusa 2 Mission
Technically speaking, the Hayabusa 2 space probe is identical to its predecessor, except for the collection method used.
The objective of the Hayabusa 2 space probe is the study of the asteroid Ryugu, of type C. This category simply refers to carbonaceous asteroids that are C-shaped. This asteroid shape represents about 75% of known asteroids and contains potentially organic materials, a characteristic sought in order to better understand the development of the Solar system.
Two main objectives were assigned to Hayabusa 2. Initially the probe was to study the asteroid Ryugu as a whole and from distance using several scientific instruments such as a near infrared spectrometer, a laser altimeter or multispectral cameras. Then in a second step, the probe had to collect samples in order to study the Ryugu composition.
The Proceedings of The Mission
The first phase of the mission began on December 3rd, 2014 with the launch of the space probe from the Tanegashima launch base. After launch, the transit phase began, during which the space probe used its ionic propulsion (acceleration of ions at very high speed) to adjust its trajectory. The route plan of the Hayabusa 2 probe was determined so that in 2015 the probe would fly over the Earth and use gravity assistance to gain speed. Subsequently, several speed and trajectory adjustments were made between 2016 and 2017 before June 27, 2018, when Hayabusa 2 space probe arrived near the asteroid Ryugu.
The second phase could then begin. The first two months of the mission were purely dedicated to the remote analysis of Ryugu in order to better understand its physical characteristics and therefore to determine the most suitable landing sites. Performing a landing maneuver is never easy, but performing one on an asteroid is even harder. The landing site must meet several criteria: not be located more than 200 meters from the equator so that the teams can monitor operations, the inclination of the ground in relation to the Sun must not exceed 30° in order to receive sufficient lighting and the temperature must be below 97° Celsius. Hence the global study of Ryugu.
Once the data had been collected, the Japanese teams were able to choose the most suitable landing site. But before that, two rehearsals were organized to make sure that the automatic sequence of operations of the Hayabusa 2 probe was correct.
In parallel, the probe deposited on Ryugu, on September 22 and October 3, 2018, mini-rovers in addition to the MASCOT lander, which made it possible to send up-close photos of the asteroid. The MASCOT lander, developed by the German space agency in collaboration with the French space agency, also performed an in situ mineralogical analysis of the asteroid ground.
The third and most important phase of the mission, the sampling, was postponed until February 2019. Finally, after several years, on February 21, 2019 the Hayabusa 2 space probe began its descent towards the surface of Ryugu. This method is simple: the probe hits the ground of the asteroid, with enough pressure to create an impact. This impact raises a cloud of dust which then should penetrate into a cone before being stored in the compartments provided for this purpose.
As of April 2019, the goal for Hayabusa 2 is to dig a crater and collect a sample from the deeper layers of the asteroid. The aim is to obtain, among other data, the characteristics of the soil unaltered by the exposure of the space vacuum, to measure the degree of fragmentation of the rocks and to measure the size of a crater on Ryugu as a result of its impact.
To carry out this mission, the probe released an impactor, before quickly moving away to avoid any fallout. Then after a while, she dropped a camera to film the impact. Most of the models predicted that the diameter of the impact will be around 10 meters, the camera showed that it was actually 20 meters.
Then came the difficult question of a second sample. Sampling presents many risks for the space probe, and could damage it when the first sampling seemed to be a success. The Japanese teams wondered if they should be reasonable and not tempt the devil? Or should they be greedy and attempt a second sample at the risk of losing the first? The second option was chosen and on July 11, 2019, Hayabusa 2 obtained a second sampling.
Once its missions were completed, Hayabusa 2 returned to Earth on November 13, 2019. More than a year later, the capsule detached from the space probe and landed in the Woomera Desert in Australia on December 5, 2020.
The mission control team was never 100% sure that Ryugu’s sample collection was successful. Their joy was great when they saw that Hayabusa 2 had indeed collected samples from Ryugu and that in addition the harvest was good: it seems that the probe recovered 1 gram of matter while the objective set was 100 milligrams.
The samples will be analyzed at the JAXA Extraterrestrial Sample Conservation Center, and the analysis will be carried out by an international team with French researchers.
There is a scientific consensus to say that this mission is exceptional and that its success is a real feat. The samples taken will allow us to learn more about the phases of formation of the solar system and the role of asteroids in the emergence of life on Earth.
The mission control team noticed that the Hayabusa 2 space probe was still in perfect working order and still had half of its fuel reserve. Hayabusa 2 was sent to study the asteroid 1998 KY26, and is expected to reach it in July 2031.