Not before launch, during launch.
The structure of the payload bay (and the other Orbiter compartments except for the crew compartment) was not strong enough to withstand either crush loads from a vacuum in the bay / atmosphere outside situation, or burst loads from a atmosphere inside / vacuum outside situation. Accordingly, the bay and other volumes were ...
"Is that really all that holds it together?"
There are several different attach mechanisms used to hold the various parts of the ISS together. The mechanism used depends on what kind of component is being used (pressurized, unpressurized) and who built it (US, Russia, Japan).
The US pressurized modules are held to each other by Common Berthing
The ISS is pressurized to nominally Earth sea-level atmospheric pressure - about 1013hPa (14.7 pounds per square inch). Docking rings look to be about 2.2 meters in diameter, so appear to have a cross-sectional area of about 3.8m² (5880 square inches). That means each docking ring (assuming they are all that size) is constantly under about 385 kN (86,500 lbs)...
The long boom holding the panels can be retracted (the term used instead of "folding").
It is not done lightly, for fear of not being able to reverse it. It has only been done a few times, once when a truss (the P6 truss) was relocated, and once to work out an issue. During the extension of the boom during the relocation task, the panels tore, ...
According to The Logic of Microspace: Technology and Management of Minimum-Cost Space Missions by Rick Fleeter (Microcosm & Kluwer, 2000), p.130, the de-facto standard mechanism for separating spacecraft from launch vehicles is the Marman ring.
The spacecraft and launch vehicle each have a truncated cone structure, the wide side of each fitted against ...
tl;dr - each bay of the mast collapses as it is pulled into the cylinder.
The ISS solar array mast is a truly ingenious mechanical structure which can be retracted into a remarkably small canister. It was developed by ATK and is called a Folding Articulated Square Truss (FAST) mast.
This picture shows a FAST mast without arrays.
The mast is composed of ...
There is an "intermodule umbilical" that is "shed" at module separation.
In preparation for the split of the modules, external cable lines
connecting the three main sections of the spacecraft and the six
petals of the thermal protection layers on the Descent Module, SA, are
shed. The Habitation Module is then depressurized, while the ...
That's the "probe and drogue". The complicated thing is the probe, the conical thing is the drogue.
The docking between the Apollo command and lunar modules employed the
use of a "probe and drogue" system. The probe was mounted in the
docking tunnel of the command module, while the conical drogue was
mounted in the docking tunnel of the lunar module....
The only hold-downs are the eight SRB bolts.
This leads to the "Shuttle twang" when the main engines start. They're pushing to one side of the SRB hold downs, so they bend the stack just a bit. From "Space Shuttle Twang" by Tom Irvine in the Vibration Data newsletter (2010):
The orbiter’s SSMEs are offset from the vehicle stack’s center of gravity.
After docking both the probe and the drogue were removed, extracted from the tunnel and stored somewhere. Here is the transcript from Apollo 11. Some excerpts:
055:19:49 Duke: Apollo 11, Houston. It's a pretty good show here. It looks like you almost got the probe out.
055:19:54 Collins: Yeah, it's loose now.
055:22:14 Duke: We can see the probe now. ...
This paper surveys a large number of umbilical designs.
For the mechanical connections to the vehicle, it lists two types of detachable locking devices.
The type of locking mechanism used in this application
is shown in Figure 16. This system is a simple ball and
socket type of locking device where a sleeve captures ...
The Saturn holddown arms were released pneumatically with a pyrotechnic backup.
Source and Source
Please refer to What holds the Space Shuttle orbiter itself stable on the launch pad? for details on the hold-down mechanism.
In regards to the reliability of explosive bolts, see Reliability of explosive bolts and redundant initiators
1) "And also was there ...
The Space Station Remote Manipulator System (SSRMS) is a seven-jointed teleoperated manipulator used on the International Space Station (ISS). Each end of the manipulator is composed of a Latching End Effector (LEE) which serves a dual purpose: to grapple payloads, and to mount the manipulator on the ISS.
The LEE can only attach ("grapple") to specially ...
Their name seems to be "Motorized Bolt Assembly", this is what they look like:
The servo is in the rectangular box marked BMA, the bolt extends through the fine guide cone.
More about the BMA (PDF page 89-102):
The Moog Space Station Bolt Motor Actuator (BMA) is a rotary actuator comprised of a brushless DC motor, controller, and 120V DC-DC power ...
Prior to ASTP, both Apollo and Soyuz spacecraft used a probe-and-drogue docking system, which requires different hardware at each end of the docking interface. This means that if you want two spacecraft to dock with the same space station, for example, the spacecraft can't dock with each other.
In order to support ship-to-ship docking, therefore, an all-...
It's the soil sampling arm and scoop.
This Surveyor mission was the first one that carried a surface-soil
sampling-scoop, which can be seen on its extendable arm in the
pictures. This mechanism was mounted on an electric-motor-driven arm
and was used to dig four trenches in the lunar soil. These trenches
were up to seven inches (18 centimeters) ...
This page describes in some detail the design of the holddown mechanism:
It doesn't say how they were tested but it says they were built by Space Corp. and where tested in Huntsville, with the final test being on May 25, 1965 and tested to make sure it could hold the thrust of 725,747 kilograms....
From CSM06 Command Module Overview page 49 and 50:
For most of an Apollo mission, the command and service modules are
attached; they separate only a short time before the command module
enters the atmosphere.
The two modules are connected by three tension ties which extend from
the CM's aft heat shield to six compression ...
The major claimed advantage of the APAS was that it can be applied to more massive vehicles because it incorporates a damping system. Buran was going to be much more massive than Soyuz.
Source: United We Orbit
Prior to launch the Orbiter was mounted on the External Tank and the External Tank was mounted to the Solid Rocket Boosters. The entire assemblage was referred to as "the stack".
The entire weight of the stack was supported by four posts at the bottom of each Solid Rocket Booster (eight total). The boosters were attached to the posts by large bolts (aka "...
They do this by moving a "torquer" in their interior, which rests atop
a disk-shaped turntable.
"By rotating the torquer, a reaction force against the asteroid
surface makes the rover hop with a significant horizontal velocity," a
team of researchers led by JAXA's Tetsuo Yoshimitsu wrote in a 2012
study outlining the concept. "After hopp[ing] ...
MINERVA-II consisted of three rovers: MINERVA-II1, a pair of rovers developed by JAXA, and MINERVA-II2, a single rover developed by a consortium of Japanese universities. MINERVA-II1 and MINERVA-II2 used completely different mechanisms for hopping. The only real details I could find about either mechanism are in Japanese; in the rest of my answer, I include ...
Most of the time Remove Before Flight mechanisms disconnect the batteries from everything else. The system might still obtain some power though the solar panels, or via an external connector (Still on the ground), but will not be able to power themselves via the batteries. The ones that I have seen are purely mechanical in nature.
Another mechanism used on some Shuttle payloads was the "Super*Zip" system, which was a metal band encircled by a pyrotechnic cord or cords. The design intent was that the firing of the pyrotechnic device would split the band, freeing the payload.
Source NASA TM 4031 Investigation of Super*Zip Separation Joint
The system became infamous on shuttle mission ...
This question has been intriguing me for a long time and I can't find a definite answer. So far, from what I've found, the answer is "no".
For the most powerful launchers, I found the following information:
SpaceX uses only hold down clamps
Ariane 5 is free-standing
Proton uses only hold down clamps
From one of the references in this answer I ...