Tag Archives: NEO

Another moon for Earth

Astronomers have discovered an asteroid whose solar orbit is almost identical to Earth’s, and has it hovering so near the Earth that it is almost another moon.

Based on orbital data the scientists estimate that the asteroid, between 300 to 1000 feet in diameter, has been hovering near Earth for the past 775 years, and it will only drift away in about 165 years from now.

Correction: Engineer and regular reader James Fincannon emailed me to note that this asteroid really doesn’t have an orbit “almost identical to the Earth.” As he wrote, “Seems to go between Venus and Mercury and then all the way out to Mars! It seems to pass by Earth occasionally.” Thus, this recent period of closeness is only a temporary one.

Another rock will fly past the Earth today, killing no one.

Chicken Little report: Another rock will fly past the Earth today, killing no one.

The 33-foot-wide (10 meters) near-Earth asteroid 2014 EC will come within 34,550 miles (55,600 kilometers) of Earth’s surface this evening (March 6) — just 14 percent of the distance between our planet and the moon, which is about 239,000 miles (385,000 km) on average.

The key quote, however, is this:

Such back-to-back flybys are pretty special, though they can’t exactly be called rare events, [JPL scientist Don] Yeomans said. “For small asteroids, one would expect a flyby of the Earth, to within the moon’s distance, about every two weeks,” he said.

In other words, these flybys happen a lot, with no consequences.

A 100-foot diameter newly discovered asteroid will zip past the Earth inside the Moon’s orbit today at 4:07 pm Eastern.

Chicken Little report: A 100-foot diameter newly discovered asteroid will zip past the Earth inside the Moon’s orbit today at 4:07 pm Eastern.

The asteroid, dubbed 2014 DX 110, is about 100 feet in diameter and is set to come within 216,000 miles of Earth — a close shave by astronomical standards, considering our Moon orbits the Earth at a distance of about 238,900 miles.

While an object that size may not seem imposing, if it were to strike the Earth, it would release a devastating amount of energy greater than a nuclear weapon. The infamous asteroid that exploded over Tunguska, Siberia, on June 30, 1908, has been estimated to be about 30 meters to 60 meters — 100 feet to 200 feet — in diameter.

While it is true that the impact would be significant, this news report does the typical fear-mongering to make the story seem interesting. The problem, however, is that the detection of these fly-bys is becoming more frequent. The number of asteroids isn’t changing, but our ability to spot them is, and with more frequent discoveries comes more frequent news stories like this. I fear that such stories — fueled by press releases from various astronomy organizations — are going to begin to sound like a kid “crying wolf” to the general public. The threat from an asteroid impact is real, even if most asteroids miss us. Desensitizing the public to the threat is not a good thing.

A newly discovered half-mile wide asteroid has 1 in 63,000 chance of hitting the Earth in 2032.

A newly discovered half-mile wide asteroid has 1 in 63,000 chance of hitting the Earth in 2032.

That’s the Russian report above, which on these matters tend to be panic-stricken. Here’s the JPL version, which downplays the concern.

NASA will reactivate the Wide-field Infrared Survey Explorer (WISE) next month to use it to look for more near Earth asteroids.

NASA will reactivate the Wide-field Infrared Survey Explorer (WISE) next month to use it to look for more near Earth asteroids.

This decision raises two thoughts.

  • Why did they shut it down in the first place if it was still viable and could still do important research? If the cost wasn’t worth the benefit then, how has this equation changed now? And if the cost was worth the benefit, it then was foolish to shut it down in the first place. Though it costs money to operate these things, it is always cheaper to keep something running than to build something new. The press announcement above doesn’t really address these issues, and I wish it did.
  • I wonder if this decision is somehow related to the end of the Kepler mission. With Kepler out of service, maybe NASA decided to shift the funds to run that telescope over to WISE. They do not say, but the timing is interesting. This decision could be a hint that Kepler doesn’t really have another mission it can fulfill, and thus the money to run it has already been put elsewhere.

New data has allowed scientists to lower the chance that the asteroid Apophis will hit the Earth in a future orbit.

New data has allowed scientists to lower the chance that the asteroid Apophis will hit the Earth in a future orbit.

Recent observations from Pan-STARRS PS1 telescope at Haleakala, Hawaii have reduced the current orbital uncertainty by a factor of 5, and radar observations in early 2013 from Goldstone and Arecibo will further improve the knowledge of Apophis’ current position. However, the current knowledge is now precise enough that the uncertainty in predicting the position in 2029 is completely dominated by the so-called Yarkovsky effect, a subtle nongravitational perturbation due to thermal re-radiation of solar energy absorbed by the asteroid. The Yarkovsky effect depends on the asteroid’s size, mass, thermal properties, and critically on the orientation of the asteroid’s spin axis, which is currently unknown. This means that predictions for the 2029 Earth encounter will not improve significantly until these physical and spin characteristics are better determined.

The new report, which does not make use of the 2013 radar measurements, identifies over a dozen keyholes that fall within the range of possible 2029 encounter distances. Notably, the potential impact in 2036 that had previously held the highest probability has been effectively ruled out since its probability has fallen to well below one chance in one million. Indeed only one of the potential impacts has a probability of impact greater than 1-in-a-million; there is a 2-meter wide keyhole that leads to an impact in 2068, with impact odds of about 2.3 in a million.

The second paragraph basically says that the keyholes that might bring Apophis back to Earth are very small, making it unlikely that the asteroid will fly through any one of them in 2029. The first paragraph however notes that it will be impossible to chart the asteroid’s course accurately enough to rule out this possibility until we have more data on the asteroid itself.

Scientists have released some results from their look at asteroid 2012 DA14 during its fly-by last week.

Scientists have released some results, including video, from their look at asteroid 2012 DA14 during its fly-by last week. Key quote:

The asteroid’s path was perturbed by Earth’s gravitational field in such a way that it won’t come as close in the foreseeable future.

The video, which I have embeded below the fold, was produced from radar data. It clearly shows the asteroid’s rotation.
» Read more

A 150 foot wide asteroid will buzz the Earth tomorrow at a distance of only 17,000 miles.

Chicken Little report: A 150 foot wide asteroid will buzz the Earth tomorrow at a distance of only 17,000 miles.

There have been numerous news articles about this fly-by for the last two weeks, all hyping the dangers of an impact that in this case simply won’t happen. A threat of an impact from an asteroid is real and should be dealt with, but the reporting here has at times been somewhat silly. Asteroid 2012 DA14 is not going to hit us as it goes by. All that will happen is that scientists will have take advantage of this opportunity to look at it.

On Wednesday Apophis will pass the Earth at a distance of 9 million miles, allowing astronomers to gather more data about this asteroid’s orbit and composition.

On Wednesday Apophis will pass the Earth at a distance of 9 million miles, allowing astronomers to gather more data about this asteroid’s orbit and composition.

Having crossed outside Earth’s orbit, Apophis will appear briefly in the night-time sky. Wednesday 9 January will afford astronomers the rare opportunity to bring a battery of telescopes to bear: from optical telescopes to radio telescopes to the European Space Agency’s Infrared Space Observatory Herschel. Two of the biggest unknowns that remain to be established are the asteroid’s mass and the way it is spinning. Both of these affect the asteroid’s orbit and without them, precise calculations cannot be made.

Impressive radar images of near-Earth asteroid 2007 PA8 were taken during its recent fly-by of Earth.

Impressive radar images of near-Earth asteroid 2007 PA8 were taken during its recent fly-by of Earth.

The images … reveal possible craters, boulders, an irregular, asymmetric shape, and very slow rotation. The asteroid measures approximately one mile wide (about 1.6 kilometers).

The asteroid poses no threat to Earth. The resolution of the images, however, is astonishing, especially considering it was done by radar.

Astronomers have videotaped the fly-by of a 23-foot-wide asteroid as it zipped past the Earth on May 29 at a distance of only about 12,000 miles.

Astronomers have videotaped the fly-by of a 23-foot-wide asteroid as it zipped past the Earth on May 29 at a distance of only about 12,000 miles. The video is below the fold.
» Read more

Scientists have concluded that a 460 foot diameter asteroid only has a 1 percent chance of hitting the Earth in 2040.

O goody: Scientists have concluded that a 460 foot diameter asteroid only has a 1 percent chance of hitting the Earth in 2040.

Observations to date indicate there is a slight chance that AG5 could impact Earth in 2040. Attendees expressed confidence that in the next four years, analysis of space and ground-based observations will show the likelihood of 2011 AG5 missing Earth to be greater than 99 percent.

It appears that they won’t really be able to pin down the impact odds for 2040 until 2023, when the asteroid passes the Earth at a distance of 1.1 million miles.

Capturing an asteroid into Earth orbit

orbital path after asteroid capture

Want to mine an asteroid? Rather than travel to it with all their mining equipment, three Chinese scientists have proposed a better way. In a paper published today on the Los Alamos astro-ph preprint website, they have calculated the energy required to shift the orbits of the six thousand near-Earth asteroids and place them in Earth orbit for later mining. Of these, they found 46 asteroids that had the potential for such an operation, and two likely candidates for a space mission. One 30-foot-wide asteroid, 2008EA9, will actually be in the right place for this technique in 2049. As they write,

It can be seen that the velocity increment of the 2008EA9 is relatively small (-1.00km/s) and it will very close approach [approximately 645,000 miles] to the Earth in [February] 2049. Moreover the size of the NEO 2008EA9 is very small so that the capturing of it is relatively easy.

The real problem, of course, is adding that small “velocity increment” to the asteroid.
» Read more

Infrasonic detection of a near-Earth object impact over Indonesia on 8 October 2009

From a paper published on Saturday in Geophysical Research Letters, scientists describe the after the fact detection of the impact of a near-Earth object about 6 to 10 yards in diameter over Indonesia in 2009. From the abstract:

We present analysis of infrasonic signals produced by a large Earth-impacting fireball, believed to be among the most energetic instrumentally recorded during the last century that occurred on 8 October, 2009 over Indonesia. This extraordinary event, detected by 17 infrasonic stations of the global International Monitoring Network, generated stratospherically ducted infrasound returns at distances up to 17 500 km, the greatest range at which infrasound from a fireball has been detected since the 1908 Tunguska explosion. From these infrasonic records, we find the total source energy for this bolide as 8–67 kilotons of TNT equivalent explosive yield, with the favored best estimate near ∼50 kt. Global impact events of such energy are expected only once per decade and study of their impact effects can provide insight into the impactor threshold levels for ground damage and climate perturbations.

Want to go to an asteroid?

A paper published today on the Los Alamos astro-ph preprint website has taken a close look at identifying the best nearby asteroids ideal for mounting a manned mission. The conclusion: our survey of such asteroids is very incomplete (only 65 known), and due to their location in Earthlike orbits they are very difficult to study.

Ultra-low delta-v NEOs are not readily found. Their closely Earth-like orbits mean that most of the time they are in the daytime sky, as seen from the Earth, and so are effectively undetectable. As they approach within <1AU of the Earth they start to lie near quadrature, and so come into the dawn or dusk sky on Earth. The strong scattered sunlight background makes optical surveys toward the dawn or dusk much less sensitive and, in practice, surveys do not look in these directions, preferring to observe where the sky is dark, within 45 degrees, and at most 60 degrees, of the anti-Sun, opposition, direction. As a consequence the lowest delta-v NEOs are undercounted by current surveys, and the factor by which they are undercounted is not yet known.

The paper proposes building a dedicated unmanned infrared mission and placing it in a Venus-like orbit where it would be better placed to see these difficult but important objects.

Newly discovered asteroid orbits in union with Earth

Newly discovered asteroid follows the Earth as it orbits the Sun, and has been doing it for a quarter million years.

Currently, three other horseshoe companions of the Earth are known to exist but, unlike 2010 SO16, these linger for a few thousand years at most before moving on to different orbits. Also, with an estimated diameter of 200–400 metres, 2010 SO16 is by far the largest of Earth’s horseshoe asteroids. The team has already used the Las Cumbres Observatory’s Faulkes Telescope in an on-going campaign to track the object and refine its orbit further. “It is not that difficult to spot with a medium-sized professional telescope”, says Dr Asher. “It will remain as an evening object in Earth’s skies for many years to come.”

Quarter-mile diameter asteroid to pass only 200,000 miles from the Earth on November 8, 2011

Get those telescopes out! A asteroid, a quarter-mile in diameter, is going to pass only 200,000 miles from the Earth on November 8, 2011. Key quote:

Although classified as a potentially hazardous object, 2005 YU55 poses no threat of an Earth collision over at least the next 100 years. However, this will be the closest approach to date by an object this large that we know about in advance and an event of this type.