WASHINGTON, June 4 (Xinhua) -- Orbital ATK's Cygnus spacecraft was on Sunday successfully unberthed from the International Space Station, beginning the next phase of its mission before it reenters Earth's atmosphere, the U.S. aerospace company said.
During the next week, the spacecraft will conduct three secondary payload missions including the Saffire-III fire experiment, deployment of four CubeSats and an experiment to further study spacecraft conditions upon reentry into the Earth's atmosphere, the company said in a statement.
For the Saffire-III fire experiment, engineers will remotely and intentionally ignite and record a 20-minute large-scale fire that will grow and advance until it burns itself out inside the vessel, after Cygnus moves to a stable orbit, the company and the U.S. space agency NASA said.
It will be the third time the spacecraft has been used to study the behavior of fires in microgravity. The first two experiments were successfully completed in June and November of 2016 respectively.
Like Saffire-I, the third Saffire experiment will burn a single large piece of fabric at different air flow rates. Saffire II burned nine samples of different materials.
"As the first chance to actually study a realistically scaled fire, the Saffire experiments have provided valuable insight into fire behavior inside a confined low-gravity environment," David Urban, Saffire principal investigator, said in a NASA statement.
NASA said it "will use this knowledge to create a safer environment for human missions, work toward preventing spacecraft fires and validate operational protocols for dealing with fire emergencies in space."
Next, the spacecraft will use a deployer to release four CubeSats into orbit for global ship tracking.
The final experiment will use three Reentry Data Collection Flight Recorders to provide crucial data about the extreme conditions a spacecraft encounters when reentering the Earth's atmosphere, according to the company.
It will also test the performance of different heat shield materials that may be used on future U.S. space missions.
The resupply mission, known as OA-7, began on April 18 when Cygnus was launched aboard a United Launch Alliance Atlas V rocket from Cape Canaveral Air Force Station.
Upon arrival at the orbiting laboratory, Cygnus delivered about 7,600 pounds (3,450 kilograms) of cargo and science experiments to the astronauts.
Prior to departure, the crew loaded the spacecraft with approximately 4,300 pounds (1,950 kilograms) of items for disposal marking the largest amount of material removed by Cygnus during its cargo resupply missions.
The OA-7 mission is scheduled to end on June 11 when Cygnus is scheduled for a destructive reentry into Earth's atmosphere over the Pacific Ocean.
