Today's word is ... "frangible"

Frangible items are designed to break into fragments, rather than deforming and remaining a single piece.

The space program makes wide use of frangible nuts and bolts as connectors that hold items together until an exact moment when they have to be separated quickly. This quick separation is accomplished with an explosive charge, referred to as a "pyro" (for pyrotechnic device) or an NSD ("NASA Standard Detonator"). The astronaut (or the computer system) throws a switch to activate a certain sequence; the pyro blows and the frangible nuts and bolts that held the item together shatter, allowing the items to separate.

Examples of this in action would be separating the spent solid rocket boosters from the Space Shuttle, releasing a satellite from the Shuttle's payload bay, or even deploying the spring-loaded solar panels on the MER Mars rovers. The frangible nuts and bolts in the picture above are from the Space Shuttle program.

In my mind, the most famous film depiction of pyros was in 2001: A Space Odyssey, when the explosive bolts were used to blow off the EVA pod's door so that Dave Bowman could quickly enter the emergency airlock.

Gemini VI and VII rendezvous

Gemini VI, commanded by Wally Schirra with Tom Stafford flying as Pilot, was launched on December 15, 1966. In what was perhaps the most significant "space first" of the US to that date, it was the first time two piloted vehicles had successfully rendezvoused in orbit.

The mission of Gemini VI changed substantially from its initial concept. Originally, Gemini VI was to have docked with an Agena target vehicle in October 1966. However, the Agena failed during launch and never reached orbit. The Gemini VI vehicle lacked the fuel cells needed for a long-duration space flight like Gemini VII, but NASA worked out a quick mission that would demonstrate rendezvous capability.

I remember the excitement of seeing the photos from the mission, which quickly became available just after Gemini VI landed the next day. There was no TV from spacecraft at that point, so we couldn't see the event as it happened, and we had to settle for still photos in the newspapers and magazines. It was so cool to see a photo of an actual capsule in orbit. It was the first time the general public had ever seen something like that...our views of spaceflight up to that point had only been launch, recovery, and pictures taken out the window. Now, we got to see the full Gemini spacecraft, with its contrasting black capsule and white adapter sections, and the surprise of the gold foil tendrils snaking out the back of the ship.

These two items from my collection are an access badge to the Gemini VI spacecraft, from the collection of a former ground crew worker at KSC, and a small fragment of the heat shield from Gemini VI.