After three and a half years of flight, the Hayabusa2 probe will reach the asteroid Ryugu. Its task: Collect asteroid dust. The German landing device MASCOT is also on board. It's due to land on Ryugu in October.
Image: DLR CC-BY3.0
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Hayabusa 2, or the "Falcon2," has been on the road for more than three years.
Finally, on Wednesday, June 27, the space probe from the Japanese space agency JAXA arrives at the asteroid "162173 Ryugu." This asteroid, named after a mystical Japanese underwater castle, about 300 million kilometers, or 186 million miles, from Earth.
Asteroids, like comets, are celestial bodies. They allow us to look back into the history of the solar system more than four billion years ago. This makes them interesting for researchers.
But asteroids are also in focus because they are a potential threat to us.
Ryugu's trajectory will remain far from Earth for the next few centuries, but similar asteroids nearer to our planet could one day become dangerous. That's why planetary researchers want to know as much about them as possible.
MASCOT might look like a shoe box - but it does have an arm to move aroundImage: DLR CC-BY3.0
A landing device made in Germany
On board Hayabusa2 is a special little package from Germany: the "Mobile Asteroid Surface Scout" (MASCOT) landing vehicle, built by the German Aerospace Center (DLR) and the French space agency CNES.
The MASCOT scout is equipped with a swinging arm that allows it to jump on the asteroid surface to improve and change its position if it falls unfavorably. It has a camera, a radiometer, a spectral microscope and a magnetometer—and weighs a total of 9.6 kilograms (21 pounds) and measures in at about 30 x 30 centimeters, or 1 square foot.
The components—an orbiter and a lander—at first seem to resemble Rosetta and Philae, which together journeyed to the comet Chury (2004-2016). But only at first glance.
Unlike the Rosetta spacecraft, Hayabusa2, if all goes well, will send a capsule containing rock samples all the way back to Earth.
And Hayabusa2 doesn't just have one lander, but four. In addition to Mascot, three mini landing robots called "Minerva-II" are to be deployed. Their job: to move across the asteroid's surface and examine it.
That said, a lot will first to happen first: Hayabusa2 will orbit the asteroid at a distance of about 20 kilometers, measure it and explore it with its remote sensing instruments for 18 months, or until the end of 2019. During that time its infrared spectrometer will measure the mineral and water content and a thermal imaging camera to investigate the temperature and thermal properties of the asteroid.
Only in 2020 will Hayabusa2 deliver the asteroid dust back to earthImage: DLR CC-BY3.0
Low gravity worries engineers
And Hayabusa2 has another special feature to offer: It is to drop a copper body weighing two kilograms onto the asteroid, which the researchers hope will leave an artificial crater. Through him the probe should take a look under the surface of the comet and analyze its inner life.
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A greater challenge for the mission will probably be the minimal gravity of the asteroid. Especially the landing maneuvers of the robots must be initiated carefully. If they fall too quickly, they can bounce off the surface and bounce around uncontrollably.
Collecting asteroid stones and dust and transporting them back to Earth is becoming most complicated. To do this, the spacecraft Hayabusa2 itself must briefly touch Ryugu, collect the asteroid material and lift it off again.
How does asteroid dust get back to Earth?
Hayabusa2 uses a complex mechanism to collect the asteroid material: the probe deposits a cylindrical device on the surface, which - similar to an anti-personell-mine - launches a projectile onto the asteroid on contact with the surface. Then a catcher absorbs the whirled up dust and particles.
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At the end, the probe packs the captured asteroid particles into a capsule. This is closed and returns together with Hayabusa2 back to earth. If all goes well, it will land by the end of 2020.
In 2010, the Japanese space agency succeeded for the first time in bringing asteroid dust to Earth with the Hayabusa probe. Currently the NASA probe Osiris-REx is on its way to the asteroid 101955 Bennu, also known as 1999RQ. She too is expected to take soil samples and bring them back to Earth in 2023. Bennu is more dangerous than Ryugu. The probability that it will hit the earth in the last quarter of the 22nd century is 1:2700.
Threat from above
About 10,000 asteroids loom close to Earth. This year has already witnessed a lot of astronomical activity. And Europe is building what could become an asteroid early warning system.
Image: AP
European early warning system
About 10,000 asteroids loom close to Earth. They could be dangerous. The European Space Agency (ESA) is building an early warning system in Frascati, Italy. Data from telescopes like this one on Tenerife will be collated there.
Image: IQOQI Vienna
Passing blast
If you're wondering how important early warning systems are, think of the meteorite that struck Earth near Chelyabinsk in Russia on 15 February 2013. The blast was estimated to have been as strong as between 100 and 1000 kilotons of TNT explosives. Almost 1500 people were injured.
Image: picture-alliance/dpah
A big splash
Before it had burned up in the Earth's atmosphere, the meteorite is estimated to have had a diameter of 20 meters. All that was left was a piece weighing only about a kilogram. But it still managed to smash a six meter wide hole in the ice.
Image: Reuters
Bigger and badder
But an asteroid named "2012 DA14" was much more dangerous. It weighed 130,000 tons. On the same day as the Chelyabinsk strike, 2012 DA14 flew passed our planet at a distance of just 27,000 kilometers. That is closer than some satellites.
Image: NASA/Science dpa
Whizz by Earth
A number of other asteroids and comets are expected to come close to Earth this year. Scientists are keeping a close eye on them because even the smallest rocks can be dangerous.
Image: picture-alliance/dpa
Comets and shooting stars
Comets consist of a cloud of gas and a huge tail of gas, stones and particles of dust. When the tiny grains of dust from a comet scrape the Earth's atmosphere, they can get as hot as 3,000 degrees Celsius. They start to glow and become a shooting star.
Image: picture alliance / dpa
The most famous meteor shower
The Perseids are a prolific meteor shower, associated with the comet Swift-Tuttle. Every summer, the meteor shower crosses the Earth's orbit. The Perseids are named after the constellation they are closest to when they can be seen. It is derived from Perseus, a character from Greek mythology.
Image: AP
When meteoroids don't burn up
Meteors dust burns up in our atmosphere. Most meteorites (meteoroids that survive falling through the atmosphere) are harmless and are often no bigger than a stone. But large meteorites can cause a lot of damage. One of the largest meteorite craters is the Barringer Crater in Arizona. It has a diameter of 1,000 meters and is 50,000 years old.
Image: cc-by/LarryBloom
End of an era
About 65 million years ago, a giant meteorite slammed into the Yucatan Peninsula (simulated in the image to the right). It led to the creation of the Chicxulub Crater, which is more than 180 kilometers in diameter. Experts believe the impact wiped out the dinosaurs. More recent evidence suggests that debris from a collision between two asteroids 160 million years ago led to the event.
Image: picture alliance/dpa
Burnt rocks from outer space
Meteorites look like burnt rocks. Their crust is formed when the meteorite melts upon entering the Earth's atmosphere. Other planets are also struck by meteorites. NASA's Opportunity Rover discovered the first extraterrestrial meteorites on Mars in 2005.
Image: picture-alliance/ dpa/dpaweb
Dust and gas
It's not just the dust from comets that reaches Earth - but the comets do, too. Experts believe comets to be bits leftover from the creation of planets. They may also hold secrets about the beginnings of our solar system.
Image: AP
Large chunks of rock
Almost all of meteorites found on Earth have come from asteroids - that is 99.8 percent of the more than 30,000. And just like comets, asteroids are created when a planet is being formed. They have no permanent atmosphere and hardly any gravity.
Image: picture-alliance/ dpa
And after all that...
... the chance of a large asteroid hitting Earth in the next 100 years is (said to be) quite small.
