A “potentially dangerous asteroid” is predicted to pass safely by Earth on March 21 – tech2.org

A “potentially dangerous asteroid” is predicted to pass safely by Earth on March 21

NASA Infrared Telescope Installation

This photo shows the view from inside the dome of NASA’s Infrared Telescope Facility during a night of observation. The 3.2-meter (10.5-foot) telescope on Hawaii’s Mauna Kea will be used to measure the infrared spectrum of asteroid 2001 FO32. Credit: UH / IfA

The interplanetary intruder won’t get any closer than 1.25 million miles from Earth, but it will present a valuable scientific opportunity for astronomers.

The largest asteroid predicted to pass our planet in 2021 will be at its closest on March 21, giving astronomers a unique opportunity to get a good look at a rocky relic that formed at the dawn of our solar system. .

Named 2001 FO32, the near-Earth asteroid will make its closest approach at a distance of about 1.25 million miles (2 million kilometers), or 5 1/4 times the distance from Earth to the Moon. There is no threat of a collision with our planet now or for centuries to come.

“We know the 2001 FO32 orbital path around the Sun very precisely, as it was discovered 20 years ago and has been tracked ever since,” said Paul Chodas, director of the Center for Near Earth Object Studies (CNEOS), who is managed by POTJet Propulsion Laboratory in Southern California. “There is no chance that the asteroid will get closer to Earth than 1.25 million miles.”

Still, that distance is close in astronomical terms, which is why 2001 FO32 has been designated a “potentially dangerous asteroid.” CNEOS calculates high-precision orbits for near-Earth objects (NEOs) in support of NASA’s Planetary Defense Coordination Office, relying on ground-based telescopes and radars to help accurately characterize the orbit of each NEO to improve assessments long-term hazards.

During this approach, 2001 FO32 will pass at about 77,000 mph (124,000 kph), faster than the speed at which most asteroids encounter Earth. The reason for the asteroid’s unusually fast approach is its highly inclined and elongated (or eccentric) orbit around the Sun, an orbit that is tilted 39 degrees relative to Earth’s orbital plane. This orbit brings the asteroid closer to the Sun than Mercury and twice as far from the Sun as Mars.

Inclined orbit of asteroid 2001 FO32

This diagram shows the long, inclined orbit of 2001 FO32 as it travels around the Sun (white ellipse). Due to this orbit, when the asteroid approaches Earth, it will travel at an unusually fast speed of 77,000 mph (124,000 kph). Credit: NASA / JPL-Caltech

As 2001 FO32 makes its journey into the solar system, the asteroid picks up speed like a skater rolling down a halfpipe and then slows down after being thrown into deep space and spinning toward the Sun. It completes an orbit every 810 days ( about 2 1/4 years).

After its brief visit, 2001 FO32 will continue its solitary journey and will not come as close to Earth again until 2052, when it will pass about seven lunar distances, or 1.75 million miles (2.8 million kilometers).

Astronomical geology

Asteroid 2001 FO32 was discovered in March 2001 by the Lincoln Near-Earth Asteroid Research (LINEAR) program in Socorro, New Mexico, and had been estimated, based on optical measurements, to be approximately 3,000 feet (1 kilometer) wide. In more recent NEOWISE follow-up observations, 2001 FO32 appears to be faint when viewed at infrared wavelengths, suggesting that the object is likely less than 1 kilometer in diameter. Analysis by the NEOWISE team shows that it is between 1,300 and 2,230 feet (440 and 680 meters) wide.

Even if it is on the smaller end of the scale, 2001 FO32 will still be the largest asteroid to pass this close to our planet in 2021. The last remarkably large asteroid approach was that of 1998 OR2 on April 29, 2020. While Since 2001 FO32 is somewhat smaller than 1998 OR2, it will be three times closer to Earth.

The March 21 encounter will provide an opportunity for astronomers to gain a more precise understanding of the size and albedo of the asteroid (that is, how bright or reflective its surface is), and a rough idea of ​​its composition.

This will be accomplished, in part, with the use of NASA’s Infrared Telescope Facility (IRTF), a 3.2-meter (10.5-foot) telescope on Hawaii’s Mauna Kea that will observe the asteroid in the days leading up to it. to the close approach with his workhorse. infrared spectrograph, SpeX. “We’re trying to do geology with a telescope,” said Vishnu Reddy, an associate professor at the Lunar and Planetary Laboratory at the University of Arizona in Tucson.

When sunlight hits the surface of an asteroid, minerals in the rock absorb some wavelengths while reflecting others. By studying the spectrum of light reflected from the surface, astronomers can measure the chemical “fingerprints” of minerals on the asteroid’s surface. “We are going to use the IRTF to get the infrared spectrum to see its chemical composition,” Reddy explained. “Once we know that, we can make comparisons with meteorites on Earth to find out what minerals 2001 FO32 contains.”

For example, if 2001 FO32 were identified as rich in iron, that would mean that it is denser and therefore more massive than a stony asteroid of similar size; Observations showing a surface with a low albedo (meaning it’s dark) may indicate that the asteroid contains a large amount of carbon, suggesting it could be the nucleus of a long-dead comet.

A closer look

In addition, radar observations can be made by the Deep Space Network (DSN) to obtain a detailed view of the asteroid. An operation of NASA’s Space Navigation and Communications (SCaN) program, the DSN comprises three ground stations: one in California (Goldstone), one in Spain (Madrid) and one in Australia (Canberra). Your satellite dishes can be used to bounce 2001 FO32 radio signals so that other radio antennas can receive them. Such radar observations can provide additional information about the asteroid’s orbit, provide a better estimate of its dimensions and rotational speed, and help glimpse surface features (such as large rocks or craters). They could even reveal any small satellites that may be towed.

“Observations going back 20 years revealed that about 15% of near-Earth asteroids comparable in size to FO32 from 2001 have a small moon,” said Lance Benner, lead scientist at JPL. “Currently little is known about this object, so the very close encounter provides a rare opportunity to learn a lot about this asteroid.”

More than 95% of near-Earth asteroids the size of 2001 FO32 or larger have been discovered, tracked, and cataloged. None of the large asteroids in the catalog have any chance of impacting Earth over the next century, and it is extremely unlikely that any of the undiscovered asteroids of this size will be able to impact Earth either. Still, efforts continue to discover all the asteroids that could pose an impact hazard. The more information that can be gathered about these objects, the better mission designers can prepare to deflect them if one threatens Earth in the future.

Meanwhile, amateur astronomers can gather their own information on 2001 FO32. “The asteroid will be brighter as it moves through the southern skies,” said JPL’s Chodas. “Amateur astronomers in the southern hemisphere and in low northern latitudes should be able to see this asteroid using moderately sized telescopes with apertures of at least 8 inches in the nights before the closest approach, but they will probably need star charts to find it. “

JPL hosts CNEOS for NASA’s Near-Earth Object Observation Program at NASA’s Planetary Defense Coordination Office. The University of Hawaii manages the IRTF under contract with NASA. The SpeX instrument was built at the University of Hawaii.

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