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NASA is already in the mood for high expectations for the most important and complex moment of the OSIRIS-REx mission: collecting samples from the surface of the asteroid Bennu, specifically within a crater called Nightingale. The collection maneuver will take place tomorrow (20), but the space agency is already sharing a series of information and scientific curiosities about space rock.
It will be the first time that an American spacecraft has attempted such a mission. The spacecraft in question is OSIRIS-REx, and the samples it will bring to Earth in 2023 should provide scientists with clues about the formation of the Solar System. The task will not be easy. In fact, there are a number of challenges during each sequence of maneuvers that the robotic probe will have to perform.
In addition to being a relatively small asteroid, about 500 meters in diameter, there are several house-sized rocks on its surface. NASA compared the maneuvers needed to land with trying to park a truck in a parking lot where there is only one free space. Considering that everything will be done in a place far from our planet, without video transmission exactly in real time (given the distance, which impacts the speed of communication), it does not seem to be a very easy thing to do from a distance .
But NASA seems to be well prepared for that. And confident too. So much so that there will be live coverage during the collection event, in which the space agency will share the smallest details with the public while OSIRIS-REx does its job. Until then, take a look at some of the curiosities and information that make Bennu so interesting to scientists, to the point of carrying out a mission of this size just to collect 60 grams of samples.
1) Darkness
Bennu has a large amount of carbon in its composition, and this makes the asteroid’s surface capable of reflecting only about 4% of the sunlight that hits it. Venus, by comparison, reflects about 65% of sunlight; It’s no wonder that this planet is generally the brightest object in the night sky. In other words, Bennu would be very dark, even if he was closer to us.
In addition, it has not undergone many changes that would change its composition, so the material below its surface contains chemical elements and rocks that have been preserved since the birth of the Solar System.
1) old age
Another important mark of space debris called Bennu is precisely its age, and especially the time that it has remained intact for billions of years. According to scientific calculations, it seems to have formed in the first 10 million years of the history of our Solar System. In other words, it is more than 4,500 million years old.
Its origin appears to have been the main asteroid belt, located between the orbits of Mars and Jupiter, but today it is not that far. When the asteroid absorbs sunlight and emits energy again in the form of heat, it ends up undergoing something called the Yarkovsky Effect, causing it to slowly approach the Sun and, therefore, Earth. This also means that its rotation is retrograde, because if it were proclaimed, the resulting force would push the body away from our star.
3) What do you mean by rubble?
Sometimes you will find descriptions of Bennu saying that he is a space “rubble”. Well, we called it that in the previous paragraphs. But don’t let the term fool you, as this by no means means that it is “junk” with little use. The word debris is used because the asteroid is actually made up of debris from other asteroids even older than it.
The rocky pieces accumulated over time through the attraction of gravity, and ended up compressing and forming a new object. These “remnants” of ancient asteroids probably come from bodies much larger than Bennu itself, about 100 km across. It probably took only a few weeks for these space fragments to clump together in the pile of debris that is Bennu, a small 500-meter rock.
Being made of fragments, Bennu looks like Swiss cheese: it is full of holes inside. About 20 to 40% of its volume is just an empty space inside. If it starts spinning much faster or interacts with another space object, it may fall apart. Fortunately, OSIRIS-REx arrived in time before that happened.
4) Sowers of life?
Well, if Bennu has so much information preserved inside him, what can he reveal to us? A lot, including the origin of life on Earth. It is that the asteroid may be made of material that contains the same molecules that were present in the Solar System when life formed on Earth.
All life forms on Earth are based on chains of carbon atoms linked to oxygen, hydrogen, nitrogen, and other elements. Do you remember that Bennu is carbonaceous? It may be that this material contains clues about the origin of these elements and their role here on our planet. We know that space rocks have always fallen into our atmosphere, so it could be that they brought the fundamental elements for the formation of life.
But scientists also know that the chances are high that the asteroid’s organic material is not biological, so this may not be the time when we find clues to the origin of life. Still, it’s worth a try!
5) Rich in platinum and gold
Although gold and platinum are valuable here on Earth, they are relatively easy to find on asteroids. After all, these elements are created through nuclear mergers when a star explodes in a supernova, spreading throughout the universe. In the case of Bennu, it is very likely that it is also rich in platinum and gold.
Therefore, studying this asteroid will help scientists understand more about this topic, and perhaps they can say whether it is feasible to create more robust missions to search for the valuable minerals in these space rocks. Most importantly, the presence of water would be of great value, as it could be used for drinking or separated into its components to obtain breathable air and rocket fuels. Transporting this type of raw material from an asteroid to, say, the Moon, can greatly help astronauts on space missions.
6) Collision with Earth?
Since its discovery in 1999, Benu has been considered an object close to us. This does not mean that it is as close as the Moon, for example, or that it will hit our planet in the next few years. In fact, the chances are slim, but there are. And if they exist, it will be classified as potentially dangerous.
To reassure you, the probability of an impact between the years 2169 and 2199 is only 1 in 2700. But remember, it continues to move closer to Earth, so if it presents a threat at any point, even after those distant dates, scientists they will continue to keep you under observation.
7) Landing in Bennu is risky
Collecting samples from Bennu will be a high risk task for the physical integrity of OSIRIS-REx. In addition to being a relatively small asteroid, there are several house-sized rocks on its surface. The complexity of the TAG (acronym for “Touch-And-Go”, the name of the event that consists of touching the surface of the asteroid to collect samples and return to space just a few seconds later) consists not only in descending to the ground of Bennu without colliding with rocks, but also staying on the correct slope and speeds so as not to fall and not to damage the robotic instruments that will touch the ground.
Without knowing these details before filming the OSIRIS-REx, the scientists designed the spacecraft to land within a much larger area than Bennu offers, roughly the size of a parking lot with 100 spaces. Now the probe is expected to maneuver in a location of less than 100 square meters, an area of about five parking spaces.
8) Egyptian mythology
Bennu was named after a nine-year-old boy who won the “Name that asteroid!” Contest. Michael Puzio won the contest by suggesting that the OSIRIS-REx arm and solar panels and their harvesting mechanism resembled the neck and wings in illustrations of Bennu, a deity that ancient Egyptians portrayed as a gray heron.
This deity was linked to the Sun, creation and rebirth, and was also the ba (soul) of Osiris, which arose after the death of the god at the hands of Seti. The myth seemed to fit like a glove on the asteroid, as it is an object dating back to the creation of the Solar System.
9) Vesta
How many asteroids did it take to break apart to form Bennu? That question may be difficult to answer for now, but scientists already have clues to begin making a list. A very likely name for one of Bennu’s “fathers” is Vesta. the second largest asteroid in the Solar System, now a protoplanet.
The scientists found a type of rock brighter than the others on Bennu’s surface and decided to study the light reflected from it with the OSIRIS-REx spectrometer. They concluded that Bennu received these rocks possibly from the asteroid that originated it after being hit by a “vestoid”, that is, a fragment of Vesta. “When the main asteroid was destroyed, some of its debris accumulated under its own gravity on Bennu, including some of Vesta’s pyroxene,” said Hannah Kaplan, a space scientist and researcher at the Goddard Space Flight Center.
While the poor asteroid hit by Vesta appears to have been destroyed, it remains in its normal orbit.
10) More surprises ahead
The OSIRIS-REx navigation camera showed the scientists that Bennu often ejects particles of itself into space a few times a week. This means that it is an active asteroid, which is rare.
More recently, the mission team discovered that sunlight can break up Bennu’s rocks and that pieces of other rocks are scattered across its surface. It will be a curious task trying to find out how many older asteroids Bennu is made of. You can certainly have even more surprises in store for us, so it’s worth paying attention to tomorrow’s collection mission and keeping track of the investigations that will follow.
Source: NASA
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