Observer Effect ( short story ) Observer Effect was the fourth short story in the Short Trips anthology " " . It was written by Lance Parkin . It featured the Fourth Doctor and Sarah Jane Smith . Summary . The TARDIS materialises inside a spacecraft . The Doctor and Sarah learn that they are in the Kuiper Belt , inside the hold of the spacecraft . An alarm sounds , and smoke pours through a door in the hold . They open the door and rescue an astronaut , Chang Hu . The small console room is on fire , and the Doctor puts it out , though there is much damage . Chang Hu is surprised by their appearance on the ship , but assumes they are from " the Corporation " . They pass through a greenhouse , where they find Lendal and Talbot . Chang Hu starts to tell the Doctor their story when Warry , another astronaut , buzzes on the intercom that he is trapped in the control room , on the far side of the science module . Another astronaut , Duncan , enters and informs Chang Hu that she cannot get to the science module . She thinks Barrett is in there . Warry notes that the instruments say the science module has been depressurised . Apparently Barrett opened the airlock from the science module . The science module is littered with debris . At first Duncan suspects the Doctor and Sarah , but it doesn ' t take long to convince her and the others that they weren ' t involved . The Doctor has an idea but wants the others to figure it out . The Doctor studies the airlock while Sarah helps the astronauts clean the science module . The Doctor reveals to Sarah that he thinks Barrett found something outside in the Kuiper Belt . Something that has been waiting since before the Solar System formed . He investigates the computer Barrett was using , and finds evidence of an encrypted data stream , hidden in the regular transmissions sent by the spacecraft back to Earth . Chang Hu takes Sarah to the shower , and on the way he tells her his life story , how his father was part of the space program and intended for Chang Hu to be the first of the space men . After Sarah finishes her shower , she shows the Doctor what she discovered — there is a tiny camera in the shower . He tells her the astronauts are being monitored , but that it ' s not a big deal , and heads back to the computer . Sarah talks with Talbot , mentioning the camera , but is surprised when Talbot doesn ' t know what she means . She brings the astronauts to the science module , where the Doctor shows them what he found . He plays the recording of Barrett ' s last actions . They all watch as Barrett types on the computer , stands up and looks right at the camera , shouting something , returns to the computer , then goes to the airlock and opens it . The Doctor and Sarah learn that the astronauts don ' t know about the cameras that are monitoring them . Sarah , however , realises that Chang Hu knows about the cameras . He explains that their actions are being sent back to Earth as entertainment . This is done to raise funds for the space missions . The Doctor deduce s that Barrett must have discovered the cameras , believed that the spacecraft was a fake , and walked outside the airlock to prove it . The other astronauts almost believe it ' s a fake as well , but Chang Hu convinces them they really are in space . They are angry at first , but he convinces them they will be famous when they return to Earth . The Doctor and Sarah decide they should leave while the cameras are still down . Back in the TARDIS , Sarah is pleased that she was right this time . Notes . " to be added "