Sun Probe
Season 1, Episode 11
Sun Probe 01
Original Transmission December 9 1965
Written by Alan Fennell
Directed by David Lane
Edited by Peter Elliot
Production Order
City Of Fire
The Uninvited
Broadcast Order
The Uninvited
Operation Crash-Dive

Sun Probe is the 4th produced episode and the 11th broadcast episode of the first series of Thunderbirds.


When the retrorockets on board the Sun Probe fail, the spacecraft becomes locked on a collision course with the Sun. It is up to the Tracy family to rescue the crew and Thunderbird 2 and Thunderbird 3 are launched to try to remote-fire the rocket's retros by radio beam. But when Thunderbird 3 runs into difficulties itself, will Virgil and Brains, with the unlikely help of Brains' robot, Braman, be able to save Alan, Scott and Tin-Tin from the heat?


At Cape Kennedy, Colonel Benson supervises the launch of the Sun Probe, a manned rocket which will reach solar orbit within a week and extract material from a solar prominence.

Some time later, on Tracy Island, the International Rescue team are watching a news programme charting Sun Probe’s final approach towards the Sun. Jeff is curious why Brains is not watching. The genius is in fact testing the abilities of his latest invention, an intelligent humanoid robot which he has called Braman.

On television, Professor Heinz Bodman explains that a small probe will separate itself from the manned solar module and fly through the solar flare. Inside the solar module, solarnauts Colonel Harris, Asher and Camp increase the spacecraft's refrigeration to combat the intense heat and radiation. Firing retrorockets and settling into the correct orbit, they launch the probe, which catches the flare and the vital solar matter. However, as the probe docks with the solar module, the radiation finally interferes with Sun Probe’s control systems to such an extent that the solarnauts cannot fire the retros necessary to break the craft out of a collision course with the Sun.

International Space Command have insufficient technology to remote-fire Sun Probe's retros by radio beam. On TV, Colonel Benson implores International Rescue to save the crew. Jeff calls Cape Kennedy to accept Benson's request, and later holds a meeting with the team. Realising that they can only recover the Sun Probe by successfully transmitting the appropriate radio signal, Alan and Scott advise that they should launch Thunderbird 3 to communicate it in close proximity to the craft, but Virgil argues that Thunderbird 2's radio complex is more powerful and that it would be more convenient to broadcast the signal from Earth. Jeff accepts Gordon’s suggestion that they launch both craft in a two-pronged rescue attempt.

Alan, Scott and Tin-Tin blast off in Thunderbird 3 at sunrise after the craft has been modified by Brains. In the Tracy Island computer room, Virgil plots the optimum global position from which Thunderbird 2 should transmit the signal. Having checked their equipment, and decided that they will take the mobile computer in addition to the transmitter truck inside the pod, Virgil and Brains take off in Thunderbird 2, bound for the Himalayas.

On board Sun Probe, Asher is getting anxious - only 24 hours remain before they crash into the Sun. Having reached the danger zone, Alan contacts the solarnauts from Thunderbird 3 and explains International Rescue's plan. However, their first signal transmission falls short by four hours. Alan is doubtful that Thunderbird 3 will stand up to the heat and radiation if they go much closer to the Sun.

Meanwhile, Virgil and Brains touch down during a blizzard on a flat ledge on Mount Arkan. Donning auxiliary clothing, they drive the Transmitter Truck out of Thunderbird 2's pod and proceed up the mountainside. Virgil aligns the transmission dish, but their first radio beam is too weak and Brains realises that adjustments must be made. Thunderbird 3's second beam is still two hours short. As the solarnauts grow delirious, the hull of the solar module begins to crack and the craft's refrigeration plant ceases to function, Alan, Scott and Tin-Tin, also weak, make a third desperate attempt to fire Sun Probe’s retros. When even this fails, Tin-Tin overruns the power on the safety beam and it finally penetrates. Harris, now the only solarnaut conscious, believes that the rocket is disintegrating, but then recognises the sound of the retros and joyfully wakes Asher and Camp.

With Sun Probe out of danger, Alan tries to activate Thunderbird 3's retros - but they will not work. As television newsflashes report that the International Rescue ship is now heading for the Sun itself, Gordon infers that the retros must have failed and Jeff notifies Virgil on Mount Arkan.

Brains concludes that they must switch the target of their retro-firing beam to Thunderbird 3 and he and Virgil hurry to the pod to calculate the frequency on the mobile computer. They open a storage box - to find only Braman packed in it. In the Thunderbird 3 lounge, Tin-Tin has passed out without deactivating the safety beam and Alan deduces that this must be reducing the power to the retros. Leaving Scott unconscious, Alan uses the lift to descend to the lounge but collapses himself before he can switch off the power.

Knowing that they have loaded the wrong equipment, Brains despairs until he realises that Braman could calculate the frequency. Having read out the formula, he and Virgil wait restlessly while the robot computes the answer. Rushing back to the transmitter truck, Virgil has little time to explain their plan to Jeff before they activate the signal. The beam is successful and Thunderbird 3's retros fire. As the craft turns away from the Sun, Alan regains consciousness and Virgil and Brains detect the impulses. On Tracy Island, Jeff promises a hero's welcome for Alan, Scott and Tin-Tin.


Regular CastEdit

Guest Voice CastEdit


  • Sun Probe seems to form a two-part story with The Perils of Penelope, because the Sun Probe launch is shown in both episodes (as a flashback in this episode). Because Sun Probe takes one week to reach the Sun, the events of The Perils of Penelope must occur immediately before this episode. However, the episodes were neither produced nor broadcast consecutively.
  • Extensive footage from Sun Probe is featured as a flashback in Security Hazard.
  • Sun Probe features the first appearance of Braman. He is also seen in Edge of Impact and The Cham-Cham.
  • According to Jeff, this is Tin-Tin's first mission.
  • Although Grandma Tracy does not appear in this episode, Jeff tells Virgil that she will organise auxiliary clothing for the Mount Arkan trip. This indicates that Grandma is already living Tracy Island, even though she is shown to have her own home in Move - and You're Dead.
  • "Sun Probe" was serialised in issues 6-8 of Thunderbirds: Comic by Alan Fennell and Malcolm Stokes in 1991-92.
  • When Virgil and Brains find Braman in the pod, we can also see the laser cutter from the episode 30 Minutes After Noon and the neutraliser tractor from the episode Move and you're Dead.
  • John Tate takes part in this episode but is uncredited. He later provides voices in Danger At Ocean Deep, Attack Of The Alligators!, The Cham-Cham, Security Hazard, Atlantic Inferno and Path Of Destruction.
  • The Transmitter Truck reappears in Cry Wolf.


  • A diagram of the Sun Probe in the TV news programme displays the solarnauts’ control room being inside the probe module, but the probe is separate from the manned solar module when it flies through the solar prominence.
  • While boarding Thunderbird 3, Alan and Scott switch places on the sofa but are back in their original places when they arrive in the craft’s lounge.
  • Thunderbird 2 takes off from Tracy Island seemingly with Pod 3 selected, but the transmitter truck emerges from Pod 6 on Mount Arkan. This continuity error also occurs in Vault of Death, Move - and You're Dead, Martian Invasion, The Perils of Penelope and Day of Disaster.
  • It takes a week for the Sun Probe to reach their position, yet it takes Thunderbird 3 only 24 hours.
  • At the start of the episode, Colonel Benson is voiced by David Graham. When he appears on TV, asking for International Rescue's help, he is voiced by Ray Barrett.

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