SMALL ASTEROID NARROWLY MISSED EARTH IN 2011, HUGE ONE TO MISS TODAY (Being updated 12/12/2012)
2011 trajectory calculations were correct, let's hope the 2012 math is right too.
On May 9, 2011, I first published the matrix on this page about a 400-meter wide asteroid that would have a near miss for the Earth on November 8, 2011 at 6:28 p.m. EST. The aircraft carrier-sized asteroid named 2005 YU55 passed inside the moon’s orbit of Earth and missed us by 201,700 miles. Its speed was 29,000 miles per hour. A short movie of it is found at: http://1.usa.gov/uVJvmS. On the first matrix below the axis term is ASTEROID. 11 HESHVAN is a key term which is November 8th in YEAR 5772/2011, which is found on the matrix at skip -1. There are two words for moon. One MOON is at skip +1, the other MOON intersects and shares a letter with11 HESHVAN. It also includes ON THE EARTH in the open text. The word ASTEROID passes between ON THE EARTH and MOON, somewhat similar to what occured on its closest approach. This matrix was found against odds of 65,656 to 1. It was quite significant, especially because it is rare to have day month and year of an event on a matrix of this size. However, on December 12, 2012 a 3-mile wide asteroid, Toutatis, is scheduled to miss the Earth by about 18 times the distance to the moon. The Chinese have a rocket on the way to a close intercept, and while probably just a coincidence, on December 11, 2012, I watched the U.S. launch the X-37B from here in Cape Canaveral; and the North Koreans fired a long distance rocket that they wanted to put in orbit.
THE CALCULATED THREAT FOR THIS ASTEROID.
I asked my son, David A. Roffman (a senior majoring in Space-Physics at Embry-Riddle Aeronautical University in Daytona Beach, FL), to calculate how large an impact crater would be on Earth if/when Asteroid 2005 YU55 eventually hits the Earth. His answer is 4.4 km across (with his calculations included below for those into such math).
D = 2*ρm.11*ρp-1/3*gp-.22*R.13*Ek.22*sin1/3θ
This formula is derived from empirical results [Planetary Sciences Imke de Pater and Jack J. Lissauer second edition page 180]. It gives the diameter of the impact crater.
ρm is the planet density = 3500 kg/m3
ρp is the asteroid density = 2080 kg/m3 (assumed to be this-stone with some gaps)
gp is the surface gravity = 9.81 m/s2
R is the radius of the asteroid (assumed to be spherical) = 200 m
Ek is the kinetic energy of the impactor (2*π*R3*ρm*v2/3) = 3.485*1018 J
v is the impactor velocity = 10000 m/s (typical impactor speed is assumed)
θ is the impact angle = 90o (assumed to give maximum crater diameter)
The rule of ten (the diameter impact crater is about 10 times greater than the diameter of the impactor indicates the result should be about 4 km).
Answer using formula: 4.4 km
IMPACT CALCULATOR FROM PURDUE UNIVERSITY. Purdue offers an on-line calculator to check on the effects of an asteroid impact. Using the density of 2080 kg/m3 and 400 meter diameter (200 m radius) offered above by my son, it shows the following results for the impact crater:
Crater shape is normal in spite of atmospheric crushing; fragments are not significantly dispersed.
Transient Crater Diameter: 3.7 km (= 2.3 miles)
Transient Crater Depth: 1.31 km (= 0.813 miles)
Final Crater Diameter: 4.41 km (= 2.74 miles)
Final Crater Depth: 463 meters (= 1520 feet)
The crater formed is a complex crater.
At this impact velocity (< 12 km/s), little shock melting of the target occurs.
The calculator allows the novice to alter parameters like radius, density, angle of impact, and speed of impact. Using a angle of impact of about 45 degrees and a velocity of 11 km/s, the final crater size was close to my son’s calculation. At 20 miles from the impact, the air blast will have the following results:
Arrival time: Approximately 1.63 minutes after impact.
Peak Overpressure: 57600 Pa = 0.576 bars = 8.18 psi
Max wind velocity: 111 m/s = 249 mph
Sound Intensity: 95 dB (May cause ear pain)
Multistory wall-bearing buildings will collapse.
Wood frame buildings will almost completely collapse.
Glass windows will shatter.
~90 percent of trees blown down; remainder stripped of branches and leaves.
The air blast will arrive approximately 8.13 minutes after impact.
Peak Overpressure: 29500 Pa = 0.295 bars = 4.19 psi
Max wind velocity: 62.2 m/s = 139 mph
Sound Intensity: 89 dB (Loud as heavy traffic)
Wood frame buildings will almost completely collapse.
Glass windows will shatter.
Up to 90 percent of trees blown down; remainder stripped of branches and leaves.
Time for maximum radiation: 160 milliseconds after impact
Visible fireball radius: 8.89 km (= 5.52 miles)
The fireball appears 12.6 times larger than the sun
Thermal Exposure: 2.29 x 10^6 Joules/m^2
Duration of Irradiation: 2.37 minutes
Effects of Thermal Radiation:
Much of the body suffers second degree burns, Newspaper ignites, Deciduous trees ignite, Grass ignites.
For a comparison, Meteor Crater near Winslow, Arizona has a diameter of only 1.186 km. So the threat from this asteroid is to produce a crater 3.7 times wider.
Barry and David Roffman at Meteor Crater in 2006.
FoxNews.Com Story Coverage Published on May 9, 2011:
Big Asteroid's Approach in November Excites Astronomers
Arecibo Observatory/Michael Nolan
The near-Earth asteroid 2005 YU55 — on the list of potentially dangerous asteroids — was observed with the Arecibo Telescope's planetary radar on April 19, 2010, when it was about 1.5 million miles from Earth. An asteroid the size of an aircraft carrier will come closer to Earth this autumn than our own moon does, causing scientists to hold their breath as it zooms by. But they'll be nervous with excitement, not with worry about a possible disaster.
There's no danger of an impact when the asteroid 2005 YU55 makes its close flyby Nov. 8, coming within 201,700 miles (325,000 kilometers) of Earth, scientists say.
So they're looking forward to the encounter, which could help them learn more about big space rocks.
"While near-Earth objects of this size have flown within a lunar distance in the past, we did not have the foreknowledge and technology to take advantage of the opportunity," Barbara Wilson, a scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif., said in a statement. "When it flies past, it should be a great opportunity for science instruments on the ground to get a good look." [Photos: Asteroids in Deep Space]
Getting to know YU55
Asteroid 2005 YU55 is about 1,300 feet (400 meters) wide. It was discovered in December 2005 by the Spacewatch program at the University of Arizona in Tucson.
Because of the asteroid’s size and orbital characteristics, astronomers have flagged 2005 YU55 as potentially dangerous down the road. But the upcoming encounter is no cause for alarm, researchers said.
"YU55 poses no threat of an Earth collision over, at the very least, the next 100 years," said Don Yeomans, manager of NASA's Near-Earth Object Program Office at JPL. "During its closest approach, its gravitational effect on the Earth will be so minuscule as to be immeasurable. It will not affect the tides or anything else." [5 Reasons to Care About Asteroids]
This round space rock has been in astronomers' cross hairs before. In April 2010, astronomers at the National Science Foundation's Arecibo Observatory in Puerto Rico generated some ghostly radar images of 2005 YU55 when the asteroid was about 1.5 million miles (2.3 million km) from Earth. But those pictures had a resolution of just 25 feet (7.5 meters) per pixel. The November close pass should provide some sharper images.
"When 2005 YU55 returns this fall, we intend to image it at 4-meter resolution [13 feet] with our recently upgraded equipment at the Deep Space Network at Goldstone, California," said JPL radar astronomer Lance Benner. "Plus, the asteroid will be seven times closer. We're expecting some very detailed radar images."
A radar astronomy opportunity
Radar astronomy employs the world's biggest dish-shaped antennas. The antennas direct microwave signals at celestial targets that can be as far away as the moons of Saturn. These signals bounce off the target, and the resulting "echo" helps researchers create radar images. These images can then be used to reconstruct detailed, three-dimensional models of the object. With 4-meter-per-pixel resolution, the new views of 2005 YU55 should be pretty sharp, perhaps even showing boulders and craters, researchers said.
"We're talking about getting down to the kind of surface detail you dream of when you have a spacecraft fly by one of these targets," Benner said.
The data collected from Arecibo, Goldstone and ground-based optical and infrared telescopes also should help detail the mineral composition of the asteroid, researchers said.
"This is a C-type asteroid, and those are thought to be representative of the primordial materials from which our solar system was formed," Wilson said. "This flyby will be an excellent opportunity to test how we study, document and quantify which asteroids would be most appropriate for a future human mission."
The capabilities of the Goldstone antenna, in California's Mojave Desert, and of Arecibo are complementary. The Arecibo radar is about 20 times more sensitive and can detect asteroids about twice as far away. But its main dish is stationary, so it can see only about a third of the sky. Goldstone is fully steerable and can see about 80 percent of the accessible sky, so it can track objects for longer periods and can image asteroids at finer spatial resolution, researchers said.
Researchers are eager to train the instruments of both facilities on 2005 YU55 in November. "So stay tuned," Yeomans said. "This is going to be fun."
The images below of the orbits of this asteroid with Earth, Mars, Venus and Mercury are adapted from this video here.