Last week, Astronaut Butch Wilmore was on the International Space Station. This afternoon, he's right here answering your questions. He and Niki Werkheiser, head of NASA's 3D printing project, can talk about 3D printers in space, life aboard the ISS, and anything else you want to know!
Wilmore spent the last six months on the ISS, where, among other things, he was responsible for 3D printing and assembling the very first tool constructed entirely in space: this socket wrench.
He has been an astronaut for the past 15 years, piloted the Space Shuttle, and commanded the ISS's 42nd Expedition. Prior to joining NASA, he spent several years as a test pilot in the Navy where he logged almost 7,000 flight hours.
Werkheiser is the NASA Project Manager for the In-space Manufacturing Initiative, which just recently sent the very first working 3D printer into space (which brought us that aforementioned space socket wrench). She also designed and developed payloads for the ISS and space shuttle, and headed up the crew safety initiative for NASA's Ares launch vehicle.
They'll both be here from 4 - 4:30 EST, so start asking all your most pressing questions right now.
Update: Questions are now closed! Thanks to Butch, Niki, and everyone who submitted a question.
Top image: Wilmore, snapping a space selfie, on his first spacewalk / NASA