Meteor from earth?

Was reading up on some science news. Heard about a new meteor found last year, that has organic material inside of it, unlike anything previously found. It all sounds very interesting, and plausible, but I won't read to much into it, since it isn't the first time such claims have come and gone without resulting in anything significant.

But it got me thinking.
Did the meteor that wiped out the dinosaurs, send materials from earth into space?

I imagine that it might be very easy to test if a meteor originated from earth. Not sure though. But my thought is, that if we do find meteors with organic material on 'em. Isn't it possible, that they are just chunks of our own earth, with organic material, that was hurled into space some 60 million years ago?

Just thinking out loud.

Here is a link to the article I recently read.

reply to post by Mads1987


The short answer is: Yes - It is possible for material to be blasted off of Earth at escape velocity (>12 km/sec) so that it goes into solar orbit, then eventually re-impact the Earth.

Here is an article about Meteorites from Other Planets. It includes a post-script about meteorites from Earth.

and thanks for the link!

reply to post by Mads1987


Great thread! S+F!

Wrote about this in several other ATS threads earlier this year. I was wondering about the same scenario.
To me, it's entirely plausible that ancient impacts could have spread earth-based life through out the solar system.

It's already been established that bacteria can survive an meteor impact.

So if earth had an impact 65 millions year ago, how far could debris have traveled now? Maybe even with some lucky gravitational boosts from Jupiter, Saturn, Uranus etc. bacteria life could have left the solar system? Al thou they would have to survive radiation, and extreme cold temperatures. But as we all know, life is more resilient than previous thought.
en.wikipedia.org...

Would love to see when they penetrate the ice on Europa, dives in, and maybe finds a slightly improved red heering, or the like Upon inspecting it's DNA, scientists will discover that we have a common ancestor?

So, if life only exists on earth, there is a chance it has spread through out our galaxy?

As FOX put it once..

Saint Exupery
reply to post by Mads1987

 

The short answer is: Yes - It is possible for material to be blasted off of Earth at escape velocity (>12 km/sec) so that it goes into solar orbit, then eventually re-impact the Earth.

Here is an article about Meteorites from Other Planets. It includes a post-script about meteorites from Earth.

and thanks for the link!

That's the figure cited for "escape velocity", (or a hair less than that perhaps), which would be valid if the Earth had no atmosphere.

Because the Earth has an atmosphere, approximately 100 times more dense than that of Mars, it's far easier to knock chunks of rock off of Mars, than Earth.

I've never seen a rigorous calculation of the escape velocity from Earth taking the atmosphere into account. This would depend on things like the size, shape, mass, density and composition of the object. I wouldn't be surprised if objects the size of the martian meteorites we found would burn up in the atmosphere even if they were ejected at initially sufficient velocity to escape Earth, but they would have little problem with the 100 times thinner Martian atmosphere. Here's a calculation which I haven't confirmed that says a spherical object basically can't reach any sub-light-speed escape velocity after taking atmospheric drag into account, and a bullet would likely vaporize.

physics.stackexchange.com...

For the lower atmosphere, where most of the air is, the temp, pressure, and density of air is given by:

$T=T_0-Lh$

$p=p_0left(frac[T][T_0]right)^[frac[gM][RL]]$

$rho = frac[pM][RT] $

using the following constants:

sea level standard atmospheric pressure p0 = 101325 Pa

sea level standard temperature T0 = 288.15 K

Earth-surface gravitational acceleration g = 9.80665 m/s2.

temperature lapse rate L = 0.0065 K/m

universal gas constant R = 8.31447 J/(mol·K)

molar mass of dry air M = 0.0289644 kg/mol

The force due to air resistance can be written:

$F = -rho v^2 C_d A$

where $C_d$ is the coefficient of drag, $v$ is the velocity, and $A$ is the surface area of the projectile. The goal is to get out of the atmosphere (where force of gravity is roughly constant) with the Earth's escape velocity, $11.2$ km/s. For a bullet-shaped 1-kg projectile of steel, $C_d approx 0.04$ and $A approx 4times 10^[-4]$ m$^2$. This leads to a initial velocity of $13.5$ km/s. While not much higher than the vacuum value, it is still high enough that the bullet would probably vaporize in the atmosphere.

Interestingly, if one used a sphere instead of a bullet, then $C_d=0.4$, $A=4times 10^[-3]$ m$^2$, the air resistance is 100 times higher, and thus a much greater velocity is needed. But since the drag scales like $v^2$, this leads to much higher drag. So much so, that even if one could launch the ball at the speed of light (Newtonians only, please!), it still could not make it out of the atmosphere!

It would take a really large impact and after ejecting a really large object, much of which would burn up, there could be some left which escaped Earth, I would guess (the theory about the creation of the moon is one example but that took an impact of an object roughly the size of Mars) but I haven't done the math myself. The impact that killed the dinosaurs might be large enough.

If we found any such meteorites that returned to Earth, I suspect we might be able to identify them as having an earthly origin. I haven't heard of any such meteorites being found and apparently the meteorite mentioned in the OP story is not believed to be from Earth either.

reply to post by Arbitrageur


A few of things to point out:

1) The air pressure at sea level is at 101.325 kPa. However, as we rise in altitude that pressure drops.....dramatically. Go up 10 km and the pressure drops to 24.28 kPa. At 20km the pressure has dropped to only 5.8 kPa. At 30km to only 1.3 kPa.

2) Velocity of the rock ejected from a massive impact will depend upon the energy imparted to it from the impact event. We know that that escape velocity for Earth (not taking into account the air drag as you mentioned) is about 12km per second. Assuming a vertical path for the rock, the first second of flight it will be at 12km, where the air pressure has already dropped from 101.325 kPa to only 18.24 kPa. I do not see where this is taken into account in what you presented.

3) Density and size of the ejecta: Obviously the larger and more dense the object, the more energy needed to impart that escape velocity. However, it is not very hard to believe that a 7km wide object hitting the earth (ala KT event) would not be able to get some super sized boulders into space, the size of houses or even bigger.

The problem with 101.325 kPa keeping an object from reaching space and escaping is Time vs. Size vs. Velocity. While you are right that at sea level the drag is great, within only 1 second, the air pressure has dropped to 6 times less than that, and only 2 seconds later, the air pressure is now over 30 times less than that.

eriktheawful
reply to post by Arbitrageur

 

A few of things to point out:

1) The air pressure at sea level is at 101.325 kPa. However, as we rise in altitude that pressure drops.....dramatically. Go up 10 km and the pressure drops to 24.28 kPa. At 20km the pressure has dropped to only 5.8 kPa. At 30km to only 1.3 kPa.

Right. That's why I said "I've never seen a rigorous calculation of the escape velocity from Earth taking the atmosphere into account."

The implication of course being that I didn't think the calculations I attached were rigorous, and didn't include factors like those you mentioned, and other factors you didn't mention. I also didn't think the source cited by Saint Exupery was very reliable.

2) Velocity of the rock ejected from a massive impact will depend upon the energy imparted to it from the impact event. We know that that escape velocity for Earth (not taking into account the air drag as you mentioned) is about 12km per second. Assuming a vertical path for the rock, the first second of flight it will be at 12km, where the air pressure has already dropped from 101.325 kPa to only 18.24 kPa. I do not see where this is taken into account in what you presented.

3) Density and size of the ejecta: Obviously the larger and more dense the object, the more energy needed to impart that escape velocity. However, it is not very hard to believe that a 7km wide object hitting the earth (ala KT event) would not be able to get some super sized boulders into space, the size of houses or even bigger.

I saw a video where scientists tried to re-create impacts using high speed projectiles into the ground, in a lab. I don't recall seeing anything ejected vertically, in those test videos, regardless of the angle of impact.

We've seen boulders the size of houses enter the Earth's atmosphere and explode at altitudes even where the atmosphere is much thinner at higher altitudes you mention. Take the bolide that exploded 23.3km above Chelyabinsk in February, for example...that was roughly the size of a house right? So if that didn't even survive the thinner part of the atmosphere, I don't think it's a foregone conclusion it would survive the thicker part of the atmosphere near the Earth's surface. Maybe some small pieces of an object that size could escape.