Friday, 22 August 2008

More on the USA 193 shootdown

The online Bulletin of the Atomic Scientists has published an essay by Harvard astrophysicist Yousaf Butt with a very critical view of the official reasons given for the USA 193 shootdown.

Butt filled a request through the Freedom of Information Act and obtained the report featuring the re-entry model and analysis that was used. And found it to be flawed and on closer look not quite supportive of the alledged 'danger' of the re-entry of USA 193's hydrazine fuel tank.

The report is very cautious and it's authors already note that some of the model assumptions are not realistic. Importantly, it shows that even with these assumptions maintained, much of the tank's titanium outer layer will ablate according to the model (remember how Oberg denied this in his essay?!), leaving only a very thin outer shell 1/5th or less of the original thickness. This assumes uniform ablation (which is not realistic).

Butt argues that when more realistic assumptions are made, this suggests the tank would likely have been destroyed upon reentry.

You can read the essay here, and it includes a link to the report pdf.

The essay highlights:

  • A NASA study on the survivability of USA-193's hydrazine fuel tank used an oversimplified model, leading to an overly optimistic assessment of the tank's survival.
  • But even this study showed how the tank would have burned up when reentering the atmosphere.
  • Therefore, Washington's contention that the tank would have hit the ground intact, posing a health hazard, seems questionable.
Another thing to note is that the tank was not completely filled with fuel, but 76% filled. This turns out to be of importance in assessing the fate of the tank.

(with thanks to John Locker for te 'heads up')

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