[FPSPACE] How does your Atlas crumple?

[DwayneDay]

A package full of copies of the September Spaceflight went _ka-thunk_ against my door yesterday and I thought I'd mention one of the articles inside.

Joel Powell (who I do not think reads FPSpace) has an article in there on Atlas ICBM and rocket ground accidents.  This might seem a little arcane to most of you, but Joel has done some clever and useful research on this subject.

As everyone knows, the Atlas "balloon tank" was famous for gaining its structural strength from internal pressurization.  It is like a sealed soda can--stand on it and it will support your weight, but stick a nail in its side and stand on it and it will crumple (and soak your foot in sodapop--Kids!  Do not try this at home!).

Anyway, the Atlas could not be loaded with any payload unless it was pressurized (I think that it did not _always_ have to be pressurized, but if it was standing upright or had any payload, it had to be pressurized).  Naturally things went wrong from time to time.  On one occasion some not-very-smart USAF man (not clear if it was an officer or enlisted) raised Atlas 78D into the closed roof of an above-ground shelter, which collapsed the thin skin at mid-fuselage.

Mr. Powell gets kudos for a good bit of historical research.  He was able to identify the collapsing Atlas-Agena D at Vandenberg that appears in several videos.  According to Joel, Vandenberg Air Force Base Public Affairs released a commemorative videotape in 1989 that showed this vehicle collapsing.  He said that this was re-released by the NRO in 1993.  The video appears in the very good 1996 Discovery Channel documentaries "Spies Above" and "Secret Satellite."  And I also have it on the excellent DVD "Nukes in Space."  

A caveat here before I proceed:  the images that Joel has of this collapsing vehicle do not appear to be the same as the one in the latter three documentaries that I cited.  I am not sure if there are two different camera angles of this vehicle collapsing, or if the screencaps that he has are simply reversed, but I strongly suspect the former.  If so, then this other video, which he did not use, provides better images of the accident.  But that's a minor quibble that I'll have to look into.

This accident was interesting to us space buffs because it is quite clearly a KH-7 reconnaissance satellite vehicle that is on the pad.  The distinctive Satellite Recovery Vehicle (SRV) is visible at the nose, and it hits the ground pretty hard.  Those of us who saw this video years ago thought that we were witnessing a reconnaissance satellite meeting its doom before ever getting off the ground.  (Needless to say, you cannot drop a complex optical instrument a hundred feet onto concrete and expect it to survive.)  But the problem is that the flight numbers for these vehicles--both the actual KH-7 missions and the Agena upper stages--are known and there are no discrepancies.  That raised interesting but unsatisfying possibilities. 

Joel has finally identified the date of the accident as 11 May 1963, which was before the first actual launch of a KH-7 and apparently before the first _scheduled_ launch of the first KH-7.  He has the details of how it happened.  Unfortunately, the payload still remains somewhat of a mystery, but several of us who follow this stuff have tentatively concluded that it was most probably a ground test article.  It might have an actual Atlas (number 190D), but a dummy Agena and payload intended for pad integration tests.  Presumably they put it out there to test some things and then were planning on hauling it back down.  But a bubble developed in the propellant fill and drain system and this created a hydraulic ram effect that dislodged the connection on the vehicle side.  The pad crew managed to drain all of the LOX and the gaseous nitrogen and helium in the vehicle, but without internal pressure, it collapsed.  They undoubtedly knew that this was going to happen and that's why they turned the camera (or possibly cameras) on.

The first KH-7 launch took place atop Atlas 201D on 12 July 1963.  (Technically, it was launched from what was then known as the Point Arguello Launch Complex.)  Obviously they fixed the problem at the pad before they ever wheeled that vehicle out there.

Yes, it's a minor footnote in the annals of space history, but a nice bit of research on Mr. Powell's part.

The September issue also features articles on the June SpaceShip One flight and Cassini's arrival at Saturn.



DDAY