Ballistic Trajectories of Tektites
I've been thinking about this for a while, but struggling with the calculations. I am a geologist and not a physicist. I was on the right track, but not perfect and I knew there were problems. Then today I found this neat piece of software that appears to do exactly what I want. I found it whilst complaining to my wife that somebody must have published a program like this! She wasn't really interested...
Anyway the software is Orbit 1.2 and is shareware - free for a month with some limitations. The good news though is that it only costs US$20 plus tax to buy! I recommend it - even just to play around with! (doesn't work on Windows 7 btw).
The results you see below represent a days work (well I got up at midday and went to the shops to see if I could buy more plastic containers for my tektites - still sold out, so a casual days work). They are really a first pass and I want to review some of the papers thoroughly, rather than briefly looking through them and using what is in my memory. Basically when you play around, then the constraints for the tektite velocities and trajectories are rather limited. The velocities are slightly slower than I had imagined but appear to be in good agreement with some of the papers.
As we all know the Australasian impact was a very oblique impact - but how oblique? Did the australites come in 20 degrees, 10 degrees of less than 10 degrees? The big issue for me is the ejection angle. Basically australites must have formed in space. There is slight evidence of external drag from internal flow patterns in australites (Melnik, 1991) and the fact that almost every australite is oriented also suggests very minor distortion early on, but basically the sphericity of australites and lack of disc shapes (as in indochinites) is highly indicative/conclusive of formation in 'space'. A higher angle is favored on exit to form in space, but on re-entry the angle looks to be very oblique (perhaps below 10 degrees). Maybe we need to review the exit mechanism and whether disruption of the tektite melt could have occurred after 1,500 km or nearly 4 minutes? I think this model is over simplified and that tektite melts were probably ejected at very high velocities, possibly very low angles, and were slowed by the atmosphere to the region of 6.5 to 7 km/s by the time they reached 'space' at c. 120 km altitude.
Anyway, see below what I have been up to today and download the software and play around - it's very revealing.
I welcome any comments of suggestions. Like I have said, this is not really my area, but is something that greatly interests me. You can email me at aubrey 'at' tektites.co.uk