SpaceX readies Dragon for launch to space station

SpaceX engineers loaded last-minute equipment and research gear aboard a Dragon cargo ship Friday, setting the stage for launch atop a Falcon 9 rocket early Saturday on a two-day flight to the International Space Station.

Loaded with more than 5,100 pounds of cargo, including 20 mice in a compact habitat, spacesuit batteries, an experimental 3D printer, IMAX cameras and an instrument to measure ocean wind speeds, the Dragon cargo craft was scheduled for liftoff from pad 40 at the Cape Canaveral Air Force Station at 2:14 a.m. EDT Saturday, roughly the moment Earth's rotation carries the pad into the plane of the space station's orbit.

Assuming an on-time launch, the Dragon cargo ship is expected to rendezvous with the space station early Monday, pulling up to within about 30 feet and standing by while the lab's robot arm locks on around 7:30 a.m. and pulls the capsule in for berthing at the Earth-facing port of the forward Harmony module.

If all goes well, the spacecraft will remain attached to the station until around Oct. 18, returning to a Pacific Ocean splashdown, bringing some 3,800 pounds of research samples and equipment back to waiting scientists and engineers.

Hans Koenigsmann, vice president of mission assurance at SpaceX, told reporters Friday the rocket and capsule were in good shape and ready for flight, but forecasters predicted a 50 percent chance of rain and thick clouds that could force a 24-hour delay. The outlook for Sunday calls for a 70 percent chance of acceptable weather, and a third launch opportunity may be available next Tuesday if needed.

If the Dragon is not off the ground by then, SpaceX will have to stand down until Sept. 28 to make way for the launch of a Russian Soyuz spacecraft carrying three fresh crew members to the outpost. The Soyuz TMA-14M spacecraft, carrying commander Alexander Samokutyaev, flight engineer Elena Serova and NASA astronaut Barry "Butch" Wilmore, is scheduled for launch Sept. 25 from the Baikonur Cosmodrome in Kazakhstan.

Joining station commander Maxim Suraev, European Space Agency astronaut Alexander Gerst and NASA flight engineer Reid Wiseman, the combined six-member Expedition 41 crew faces a particularly busy Fall schedule, unloading the SpaceX cargo ship, repacking it with samples and equipment for return to Earth, capturing an Orbital Sciences Cygnus cargo craft in mid October and carrying out three spacewalks Oct. 7, 15 and 22.

The first two EVAs will be conducted using NASA spacesuits that require replacement batteries. Two new batteries are going up on the Dragon cargo ship and two more aboard the Soyuz.

This is SpaceX's fourth operational Dragon launch under a $1.6 billion contract with NASA that calls for at least 12 flights to deliver some 44,000 pounds of cargo to the space station. Orbital Sciences holds a $1.9 billion contract for eight flights to launch about 40,000 pounds of cargo.

The SpaceX CRS-4 flight comes just 13 days after the company successfully launched a commercial communications satellite for AsiaSat and just four days after winning a $2.6 billion contract from NASA to develop a piloted space taxi to ferry astronauts to and from the station.

Boeing is designing its own crew capsule under a separate $4.2 billion contract and NASA hopes both companies will be ready for flights to the station by 2017.

Koenigsmann said the rapid fire launch pace at the Cape over the past few weeks has been a challenge, but also a sign of things to come for SpaceX.

"The CRS-4 mission has become somewhat of a routine, I would say cautious routine, because obviously we've got to be super careful that everything is reliable and working well and checked out and triple checked again," he said. "But I also sense that by now we're doing more and more experiments, we're bringing up expensive hardware, we know this is transitioning to a routine cargo taxi, basically, along the way.

"I hope we demonstrate all our reliability, on time, bringing these experiments up in a reliable and safe fashion."

The cargo for the CRS-4 mission includes about a month's supply of food for the station crew, clothing, spare parts and a wide variety of experiment hardware and equipment, including IMAX camera equipment, exercise gear, a small "SpinSat" satellite for tests of micro thrusters and a nitrogen/oxygen recharge system for the station's airlock.

The mice are the first live animals launched by SpaceX. They are part of two investigations, one to simply test the animal life support equipment and the other to learn more about how muscle atrophies in weightlessness and the role of a specific protein that may reduce that degradation. Researchers say the results could help astronauts on long-duration missions as well as elderly or bed-ridden patients on Earth.

Ten of the rodents will return to Earth aboard the Dragon capsule and the other 10 will come down in January aboard a SpaceX cargo ship scheduled for launch in early December.

NASA is providing an instrument known as a rapid scatterometer, or RapidScat, that will be mounted on the station's Columbus module to measure ocean wind data, filling a gap left after a NASA satellite with a similar instrument ceased operations in 2009.

In a more down-to-Earth experiment, Cobra Puma Golf Co. hopes to find out if weightlessness offers any advantages when it comes to building high-performance golf clubs.

"We've put together an experiment that's going to help us understand how plating in a microgravity environment will potentially improve crystalline growth, adhesion, durability," said Mike Yagley, Cobra Puma director of research and testing. "All of those things are very critical to making a very good golf club."

He said golf clubs experience enormous stress, up to 7,000 Gs "and some environments are even more stressful than what you see in space."

"That research is very fundamental to being able to improve the durability, potentially the adhesion characteristics of multi materials, the structural integrity of the surface," he said. "So ultimately, we'll get a very fundamental understanding of how the micro gravity environment could improve a process that we use in making a golf club."

The CRS-4 payload that has generated the most attention is an experimental printer provided by a California company known as Made In Space in partnership with NASA. The printer will be used to test 3D printing technology in weightlessness before NASA transitions to operational printers down the road that could be used to fabricate tools and other hardware in orbit.

"It's especially important when we consider space travel, human space exploration," said NASA project manager Niki Werkheiser. "From day one, the supply chain has been very constrained. We have to launch every single thing that we ever need from Earth. So being able to make what you need on orbit when you need it is a real game changer."

Such printers build up three-dimensional objects layer by layer in an additive fashion, following computer commands based on precise 3D modeling of the desired object. For this initial experiment, files will be uplinked from the ground directly to the printer.

"So you can imagine how cool it will be to uplink or email a part to space instead of launching it," Werkheiser said.

Future missions to Mars or other deep space targets will take years to complete and it will not be feasible to carry everything a crew might need, she said. 3D printers on such missions would permit crews to print everything from electronic circuits to spare parts and even components for large structures.

"I think it's a certainty that NASA will reach the point of manufacturing replacement parts, manufacturing tools as needed and relying on those instead of, not in addition to, things that are brought from Earth," said Jeff Sheehy, senior technologist with NASA's Space Technology Mission Directorate.

"If we're really going to set up shop on Mars, we have to get there, we really can't afford to bring everything we need for an indefinite amount of time. We may do that for the first mission, but we need to get to the point where we can make things that we need as we go."

SpaceX has been experimenting with 3D printing for the past several years, using a printed engine valve in a flight earlier this year. The company has even printed an engine thrust chamber and successfully test fired it more than 80 times.