As the on-board Draco thrusters make a final few bursts to maneuver towards the ISS, another team of SpaceX engineers in McGregor, Texas, will be watching to see if the small engines they tested extensively will perform as expected and steer the spacecraft within reach of the station's robotic arm.

Many of those same engineers are undoubtedly also busy reviewing data and images from Sunday's launch. About 79 seconds after lift-off, one of the nine Merlin rocket engines suffered a failure and had to be shut down during the ascent. That same engine had been fired on a test stand above the central Texas grasslands and performed perfectly before it was even considered to be counted on for Sunday's launch. But as SpaceX is fond of reminding us, this is rocket science and things don't always go as planned