From Bruce M:

It turns out that the antenna was designed and built entirely by good old
Uncle Sam, and specifically by TRW:
http://www.st.northropgrumman.com/astro-aerospace/SiteFiles/docs/pdfs/marsis

What this paper drives firmly home is the danger of depending mostly on
mathematical simulations to try to describe the behavior of real-world
substances. Since that problem has bedeviled engineers for most of the past
century (or two), one would think TRW would have recognized the risk level
of their gamble. I suspect from the description of the "hinges" (actually
just points along the fiberglass tubes where a slot-shaped cutout in one
side of the tube allows the tube to be folded at that point) that one of the
tubes simply cracked at that point, either before or during unfolding.

"The tube elements were tested to demonstrate... hinge actuation
reliability. Multiple operations of sample hinges were made under all
temperature extremes, including in liquid nitrogen. The tests did
demonstrate some problems with the initial cutout configuration. Design
modifications were made, arriving at the shape shown in the figures...

"Conclusions: This program required new methods to be developed to validate
the design and to assure performance of flight hardware. A combination of
[computer] analysis and [limited] component test was utilized to accomplish
this goal."

Put not your trust entirely in numbers. Particularly to simulate mechanical
operations, and particularly in space.