DailyMail
Human life could be wiped out
on March 16, 2880 because a
huge asteroid is hurtling towards
Earth - and experts don't know
how to stop it
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Asteroid 1950 DA has a 0.3 per cent chance of hitting Earth
in 867 years
A possible impact date for 1950 DA is on 16 March, 2880,
scientists say
If it hits, it would do so with a force of 44,800 megatonnes
of TNT
But scientists say there is no cause for concern as the risk
is low
Asteroid's body defies gravity due to forces known as van
Der Waals
These forces have never been spotted on an asteroid
before
Scientists say they are now closer to finding out how to
stop the rock
By ELLIE ZOLFAGHARIFARD FOR MAILONLINE
PUBLISHED: 03:11 AEST, 16 August 2014 | UPDATED: 01:48 AEST, 17 August 2014
The date of Earth's potential destruction has been set at 16 March 2880,
when an asteroid hurtling through space has a possibility of striking our
planet.
Researchers studying the rock found that its body rotates so quickly that
it should break apart, but somehow remains intact on its Earth-bound
trajectory.
They believe it is held together by cohesive forces known as van der
Waals - and although this is considered a major breakthrough, scientists
still don't know how to stop it.
The discovery was made by researchers at the University of Tennessee
(UT), Knoxville.
Previous research has shown that asteroids are loose piles of rubble
held together by gravity and friction.
WHAT IS ASTEROID 1950 DA?
The asteroid, named 1950 DA, is a rock two-thirds of a mile in diameter,
travelling at about 15 km (nine miles) per second relative to the Earth.
It is approximately 3,280ft (1,000 metres) in diameter, but rotates once
every two hours and six minutes.
At this rate, the rock should break apart and eventually disintegrate, but
it is not showing any signs of doing so.
In fact, the rotation is so fast that at its equator, 1950 DA effectively
experiences negative gravity.
If an astronaut were to attempt to stand on this surface, he or she would
fly off into space unless he or she were somehow anchored.
The presence of cohesive forces has been predicted in small asteroids,
but definitive evidence has never been seen before.
It is due to swing so close to Earth it could slam into the Atlantic Ocean
at 38,000 miles per hour.
It is estimated that if 1950 DA were to collide with the planet, it would do
so with an force of around 44,800 megatonnes of TNT.
Although the probability of an impact is only 0.3 per cent, this represents
a risk 50 per cent greater than an impact from all other asteroids.
However, the UT team found that the asteroid, called 1950 DA, is
spinning so quickly that it defies these forces.
It is approximately 3,280ft (1,000 metres) in diameter, but rotates once
every two hours and six minutes.
At this rate, the rock should break apart and eventually disintegrate, but
it is not showing any signs of doing so.
Ben Rozitis, a postdoctoral researcher; Eric MacLennan, a doctoral
candidate; and Joshua Emery, an assistant professor in the Department
of Earth and Planetary Sciences, wanted to know what keeps the body
from breaking apart.
By calculating 1950 DA’s temperature and density, the team detected
the cohesive forces that stop it breaking up.
'We found that 1950 DA is rotating faster than the breakup limit for its
density,' said Rozitis.
'So if just gravity were holding this rubble pile together, as is generally
assumed, it would fly apart. Therefore, interparticle cohesive forces must
be holding it together.'
In fact, the rotation is so fast that at its equator, 1950 DA effectively
experiences negative gravity.
If an astronaut were to attempt to stand on this surface, they would
would be flung off into space.
The presence of cohesive forces has been predicted in small asteroids,
but definitive evidence has never been seen before.
The findings, published in this week's edition of the science journal
Nature, have potential implications for defending our planet from a
massive asteroid impact.
'Following the February 2013 asteroid impact in Chelyabinsk, Russia,
there is renewed interest in figuring out how to deal with the potential
hazard of an asteroid impact,' said Professor Rozitis.
ANIMATION: Asteroid 1950 DA's potential trajectory
A simulation of an asteroid impact tsunami developed by scientists at the
University of California, Santa Cruz, shows waves as high as 400 feet sweeping
onto the Atlantic Coast
'Understanding what holds these asteroids together can inform
strategies to guard against future impacts.'
This research reveals some techniques, such sending a massive object
on a collision course with the asteroid, could worsen the effects.
For example, this technique could get in the way of forces keeping the
asteroid together, causing it to break apart into lots of smaller,
threatening asteroids that could be on a collision course for Earth.
This may be what occurred with the asteroid P/2013 R3, which was
caught by the Hubble Space Telescope in 2013 and 2014 coming
undone, possibly due to a collision with a meteor.
'With such tenuous cohesive forces holding one of these asteroids
together, a very small impulse may result in a complete disruption,' said
Professor Rozitis.
The asteroid is travelling at about 9 miles (15km) a second relative to the
Earth.
It is due to swing so close to Earth it could slam into the Atlantic Ocean
at 38,000 miles per hour.
It is estimated that if 1950 DA were to collide with the planet, it would do
so with a force of around 44,800 megatonnes of TNT.
Although the probability of an impact is only 0.3 per cent, this represents
a risk 50 per cent greater than an impact from all other asteroids.
Over the long timescales of Earth's history, asteroids this size and larger
have periodically hammered the planet.
The so-called K/T impact, for instance, ended the age of the dinosaurs
65 million years ago.
Asteroid 1950 DA was discovered on 23 February 1950. It was observed
for 17 days and then faded from view for half a century.
Then, an object discovered on 31 December 2000 was recognised as
being the long-lost 1950 DA.
The New Year's Eve sighting was exactly 200 years to the night after the
discovery of the first asteroid, Ceres.
It was found that the asteroid 1950 DA has a trajectory that for a 20minute window on March 16, 2880, a collision cannot be entirely ruled
out.
Enlarge
This graphic shows the orbits of all the known Potentially Hazardous Asteroids
(PHAs), numbering over 1,400 as of early 2013. These are the asteroids
considered hazardous because they are fairly large (at least 460 feet or 140 meters
in size), and because they follow orbits that pass close to the Earth's orbit
VAN DER WAALS FORCES
Van der Waals forces are the attractive forces that hold molecules close
together and are fundamental for chemistry, biology and physics.
They arise due to attraction between oppositely charged areas of
substances.
The strength of Van der Waals' forces is related to the size of atoms and
molecules.So the bigger the atom or molecule the bigger the Van der
Waals' force.
However, they are among the weakest known chemical interactions, so
they are notoriously hard to study.
But scientists claim there is no cause for concern.
If it is eventually decided 1950 DA needs to be diverted, the hundreds of
years of warning could allow a method as simple as dusting the surface
of the asteroid with chalk or charcoal, or perhaps white glass beads.
This would change the asteroid's reflectivity and allow sunlight to do the
work of pushing the asteroid out of the way.
Nasa is currently tracking all 1,400 potentially hazardous asteroids so far
identified and predicting their future close approaches and impact
probabilities.
As part of this effort it is working on the development of an infrared
sensor that could improve its asteroid tracking capabilities, dubbed the
Near Earth Object Camera (NEOCam) sensor.
Once launched, the space-based telescope would be positioned at a
location about four times the distance between Earth and the moon.
From this lofty perch, NEOCam could observe the comings and goings
of near Earth objects, including PHAs, without the impediments such as
cloud cover and daylight.
The Near-Earth Object Camera (NEOCam) is a mission proposed to NASA to find
potentially hazardous asteroids. The mission will use a new sensor, called the
NEOCam chip, that has more pixels and better sensitivity than previous
generations of infrared sensors
Read more: http://www.dailymail.co.uk/sciencetech/article-2726039/Impossible-asteroid-hurtling-Earthdefying-laws-physics-experts-dont-know-stop-it.html#ixzz3DN7GXyxP
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