The STS-87 patch is shaped like a space helmet symbolizing the Extravehicular Activity (EVA) on the mission in support of testing of tools for the assembly of the International Space Station (ISS). Earth is shown reflected on the backside of the helmet. The Space Shuttle Columbia forms the interface between the Earth and the heavens, the back and front sides of the helmet in profile. The three red lines emerging from Columbia represent the astronaut symbol as well as the robot arm, which was used to deploy and retrieve the Spartan satellite.
The text 'µg' represents the payloads studying microgravity science in space on this United States Microgravity Payload (USMP-4) mission. Gold flames outlining the helmet visor represent the corona of the Sun, which will be studied by Spartan. The flag of Ukraine is next to the name of the payload specialist who is the first person from that nation to fly on the Space Shuttle.
https://mix.msfc.nasa.gov/abstracts.php?p=3606 (direct link)
NASA Facts (Source PDF)
NASA Marshall Space Flight Center (NASA-MSFC), Image ID: MSFC-9710390