Bennu is an asteroid that whizzes previous Earth each few years. In truth, there’s a likelihood — although a slim one — that the asteroid will collide with Earth within the close to future (lower than 200 years from now).
Because it flies so near our planet, the near-Earth object (NEO) is the goal of a NASA mission to gather a pattern and return it to Earth. Scientists assume the house rock could comprise the constructing blocks of life.
Bennu was found by the Lincoln Near-Earth Asteroid Research (LINEAR) mission, which detects and tracks near-Earth objects, in 1999. It was provisionally named 1999 RQ36, which signifies that it was the 916th object noticed within the first half of September 1999, in line with the Planetary Society. After its orbit was exactly measured, the item was given an official sequential quantity, and since 1999 RQ36 was the 101,955th asteroid to obtain a quantity, its official title turned Asteroid 101955.
The title Bennu was chosen after a “Name That Asteroid!” contest held by the University of Arizona and different companions. Michael Puzio, a third-grade pupil in North Carolina, suggested using the name of an Egyptian mythological bird. Michael mentioned the form of the spacecraft (together with its outstretched pattern arm) reminded him of the heron god, which was known as Bennu. Only about 5 p.c of numbered asteroids have been given names, in line with the Planetary Society.
Size and composition
Bennu has a form that appears a bit like a spinning prime. It is roughly 500 meters (1,640 ft) in diameter and orbits the solar as soon as each 1.2 years, or 436.604 days. Every six years or so, it comes very near Earth — about zero.002 AU, according to the University of Arizona. (An astronomical unit is the space between the Earth and the solar. So, zero.002 AU is roughly 186,000 miles or 300,000 kilometers — effectively throughout the orbit of Earth’s moon.)
Bennu is a part of a small class of carbonaceous (darkish) asteroids that doubtless have primitive supplies in them. Called a B-type class, Bennu and different asteroids prefer it have supplies akin to volatiles (compounds with a low boiling level), amino acids and natural molecules which can be all could have been precursors to life on Earth, in line with the University of Arizona.
Measurements by telescopes (together with the Arecibo Observatory Planetary Radar and the Goldstone Deep Space Network) recommend that Bennu has a density less than rock, in line with NASA. The company describes Bennu as a “rubble pile” that could be a loosely-held-together group of mud, rock and boulders with gaps inside. Spitzer Space Telescope observations in 2007 instructed that Bennu has moderate-sized regolith (soil) grains throughout its floor; a number of different observations additionally trace that Bennu is probably going a easy object.
Because Bennu is so darkish, it tends to soak up the solar’s radiation. Bennu then radiates this in flip as warmth, which impacts its orbit. This “push” on Bennu’s orbit known as the Yarkovsky impact. Bennu’s orbit and form are additionally formed because it repeatedly passes near Venus and Earth, NASA added.
Asteroids akin to Bennu are helpful for astrophysicists as a result of they inform scientists concerning the situations below which the photo voltaic system fashioned. The leading theory for the solar system’s formation— in a nutshell — states nebula (cloud of gasoline) was disturbed by an out of doors occasion, akin to a stellar explosion. The nebula contracted and in its coronary heart, a few of the materials coalesced into our solar. Surrounding the younger solar was a disc of rock and gasoline that over time, step by step got here collectively into the planets we observe as we speak.
The planets fashioned out of constructing blocks known as chondrules, which originated as molten rock. Scientists recommend that Bennu additionally could have a whole lot of chondrules inside it. “On planets like Earth, the unique supplies have been profoundly altered by geologic exercise and chemical reactions with our environment and water. We assume Bennu could also be comparatively unchanged, so this asteroid is sort of a time capsule for us to look at,” said Edward Beshore, deputy principal investigator on the University of Arizona, in a 2015 NASA statement.
Bennu could have been fashioned out of a collision. Crashes have been frequent within the early photo voltaic system as a result of there was a lot materials floating round. There are a number of large impression craters within the photo voltaic system between the ages of three.eight billion and four.1 billion years previous, suggesting that there might need been a “late heavy bombardment” the place asteroids smacked into a number of planetary our bodies. Some theories recommend that the bombardment occurred after Jupiter migrated nearer in to the solar, disrupting small our bodies alongside its approach, in line with NASA.
Bennu’s collision – if it occurred in any respect – doubtless occurred just a little later, roughly one billion years in the past. Bennu was fashioned from the particles after a planetesimal (a small physique on its option to rising giant sufficient to change into a planet) crashed into an asteroid.
Bennu is the goal of the OSIRIS-ReX (Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer) mission. OSIRIS-ReX will arrive at Bennu in 2019 and amongst different actions, scoop up a pattern that will probably be returned to Earth in 2023.
OSIRIS-ReX will even doc the pattern web site, map the asteroid, measure the Yarkovsky impact and evaluate its observations to ground-based telescopes, according to the University of Arizona.
The scientists are additionally looking for natural matter, which incorporates molecules akin to carbon and hydrogen. Organics are key to life on Earth. While not all natural molecules are for all times processes, learning them on places akin to Bennu give scientists an thought as to how organics might need spurred the origin of life.
“By bringing this materials again to Earth, we are able to do a much more thorough evaluation than we are able to with devices on a spacecraft, due to sensible limits on the scale, mass, and power consumption of what might be flown,” Beshore added. “We will even put aside returned supplies for future generations to review with devices and capabilities we won’t even think about now.”
OSIRIS-ReX managers selected Bennu from 7,000 near-Earth asteroids recognized in 2008, when the mission was chosen to go ahead, according to the University of Arizona. Bennu had an orbit permitting for pattern return, it had a small diameter (lower than 200 meters or 650 ft) and it additionally was carbon-rich. At the time, there have been solely 5 recognized asteroids that met all of these parameters, and Bennu was chosen from them.
Bennu is likely one of the most harmful “probably hazardous asteroids” that come inside Earth’s neighborhood, according to a study led by University of Arizona principal investigator Dante Lauretta that was printed in 2015. Bennu has a 1-in-2,700 likelihood of impacting the Earth someday within the late 22nd century.
It is extra doubtless, nevertheless, that Bennu would impression Venus slightly than Earth. But its orbit might change over time. The investigators added: “It [Bennu] will most certainly finish its dynamical life by falling into the solar … There is an opportunity that Bennu will probably be ejected from the inside photo voltaic system after a detailed encounter with Jupiter.”
Nevertheless, scientists and engineers with the U.S. authorities have drawn up plans for a spacecraft that would knock large, incoming house rocks off beam by way of blunt-force impression or blow them to bits with a nuclear warhead, BuzzFeed News reported.
The researchers introduced the idea car, generally known as the Hypervelocity Asteroid Mitigation Mission for Emergency Response (HAMMER), in a examine within the February difficulty of the journal Acta Astronautica. And the group will focus on HAMMER at an asteroid-research convention in May, in line with BuzzFeed News.
Each HAMMER spacecraft would weigh about eight.eight tons (eight metric tons). If an asteroid risk is detected early sufficient, a fleet of the autos might be dispatched to collide, nuke-free, with the house rock, altering its trajectory sufficient to spare Earth from an impression.
To arrive at these outcomes, and refine HAMMER’s design, the group modeled how one can cope with a possible real-life situation: What if Bennu was headed proper for our planet?
“Bennu was chosen for our case examine partially as a result of it’s the best-studied of the recognized NEOs,” the researchers wrote.