Derrick Matthews, moderator with NASA Communications, fields questions from NASA Social participants during a What’s On Board science briefing at the agency’s Kennedy Space Center in Florida on April 29, 2019. The briefing was held for SpaceX’s 17th Commercial Resupply Services (CRS-17) mission to the International Space Station. The SpaceX Falcon 9 rocket and Dragon cargo module are scheduled to launch no earlier than May 3, 2019, from Space Launch Complex 40 on Cape Canaveral Air Force Station in Florida.