Yes, it would be a command test to coordinate the men on the spacewalk.  Without magnetic boots or a selenite pattern void suit, a spacewalk requires a trade (voidfarer) check to successfully navigate via  void-steel grappling.  A successful check will enable you to navigate over the ship, so you can get to where you need to go.   Failing by more than two degrees of failure will cause you to fall off the ship and need rescue.  (though a simple firearm discharge will usually solve that problem)<br/><br/>Fighting in the void has two main complications; recoil, and suit punctures.  Projectile weapons will cause you to bounce around when there's no gravity, unless you take a brace weapon action before firing it.  (I won't make any particular rules concerning this, just remember that firing a gun in zero gravity will impart momentum to you)  Each hit you take in zero gravity will expose you to the effect of gradual depressurization, meaning you've only got a number of rounds equal to twice your toughness  bonus to repair the armor leak before you take damage.  Every void suit is assumed to have a sealing kit, so repearing each hole is a half action or reaction, meaning that a character can fix three holes per round if he does nothing but seal leaks.   If your suit has no leaks for a full round, the length of time you can go before taking damage resets.<br/><br/>So, having said that, you're likely to face resistance when you go up top.  For Rogue Trader Cortez, the crew can provide him a Selenite pattern void suit, though pretty much anyone else except Baromir will have to make do with a regular void suit.