Despite Meri's disapproval, Sirius goes forward with his mission. As the sole passenger on his spacecraft, the Meriwell, Amory's only companion is a computer system known as the All Mother, which also operates inside his spacesuit.
The passage describes a situation where the protagonist, Sirius, is on a solo mission despite opposition from another character, Meri.  The All Mother, a sophisticated computer system, acts as both a companion and an essential part of the spacecraft's functionality for Amory.