SpaceX the Alan Notes

An unmanned SpaceX Dragon cargo capsule sits atop its Falcon 9 rocket at the private spaceflight company's launch pad at Cape Canaveral Air Force Station in Florida on Sept. 19, 2014. Bad weather prevented a planned early-morning launch toward the International Space Station for NASA on Saturday, Sept. 20.
Credit: SpaceX

"We have scrubbed today's launch opportunity because of inclement weather, " NASA spokesman Mike Curie said during the countdown commentary about a half hour before the targeted 2:14 a.m. EDT (0614 GMT) launch time on Saturday.

SpaceX's Dragon is carrying some unusual cargo among its 2.5 tons of astronaut supplies, science experiments and new hardware being hauled to the space station. That haul includes 20 mice that will live inside a new rodent habitat, the first 3D printer built for space and a NASA device called RapidScat, designed to track ocean winds on Earth from the space station.

The forecast for Sunday calls for a 40-percent chance of good launch weather for SpaceX's Falcon 9 and Dragon, according to NASA weather experts. If all goes well, the Dragon spacecraft will arrive at the station on Tuesday (Sept. 23) and be captured by astronauts using the outpost's robotic arm.

"We're hoping the weather will be more favorable, " Curie said.

Quiz: How Well Do You Know SpaceX's Dragon Spaceship?

The spaceflight company SpaceX is one of several firms building private space taxis and cargo ships to launch astronauts and supplies into space. But there's more to SpaceX than meets the eye. Test your SpaceX know-how here.

0 of 10 questions complete

The spaceflight company SpaceX is one of several firms building private space taxis and cargo ships to launch astronauts and supplies into space. But there's more to SpaceX than meets the eye. Test your SpaceX know-how here.

0 of questions complete

The mission is the fourth of 12 SpaceX delivery missions to the space station using its Dragon spacecraft and Falcon 9 rockets. The Hawthorne, California-based company has a $1.6 billion contract with NASA for those resupply flights. NASA also has a separate cargo delivery contract with the Virginia-based company Orbital Sciences, which uses its own Antares rockets and Cygnus spacecraft for the flights.

Earlier this week, NASA also picked SpaceX as one of two companies that will fly American astronauts to the station on commercial space taxis. The space agency tapped SpaceX's manned Dragon Version 2 spacecraft and the Boeing CST-100 capsule as the future ferry ships for U.S. astronauts headed to the International Space Station.