NASAThe first mission to return a sample of an ancient asteroid reached its destination, the asteroid Bennu, on December 3, 2018. This mission, the origins, the spectral interpretation, the identification of resources, the security regolith Explorer or OSIRIS-RExis a seven-year voyage to be completed with the delivery to Earth of at least 60 grams (2.1 ounces) and possibly up to two kilograms (four and a half pounds) of sample. It promises to be the greatest amount of extraterrestrial material brought back from space since the Apollo era.
The 20-year anniversary of the asteroid’s discovery was in September 2019 – and scientists have been collecting data ever since. Here’s what we already know (and some we hope to find out) about this pristine remnant from the early days of our solar system.
1. It’s very, very dark …
Bennu is classified as a Type B asteroid, which means that it is high in 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, Venusreflects about 65 percent of the incident sunlight and the earth reflects about 30 percent. Bennu is a carbonaceous asteroid that has not undergone drastic changes in its composition. This means that on and below its jet black surface are chemicals and rocks from the birth of the solar system.
2.… and very, very old.
Bennu has been (mostly) undisturbed for billions of years. Not only is it practically close and carbonaceous, but it’s so primitive that scientists have calculated that it was formed in the first 10 million years of our solar system’s history – over 4.5 billion years ago. Thanks to the Yarkovsky effect – the slight pressure that arises when the asteroid absorbs sunlight and releases this energy again as heat – and gravitational tugs from other celestial bodies, it has moved ever closer to Earth from its probable place of birth, the main asteroid belt in between Mars and Jupiter.
3. Bennu is an asteroid made of rubble – but don’t let the name fool you.
Is Bennu space junk or scientific treasure? While “Pile of Debris” sounds like an insult, it is actually a true astronomical classification. Debris pile asteroids like Bennu are celestial bodies made up of lots of rocky debris that has been compressed by gravity. This type of detritus occurs when an impact shatters a much larger body (for Bennu, it was a parent asteroid about 60 miles [about 100 km] wide). In contrast, Bennu is about the size of the Empire State Building. It probably took only a few weeks for these fragments of space wrecks to melt into the heap of debris Bennu. Bennu is full of holes, 20 to 40 percent of his volume is empty. The asteroid is actually in danger of flying apart if it spins much faster or if it interacts too closely with a planetary body.
4. Asteroids can contain clues to the origin of all life on earth …
Bennu is a primal artifact preserved in the vacuum of space and orbiting between planets and moons as well as asteroids and comets. Because it is so old, Bennu could be made of material that contains molecules that were present when life first formed on Earth. All life forms on earth are based on chains of carbon atoms bound to oxygen, hydrogen, nitrogen and other elements. Organic material, as scientists hope to find in a sample from Bennu, does not necessarily always come from biology. However, it would be another quest by scientists to find out what role organic asteroids play in catalyzing life on Earth.
5. … but also platinum and gold!
Alien jewelry sounds great, and Bennu is likely rich in platinum and gold compared to the average earth’s crust. While most are not made almost entirely of solid metal (Asteroid 16 Psyche maybe!), Many asteroids contain elements that could be used industrially in place of Earth’s finite resources. Studying this asteroid closely will provide answers to questions about whether asteroid mining is possible while exploring and traveling through space. Although rare metals attract the most attention, water is probably the most important resource in Bennu. Water (two hydrogen atoms bound to an oxygen atom) can be used for drinking or separated into its components to create breathable air and rocket fuel. Given the high cost of moving materials into space, the cosmic beyond is closer than ever to humans when astronauts can draw water from an asteroid for life support and fuel.
6. Sunlight can alter the entire flight path of the asteroid.
Gravity isn’t the only factor linked to Bennu’s fate. The sun-facing side of Bennu is warmed by sunlight, but a day on Bennu only lasts 4 hours and 17.8 minutes, so the sun-facing part of the surface is constantly shifting. As Bennu continues to spin, he expels this heat, giving the asteroid a tiny thrust toward the Sun at around 0.29 kilometers per year and changing its orbit.
7. There is a small chance Bennu will affect Earth by the end of the next century.
The NASA-funded Lincoln Near-Earth Asteroid Research team discovered Bennu in 1999. NASA’s Planetary Defense Coordination Office continues to track near-earth objects (NEOs), particularly those like Bennu, which are within approximately 7.5 million of the area Kilometers are in orbit and are classified as potentially dangerous objects. Between the years 2175 and 2199, the probability that Bennu will affect Earth is only 1 in 2,700, but scientists still don’t want to turn their backs on the asteroid. Bennu is tumbling through the solar system in a path that scientists confidently predicted, but they will refine their predictions with the measurement of the Yarkovsky effect by OSIRIS-REx and future observations from astronomers.
8. Bennu’s sampling will be more difficult than we thought.
Early Earth-based observations of the asteroid indicated that it had a smooth surface with a regolith (the top layer of loose, unconsolidated material) made up of particles less than a few inches in size – at most. Since the OSIRIS-REx spaceship was able to take higher resolution images, it became clear that the sampling of Bennu would be far more dangerous than previously thought: New images of Bennu’s surface show that it is mostly covered with massive boulders, not small stones . OSIRIS-REx was developed for navigation in an area on Bennu of almost 2,000 square meters (meters), which is approximately the size of a parking lot with 100 parking spaces. Now it has to maneuver to a safe location on Bennu’s rocky surface within a confinement of less than 100 square feet, an area equivalent to about five parking spaces.
9. Bennu was named after an ancient Egyptian deity.
Bennu was named in 2013 by a nine-year-old boy from North Carolina who won the Name this asteroid! Contest, a collaboration between the Mission, the Planetary Society, and the LINEAR Asteroid Survey that Bennu discovered. Michael Puzio won the competition by suggesting that the spacecraft’s TAGSAM (Touch-and-Go Sample Mechanism) arm and solar panels resemble the neck and wings that illustrate Bennu, who the ancient Egyptians usually depicted as a gray heron. Bennu is the ancient Egyptian deity associated with the sun, creation and rebirth. Puzio also noted that Bennu is the living symbol of Osiris. The Bennu myth fits the asteroid itself, as it is a primitive object that dates back to the creation of the solar system. Issues such as origins and rebirth are part of the history of this asteroid. Birds and bird-like creatures are also a symbol of rebirth, creation, and origins in various ancient myths.
10. Bennu still surprises us!
The spacecraft’s navigation camera observed that Bennu was spitting out streams of particles several times a week. Bennu is apparently not just a rare active asteroid (only a handful of them have been identified so far), but possibly Ceres, which was studied by NASA’s Dawn mission and was among the first of its kind to observe humanity from a spaceship Has. More recently, the mission team discovered that sunlight can crack stones on Bennu and that bits of another asteroid are scattered across its surface. As the mission progresses, more pieces will be added to Bennu’s cosmic puzzle, each bringing the evolutionary history of the solar system into ever sharper focus.
Goddard offers the entire mission management, system technology as well as security and mission assurance for OSIRIS-REx. Dante Lauretta of the University of Arizona, Tucson, is the lead researcher, and the University of Arizona also leads the science team and the planning and computing of the scientific observation mission. Lockheed Martin Space in Denver built the spacecraft and offers 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, administered by NASA’s Marshall Space Flight Center in Huntsville, Alabama for the agency’s Science Mission Directorate in Washington.