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Is An Asteroid Collision Inevitable?

Jan 19, 13 Is An Asteroid Collision Inevitable?

NEAs and PHAs

Space photography has recent advances showing shocking information. “Our team was surprised to find the overabundance of low-inclination PHAs,” (Amy Mainzer/NASA/Jet Propulsion Lab). In other words, some asteroids are making closer approaches to earth than once thought. Mainzer, leader of the WISE asteroid-hunting mission, has used the NEOWISE project for all asteroid predictions.

Near-Earth Asteroid (NEA) orbits are closest to earth’s orbit. Some NEAs’ orbits intersect earth’s, and a future collision with earth may exist. Thousands of NEAs exist. Estimates of kilometer-size asteroids are (+/-) 2000. [largest: 1036 Ganymed, at 32km.]

NASA has studied Potentially Hazardous Asteroids (PHAs) more carefully. PHAs have the worst collision classification. Many were photographed, and 1364 have been found to date with NASA’s Wide-field Survey Explorer (WISE) telescope [launched 12/09]. PHAs are >100m across, and dangerously aligned with the earth’s orbit.

Asteroid Payload Capability

An asteroid one-half the size of these spotted could deliver the payload equivalent of a 3-megaton nuclear bomb, enough to “produce severe environmental damage on a global scale,”  CNN reported.

A recent survey says as many as 6,200 PHAs are orbiting close to earth. Because of their size, PHAs will survive the passage through earth’s atmosphere.

From Lindley Johnson (Program Scientist/NEOs): “The NEOWISE analysis shows us we’ve made a good start at finding those objects that truly represent an impact hazard to earth. But we’ve many more to find, and it will take a concerted effort during the next couple of decades to find all of them that could do serious damage or be a mission destination in the future.”

Unfortunately, NASA estimates only 20-30% of these objects have been charted. Where exactly, are those 70-80% of PHA’s known to exist? With space being so large, NASA downplays chances of earth impact.

Other Orbit Changers

However, NASA does not discuss ‘other forces’ which may affect the orbit of any asteroid.

In 1902, Ivan Yarkovsky wrote the solar heating of an object in space would cause it to experience a tiny force, leading to large long-term effects in the orbits of asteroids. The Yarkovsky effect, can turn many asteroids into sun-guided missiles targeting earth.

The Yarkovsky-O’Keefe-Radzievskii-Paddack effect [YORP] is a second-order variation on the Yarkovsky effect, which can also change an asteroid’s orbit.

The Poynting-Robertson effect is when solar radiation causes an asteroid to slowly spiral into the sun, and possibly change its orbit pattern towards earth.

On 5/24/12, Steven Chesley (NASA-asteroid sample return mission OSIRIS-REx), admitted asteroid 1999 RQ36 passed much closer to earth than predicted. He showed how it deviated from its gravity-ruled orbit by 100 miles (160 km) in the last 12 years, due to the Yarkovsky effect.

Asteroid [1950 DA] has a known Yarkovsky effect (15,000 km /last 100 years). Models show a possible collision in 2880.

Other orbit-changers include close ‘flybys’ to other celestial bodies (e.g., planets, moons, and other asteroids). This occurs more often than mentioned.

Jupiter’s Past

Most remember comet Shoemaker-Levy 9 [21 fragments] slashing into the Jovian atmosphere in 1994. If Jupiter’s gravity was not present, the probability of asteroid impacts on the inner planets would be greater.

Asteroids [1999 RQ36], [2012 TC4], [1950 DA], [2012 DA4], [2012 EO88], [1997 XF11], [2011 AG5] (Apophis), and many others, are scheduled to collide, or come dangerously close, to earth in the near future. If Apophis misses in 2026, it’ll swoop by for another pass in 2028, 2034, and 2036. In fact, all PHAs will orbit back around for many, many more passes.

Astronomers know Apophis is 1066ft (325m) wide. That’s 20% larger than the previous estimate of 885ft. That 20% diameter increase (from 270m to 325m) translates into a 75% increase in estimates of volume/mass, and means a slight orbit change.

Real Asteroid Universe

In the Asteroid Discovery Animation (Scott Manley), one gets an idea of how asteroid detection over the last 30 years has improved. From this 3 minute documentary, one gets a sense of the actual number of asteroids.

Green points mark asteroids not expected to approach earth immediately. Over 300 known yellow objects are earth approaching asteroids. Red points are PHAs that cross earth’s orbit. It is estimated 100,000-1,000,000 undiscovered asteroids are on similar earth-crossing orbits. The Increasing Rate of Asteroid Discovery shows the stark increase in discovered asteroids in just thirty years.

God has been quoted {Matt 24:36}: “But of that day and hour no one knows, not even the angels of heaven, nor the Son, but the Father alone.”, concerning man’s outcome during the possible “end-of-the-world” scenario. However, it’s not known whether He mentioned the “how”.

Image Credit: Mopic / Shutterstock

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