Before dawn today, June 29, SpaceX successfully launched its fifteenth commercial supply mission to the International Space Station.  Meanwhile, Rocket Lab is moving the “It’s Business Time” rocket back to the hanger for troubleshooting after a pair of launch attempts over the past week.

SpaceX Dragon CRS-15 left Cape Canaveral Air Force Base pad 40 at around 5:42 A.M. ET, carried aloft onboard the company’s Falcon 9 rocket.  The previously flown — or “flight proven”  as the company prefers — Dragon spacecraft is carrying more than 5,900 pounds of supplies and payloads to the International Space Station.  Capture and berthing to the station is expected to occur on Monday morning, July 2.

Today’s Falcon 9 launch also used a flight-proven first stage.  This was the last flight for the Block 4 version of the Falcon 9 first stage and no attempt was made to fly it back.  Future flights of Falcon 9 will use the company’s Block 5 first stage, designed for rapid turnaround and minimal refurbishing for up to 10 flights.  SpaceX CEO and Founder Elon Musk says the Block 5 should be capable of flying up to 100 times, a vast improvement over a two flight lifetime of earlier versions.

Space IT related cargo onboard CRS-15 includes a self-propelled IBM Watson astronaut assistant and the third launch of a Made-in-Space ZBLAN payload to create low-loss fiber optic cable. When it returns to Earth about a month later, the Dragon capsule will be bringing back the earlier Made-in-Space hardware, according to Physics Central.

Rocket Lab’s “It’s Business Time” made its second launch attempt on the evening of June 26 (ET).  Problems with a motor controller during pre-launch checks forced a scrub.  The motor controller problem previously arose during a dress rehearsal in April, so Rocket Lab needs to figure out what the issue is before scheduling a new launch window.  A first launch attempt on June 22/23 was scrubbed due to problems with downrange tracking.