For the first time in the history of commercial spaceflight, a used spacecraft has blasted off on a mission to deliver cargo to the International Space Station (ISS).

After lightning strikes delayed the launch on Thursday (June 1), lingering storm clouds parted just enough for SpaceX's Falcon 9 rocket to safely lift off from NASA's historic Pad 39A at the Kennedy Space Center in Florida today (June 3).

The Falcon 9 rocket, topped with SpaceX's first refurbished Dragon cargo craft, took to the skies at 5:07 p.m. EDT (2107 GMT). About 8 minutes after liftoff, the first-stage rocket booster returned to Earth to stick a landing at nearby Cape Canaveral Air Force Station. [Launch Photos: SpaceX's 1st Reused Dragon Spacecraft]

A little over 10 minutes into the flight, the Dragon separated from the Falcon 9's second stage, deployed its solar arrays and began its three-day trek to the ISS. On Monday (June 5), the spacecraft will dock at the space station's Harmony module, delivering close to 6,000 lbs. (2,700 kilograms) of supplies and science experiments to the Expedition 52 crew.

Today's launch marked the 100th mission to lift off from Launch Complex 39A, where NASA's Apollo missions and dozens of space shuttle missions were also launched. "For [SpaceX], it's the seventh launch this year, and you can tell that we picked up the rate significantly," Hans Koenigsmann, vice president of flight reusability at SpaceX, said in a prelaunch briefing on Wednesday (May 31).

"We are hoping to stay at this rate through the rest of the year and work our backlog down. We're hoping to also fly more and more refurbished Dragons, and the same is true for the first stages," he said. "The next launch after this is also refurbished first stage."

A SpaceX Falcon 9 rocket carrying a used Dragon cargo craft blasts off from NASA's Kennedy Space Center in Florida on June 3, 2017. (Image credit: SpaceX)

Another historic 1st for SpaceX

Today's mission is the latest in a series of historic firsts for SpaceX, the private spaceflight company founded by billionaire entrepreneur Elon Musk. In March, the company successfully launched and landed a used rocket booster for the first time. SpaceX is also the first and only company to have landed a rocket booster during an orbital mission (though Jeff Bezos' Blue Origin has achieved this multiple times on suborbital journeys). And in 2012, SpaceX's Dragon capsule became the first private spacecraft to dock at the ISS.

With the ultimate (and highly ambitious) goal of being able to reuse all major components of their launch vehicles, SpaceX is now putting the Dragon to the test. The capsule first flew on a cargo mission to the space station on Sept. 21, 2014, for the cargo resupply mission CRS-4, and it returned to Earth with a splashdown in the Pacific Ocean one month later.

"Once this capsule landed, we refurbished it, inspected it, made sure everything is qualified for the next flight," Koenigsmann said.

But the capsule isn't 100 percent reused parts, Koenigsmann added. Certain parts had to be replaced for a number of reasons, such as exposure to seawater during splashdown, he said, and the heat shield needed to be replaced for safety. "But I can tell you the majority of this Dragon has been in space before and has been docked to the station for a couple of weeks."

The next steps toward full reusability for SpaceX involve figuring out how to refurbish the second-stage rocket booster and the payload fairings — an ambitious but important goal, Koenigsmann said.

"This whole notion of reuse is something that's very important to the entire space industry and NASA as well as Space X and others," Kirk Shireman, manager of NASA's ISS program, said in the briefing. "The idea of reuse is important for economic reasons as well as technical reasons." [SpaceX Gaining Substantial Cost Savings From Reused Falcon 9]

Science on board

Along with food, water, clothing and other gear for the astronauts at the space station, the Dragon will deliver plenty of science experiments.

The experiments on board will support about 220 investigations currently happening at the space station. "They span a multitude of scientific disciplines, including biological research, the physical sciences, the human research that we're doing with the astronauts, the technology demonstration studying Earth and space from the ISS, and then last but not least, the educational activities that students have an opportunity to participate in," Camille Alleyne, an associate space station program scientist at NASA's Johnson Space Center in Houston, said at the briefing.

One astrophysics experiment, called the Neutron star Interior Composition ExploreR (NICER), will investigate the possibility of utilizing neutron stars — the ultradense cores of dead stars — to develop a type of interstellar GPS navigation system.

A new, experimental type of solar panel is also flying to the space station on the Dragon. Called the Roll Out Solar Array (ROSA), these new solar arrays are smaller, lighter and more efficient than the current solar panels that power the ISS.

The Dragon also contains some live passengers, including 40 mice and thousands of fruit flies. For a project called Rodent Research-5, the mice will help researchers study a new drug for osteoporosis, or bone density loss. The fruit flies will help investigators study the prolonged effects of spaceflight on the human heart.

More Earth-observation instruments are also on their way to the ISS. The Multiple-User System for Earth Sensing (MUSES) facility, developed by Teledyne Brown Engineering, contains new high-resolution digital cameras and hyperspectral imagers, bringing new capabilities to the space station's suite of Earth-observing technologies.

Email Hanneke Weitering at hweitering@space.com or follow her @hannekescience. Follow us @Spacedotcom, Facebook and Google+. Original article on Space.com.