How can I estimate the maximum mass that can be safely handled in low to no g?

Many countries, authorities and companies have the concept of a maximum weight limit for manual handling, both to protect their workers and to protect themselves from lawsuits.

Interstellar Shipping Incorporated (I.S.I.) also has such limits, but their requirements are a little more complicated. As they work on ships that may be accelerating or just floating (at anywhere between 0.5 and 0 g) the weight of the objects in question will obviously be lower.

But the mass of the thing won't, which means that it's inertia will still make it hard and potentially dangerous to handle. On Earth we forget the inertia in many cases because we're primarily focused on supporting the weight of the thing. In low to no gravity inertia is the main concern and our normal intuition about how to lift is flawed.

The commonly given example in the health and safety briefings is someone straining to pick up a crate of depleted uranium shells in low g, forgetting that they would have to arrest the forward motion of the crate, and crushing all their fingers between the crate and a doorframe when they couldn't correct it's course. The employee also caused damage to the frame of the door, for which they were fired (this may be an apocryphal tale).

So the question I.S.I. has for this site is: what guidance should be given about working in low g to avoid injuries, property damage and lawsuits caused by the disconnect between weight and inertia? Assume this is being given for a maximum of two employees (two man lift limit) and anything above that is covered by lifting machinery.

Good answers will include information on maximum safe mass for some g force between 0 and 0.5 g, necessary lifting techniques and (preferably) some description of how those numbers and techniques were arrived at.

Bonus points if the advice is generalisable to any low value of g. If it isn't please state what value your advice is for and I.S.I. will compile a suitably comprehensive and not at all overly long winded safety guide.

Note: I've tried searching for any existing guidance around manual work on the ISS, but failed to find anything of use. If you find any please feel free to use it as a starting point (and include a link so I can add more useless knowledge to my brain!)

posted over 4 years ago

Joe Bloggs‭

26 reputation 41 2 3 0