propulsionChallenge

Given a predicate that represents a relationship or action between entities, generate a one-sentence description explaining its meaning.  
# Instructions
Focus on describing the relationship, not the entities themselves. 
# Response Format
Begin the description with \' Indicates...\'

Predicate: propulsionChallenge

Indicates a relationship where an entity faces difficulty, limitation, or inefficiency in generating or sustaining the propulsion needed for movement or thrust.