Every year, on the Saturday nearest the summer solstice, the Rachel Carson Trail Challenge invites adventurous souls to embark on a 37-mile endurance trek. Taking place from sunrise to sunset, the hike covers nearly the entire length of the rugged, geographically diverse Rachel Carson Trail, which runs north and east of Pittsburgh and includes a cumulative elevation gain of close to 7,000 feet. She notes that completing the RCT Challenge is not for the faint of heart. Named for Rachel Carson, who is credited with launching the environmental movement with her 1962 book “Silent Spring,” the trail fittingly passes by Carson’s childhood home in Springdale. Mark Eyerman, a longtime RCT volunteer and trail manager, says the trail is all about the city’s history and heritage.