Wave on March 5 hello for the most infamous asteroid that will not hit the earth in 2029.
Astronomers first saw the space rock now known as Apophis in 2004. This is exactly the kind of object most people probably want to know: it’s terribly large and sometimes comes uncomfortably close to the earth. On April 13, 2029, Apophis is so close to Earth that it is through the kingdom of especially high satellites.
(It will not hit the earth. Do not panic. Continue.)
Scientists are excited. They calculated how rarely does a large object move so close to the earth. “It’s something that happens about once every 1,000 years, so it’s getting a lot of interest,” Marina Brozović, a radar scientist at NASA’s Jet Propulsion Laboratory in California, told Space.com.
Related: Large asteroid Apophis flies through Earth on Friday the 13th in 2029, a happy day for scientists
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The March fly will not be nearly as staggering as the near-approach of 2029; Apophis will come only a tenth of the average distance between the earth and the sun, more than 40 times as far as the moon from the earth. But scientists have big goals for Apophis’ 2029 flight, and to get the most out of the event, they need to do as much as possible about the space rock.
And next month is their last real chance to study Apophis before the big day.
“Apophis in 2029 is going to be an incredible acting opportunity for us,” Brozović said. “But before we get to 2029, we are preparing.”
Meet Apophis
Like all asteroids near Earth, Apophis has been rattling in the inner solar system for thousands of years, unnoticed by humans. Scientists believe it is more than 300 meters wide, about the height of the Eiffel Tower. It’s a mix of rock and metal, according to NASA, and can form a bit like a peanut, with two unequal buds.
Astronomers first noticed Apophis in 2004. The discovery of the asteroid is a perfect example of this. planetary defense, the task of locating asteroids on Earth, locating their exact orbits and determining whether they are in danger of hitting Earth. Warning is forearm, so the theory goes out, and scientists hope people can find a way to defend themselves if they can identify a major future impact with enough warning.
Related: Defending Earth Against Dangerous Asteroids: Questions and Answers with Lindley Johnson of NASA
And for a brief moment, it seemed as if Apophis on April 13, 2029 had almost a 3% chance of colliding with the earth. (Even the best observations have some uncertainty, and the further a path is planned in advance, the more uncertainty accumulates..) The early concern inspired his name, referring to an Egyptian ‘devil serpent’ that evil and personify chaos’, as NASA puts it.
Some of Apophis’ flies are quite commonplace, others fairly close. But more accurate observations have fueled any fear of collision only until 2036, dan until 2068, when scientists can not yet rule out a collision quite positively.
If Apophis and Earth ever collide, hope you will not see the day. Two asteroids have hit the earth in the last century or so. One has the Siberian forests of Tunguska in 1908, crushing the others in the air above Chelyabinsk, Russia, in 2013.
They are nothing compared to Apophis. “Apophis is 300 times more massive than Tunguska, 5,000 times more massive than Chelyabinsk, so it’s an object that definitely grabs your attention,” Richard Binzel, a planetary scientist at the Massachusetts Institute of Technology, told Space.com.
A natural experiment
At the moment, Apophis is thinking of his own business, like thousands of other cosmic pieces, orbiting the sun every 323.6 Earth days. The asteroid has been howling through space and is completely unusual.
That will change.
Nine or more loops around Apophis and another eight loops for the earth will bring the objects just within 31,900 kilometers. Scientists know that Apophis will not hit the earth this time. But depending on how the two rocks beat past each other, Apophis may never look the same.
Same gravity which keeps our everyday lives anchored to the earth’s surface, will draw Apophis through the close encounter. Scientists think there is a chance that the Earth’s gravity will be strong enough to scatter rocks on the surface of Apophis, or even stretch the asteroid, as if it were salt water instead of rock.
How dramatic the piece will be depends on a number of factors. First, the exact form of Apophis. Then the orientation of it during flying: when a broad side looks at the earth, each patch feels less gravity; if a narrow head does this, the asteroid is set up for a tug of war. Then, what’s in there: solid, dense rock would withstand the gravity of the earth more, a loose cluster of smaller rocks would give more.
Some of these properties that scientists can study from the earth. But the inside of Apophis is at a distance impenetrable – except perhaps by the 2029 fly.
“How Apophis itself reacts is physically about how Apophis is composed. And that’s something we do not know – we do not know how asteroids are composed, we have never been able to look in an asteroid,” Binzel said. “We see the asteroid looking outside. This is a chance where the asteroid can look inside. In other words, does the inside of the asteroid reveal itself to some extent that we can do so on the outside?”
This is an incredible experiment that is purely arranged by random orbits.
Related: Comet Shoemaker-Levy 9’s epic crash with Jupiter in photos
Scientists have been here once. In 1993, astronomers spotted a new comet Shoemaker-Levy 9 – only to realize that the discovery was actually a clutch of comet fragments, the rubble of a comet that passed too close to massive Jupiter to survive the experience. But the right highlight? These fragments were on their way to hit the planet the following year.
“The predictions for the impact of Shoemaker-Levy 9 range from nothing will happen – it will be a dud, a flop, to almost parallel to what we actually observed,” Binzel said. “There was enormous uncertainty about which would be the outcome of the Shoemaker-Levy 9 impact, simply because it challenged the state of our knowledge. And the parallel with Apophis is therefore that there are a wide variety of predictions that will happen physically to Apophis himself during the encounter: Apophis can go through the earth and not care, or Apophis can go through the earth and be drawn so significantly that it seismically trembles. ‘
But in the 1990s, astronomers followed spacecraft and telescopes to collide for a week from collisions that had scars. Jupiter’s cloud for a few weeks. The Shoemaker-Levy 9 observations taught scientists about not only the comet fragments and the icy lump they once made up, but also about Jupiter and its atmosphere.
“I think Apophis is a lot like Comet Shoemaker-Levy 9: it’s an extremely rare natural experiment that we discovered with a short delivery time,” Binzel said. “This is something that rarely happens. Nature does something wonderful for us as a natural experiment, and the challenge is how we utilize the natural experiment.”
And Apophis observations would tell scientists of a different taste of close encounter than Shoemaker-Levy 9, since the earth’s gravity will not be strong enough to tear the rock apart.
“It will not cause this kind of big event, but it still makes sense to understand how the object can be affected by this slightly-distant near-fly,” said Yaeji Kim, a doctoral student in aeronautical engineering at the University of Auburn, Alabama, told Space.com. “No object has been observed in this kind of phenomenon. From that kind of point of view, Apophis is a very rare case.”
Related: Radar views show that the big asteroid of 1998 OR2 tumbles into space before Earth’s fly (video)
Preparing for 2029
Making the most of the 2029 fly will depend on the basic data: what Apophis scientists know before the dramatic encounter with it Earth. This means that the observations collected this year matter. Apophis will be closest to Earth this year on March 5 at 20:15 EST (0115 GMT on March 6).
‘Nearest’ here is a relative term: the asteroid will stay healthy 0.11 astronomical units (the average distance between the earth and the sun, or about 150 million km). This is almost 44 times the distance between the earth and the moon.
But it is close enough for scientists’ most powerful tool to study asteroids from Earth: planetary radar. Take a powerful radar beam, aim it at a mysterious object and then wait. Use a sensitive radio telescope to capture the echo bouncing back through intricate processing, resulting in a sonogram-like image.
“We like asteroids coming close, but, you know, just enough so that we can get a really good signal and that we can get amazing images,” Brozović said.
Related: Scientists have just looked at a newly discovered asteroid zoom through the earth. Then they saw the moon of it.
With good radar images, for example, scientists can see what shape an asteroid takes: potato, peanut butter, or even some cherries bound only by gravity. Under particularly friendly conditions, radar can detect rocks on the surface of a space rock. It also sharpens the ability of scientists to track down an asteroid’s orbit.
Scientists’ top priority during the preparation for the Apophis flyby 2029 is to sharpen their view of the rock shape and its intricate rotations, Binzel said. “We know that Apophis is in a very complicated state, it is spinning and tumbling at the same time,” he said. “The 2021 meeting gives us a time frame.”
If scientists want to make predictions about what exactly will happen to Apophis during the encounter in 2029, they will feed the current best wisdom of form and the twisted rotation into models – but the predictions that follow will be just as strong as the data. .
Related: With the loss of Arecibo’s giant dish, people are more vulnerable to space rock, scientists say
It is uncomfortable that the Earth lost its most powerful planetary radar system in December Arecibo Observatory Radio Telescope collapsed in Puerto Rico. Each radar system has its strengths and weaknesses, and Arecibo would have shone during this preparatory close approach. Without it, scientists do not know how much they will be able to improve the existing radar observations of Apophis.
But they will try, thanks to the planetary radar system at NASA’s Goldstone Deep Space Communications Complex in California, which Apophis must study from March 3 to March 14 to cover this flight. Researchers also hope to use the Green Bank Telescope in West Virginia to capture the echoes, rather than changing Goldstone’s settings back and forth between sending and receiving; if they can use two telescopes, the data will be sharper.
“Arecibo was really a power station, the most powerful radar on the planet, so we just can not make it up,” Brozović said. “But we’re still going to get good data.”
Email Meghan Bartels at [email protected] or follow her on Twitter @meghanbartels. Follow us on Twitter @Spacedotcom and on Facebook.