He had left the base in the Total Survival Suit (TSS) to explore the area and, like two others before him named Stone and Carter, (PROSE: Kinda) failed to return. The TSS machine was empty when it was discovered in the jungle by the Fifth Doctor and Adric. (TV: Kinda).
Behind the scenes Edit
- It is never revealed on-screen or in Terrance Dicks's novelisation of the story exactly what became of Roberts and the two other expedition members.