This photo shows the view from the dome of NASA’s infrared telescope facility during a night observation. The 3.2 meter (10.5 ft) telescope above Hawaii’s Mauna Kea is used to measure the infrared spectrum of the 2001 asteroid FO32. Credit: UH / IfA
The interplanetary interoperator will not come closer than 1.25 million miles to Earth, but it provides a valuable scientific opportunity for astronomers.
The largest asteroid to be predicted by our planet in 2021 will be the closest on March 21, giving astronomers a rare opportunity to take a good look at a rocky remnant that formed at the beginning of our solar system.
The 2001 asteroid named FO32, 2001, will reach the nearest approximation at a distance of about 1.25 million miles (2 million kilometers) – or 5 1/4 times the distance from the 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 orbit around the sun very accurately, since it was discovered 20 years ago and has been followed ever since,” said Paul Chodas, director of the Center for Near Earth Object Studies (CNEOS), which is managed. by NASA‘s Jet Propulsion Laboratory in Southern California. “There is no chance that the asteroid will come closer to Earth than 1.25 million miles.”
However, the distance is astronomically close, which is why FO32 2001 is designated as a ‘potentially dangerous asteroid’. CNEOS calculates high-precision orbits for near-Earth objects (NEOs) in support of NASA’s Planetary Defense Coordination Office, and relies on telescopes and ground-based radar to accurately characterize each orbit of the NEO to improve long-term hazard assessments.
During this approach, FO32 will pass at approximately 77,000 km / h (124,000 km / h) – faster than the speed at which most asteroids reach Earth. The reason for the asteroid’s extremely fast close approach is its highly inclined and elongated (or eccentric) orbit around the sun, an orbit tilted 39 degrees to Earth’s orbital plane. This orbit takes the asteroid closer to the sun than Mercury and twice as far from the sun as March.
This diagram shows the elongated and oblique orbit of 2001 FO32 as it moves around the sun (white ellipse). As a result of this orbit, as the asteroid approaches its near Earth, it will move at an extremely fast speed of 124,000 km / h. Credit: NASA / JPL-Caltech
When FO32 travels to its inner solar system in 2001, the asteroid picks up speed like a skateboarder unrolling from a half-pipe, and then slows down after being thrown back into deep space and swinging back to the sun. It completes one job every 810 days (approximately 2 1/4 years).
After its brief visit, FO32 will continue its solitary journey in 2001 and only come close to Earth again in 2052, when it will pass at approximately seven lunar distances, or 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 was estimated from optical measurements about 1 mile wide. In more recent follow-up observations by NEOWISE, FO32 appears to be vague when observed in infrared wavelengths, indicating that the object is probably less than 1 kilometer in diameter. Analysis by the NEOWISE team shows that it is between 440 and 680 meters wide.
Even at the smaller end of the scale, 2001 FO32 will still be the largest asteroid to pass near our planet in 2021. The last major asteroid approach was the OR2 of 1998 on April 29, 2020. While 2001 FO32 is slightly smaller than 1998 OR2, it will be three times closer to Earth.
The March 21 meeting will give astronomers the opportunity to gain a more precise understanding of the size and albedo of the asteroid (ie, 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 ft) telescope on top of Hawaii’s Mauna Kea that will detect the asteroid in the days before the close approach. using his work cell. infrared spectrograph, SpeX. “We’re trying to do geology with a telescope,” said Vishnu Reddy, an associate professor at the University of Arizona’s Lunar and Planetary Laboratory in Tucson.
When sunlight falls on the surface of an asteroid, minerals in the rock absorb some wavelengths while being reflected again. By studying the spectrum of light reflected from the surface, astronomers can measure the chemical “fingerprints” of the minerals on the surface of the asteroid. “We are going to use the IRTF to show the infrared spectrum its chemical composition,” Reddy explained. “Once we know this, we can make comparisons with meteorites on Earth to determine which minerals 2001 FO32 contains.”
For example, if FO32 were identified as iron-rich, it would mean that it is denser and therefore more massive than a rocky asteroid of the same size; observations showing a surface with a low albedo (meaning it is dark) may indicate that the asteroid contains a lot of carbon, suggesting that it may be the core of a long-dead comet.
A closer look
In addition, radar observations can be made by the Deep Space Network (DSN) to get a detailed picture of the asteroid. The DSN is an industry of NASA’s Space Communications and Navigation Program (SCaN) and consists of three ground stations – one in California (Goldstone), one in Spain (Madrid) and one in Australia (Canberra). Their dish antennas can be used to reflect radio signals from 2001 FO32 so that other radio antennas can receive them. Such radar observations can provide extra insight into the orbit of the asteroid, a better estimate of its dimensions and rotational speed, and help to see the surface features (such as large rocks or craters). They can even reveal any small satellites that are in tow.
“Observations dating back 20 years have shown that about 15% of the Earth’s asteroids comparable in size to FO32 2001 have a small moon,” said Lance Benner, chief scientist at JPL. “Little is known about this object at present, so the very close encounter provides an excellent opportunity to learn a lot about this asteroid.”
More than 95% of the Asteroids near Earth of 2001 FO32 or greater have been discovered, detected and cataloged. None of the major asteroids in the catalog have a chance of affecting the Earth during the next century, and it is highly unlikely that any of the remaining undiscovered asteroids of this size could affect the Earth as well. Attempts are still being made to discover all asteroids that could pose an impact hazard. The more information about these objects can be gathered, the better mission designers can prepare to deduce them should the earth threaten in the future.
Meanwhile, amateur astronomers can gather their own information about 2001 FO32. “The asteroid will be the brightest as it moves through the southern sky,” JPL’s Chodas said. ‘Amateur astronomers in the southern hemisphere and low northern latitudes should be able to see this asteroid using moderate telescopes with diaphragms of at least 8 centimeters in the nights that follow the closest approach, but they will probably need star charts to do so. to find. ”
JPL presents CNEOS for NASA’s near-Earth observation program in NASA’s planetary defense coordination office. The University of Hawaii manages IRTF under contract with NASA. The SpeX instrument was built at the University of Hawaii.