Update, Jan. 9: Tuesday's launch was scrubbed due to a problem with the rocket's upper stage. The next launch attempt is set for Saturday, Jan. 10 at 4:47 a.m. EST (9:47 UTC).
Tomorrow morning, SpaceX will attempt to pick up where they left off last month, launching a Dragon spacecraft to the International Space Station and landing a used Falcon 9 rocket stage on an uncrewed spaceport in the Atlantic Ocean.
Just don't call it a barge.
"It's an autonomous drone ship," said Hans Koenigsmann, responding sharply to my question about the landing site, in which I used the word "barge." It's not surprising SpaceX's vice president for mission assurance wants to be clear on the difference—most barges don't come equipped with thrusters, or the ability to hold a position within three meters in the middle of a stormy sea.
The rebuke notwithstanding, Koenigsmann was mostly smiling as he answered reporters' questions during a Monday afternoon press conference at Kennedy Space Center in Florida. SpaceX's Falcon 9 and Dragon are scheduled to lift off from Cape Canaveral Air Force Station at 6:20 a.m. EST Tuesday (11:20 UTC). Koenigsmann said the first stage recovery attempt will begin at about the time Dragon is released into its preliminary orbit.
"It's an experiment," he said, noting that it was CEO Elon Musk who gave the landing a 50 percent chance of success. Despite an air of caution, he added, "I'm going to be super excited if this works."
The primary goal of Tuesday's CRS-5 mission is to deliver more than two tons of supplies to the space station, which suffered a missed cargo delivery after the loss of an Orbital Sciences Corporation Antares rocket last October. Dragon will be carrying about 1.8 tons of pressurized cargo. "I think that's the most we've crammed into a Dragon to date," said Mike Suffredini, NASA’s ISS Program manager.
NASA hosted two other briefings Monday to discuss the array of science and technology experiments awaiting Dragon's arrival—256 in all, according to SpaceX. One notable piece of equipment coming to the station is CATS, the Cloud-Aerosol Transport System. CATS will be mounted to the outside of the orbiting laboratory to measure the worldwide distribution of clouds and aerosols.
SpaceX has not revealed where their autonomous spaceport drone ship will sit in order to retrieve the used Falcon 9 stage. However, rocket operators must issue a Notice to Mariners advising boats how to stay away from falling rocket stages. Wayward ships wandering into these restricted zones are occasionally responsible for delaying launches.
The Notice to Mariners containing details for the prior Dec. 19 launch date includes a trapezoidal region about 200 miles off the east coast of the United States, stretching roughly from Jacksonville, Fla. to Savannah, Ga. Rockets heading to the ISS from Cape Canaveral launch on a northeastern trajectory in order to match the station's orbital inclination of 51.6 degrees.
A number of Internet discussion boards have tracked SpaceX's drone ship as it departed from Jacksonville. It is believed to be accompanied by two crewed support ships, the Go Quest and the Elsbeth III. As of Monday afternoon, both ships were holding a position within the keep-out zone.
Despite tomorrow's early launch time, SpaceX CEO Elon Musk is scheduled to participate in a Reddit IAmA at 9 p.m. EST. Given Musk's penchant for using social media to reveal information about his company's plans, it should be an interesting read.