51-L SRB Chamber-Pressure Cover-Up
The Report of the Presidential Commission on the Space Shuttle
Challenger Accident states in its Executive Summary,
under The Cause of the Accident: "Shortly after lift off, the
STS 51-L right Solid Rocket Motor
chamber pressure was 22 pounds per square inch higher than that
of the left solid. This would correlate to a postulated radial
crack through the grain spanning a 90-degree, pie-shaped wedge
of the solid. However, with a crack of this nature, the chamber
pressure would have remained high for approximately 60 seconds.
Telemetry shows that the right Solid Rocket Motor chamber
pressure did not remain high past 20-24 seconds and, therefore,
the existence of a propellant crack was ruled out."
Nevertheless, Mission Control's Ascent Flight Director made no mention
of this 22 psi differential in SRB Pc when he reported to the nation on
launch day that he had been aware of nothing out of the ordinary.
The follow-up report below relates that on no previous mission with SRBs
such as those flown on the fatal launch had a differential greater than
4 to 9 psi been observed.
To make matters even worse, the chamber-pressure plot attached to the
follow-up report (for Challenger Mission 51-L) confirms a cover-up in
Mission Control that the Rogers Commission never exposed. The plot
(below) does not show the right SRB having chamber pressure 22 psi
higher at lift-off!
Furthermore, notice that the ignition interval is incomplete (among others). Plotted chamber pressure does not begin at t=0, as it should.
It is thus impossible for an engineer to determine whether the chamber pressures
uniformly reached their maximum operating range within one-half second, as expected.
In light of my prelaunch warnings to the Senate about massive leaks of cryogenic hydrogen at the base of the left
booster, these discrepancies become more than glaring. They constitute a basis for
an investigation by a Joint Committee of Congress!
[The portions of the report reproduced below have been released by NASA's
Johnson Space Center under the Freedom of Information Act.]
Copyright 2003-2005 by John Thomas Maxson. All rights reserved.
STS 51-L
FLIGHT OPERATIONS TEAM
SUMMARY REPORT
February 18, 1986
Approved by:
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