Professor Jaeger was a scientist, and one of the greatest minds of the Earth Empire in the 30th century. The Marshal of Solos assigned him to find a way to permanently change the atmosphere of Solos to make it habitable for humans.
When the Third Doctor was taken to Jaeger's laboratory, he considered it adequate. Jaeger was assigned to, not only change the atmosphere of Solos, but for the present time help the Doctor open and therefore find out what was inside the message pod sent to him by the Time Lords. The Doctor was openly opposed to Jaeger's experiments, and said that the Solonians were concerned about it, but Jaeger didn't listen. He didn't see the need for the Doctor's concern. He didn't believe that particle reversal would work to open the pod, he claimed it was a senseless waste of time as it hadn't been achieved yet.
When the first test for particle reversal was carried out, Jaeger was bewildered and amazed, and he was very interested by it. When he and the Doctor tried again, the Doctor caused the circut to overload, causing an explosion, rendering Jaeger briefly unconscious so the Doctor could escape. The Marshal wasn't very impressed, and he wanted the atmosphere of Solos changed there and then, and this was very constant.
Jaeger also realised that they were experiencing Solos summer as the planet was getting hotter and hotter.
With the Earth Investigator's space shuttle on their way to Skybase One, a message was sent to the Marshal. This made the Marshal more eager to have the experiment completed, as he wanted to meet the Investigator on the surface of Solos. However, Jaeger told him the rockets were only half completed.
Nevertheless, Jaeger was ordered to fire the rockets which he did. However it caused the surface of Solos to become contaminated. When the Doctor returned to Skybase, the Marshal blackmailed the Doctor by using Jo Grant into helping Jaeger undo the damage the rockets had caused. This was done sucsessfully using the transmat's macrophaser in particle reversal. When the Investigator arrived, the Doctor accused both the Marshal and Jaeger of callous genocide.