NASA does not stop. Just celebrating the successful launch of an insight on Mars, curiosity continues to send photos from the surface of Mars and is now preparing to port this Monday, the investigation OSIRIS-REx of the asteroid Bennu. This last mission may be the most important, since the asteroid is a potential danger for the Earth, because its trajectory shows that it will "touch" our planet. Some have already called it "asteroid death" and the asteroid "Armageddon", but the official website of the US space agency says it will not affect our world and that the main interest of this unpublished mission is scientific.
After traveling two years and a billion kilometers from Earth, the OSIRIS-REx probe will reach its destination. When you arrive, you will start with nearly two years of exploring this group of cliffs, creating a map of your country and finding a safe and fertile location to collect samples.
The spacecraft will enter the orbit of Bennu on Mondays and evenings will briefly touch her surface around July 2020 to collect at least 60 grams (equivalent to about 30 sugar packs) on the earth and rocks. I could pick up to two pounds what would it be the largest sample, far from the space object, from the landing of Apollo's Moon. The spacecraft will then pack the specimen into a capsule and travel to Earth, dropping that capsule in the wilderness of Western Utah in 2023, where scientists are waiting to take it.
This search years of knowledge It pushes Bennu into the center of one of the most ambitious space missions they've ever tried. But the rock is just one of the approximate 780,000 asteroids known in our solar system. So, why did scientists choose Bennu for this transcendental investigation?
Aim for the Earth
Unlike most other asteroids that rotate around the Sun in the asteroid belt between Mars and Jupiter, Bennu's orbit is very close to Earth, even a passage. The asteroid is closer to Earth every six years and has a relatively high likelihood of affecting it at the end of the twenty-first century. It also surrounds the Sun almost on the same plane as the Earth, which facilitated the achievement of the high-energy task of launching the spacecraft from planet Earth and to Bennu. However, the launch requires considerable power, so OSIRIS-REx used Earth's gravity to retire to the orbit of Bennu when it passed through our planet in September 2017.
Asteroid approaching Earth.
The main reason why scientists are concerned to predict the directions to which asteroids are directed is I know when they are too close to Earth. Considering the influence of Yarkovsky, they estimated that Bennu could pass closer to Earth from the moon in 2135, and perhaps even closer between 2175 and 2195. Although it is unlikely that Bennu will hit the Earth at that time, our descendants use the OSIRIS-REx data and determine them the best way to divert the threatening asteroids, perhaps even using the Yarkovsky effect in favor.
The effect of Yarkovsky modifies the orbits of small objects in the Solar System as a result of the way they absorb the radiation of the Sun on one of his faces and re-radiate it while rotating. This produces a small imbalance that, slowly, over time, changes the path of the object.
Asteroids rotate on their axes just like the Earth. Small, with a diameter of 200 meters or less, often spin very quickly, to several revolutions per minute. This rapid turnaround makes the spaceship more difficult leveling the speed of the asteroid to land and collect samples. Even worse, the rapid rotation throws loose stones and dirt, a material known as "Regolith", the material that OSIRIS-REx wants to take from the surface of small asteroids. The size of Bennu, in contrast, does accessible and rich with regolith. It has a diameter of 492 meters, which is slightly larger than the height of the Empire State Building in New York, and is rotated once every 4.3 hours.
An analysis of a Bennu sample will help scientists from the planet better understand the role that Asteroids can play in the delivery of compounds that form life on Earth. It is known because he studied Bennu through terrestrial and space telescopes, that it is a carbon-rich carbon-rich asteroid. Carbon is a hinge from which the organic molecules hang. Bennu is likely to be rich in organic molecules that are made from carbon chains linked to oxygen, hydrogen, and other elements in a chemical recipe made by all known living creatures. Besides carbon, Bennu can also have another important component for life: the water, which is trapped in the minerals that make up the asteroid.
NASA's drawing of the asteroid Bennu and the space probe.
What will happen if you hit the Earth?
As asteroids slow down the atmosphere, asteroids transmit the mass, momentum and energy of the surrounding air at speeds literally astronomical. The violent entry of such bodies creates strong explosive waves that can spread hundreds of kilometers and cause significant damage to the Earth, even when it does not affect the earth.
The NASA Asteroid Threat Assessment Project (ATAP) quantifies the risk of such phenomena through a combination of observation data, high fidelity simulations, and probability models. The uncertainties in the entry conditions and the composition of asteroids were taken into account.
Simulation of what will happen if an asteroid affects the Earth.
As a result, depending on the size of the asteroid, its composition and the angle of entry into the atmosphere, the impact on the surface of the Earth can cause giant tsunami if it falls on the ocean; or catastrophic earthquakes, if it was to hit the earth. The liberated energy would be such that it would cause a death shock that would destroy entire cities. Fortunately, these types of influences are very rare. They happened only a few times over millions of years.