They're called Power Fists.
To expand on this, if you are using Terminators to capture someone, I expect simply pointing a large bore cannon or two at them might work well.
Alternitively, the Termies can use auxiliary grenade launchers attached to powerfists, their stormbolters theoretically can be used in this role as well. Grenade harnesses are used with terminator armour occasionally too.
gas-grenades or stun bombs aren't exactly unknown in 40k either.
Frankly, it depends on how thick a mountain you can force a teleport beam through. It's possible you might be able to teleport into somewhere you couldn't bomb, or at least, not without unacceptable collateral damage.
Teleport beam penetrative capabilities range from the "five metres" of solid material in Codex Imperialis, to an entire planet in a Ciaphas Cain novel.
I expect theres some middle ground and variables like density of matter, sensors etc.
A secure orbit that isnt there if the orbital defences you are proposing dropping right on top of exist.
Secure orbit ? These guys aren't designed to operate in a secure orbit, they are designed to drop into the teeth of opposing defensive forces, kick the shit out them, then leave the cleaning up to the Imperial Guard.
This is the Imperium of Man. Novel tactics like teleporting bombs is heresy. Razz
No it isn't, its actually a fairly viable tactic, they do it quite often, they just send a team along with the bomb to make sure it goes off in the right place most of the time.
Teleportation isn't exactly a smooth ride either.
Terminators are not really known for their intel gathering skills. If you want people or equipment intact in the facility you could just use a biological or chemical weapon.
You can wibble about all the alternative methods for doing shit for a long time, ultimately you are still going to have situations in which these things are either impossible, don't work, or you simply can't tell whats going on well enough, and you have to put boots on the ground.
Its basically the same reason we still have infantry today, and SWAT teams, and HRT, and whatever, rather than just lobbing tear gas/nerve gas/grenades in through holes blasted in the building/target and so forth.
When it gets to the stage of using and needing tanks, why are you using the power armour? Are they really going to be that much more effective than normal troops to justify their massively incerased drop weight, size and cost?
You can argue that this possibly isn't the case, but since the Imperium has pretty much got an unthinkable amount of resources at its disposal, and is only really limited by how fast it can move said resources around, having teams of supersoldiers who can deploy really fast, operate independant of normal logistical networks and do everything plain better is actually really useful.