Ancient impact and atmospherics

Hello all. I'm new to theses groups and I came up with something totally out of left field. I was reading a book by Rhodes about the making of the H-bomb. Teller was quoted as saying that the bomb could be made with unlimited yield, but 100MT was the upper limit as far as destruction. He said that you could make a 100MT bomb or a 1000MT bomb, the 100MT would punch a 25 mile hole in the atmosphere, the 1000MT would punch the same hole but send that same chunk of atmosphere into space with ever greater velocity. OK...

For some reason I thought of the impact event (crater centered near Yucatan Peninsula) that is correlated to the end of the dinosaurs and the KT kayer. I have read that the energy of the impact was equivalent to thousands of MT and sent enough earth into LEO that it rained down and formed the famous KT layer all over the earth. (I wonder if the debris made any visible rings in orbit?) I have read about the shock, the firestorms, and something like a yr long nuclear winter. That's all fascinating and ok with me.

I was wondering how much of the atmosphere could have been lost to space? Could it have been a significant percentage (one to five percent, maybe)? What would the average sea level barometric pressure have been before the event? What about immediately after, 6 months after, and say maybe 10 yrs after? How could this have changed long-term atmospheric patterns? Could it have significantly changed the mixture of gases in the atmosphere, like O2, CO2, and nitrous and sulphur compounds?

I know that the impact and immediate aftermath had to have been severe on the ecosystem, but if any of the things I asked about happened then what chronic effects would it have had on the life that survived the acute trauma? Could this have had just as significant evolutionary impact as the short term effects of the event?

Maybe all of this has been considered before, but I'm just a layman and was curious. Thanks for any input.

Impacts like this are likely the reason Mars has so little air now.

But the Earth has more gravity. The situation of the Earch is different.

An asteroid would have blown some air into space, but comet impacts would contribute much more water (oxygen, hydrogen) and other materials than they would take away., due to Earth's higher gravity. Asteroids have little gassy matter, comets have a lot.

Some scientists think comet impacts may have contributed a lot of the water in the Earth's oceans today.

Thanks Chris. I was thinking that the impact at the KT that coincided with the demise of the dinosaurs had been attributed to an asteroid. I know that over time comets can provide a lot of water and organics, but I was thinking of the time following the KT impact (I think it is called something like the Chixulub crater, but I've been trying to avoid spelling it). I know that it wasn't anything that ripped a huge amount (like half or something) of atmosphere from the planet, but if the earth lost a significant amount that could have lowered sea level pressure to something equivalent to say, like what it is at 8000 feet today then could that have been a factor for the life that survived the impact and influenced the evolution of small mammals and certain kinds of plants? I'm also not sure how even a fraction lower pressure translates into overall global weather changes. From the record it seems that the atmosphere had been relatively warm, humid, and stable for a fairly long time before the event. I wonder what kind of radical swings the atmosphere (and with it the surviving life forms) took and for how many thousands of years before some kind of new equilibrium was established.

Well, I'm just doing a good 'hmmmmmmm' experiment. It would be a lot easier for me to accept that the dinosaurs and other species were just wiped out in a few years from the immediate effects of the impact. ......I always have to make things hard.

The generally accepted view is that the erosion of Mars's atmosphere is due to the solar wind tearing parts of it away - unlike Earth, Mars has no magnetic field to shield it from the effects of the solar wind. On Earth, tectonic activity is the main force which causes new material to enter the atmosphere, which it does through volcanism. Mars's atmosphere is as thin as it is because it's volcanoes are extinct.

Philip Bowles

Snippage. . . . .

As was mentioned it depends GREATLY on what it is that hit us at KT. If it was a comet, you would probably do well to assume a sincere 'thickening' of the atmosphere with additional water (vapor), methane, hydrogen, CO2 and whatever else a comet would have accrued from billions of years of floating around interplanetary space.

On impact, any material that is going to 'escape' the earth has to do so with a velocity of about 25,000 miles per hour. One ft per second less than escape velocity and the object ( or molecule, or atom) will be drawn back down into the gravity well. Solid objects might well reach that velocity in the impact results, but they would need to punch through a considerable bubble of air and debris while retaining most of that velocity in order to escape. Air molecues (or atoms) would have an even more difficult time maintaining velocity with all of the turbulence (an energy dissapator) going on in the ejecta stream.

Id dareasay that very little material was actually expelled from the earth's gravitational field by the KT impact, and the material that was expelled would be very high density high velocity solid/molten fragments of the meteor/comet itself. Anybody is welcome to correct me, but I have to suspect high sectional density just to get through the debris cloud with enough remaining Kinetic Energy.

Regards

That MIGHT be just a tad oversimplistic. Mars does have a thin atmosphere. At the same time, it does not have a veritable covering of green plants releasing a steady and amazingly huge flow of gaseous oxygen either!

Regards

Yeah, I think that is what they find in the KT layer, the biggest tag being the isotopes within the glass beads (like trinitite from Alamorgordo)

Anybody is welcome to correct me, but I have to

I see your point. That was what I was looking for. Guess I was sniffing up the wrong tree. Oh, well, on to my next deep thinking mystery! Thanks for the good answers, this is a great group!

To an extent, no doubt, but it gets the point across.

Mars does have a thin atmosphere.

The thing about photosynthesis is that it converts carbon dioxide into its constituents - it releases oxygen, but only in comparable quantities to the carbon dioxide it extracts from the atmosphere. It doesn't add to the amount of gas in the atmosphere, just changes its composition.

Philip Bowles

Snippage. . . . .

Yeah, but at the same time it keep the more 'reactive' gasses in circulation instead of locked up with the first iron or calcium atom encountered! I seem to remember reading somewhere a while back that at least ONE theory was that perhaps as much as 1/2 of the oxygen that mars may have 'inherited' ended up locked up on the surface minerals (and the other half was 'boiled' out of the atmosphere by the solar radiation). The weak spot was that even with the 'light' Mars gravity, there is is not quite enough solar radiation at that distance to 'do the deed'! Maybe with the recent discovers of large water (ice) reserves, some more of that oxygen allotment can be accounted for. AND in the case of plants, how much of the O2 respired comes out of CO2 and how much out of the water?

B the way, Unless Im mistaken, C02 is a heavier molecule than O2 and would require a heavier irradiation to drive it out of ANY gravity field?? but thats a side question!

Regards

Thought that a considerable amount of volcanic vapour is recycled water from molten marine sediments?

Cheers, Christof

Snippage. . . . . .

For that matter, how come we have such a high percentage of nitrogen and even the gas giants (from who's gravity well very few things excape!) dont have all that much N2? Could it possibly be that the earth's N2 just comes from the breakdown of compounds (like ammonia, NH3) that were never 'fractionated' in the outer solar system.

Perhaps without the 'biological recycling' on Mars, nitrogen would gradually become 'fixed' in the form of solid nitrates and such.

Regards