This was a book I read in the early 80's. The opening chapter is a spaceship (owned by a salvage company?) has to rescue a passenger vessel that is trapped in the atmosphere of a Jupiter like gas giant. The passengers are saved by the salvage ship passing an umbilical to the passenger ship. This introduces the daughter of a missing scientist who has created some universe changing something. She hires the salvage ship to find her missing father. The missing father may have been found in a hollow asteroid.
Edit: book may have been published before the 80's, I used to read anything in the library that had a rocket ship on the cover. I remember the opening being a commercial operation that had to rescue a passenger vessel and concern by the captain about the cost of the operation and whether he would get paid for it.