SpaceX launched a mission to the Internantional Space Station on Saturday.

Stormy afternoon weather and a nearby lightning strike grounded the SpaceX Falcon 9 rocket Thursday, forcing a two-day delay for launch of a space station-bound Dragon cargo ship loaded with 6,000 pounds of supplies and equipment.

The scrub was a disappointment to researchers awaiting the Dragon's arrival at the station to kick off a wide variety of experiments, including one to study fast-spinning neutron stars, or pulsars, to find out if they can be used as ultra-precise navigation beacons for future deep space missions.

"The fact that we have these pulsars apparently flashing away in the sky (hundreds of times per second) makes them interesting as tools," said Zaven Arzoumanian, science lead for Neutron star Interior Composition Explorer, or NICER, instrument mounted in the Dragon's unpressurized trunk section.

"You can imagine having a system of clocks, very accurate clocks, distributed all over the sky. ... So in the same way that we use atomic clocks on GPS satellites to navigate our cars on the surface of the Earth, we can use these clock signals from the sky, from pulsars, to navigate spacecraft anywhere in the solar system."

This was the 100th launch from pad 39A which sent the Apollo 11 moonship on its way to the first lunar landing in 1969 and hosted the first and last space shuttle missions in 1981 and 2011 respectively. SpaceX now operates the launch complex under a 20-year lease with NASA.