It's no secret that last week's episode with the second part of SOS did leave more questions than answers.
Yes, it provided conclusively that Braman was not the one making the distress call from when he was aboard the Calypso or from the bottom of the Ocean off the coast of West Africa (which I have to question heavily how TB4 was able to make it there in break-neck speed when it's only a scout-craft).
But the revelation came at the end with Brains revealing that the Data aboard the Calypso and Braman provided data as to where the distress call was coming from.
Now, with this twist, it does actually make sense. If Jeff has been alive after all this time, then it wouldn't make sense for International Rescue not to find him on Earth as Jeff is not someone that goes missing that easily.
But to the next point of call, how will IR go about rescuing him if he's at the farthest reach of the deep space mission outside of the Solar System?
Thunderbird 3 is the only logical choice as it's designed for space rescues and deliveries to Thunderbird 5 and to when the Space Elevator is out of commission, as was seen in End Game when Alan was helping with repairs.
But even, TB3 has limits as I don't think Brains built her with that kind of deep space exploration in mind. She was able to reach the Sun in Slingshot and has gone to Mars twice over the last 2 seasons, but even then those are sustainable trips with regards to her fuel consumption.
Now, whether TB3's fuel tanks can be modified where she can use the fuel for longer and be able to make it back to earth, I don't know.
Not being an engineer in the air and space industry, it's not for me to say.
My theory at the moment is this, IR will contact the same outfit that produced the Zero-X, since that was clearly the space-craft that was used in the trailer/interview with Lee Majors who is taking up the iconic role as the Founder of International Rescue, and use that to go into deep space to look for their Father and home-in on his last know co-ordinates. That's the only way I can see this working.
To end with this, I will say that the writing and with the score of the way SOS Part 2 ended with Braman's monotone voice repeating Jeff's distress call of:"Is anybody out there? I'm all alone..." was chilling as this is coming from one of the most strong minded character in Thunderbirds history and he is asking for help when he is possibly the only living soul where he is.
The video to this theory is also in this video as I like to give people the option of either a text theory or a video theory.
Like I said at the end of Mission 13:"The search for Jeff Tracy, is on."
Thunderbirds Are Go | Up from the Depths Part 2 Review