The unpiloted ISS Progress 56 resupply spacecraft, packed with nearly three tons of cargo for the Expedition 40 crew, launched from the Baikonur Cosmodrome at 5:44 p.m. EDT Wednesday (3:44 a.m. Thursday, Kazakh time) to begin a 6-hour, 4-orbit flight to the International Space Station.

At the time of launch, the station was flying about 260 miles above northeast Kazakhstan, having passed directly over the launch site three minutes earlier.

A series of thruster firings by Progress over the next several hours will adjust the orbit to put the Russian space freighter on track for a rendezvous with the station and an automated docking to the Earth-facing port of the Pirs docking compartment at 11:30 p.m.

The new Progress is loaded with 1,764 pounds of propellant, 48 pounds of oxygen, 57 pounds of air, 926 pounds of water and 2,910 pounds of spare parts, experiment hardware and other supplies for the Expedition 38 crew. Expedition 40 Flight Engineers Alexander Skvortsov and Max Suraev will open the hatch to Progress Thursday morning to begin unloading the cargo.

Progress 56 is slated to spend about three months docked to the complex before undocking to make way for ISS Progress 57.

The ISS Progress 55 cargo craft, which undocked from Pirs on Monday, is now a safe distance from the complex for a series of engineering tests prior to being sent to a destructive re-entry over the Pacific Ocean on July 31.

The station's crew began the workday at 6 a.m. Wednesday, four hours later than the usual 2 a.m. reveille to accommodate the late-night arrival of Progress.

Commander Steve Swanson and Flight Engineer Alexander Gerst participated in more Ocular Health exams as flight surgeons track the vision health of the astronauts aboard the station.

NASA recently identified that some astronauts experience changes in their vision, which might be related to effects of microgravity on the cardiovascular system. Researchers are working to understand and prevent these changes in astronauts. With guidance from the Ocular Health team on the ground, Gerst performed an ultrasound scan of Swanson's eyes.

Flight Engineer Reid Wiseman then pitched in to help out with Wednesday's exams and conducted an ultrasound scan of Gerst's eyes. Swanson and Gerst later measured each other's blood pressure and collected electrocardiogram data for Ocular Health.

Swanson also temporarily removed the Multi-user Droplet Combustion Apparatus from the Combustion Integrated Rack's combustion chamber to replace some igniter tips.

The commander then moved on to assist Wiseman, who was participating in another round of data collection for the Sprint exercise study. Sprint measures the effectiveness of high-intensity, low-volume exercise training in minimizing the loss of muscle mass and bone density that occurs during spaceflight. Station crew members currently work out around 2 0.5-hours every day, and the Sprint team is looking into ways to reduce that total exercise time while maintaining crew fitness

Wiseman also set up and photographed new test samples for the Binary Colloidal Alloy Test, or BCAT. Results from this ongoing investigation of colloids - mixtures of small particles distributed throughout a liquid - will help materials scientists to develop new consumer products with unique properties and longer shelf lives.

For the ongoing Burning And Suppression of Solids experiment, or BASS, Gerst conducted a series of flame tests at reduced oxygen pressure to get a stable blue flame for a longer period of time. Housed inside the station's Microgravity Science Glovebox, BASS is investigating the hypothesis that some materials may actually become more flammable in space.

Results from BASS will help screen materials for their use aboard future spacecraft. The research also provides scientists with improved computational models that will aid in the design of fire detection and suppression systems both in space and here on Earth.

Gerst also used several dermatology tools on his forearm to collect data for the Skin B experiment, which investigates the accelerated aging of skin that seems to occur during spaceflight. Results from this study will improve the understanding of the mechanisms of skin aging as well as provide insight into the aging process of similar body tissues.

On the Russian side of the station, Suraev and Flight Engineer Oleg Artemyev began the day with an examination of the veins in their lower legs to provide data on the body's adaption to long-duration spaceflight.

With Progress 56 slated to arrive at the station well-past the crew's usual bedtime, all three Russian cosmonauts aboard the station took a 4-hour nap at beginning 12:30 p.m.

The station also conducted a "deboost" Wednesday morning to steer clear of some space debris.

The engines of the station's Zvezda service module conducted a 32-second firing at 6:57 a.m. EDT to slightly lower the orbit of the complex and steer clear of a fragment of debris from a Russian Breeze-M upper stage used in the launch of a Russian satellite in December 2011.

The "deboost" of the station was coordinated between NASA and Russian flight controllers after tracking data confirmed that the fragment would have posed a high probability of a conjunction with the station. Although last-minute tracking data indicated that the fragment would have passed a safe distance away from the station, flight controllers elected to proceed with the engine firing since it would have no impact on other activities.

Earlier data indicated that if no maneuver would have been conducted, the fragment would have made its closest approach to the station at 9:16 a.m. with an estimated radial miss distance of just 1/10 of a mile and an overall miss distance of 3.6 miles.

The maneuver lowered the station's orbit by 1.1 statute miles at apogee and 1/10 of a statute mile at perigee and left the station in an orbit of 258.8 x 256.9 statute miles.

The conjunction posed no threat to the crew, had no impact on station operations or the launch of Progress 56.