Mission profile hayabusa-2
The mission to asteroid Ryugu reveals the latest images
This innovative mission will visit the distant asteroid Ryugu and collect pieces of it to answer some of the Solar System’s most pressing questions “Sampling surface material is the most challenging task”
Professor Sei-ichiro Watanabe
The successor to Hayabusa is currently in the depths of the Solar System spying on another asteroid, with plans to steal a sample away for Earth-based analysis. Both Hayabusa missions had a common goal: to understand these ancient time capsules that are dotted throughout the Solar System. However, the Japan Aerospace Exploration Agency (JAXA) wanted to sample another type of asteroid for its second attempt to further understand their differences.
Asteroids were formed along with the planets over 4 billion years ago, and since then they have been floating around space, orbiting the Sun. Hidden within these frozen pieces of rock are the early chapters of the story of the Solar System. However, asteroids are not as black and white as thought by some; there are many types of asteroids that exhibit different features. Hayabusa visited the small near-Earth asteroid 25143 Itokawa in 2005, and successfully returned samples of the S-type (siliceoustype), 540-metre (1,772-foot) rock (at its longest dimension).
On 3 December 2014 Hayabusa2 was successfully launched on board the H-IIA launch vehicle from the Tanegashima Space Center in Minamitane, Japan. This updated version of Hayabusa includes exciting new features and landers. Onboard instruments include optical navigation cameras, a near-infrared camera and a thermalinfrared camera, but there are also deployable payloads. Where Hayabusa only had the MIcro-Nano Experimental Robot Vehicle for the Asteroid (MINERVA) minilander, which unfortunately did not go to plan due to a error in deployment, Hayabusa2 has three rovers and one main lander. MINERVA-II-1 and MINERVA-II-2 were designed to hop along the surface to conduct probes. The Mobile Asteroid Surface Scout (MASCOT) lander will use four internal instruments to examine the surface up close while jumping from one spot to the next.
So what asteroid did JAXA choose, having already sampled an S-type asteroid. “The primary objective of Hayabusa2 is to elucidate the formation, dynamical and material evolution and impact history of a carbonaceous [C-type] asteroid,” says Watanabe. A C-type asteroid is a more primitive asteroid compared to an S-type, so astronomers are hoping to delve deeper into the past.
“We can understand the evolution of building blocks of planets [planetesimals] around the ‘snow line’ – the boundary between the inner and outer Solar System,” says Watanabe. “We can also identify possible sources of water and organic materials delivered to the early Earth.”
The chosen destination was 162173 Ryugu. Not much was known about the asteroid until Hayabusa2’s arrival on 27 June 2018. Before Hayabusa2’s eyes, Ryugu began to take shape. The most striking thing is the almost diamond-like shape to it, with a mean diameter of almost one kilometre (0.6 miles). Scientists also noticed that its surface shares some similarities with Itokawa in that there are many boulders and a grooved terrain. What’s more noticeable about Ryugu though is that there are more noticeable impact features – dents in the surface.
In September and early October 2018 the Hayabusa2 team decided to release the rovers and landers. The two MINERVA-II-1 rovers, Rover-1A and Rover-1B, were the first to touch down on the mysterious asteroid, skimming across the surface and providing some magnificent images as they did so. The next to follow was the MASCOT lander, which was deployed in the opening days of October 2018. In the closing days of October the mission will begin its most exhilarating feat of scientific and engineering brilliance as Hayabusa2 conducts its first touchdown onto Ryugu and collects its first sample of interstellar rock.
“Sampling surface material of the target asteroid is the most important and challenging task for the Hayabusa2 mission. A sampler horn is extended beneath the spacecraft to conduct surface materials to a sample catcher inside the main body of Hayabusa2,” explains Watanabe. “The sampling will be performed within a few seconds, during which only the flexible sampler horn touches the asteroid’s surface, before the firing of the thrusters for ascent. Exactly speaking, the sequence is not a landing but a touch-and-go, and we call it a ‘touchdown’.”
After two touchdowns Hayabusa2 will release its impactor between March and April 2019. Its artificial surface-destroyer will plunge into Ryugu, unmasking rock that hasn’t been exposed to space in billions of years.
After this impact Hayabusa2 will collect its third and final sample, after which the remaining MINERVA-II-2 rovers will be deployed. This concludes Hayabusa2’s stay at Ryugu, and in late 2019 the craft will head back to Earth with a stocking not full of coal, but rare asteroid samples to help explain how our Solar System evolved.