Some lines from todays question reminded me of something I may or may not have seen long ago.
I seem to recall seeing a show where it described how, one time, astronauts boots stuck to the floor of the ship. Apparently, the bottom of the boots were very smooth metal and so was the surface of the floor in the ship. When these smooth surfaces came into contact with one another, the metals bonded and the boots stuck to the floor.
Am I imagining this or is this based in fact?
Close.
But Space Boots used magnets instead.
I don’t know about “space boots”, but it is true that exquisitely machined steel blocks will adhere to each other. “Johansson blocks”.
Thanks, JWK. I searched around a bit on “Johansson blocks” (and then “gel electrophoresis”) and learned a lot!
It’s amazing how 2 surfaces can almost bond at the molecular level.
I could have sworn that happened to some astronauts. <shrug>
I believe the process is often called “cold welding.” Most of the time, it’s the undesired result when finely machined parts are left unlubricated for a while. The two useful parts become one useless part.
There was a fear for a while that astronaut boots would cold-weld to the floor of the ship, but as it turns out, there’s enough dust and such even in a spaceship to prevent it from happening. Yet another SF cliche relegated to the trash heap.
Why would this be a fear for astronauts and not truck drivers?
I’ve played with very flat machined blocks, used for calibrating numerically controlled machines, and they’re pretty cool.
Maybe you’re thinking of the movie (or book) 2001: A Space Odyssey? People in that had velcro boots that stuck to the floor, so they could walk in zero g.
CurtC and Bosda,
Nope, I’m aware of magnetic boots and 2001, but I was thinking of what JWK, Saltire and Chronos mentioned: cold (vacuum) welding.
Additional searching turned up:
http://york-me.eng.hokudai.ac.jp/spacesystem/satellite/mission.htm
http://yarchive.net/space/spacecraft/cold_welding.html - message stating that, as of 1969, Lockheed said there were no known cases of unintentional cold welding in space.
http://www.islandone.org/MMSG/aasm/AASM5I.html - describes “preventing accidental vacuum welding” for the lunar igloo in the proposal for a self-replicating automated lunar factory system.
Thanks for all the info!
Yup.
Cold welding happens not just for finely machined surfaces, but also moving parts. The contact surface will polish each other and eventually bind together. That’s why you grease screw threads. The problem is more serious in space because the vacuum tends to remove lubricants, and also because air helps prevent the two surfaces from making good contact.
It shouldn’t be a problem inside a pressurized spacecraft. At least, no more than it is on earth.
Wouldn’t magnetic boots screw up the electronic systems on any metal object the touch? Magnets seem to magnetize any metal objects they come in contact with.
I don’t think there are magnetic or velcro “space boots” in real life. Astronauts find it more convenient to just float around.
But if you want to use magnetic boots, it won’t affect electronics. You don’t need very strong magnets - the kind you can get at a hardware store is enough. Magnetic storage media and CRT displays will be affected, but those are pretty much obsolete. Well, except hard drives, but I’ve never heard of a household magnet erasing a hard drive so they must be well protected.
1.) According to the book A House in Space, Skylab used “boots” with protrusions shaped like mushrooms on the soles, not magnetic boots. These locked into a gridwork that they used as a “floor”.
2.) Although SF books (like Heinlein’s Space Cadet) and 1950s movies like Destination Moon and It! The Terror from Beyond Space showed magnetic boots being used to walk on the outsides of space ships, this probably wouldn’t work on the vehicles we’ve actually sent up – they had aluminum alloy skins, and the bottom of the Space Shuttle is covered with those infamous ceramic tiles.
3.) To tell the truth, I’ve never heard of a serious effort to use magnetic boots in the space program (not that I’m in a position to). Wouldn’t the cost of sending up all that magnetic steel be prohibitively expensive?
4.) There are examples of “magnetic welding” in SF stories. Hal Clement had an excellent short story about astronauts finding an abandoned alien starship that worked using entirely different technology from ours. Clement’s story differs from others in this genre in that he actually describes the different technology. One way it differed was in having some connections made by a sort of reversible cold-welding.
Besides which, you don’t store hard drives and CRTs in the floor. Or at least, you don’t walk on whatever surface has the CRTs and hard drives.
Obsolescence is a bit of a shaky concept in the space program, by the way. Spacecraft systems are very rarely upgraded, since it’s very difficult to thoroughly test and safeguard a system against the conditions of space (mostly cosmic rays). The astronauts will have top-of-the-line laptops with them for use in experiments, but everything mission-critical (i.e., needed for them to get up there and back safely) is run by at most 386 processors, since that’s the most advanced one made in a radiation-hardened model. Likewise displays, sotrage media, etc.: If it works, you keep it.
The US astronauts do not use magnetic boots. Internal or external. I am not able to state with 100% certainty that they never have tried them, but I have seen no indication of them in any of the literature, and for seven years I worked with NASA on spacewalk tools and equipment.
They really aren’t that good of an idea anyway. First, since there is no gravity, there is no real “up”. Admittedly the panels are often arranged in the same orientation around the walls, but the astronauts free float to get where they want, and often end up upside down with respect to each other, the walls, whatever. They use built in foot restraints, and also special Velcro-down restraints to hold their feet when they need to work at a location.
Externally, similar conditions exist. Also, they only need to restrain their feet in certain locations, and most of the time do not want their feet attaching to sidewall structure while they are trying to move. Then there are electronics boxes around that they wouldn’t want to accidentally get their feet near. I can tell you that designing for the payload bay requires you to assume the astronauts will bump your payload. If there’s a specific safety reason why they shouldn’t (say, electric shock, radiation hazard, sharp point), those areas have to clearly be called out and marked, and there is much training involved in avoiding the areas.
The astronauts use metal foot restraints. They put their foot through a toe bar and then slide their heel into a slot. The Russians use a similar system on their boots, though it is different enough that they are not cross-compatible.
The US program avoids magnets. I’m not aware of any tool that has used magnetism. The Russians do have a mounting device that uses magnets as a soft-dock. Can’t remember specifics on it now, but it is not their boots.
Cold welding should not be a problem for the boots. Most of the surfaces are anodized aluminum. This was never a concern for us.