How to blow up an asteroid – Hayabusa 2 and 162173 Ryugu

Hayabusa2 is about to have a close up and personal experience with the asteroid Ryugu. In this mission the spacecraft will collect a bit of the asteroid and return to Earth.

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For billions of years asteroids have been impacting Earth causing all sorts of mayhem, just ask the dinosaurs. Now it’s our chance to get a bit of revenge with the Japanese Hayabusa2 spacecraft that is about to intercept the asteroid 162173 Ryugu. The cool thing about this close encounter with an asteroid is that in 2020 the spacecraft will come back to Earth with a bit of the asteroid, in the second asteroid sample return mission by JAXA. The mission involves orbiting the asteroid and studying it then firing a projectile into the asteroid with some explosives and then popping down to the surface to get some freshly blown up asteroid and returning to the spacecraft for the return trip to Earth. This is an immensely complicated undertaking and the Japanese Space Agency (JAXA) has really got their work cut out for them.

Image of Ryugu from 920km (Credit: JAXA)

This is the second go at returning a little bit of an asteroid to Earth by JAXA, back in 2003 they launched Hayabusa that intercepted the asteroid 25143 Itokawa and returned a few grains of it back to Earth. It was supposed to deploy a little lander as well but for some reason that didn’t work as planned. Not put off by the setbacks of the first mission JAXA designed the next spacecraft based on improvements learned from the first mission. Japan, Germany and France all collaborated on this new mission by designing and building different parts. They built the Mobile Asteroid Surface Scout (MASCOT) which is designed to land on the surface and take measurements. It has a spectrometer, a magnetometer, a radiometer and a camera and a mechanism to fly off the surface of the asteroid.

The Small Carry on Impactor (SCI) is where the explosion will come from. This consists of a small 2.5 kilogram projectile and a 4.5 kilogram shaped charge. The impactor will strike the asteroid and blow up with the spacecraft safely on the other side of the asteroid. The whole package will be released from the spacecraft and then the charge will propel the projectile into the asteroid at about 2km per second. This will carve out a crater a few meters in diameter. The reason for the impactor is to create the ability to get a sample off the asteroid that hasn’t been weathered by space, but protected by the surface of the asteroid. This will hopefully give a better understanding of what the asteroid is made of.

The spacecraft uses ion engines that consume about 1/10th of the propellant of transitional engines. The mechanism to retrieve a bit of the asteroid is very similar to the Hayabusa in that the spacecraft will land on the surface and a special tube will retrieve a sample of the surface and store it safely for return to Earth in 2020.

Hayabusa retrieving some asteroid debris (Credit: JAXA)

This will be a exciting mission to watch, especially fo those interesting in the asteroid mining possibilities of the future.