Q&A with Keith Gendreau, principal investigator of the first X-ray space communications experiment (members only)

When the countdown hit zero last Friday and the engines powering a previously flown Falcon 9 first stage roared to life for takeoff, the four astronauts strapped into a SpaceX Crew Dragon some 21 stories up started laughing.

The Falcon 9 rocket launching the Starlink 15-13 mission will fly on a south-easterly trajectory upon leaving pad 4E at Vandenberg Space Force Base. Liftoff is for 7:27 a.m. PST (10:27 a.m. EST / 1527 UTC).

In a complex bit of orbital surgery, two spacewalking astronauts cut into a $2 billion cosmic ray detector Friday, venting away life-sustaining carbon dioxide refrigerant and then snipping eight coolant lines the size of soda straws to prepare the high-tech “patient” for a coolant pump transplant.