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

The European Space Agency’s LISA Pathfinder spacecraft, now sailing around the sun on a trajectory away from Earth, was deactivated Tuesday after a nearly 18-month mission testing previously-untried lasers, vacuum enclosures, exotic gold-platinum cubes and micro-thrusters needed for a trio of gravitational wave observatories set for launch in the 2030s.

Forecasters predict mostly cloudy conditions and a chance of light rain for Tuesday morning’s scheduled takeoff of a SpaceX Falcon 9 rocket with a space station-bound supply ship, with a 40 percent chance weather could prevent liftoff during an instantaneous predawn launch opportunity.

SpaceX ran through countdown and fueling procedures with a Falcon 9 rocket at NASA’s Kennedy Space Center in Florida on Sunday, culminating in ignition of the booster’s nine first stage Merlin engines in a customary check of the launcher’s readiness before liftoff Thursday with a Dragon supply ship for the International Space Station.