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Their model suggests that Tunguska-type events of around 10 megatons should occur roughly once a century and smaller 1 megaton events once every 15 years. If t
by troels 14y ago
Their model suggests that Tunguska-type events of around 10 megatons should occur roughly once a century and smaller 1 megaton events once every 15 years.
If the rate is 1/15 years on Earth, why haven't I witnessed any yet? I suspect the answer is that Earth is rather large. Mars may not be quite as big, but it's still quite implausible that our Mars visitors should happen to be at just the wrong place at the wrong time, even with a 5-times increase in risk.
- tgflynn 14y agoIt seems like if a 1 megaton impact were occurring on Earth every 15 years people would have noticed more than seems to be the case. You would expect more than one such event per century to occur on land and I think the vast majority of the Earth's land is populated, at least sparsely. Also for the past 50 years or so governments have been very interested in tracking large explosions so even such events occurring over water should have been detected and, I would think, mentioned in the media.
- Gravityloss 14y agoYes. This doesn't pass the smell test. I first suspected the article produces a garbled version of the research, but the abstract says the same too: http://arxiv.org/abs/1212.3273 http://arxiv.org/abs/1212.3273 " In particular, for energies of one megaton or larger we find near one impact every three years for Mars, an interesting and concerning result for future Mars explorations. The corresponding calculations for our planet give a probability of one impact per 15 years"
- tomrod 14y agoDoesn't pass my smell test either. I suspect perhaps there are some jiggered parameters in the model.
- debacle 14y agoPerhaps the "1 megaton" nomer is for what encounters our atmosphere, not necessarily what impacts our surface.
- troels 14y agoThat might be the case, but then it's not really something to be worried about, is it? I mean, then they're basically saying that astronauts on Mars will see shooting stars a bit more often than on Earth.
- debacle 14y agoIt is, because on Mars there isn't an atmosphere there to burn up that 1 megaton asteroid into something more innocuous.
- danielweber 14y agoJust to be clear, Mars does have an atmosphere. It's pretty thin, but it's real enough to provide protection against micrometeorites and some of the radiation. It ain't gonna stop a school-bus sized meteorite, though.
- pavel_lishin 14y agoIt is now, and communication travels quickly now, but what about in the past? Hell, we've had one in the past century (almost) - the aforementioned Tunguska event. And nobody got around to investigating it for two decades. Today it would be big news. Last century, it was a mystery. If one had landed in the middle of Africa in 1700, would the Western world even hear about it?
- vannevar 14y agoIf they're taking an average over the Earth's entire history, and the actual distribution of impacts over time is not uniform (as seems likely), that might explain the discrepancy. Though in that case it seems odd that they would use that average to predict a probability going forward.