Apophis not going to hit Earth in 2036

Odds of impact have been way downgraded to 1 in 250,000.
http://news.bbc.co.uk/2/hi/science/nature/8296796.stm

Pat

Pat Flannery wrote:
Odds of impact have been way downgraded to 1 in 250,000.
http://news.bbc.co.uk/2/hi/science/nature/8296796.stm

Pat

"Another pass in 2068 has a three-in-a-million chance of striking Earth,
but the researchers say that as the measurements are more completely
refined, the chances of that collision will drop further."

If you know that the odds will reduce, then you know that the odds are
lower than you say they are now.

It's a shame really. Not that apophis was a high enough risk before, but
a real threat would provide a good reason for developing some space
hardware.

Sylvia.

On Oct 10, 8:49�am, Sylvia Else wrote:
Pat Flannery wrote:
Odds of impact have been way downgraded to 1 in 250,000.
http://news.bbc.co.uk/2/hi/science/nature/8296796.stm

Pat

"Another pass in 2068 has a three-in-a-million chance of striking Earth,
but the researchers say that as the measurements are more completely
refined, the chances of that collision will drop further."

If you know that the odds will reduce, then you know that the odds are
lower than you say they are now.

It's a shame really. Not that apophis was a high enough risk before, but
a real threat would provide a good reason for developing some space
hardware.

Sylvia.

I wonder if theres a threat around december 21, 2012?

J0nathan wrote:
"Sylvia Else" wrote in message
...
Pat Flannery wrote:
Odds of impact have been way downgraded to 1 in 250,000.
http://news.bbc.co.uk/2/hi/science/nature/8296796.stm

Pat
"Another pass in 2068 has a three-in-a-million chance of striking Earth, but
the researchers say that as the measurements are more completely refined, the
chances of that collision will drop further."

If you know that the odds will reduce, then you know that the odds are lower
than you say they are now.

It's a shame really. Not that apophis was a high enough risk before, but a
real threat would provide a good reason for developing some space hardware.


Oh to live in the false security of your linear (predictable) world.

We live in a non-linear (unpredictable) world. Where nothing ever repeats
twice, and the precise future cannot be predicted.

The first close approach is a critical point, so close that the smallest
error extrapolates into huge uncertainties from that point on.
What if during that first approach to Earth's gravity it should start
tumbling, or break up like Comet Shoemaker-Levey did?

What about these other uncertainties of the real-live-world that
can unpredictably change over time, especially after the first
passage?

....The spin of the asteroid,
.... Its mass
.....The way it reflects and absorbs sun-light, radiates heat
.....The gravitational pull of other asteroids passing nearby.
.....Earth's non-uniform gravity field during encounters
.....Solar energy can cause between 20 and 740 km of position change
over the next 22 years
......7 years later, the effect on Apophis' predicted position can grow
to between 520,000 and 30 million km
......Small uncertainties in the masses and positions of the planets and Sun
can cause up to 23 Earth radii of prediction error for Apophis by
2036
......The standard model of the Earth as a point mass can introduce up to 2.9
Earth radii of prediction error by 2036
...... The Earth's oblateness must be considered to predict an impact.
.......Apophis probably too close to the Sun to be measured by optical
telescopes until 2011, and too distant for useful radar
measurement until 2013.


These are all factors that are already taken into account when assessing
the possible paths that asteroids take. BTW, you left out the effect of
the moons of Jupiter.

I think you'll find that Aphophis has to pass through a narrow window on
its first pass if it's to get near Earth on its second pass. The fact
that it has to get through that narrow window imposes limits on the
values that the influencing factors can have. If they're outside those
limits, then Apophis misses the first window, and is no longer a problem
for the forseeable future.

Sylvia.

"Sylvia Else" wrote in message
...
J0nathan wrote:
"Sylvia Else" wrote in message
...

These are all factors that are already taken into account when assessing the
possible paths that asteroids take. BTW, you left out the effect of the moons
of Jupiter.

I think you'll find that Aphophis has to pass through a narrow window on its
first pass if it's to get near Earth on its second pass. The fact that it has
to get through that narrow window imposes limits on the values that the
influencing factors can have. If they're outside those limits, then Apophis
misses the first window, and is no longer a problem for the foreseeable
future.


But the point is the first passage can change the asteroid, it's spin
mass etc, changing the window and future path. The second pass
isn't predictable yet imo due to events that have not yet happened.
Although I understand all that makes a second impact less likely.
It's still unpredictable I think, which is my point. The first pass is
a critical interaction, deterministic methods can't predict through
criticality. Just as a cloud is a critically interacting system, you
can't predict it's future shape...exactly. At the first passage, the two
are close enough to critically interact, where maybe the asteroid
is altered by the close approach.


Nonlinear Science - Chaos Tamed

"This phenomena is known as sensitivity to initial conditions, or the
Butterfly Effect. It arises because the errors that accumulate from
each collision do not simply add (as linear analyses assume), but
increase exponentially and this geometric progression rapidly diverges
any initial state to one that is unpredictably far from the estimate."
http://www.calresco.org/nonlin.htm



Sylvia.

"Sylvia Else" wrote in message
...
Pat Flannery wrote:
Odds of impact have been way downgraded to 1 in 250,000.
http://news.bbc.co.uk/2/hi/science/nature/8296796.stm

Pat

"Another pass in 2068 has a three-in-a-million chance of striking Earth, but
the researchers say that as the measurements are more completely refined, the
chances of that collision will drop further."

If you know that the odds will reduce, then you know that the odds are lower
than you say they are now.

It's a shame really. Not that apophis was a high enough risk before, but a
real threat would provide a good reason for developing some space hardware.


Oh to live in the false security of your linear (predictable) world.

We live in a non-linear (unpredictable) world. Where nothing ever repeats
twice, and the precise future cannot be predicted.

The first close approach is a critical point, so close that the smallest
error extrapolates into huge uncertainties from that point on.
What if during that first approach to Earth's gravity it should start
tumbling, or break up like Comet Shoemaker-Levey did?

What about these other uncertainties of the real-live-world that
can unpredictably change over time, especially after the first
passage?

.....The spin of the asteroid,
..... Its mass
......The way it reflects and absorbs sun-light, radiates heat
......The gravitational pull of other asteroids passing nearby.
......Earth's non-uniform gravity field during encounters
......Solar energy can cause between 20 and 740 km of position change
over the next 22 years
.......7 years later, the effect on Apophis' predicted position can grow
to between 520,000 and 30 million km
.......Small uncertainties in the masses and positions of the planets and Sun
can cause up to 23 Earth radii of prediction error for Apophis by
2036
.......The standard model of the Earth as a point mass can introduce up to 2.9
Earth radii of prediction error by 2036
....... The Earth's oblateness must be considered to predict an impact.
........Apophis probably too close to the Sun to be measured by optical
telescopes until 2011, and too distant for useful radar
measurement until 2013.

Predicting Apophis' Earth Encounters in 2029 and 2036
http://neo.jpl.nasa.gov/apophis/




What if Space Solar Power ended up using laser transmission?
Could Space Solar Power double as an asteroid?




s







Sylvia.