Looking for scifi book similar to The Day of the Triffids

For years I have been searching for this science fiction novel that I read in my childhood. It is similar in concept to The Day of the Triffids. The main character is a fencing entushiast and is wearing a protective helmet which saves him from being affected by a misterious radiation which makes humankind to fall under the power of a giant alien creature, whose bright eyes are visible in the sky. Our hero gets to the alien ship and there is a free falling through atmosphere inside of an air bubble vesel inside of a block of ice. It was very entertaining but I lost the book and I have unable to remember the title or author. Around 1950-1970s. Thanks!!