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Look, I do not want to make this blog asteroids close to the little ones, all the time, but for my defense we have two spaceships approaching two tiny asteroids.
For today, I want to talk about Hayabusa-2, which arrived in June at the diamond-shaped rock bag about 1 km wide called Ryugu. Shortly after, he launched two rovers called MINERVA-II1 A and B, then a lander called MASCOT, who spent about a day taking close-up footage before his battery ran out.
Another rover, MINERVA-II2, will be dropped in the future … but the big price of the mission will be the main spacecraft that comes to the surface and retrieves samples of material to return to Earth.
It's a much more difficult goal than you might think. Hayabusa-2 is a rectangular box of about 1 x 1.2 x 1.6 meters, with two wings of solar panels 6 meters long and 6 meters long. The surface of Ryugu is covered with rocks and jagged and sharp rocks. Engineers on Earth therefore had to map the entire surface and carefully examine it to find a place where the spacecraft could get close enough without rubbing an important piece against an asteroid.
They found a likely location and on October 25th, the probe lowered to 21 meters from the surface and flew off for another time. During this approach, an onboard camera took a series of stills gathered in a truly amazing video:
He then flew again and, leaving, it took a series of images to one second of space to create this really amazing video:
So. Sensational.
It rather moved me. I am torn by the dichotomy that I see here; Ryugu is a asteroid, a pile of loose debris united by its own low gravity orbiting the sun and currently 300 million kilometers Since the earth. Yet it is so small that if you lowered it (slowly and slowly) into the foothills of the Rockies, you would hardly notice it (though it would create some excitement as it would collapse under the gravity of the Earth). It looks like a volcanic landscape image, but it's as foreign a place as our solar system can provide.
And we have some close-up animations, taken by a little robot that we sent there, and we can look in the comfort of our home the shadow of our mechanical proxy that moves, grows and contracts on the whole surface. Unbelievable.
And then there is the prosaic nature of what you see. We must not forget the objective – to bring back to Earth a piece of this landscape – and the engineering, the planning, which hides behind.
As you can see, the surface is quite rough and I can not blame the Japanese Space Agency officials for performing a series of training exercises before actually trying to land. Attempts have already been made in this way on other celestial bodies, such as Philae on comet 67P / Churyumov-Gerasimenko, and even a first version of the MINERVA rover on Asteroid Itokawa, Hayabusa-2's predecessor, Hayabusa. But these attempts have had limited success (a polite way of saying that they have not worked at all as planned). Landing and taking off again from an asteroid is extremely delicate.
For example, the distance to the surface of the asteroid is determined by laser pulses returned from the surface, but the horizontal motion is more difficult to determine. The spacecraft can then drop "target markers" that will serve as landmarks to guide its movement. He pulled out one during this maneuver.
Since the probe was only 21 meters from the surface (height of a building of four or five floors), I can assume that the shadow of the video at the closest approach is about the same size as the probe itself. This is the big rock that you see near the shadow the size of a house, rough and rough and to avoid strictly. The target area appears relatively smooth, but is still dotted with rubble. And appearances can be misleading: the sun is directly behind the probe (obviously, since you can see its shadow) and this tends to erase the details and topography of the surface. You can not see the shadows at all, which flattens the image and makes it smoother. Smaller rocks still capable of trouble can be hidden.
Of course, engineers have already mapped this area, so I guess it's as safe as possible. Now that the test has been successful, the first sample collection should occur at any time.
These will stay on board as science continues to the asteroid. In April, Hayabusa-2 will launch a high-speed projectile at Ryugu to search below the surface of the materials it will also collect, which will then be sent to Earth for analysis at the end of 2020.
And remember, in the meantime, NASA's OSIRIS-REx is getting closer to the smaller Bennu and will send us better and clearer images in the coming weeks. Do not forget that samples of this asteroid will also be sent back to Earth.
I would also like you to know and appreciate something. The word "asteroid" literally means "star," since when they were discovered in the early nineteenth century, they were far too small to be considered anything but points of light in the best telescopes.
And now we go to them. They are worlds, or pieces of worlds, with their own environments and characters, worthy of our study, at least if it is for science, then for our own safety, another dichotomy to grasp.
But, like many seemingly opposed concepts in tension, they combine to make these places attractive, places we must visit. I am very happy to be alive when I see such wonders, to know that so many others are to be explored, and to be excited by the fact that we are just getting started.
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