A Japanese resupply freighter took off Saturday with nearly six tons of cargo bound for the International Space Station, bringing fresh food, experiments, spare parts and a charming humanoid robot name Kirobo to keep the outpost's six-person crew company.

Liftoff of the H-2B rocket from Tanegashima Space Center was at 4:48 a.m. local time Sunday. Credit: MHI

The mission launched atop a 186-foot-tall H-2B rocket at 1948:46 GMT (3:48:46 p.m. EDT) from the Tanegashima Space Center, a picturesque spaceport at the southwest tip of the Japanese main islands.

Producing more than 3 million pounds of thrust from its four solid-fueled boosters and twin LE-7A main engines, the launcher rapidly ascended into the predawn sky over Tanegashima, where it was 4:48 a.m. local time.

The H-2B launcher, built and operated by Mitsubishi Heavy Industries, shed its four boosters and nose shroud a few minutes after liftoff, and its hydrogen-fueled first stage yielded to the rocket's LE-5B second stage engine to put the mission's 35,000-pound payload into orbit.

The H-2 Transfer Vehicle deployed from the rocket about 15 minutes after launch, kicking off a six-day journey to the International Space Station.

Arrival at the 450-ton complex is set for Aug. 9. NASA astronauts Karen Nyberg and Chris Cassidy will unlimber the station's robotic arm to reach out and capture the HTV as it hovers about 30 feet below the lab.

Stretching 33 feet long and spanning 14 feet across, the HTV is about the size of a tour bus. It uses GPS and laser-guided navigation systems to approach and rendezvous with the space station.

The astronauts will maneuver the HTV into position on the Earth-facing berthing port on the space station's Harmony module.

The mission is Japan's fourth cargo delivery flight to the space station. The Japan Aerospace Exploration Agency, or JAXA, pays its share of the station's operating costs by reimbursing NASA through cargo deliveries. JAXA and the European Space Agency have barter agreements with NASA to pay for space station membership through services instead of cash.

The HTV 4 mission is also named Kounotori 4. Kounotori is the Japanese word for white stork.

The fourth HTV mission is loaded with 11,900 pounds of equipment. About 8,600 pounds of cargo is riding inside the HTV's pressurized cabin, and engineers installed three items into the ship's unpressurized section.

File photo of an HTV cargo craft approaching the International Space Station on a previous mission. Credit: NASA

The HTV is hauling a main bus switching unit - a device used to distribute electrical power on the space station - and a utility transfer assembly designed to route cables between the outpost's four solar array truss segments and pressurized modules.

The switching unit and transfer assembly will be stored outside the space station to serve as spares in the event of failures with either system.

The HTV's exposed pallet also carries a U.S. military payload housing eight experiments in atmospheric observation, thermal control, radiation measurement, data processing and lightning research. The instruments, sponsored by the Defense Department and NASA, will be installed outside the space station for several years.

Japanese technicians loaded a diverse cache of equipment inside the ship's internal compartment, including food, clothes and water for the space station's crew. Other items include batteries, oxygen tanks for spacesuits, experiment samples, and a freezer to be added to Japan's Kibo laboratory module.

A talking robot named Kirobo is among the HTV's passengers.

Developed in a partnership between Japanese advertising giant Dentsu, automaker Toyota, the University of Tokyo and Robo Garage, Kirobo stands 13 inches tall and will be activated aboard the space station this fall.

Japanese astronaut Koichi Wakata, due to arrive at the space station in December, will have a conversation with Kirobo, whose designers say will demonstrate a new way to foster communication between robots and humans living alone.

The 13-inch-tall Kirobo robot during zero-gravity testing. Credit: Kibo Robot Project

The HTV is also hauling an ultra-high resolution video camera to record comet ISON as it flies through the inner solar system later this year.

Four tiny CubeSats are also aboard the cargo freighter:

• PicoDragon will collect imagery of Earth. It was built by the University of Tokyo, the Vietnam National Satellite Center and IHI Aerospace.
  
  
• ArduSat 1 and ArduSat X were developed by NanoSatisfi, a San Francisco-based start-up, with the help of crowd-funding. The satellite's developers say investors can buy time on the satellite for imaging and other research pursuits.
  
  
• TechEdSat 3 was developed by San Jose State University and the University of Idaho with oversight from NASA's Ames Research Center. The small satellite, about the size of a loaf of bread, will test a passive deorbit system called the Exobrake.

The CubeSats will be transferred inside the space station, then placed in a specially-built deployer outside the Japanese Kibo laboratory module. The deployer will jettison the satellites into orbit - a procedure first tested last year.

The HTV cargo craft is scheduled to depart the space station Sept. 4, setting course for a destructive re-entry in the atmosphere a few days later.