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10 things you need to know about Bennu

Asteroid Bennu

This mosaic image of the asteroid Bennu is composed of 12 PolyCam images collected on December 2, 201

8 by the OSIRIS-REx spacecraft with a range of 24 miles (15 miles). Credit: NASA / Goddard / University of Arizona

NASAThe first mission to return a sample of an ancient asteroid arrived at its destination, the asteroid Bennu, on December 3, 2018. This mission, Origin, Spectral Interpretation, Resource Identification, Security-Regolith Explorer, or OSIRIS-REx, is a seven-year journey concluded with the delivery to Earth of at least 2.1 ounces (60 grams) and possibly up to almost four and a half kilograms (two kilograms) of sample. It promises to be the largest amount of extraterrestrial material returned from space since the Apollo era.

The 20th anniversary of the discovery of the asteroid was in September 2019 – and since then scientists have been collecting data. Here is what we already know (and part of what we hope to understand) about this pristine remnant of the early days of our solar system.

1. It is very, very dark …

Bennu is classified as a type B asteroid, which means that it contains a lot of carbon in and along with its various minerals. Bennu’s carbon content creates a surface on the asteroid that reflects about four percent of the light that hits it – and that’s not much. In contrast, the brightest planet in the solar system, Venus, reflects about 65 percent of the incoming sunlight, and the Earth reflects about 30 percent. Bennu is a carbon asteroid that has not undergone drastic changes in composition, which means that there are chemicals and rocks on and under the deeper than black black surface since the birth of the solar system.

2. … And very, very old.

Bennu has been (mostly) undisturbed for billions of years. As well as being conveniently close and carbon, it is so primitive that scientists have estimated that it formed in the first 10 million years of our solar system’s history – more than 4.5 billion years ago. Thanks to the Yarkowski effect – the slight thrust created when the asteroid absorbs sunlight and re-emits that energy as heat – and gravitational tugs from other celestial bodies, it is getting closer to Earth than its probable birthplace: the main asteroid belt. between Mars and Jupiter.

3. Bennu is an asteroid with “ruins” – but don’t let the name fool you.

Is it Bennu’s space rubbish or a scientific treasure? While a “pile of debris” sounds like an insult, it’s actually a true astronomical classification. Destroyed asteroids like Bennu are celestial bodies made of many pieces of rock debris that gravity compresses together. This type of detritus occurs when a blow shatters a much larger body (for Bennu, it’s a parent asteroid about 60 miles away). [about 100 km] wide). Bennu, by contrast, is as tall as the Empire State Building. It probably only took a few weeks for these pieces of space debris to merge into the pile of debris that is Bennu. Bennu is full of holes inside, with 20 to 40 percent of its volume being empty. The asteroid is actually in danger of flying if it starts to spin much faster or interacts too closely with a planetary body.

4. Asteroids can suggest the origin of all life on Earth …

Bennu is a primary artifact preserved in the vacuum of space, orbiting planets and moons and asteroids and comets. Because it is so old, Bennu can be made from a material containing molecules that were present when life first formed on Earth. All life forms on Earth are based on chains of carbon atoms associated with oxygen, hydrogen, nitrogen and other elements. However, organic material such as the species that scientists hope to find in a sample of Bennu does not always come from biology. However, this will continue to be sought by scientists to reveal the role of asteroids, rich in organic matter, which catalyze life on Earth.

5. … But also platinum and gold!

Alien jewelry sounds great and Bennu is probably rich in platinum and gold compared to the average crust on Earth. Although most are not made almost entirely of hard metal (but asteroid 16 Psyche may be!), Many asteroids contain elements that could be used industrially instead of Earth’s finite resources. A close study of this asteroid will provide answers to questions about whether it is possible to extract asteroids during exploration and travel in deep space. Although rare metals attract the most attention, water is probably the most important resource in Bennu. Water (two hydrogen atoms attached to oxygen atom) can be used for drinking or separated from its components to produce breathable air and rocket fuel. Given the high cost of transporting material into space, if astronauts can extract water from an asteroid to sustain life and fuel, the space beyond is closer than ever to being accessible to humans.

6. Sunlight can change the entire trajectory of the asteroid.

Gravity is not the only factor related to Bennu’s fate. The side of Bennu facing the Sun is warmed by sunlight, but a day on Bennu lasts only 4 hours and 17.8 minutes, so the part of the surface facing the Sun changes constantly. As Bennu continues to rotate, it emits this heat, giving the asteroid a small boost to the Sun by about 0.18 miles (approximately 0.29 kilometers) per year, changing its orbit.

7. There is little chance that Bennu will influence Earth at the end of the next century.

A NASA-funded team to study asteroids near Earth discovered Bennu in 1999. NASA’s Planetary Defense Coordination Office continues to track near-Earth objects (NEOs), especially those like Bennu, which will reach about 7.6 million kilometers from Earth’s orbit and are classified as potentially dangerous objects. Between 2175 and 2199, Bennu’s chances of affecting Earth are only 1 in 2,700, but scientists still don’t want to turn their backs on the asteroid. Bennu travels through the solar system in a way that scientists have confidently predicted, but they will refine their predictions by measuring the Yarkovsky effect from OSIRIS-REx and with future observations by astronomers.

Rehearsal of NASA OSIRIS REx Matchpoint

Captured on August 11, 2020 during the second rehearsal of the OSIRIS-REx mission sampling event, this series of images shows the field of view of SamCam as a NASA spacecraft approaches the surface of the asteroid Bennu. The rehearsal brought the spacecraft to a point approximately 131 feet (40 meters) above the surface during the first three maneuvers of the sampling sequence, after which the spacecraft fired back. Credit: NASA / Goddard / Complete History of the University of Arizona

8. Sampling from Bennu will be more difficult than we thought.

Early terrestrial observations of the asteroid suggest that it has a smooth surface with regolith (the top layer of loose, unconsolidated material) composed of particles smaller than an inch (several centimeters) – at most. As the OSIRIS-REx spacecraft was able to take higher-resolution images, it became clear that sampling from Bennu would be much more dangerous than previously thought: new images of Bennu’s surface show that it is covered mainly with massive stones and not with small rocks. OSIRIS-REx is designed to run in a Bennu area of ​​nearly 2,000 square meters (meters), approximately the size of a 100-seat car park. Now it has to maneuver to a safe place on the rocky surface of Bennu within less than 100 square meters, an area of ​​about five parking spaces.

Sample site of the nightingale of Bennu

This image shows the sample Nightingale site, the main sampling site for OSIRIS-REx on the asteroid Bennu. The image is covered by the graphics of the OSIRIS-REx spacecraft to illustrate the scale of the site. Credit: NASA / Goddard / University of Arizona

9. Bennu is named after an ancient Egyptian deity.

Bennu was named in 2013 by a nine-year-old North Carolina boy who won Name this asteroid! competition, collaboration between the mission, the Planetary Society, and the LINEAR study of asteroids that Bennu discovered. Michael Puzio won the race, suggesting that the Touch-and-Go’s TAGSAM steering mechanism and solar panels resembled the neck and wings in Bennu’s illustrations, which the ancient Egyptians usually depicted as a gray heron. Bennu is the ancient Egyptian deity associated with the Sun, creation and rebirth – Pusio also noted that Bennu is the living symbol of Osiris. The myth of Bennu fits the asteroid itself, given that it is a primitive object dating back to the creation of the solar system. The themes of origin and rebirth are part of the history of this asteroid. Birds and bird-like creatures are also symbols of rebirth, creation and origin in various ancient myths.

10. Bennu still surprises us!

The spacecraft’s navigation camera notices that Bennu emits streams of particles several times a week. Bennu is apparently not only a rare active asteroid (only a handful of them have yet been identified), but probably Ceres, studied by NASA’s Dawn mission, among the first of its kind to be observed by humanity from a spaceship. Most recently, the mission team discovered that sunlight could crack rocks on Bennu and that there were pieces of another asteroid scattered on it. As the mission progresses, more pieces will be added to Bennu’s space puzzle, each putting the evolutionary history of the solar system into sharper and sharper focus.

Asteroid Bennu Particles

This view of the asteroid Benu, emitting particles from its surface on January 19, 2019, was created by combining two images taken aboard the NASA OSIRIS-REx spacecraft. Other image processing techniques were applied, such as cropping and adjusting the brightness and contrast of each image. Credit: NASA / Goddard / University of Arizona / Lockheed Martin

Goddard provides overall mission management, systems engineering and security, and mission support for OSIRIS-REx. Dante Laureta of the University of Arizona, Tucson, is the principal investigator, and the University of Arizona also leads the research team and the planning and processing of mission data. Lockheed Martin Space in Denver built the spacecraft and provided flight operations. Goddard and KinetX Aerospace are responsible for navigating the OSIRIS-REx spacecraft. OSIRIS-REx is the third mission in NASA’s New Frontiers Program, operated by NASA’s Marshall Space Flight Center in Huntsville, Alabama, for the agency’s scientific mission directorate in Washington.

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