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So I asked... "As an astronaut, what are the biggest challenges of in-space docking?"

From a human centered perspective, what are the things that need to be solved? Not all docking is automated. Why? To an astronaut, is human passage the most important type of docking or is it data connectors, or cargo, is it the large docking or small dockings that are the problem… As an astronaut (so, in a manned mission) is speed the biggest worry? Or is it leakage? Or is it stability once it’s docked? Or maybe all they want to do is being kept informed and ready for emergency actions if the automation goes wrong?  Basically, what are the things that go through the head of an astronaut in a manned mission before, during and after docking?

The answer:
Thank you for the question and a clear explanation from where the question is coming from. Here is my take on it:
1. Yes, it is true that docking was done manually for a long time on ISS since Apollo missions, but all of them had assistance from a lot of sensors onboard and visual guide. It was only a few years ago, when docking became fully autonomous starting with Soyuz, Northrop Grumman and SpaceX.
 2. Astronauts did and will continue to train for manual docking as that is the only mitigation plan for a successful docking when a crucial sensor/computer input fails.
 3. To understand the challenge of docking: there are actually two parts to it -> Rendezvous and docking. And they both have to work perfectly for a successful docking because the consequences can be disastrous, which I think you fully realize.
4. One more thing to remember, rendezvous and docking operations are highly dependent on altitude, spacecraft sizes and relative velocity. So, no one solution can be implemented to all the missions, but there are plenty of ‘one type’ of missions like Dragon docking to ISS, the solution is very very useful and important.[1:45 PM]
5. Now, to dig into the challenges the astronauts have to keep in mind  ( i will keep it to human missions to ISS as they are more complex than a cargo mission) a) rendezvous: relative velocity between the two spacecrafts, relative orientation, fuel/orbit/distance between spacecraft to safely abort and try again (short docking: 5-6 hours from launch or long docking: 2 days), unpredictable initial orbit altitude of the chaser (spacecraft docking to ISS), loss of communications with GS (happens 5 times for any given mission at min, AKA death orbits), loss of thruster (mitigation: side burns to miss ISS)
b) docking: lighting conditions (super critical), astronauts do not have a direct sight of the docking mechanism,  loss of radar input, wrong calculation for finer attitude corrections to align the spacecraft to dock with ISS, braking burn, failure to lock the docks (as a result, loss of pressure and damage to the docking mechanism), temperature fluctuations, communications between GS and both spacecrafts (super critical), undock and redock to another port on ISS (aka berthing), debris in the dock locking port.

Some considerations from the Challenge page:
“Your challenge is to design a mechanism to facilitate in-space assembly and docking.” Potential Considerations:
● This is a concept design/mechanism architecture challenge rather than a software challenge. How could you help build the shipyards and space hotels of tomorrow?
● What kind of mechanism will you design? Can your design roughly align and then precisely position two components relative to each other in space? Can it pull two components together, and lock them on contact? Is it possible to release the two components once connected, and if so, how? Or will your mechanism assist in-space assembly in a completely different way?

These are not requirements for this challenge, but rather ideas to get you started.