Sunprobe
The launch sequence for Thunderbird 3 is first seen in this episode; it reveals that the passenger entry to the massive ship is a couch in the main lounge.
The solarnauts' Sunprobe rocket matches the model of a rocket powered by a hybrid fuel made from water, seen in the later episode "Perils Of Penelope."
On the romance front, Alan and Tin-Tin become more obviously a couple on screen with this episode, often seen arm in arm or sitting in each other's laps.
It's been said that Thunderbird 3's design was based on the Russian Soyuz rockets, but the Soyuz was not introduced until 1967, long after the series went into production. You can find a drawing of it as the original "Rescue 3" in Brains' laboratory.
Alan is less than pleased with Brains' seemingly oblivious attitude, but, as an undercurrent, he is also developing a rivalry with the young scientist (who secretly has a crush on Tin-Tin).
The usually stern Jeff shows his affection, pride and admiration for Brains and the rest of his intrepid team throughout this episode.
The references to "Cape Kennedy" were historically correct, at the time; it returned to the name "Cape Canaveral" after the construction of the Kennedy Space Center.
"Brainman," Brains' early experiment in Artificial Intelligence, proves to be his only attempt at the emerging science during the series. (You'll often see this misspelled as "Braman" because of his pronunciation).
The heat and stress resistant metals developed by Brains in "Thunderbirds" are said to be what makes the vehicles seen in "Captain Scarlet And The Mysterons" and "Fireball XL-5" possible. Captain Scarlet's adventures take place at a later time in history than "Thunderbirds" and the storyline follows the events regarding the Mars exploration disaster as established in the movie "Thunderbirds Are Go." "Fireball XL-5" takes place in 2062, nearly 40 years after the dawn of International Rescue, according to the 2026 timeline. (The switch to the 2065 timeline throws everything off)!
Unfortunately for British retailers, none of them had anticipated the near-hysteria with which many fans greeted the return of "Thunderbirds" in 1991, hence the toy tie-ins were almost impossible to find in time for Christmas. Sylvia Anderson reported that she was accosted while shopping by a clerk who wanted to know why she couldn't find a Tracy Island playset for her child!
Jeff Tracy's space construction companies, Tracy Industries and Tracy Aerospace, built many projects for the US military, including the first permanent moon base.
The bright orange-red Thunderbird 3 is 287 feet high and is housed in a deep silo under the Round House on Tracy Island.
Though many of the strings of the marionettes are now clearly visible with the processing for video tape and DVD, they were effectively obscured for the original television broadcasts by a light coating of a powered spray which matched the coloring of the backgrounds.
The televideo pictures beamed back to Earth in "Sunprobe" would have to have been projected almost 93 million miles from the spaceship---but the view is from another vehicle far outside of the ship but just as close to the Sun...! (Go figure)!
It takes more than a week for the massive Sunprobe rocket to reach the area of the Sun's targeted prominence, yet the speed of Thunderbird 3 allows it to reach the same area in 65 hours.
The Thunderbirds revival of 1991-92 made the show such a hot item that even CNN devoted time to covering all of the excitement surrounding it, complete with footage of pub patrons acting out their favorite launch sequences from the series and happily humming the March Of The Thunderbirds for all to hear.
Though they have not, to this time, been reported as having been active in outer space, government officials assume that International Rescue can effect a rescue of Sunprobe. (This episode originally aired as No. 11 and the only space rescue the authorities would have known about didn't happen until "The Impostors," not aired until five episodes later).
This episode features the only time we get a really good look at the Asian-styled sitting room, used as the "war room" for plotting IR's rescue effort.
As often seen in the series, it is the gregarious Gordon who makes the most sensible rescue suggestion, though he doesn't take part in it.
Model mix-up: Alan and Scott are accidentally switched on the couch as their miniatures are used to show them transported to Thunderbird 3.
Alan is seen piloting Thunderbird 3 alone at the controls, though as shown in later episodes, he often takes Scott along for guidance during flights to Thunderbird 5 and as in their rescue effort in "The Impostors."
Grandma Tracy is not seen in this episode but is referred to as being there to organize clothing. Her trip to Tracy Island from California will be seen in "Move And You're Dead."
It is never revealed in the series why Kyrano owes his life to Jeff, but later comics stories tell of Kyrano and Tin-Tin having rescued Jeff after his private plane crashed near Kyrano's Malaysian plantation. To repay his friends, Jeff takes the Kyranos into his home years after the man's half-brother, The Hood, has stolen their plantation and fortune, the events which forced Kyrano to seek work in the US and France. Previous stories instead stated that Jeff and Kyrano originally met when Kyrano worked for the Space Agency creating palatable food for astronauts to use in flight.
Brains, Parker, Gordon and Kyrano are all voiced by the talented David Graham; at times during the series, he can be heard handling the dialog for two characters who are speaking to each other. (Gordon and Brains in "Operation: Crashdive" is a good example).
Like several other pieces of equipment, the XZ-157 transmitter unit becomes a single-use item during the series.
In this episode, International Rescue prove to be their own best customers. This theme continues in "The Perils Of Penelope," "The Cham Cham," "Move And You're Dead," "Brink Of Disaster," "The Uninvited" and "Alias Mr. Hackenbacker."
Pensive, angry and joyful faces abound in this episode, making good use of the multiple heads created for each of the main cast marionettes. Many of the main characters had up to seven separate heads to reflect various emotions.
Now wouldn't it have made far more sense to project the beam needed to activate the retrorockets on Sunprobe from Thunderbird 5 instead of Thunderbird 2, since the satellite is 2000 miles above the Earth? There would have been no question of interference with the signal from up there, but then, of course, John might have gotten a chance to participate in the rescue...! (Can't have THAT)!