[image-110][image-51][image-78]Orbital Sciences Corporation’s Cygnus spacecraft, which delivered nearly one-and-a-half tons of supplies and scientific equipment to the International Space Station in January, completed its first commercial cargo mission to the orbiting laboratory Tuesday.
NASA astronaut Mike Hopkins, with assistance from Japan Aerospace Exploration Agency astronaut Koichi Wakata, used the station’s 57-foot Canadarm2 robotic arm to detach Cygnus from the Earth-facing port of the Harmony node at 5:15 a.m. EST. While Wakata monitored data and kept in contact with the team at Houston’s Mission Control Center, Hopkins released Cygnus from the robotic arm at 6:41 a.m.
At the time of release, the station was orbiting about 260 miles over the southern Atlantic Ocean off the coast of Argentina and Uruguay.
From their vantage point inside the station’s cupola observation deck, the two flight engineers monitored telemetry from Cygnus as the unpiloted resupply ship -- now loaded with trash -- conducted a 1-minute, 30-second departure burn to move a safe distance away from the station.
The U.S. commercial cargo craft will begin its deorbit sequence shortly after 8 a.m. Wednesday to enable it to slip out of orbit for a destructive entry into Earth's atmosphere. Cygnus will burn up over the Pacific Ocean later that afternoon.
During its first official commercial resupply mission, designated Orbital-1, Cygnus delivered 2,780 pounds of supplies to the space station, including vital science experiments for the Expedition 38 crew. Cygnus launched from NASA’s Wallops Flight Facility on Jan. 9 aboard an Orbital Sciences Antares rocket and arrived at the complex Jan. 12.
The departure of Cygnus clears the way for the arrival of Space Exploration Technologies’ Dragon cargo ship on its third commercial resupply mission, SpaceX-3. Dragon is set to launch from Cape Canaveral Air Force Station in Florida on March 16.
In addition to Cygnus departure activities, the six-person Expedition 38 crew tackled a variety of scientific experiments and routine maintenance tasks Tuesday.
Flight Engineer Rick Mastracchio, who began the day performing a leak check at the vestibule where the soon-to-depart Cygnus was berthed, spent most of the morning collecting air samples in the U.S. segment of the station. These air samples will be incubated for five days and tested for signs of microbial contamination.
Later, Mastracchio cleaned soot from the hardware for an experiment known as the Burning and Suppression of Solids, or BASS, located in the Microgravity Science Glovebox. Afterward he fired up the experiment for a pair of flame tests and calibrated the hardware. Results from BASS, which takes a look at how a variety of materials burn and extinguish in microgravity, may lead to lead to improvements in spacecraft materials selection and strategies for putting out accidental fires aboard spacecraft. The research also provides scientists with improved computational models that will aid in the design of fire detection and suppression systems here on Earth.
[image-94]Hopkins spent some time swapping out a fiber optic cable for the Light Microscopy Module inside the Fluids Integrated Rack. Hopkins also collected surface samples throughout the station to check for bacterial and fungal contamination.
On the Russian side of the orbiting complex, Commander Oleg Kotov performed the Albedo experiment, which takes a look at using the solar radiation reflected from the Earth to provide power for the station. The commander also used the treadmill in the Zvezda service module as he participated in the Motocard study, which examines how long-duration spaceflight affects a cosmonaut’s gait and ability to walk or run.
Flight Engineers Sergey Ryazanskiy and Mikhail Tyurin performed the Bar experiment, studying methods and instruments for detecting the location of an air leak from one of the station’s modules.
Ryazanskiy also studied chemical luminescent reactions in the Earth’s atmosphere for the Relaxation experiment. Tyurin meanwhile conducted the Uragan Earth-observation experiment, which seeks to document and predict the development of natural and man-made disasters on Earth.