Nasa has lit an experimental fire onboard a cargo delivery space capsule to study the risks and improve astronaut safety in future missions.
The Saffire-I experiment took place aboard the Orbital ATK Cygnus spacecraft after it departed from the International Space Station (ISS) on Tuesday. After the spacecraft moved away from the space station sufficiently, controllers at Nasa’s Glenn Research Center in Cleveland, Ohio, remotely triggered the fire.
“Saffire-I has been ignited inside the Orbital ATK Cygnus cargo spacecraft and telemetry indicates a burn of the cotton-fiberglass material blend,” Nasa said in a blog post. “The largest fire started in space is now burning successfully.”
The experimental payload will continue burning for eight days until the Cygnus capsule re-enters the Earth’s atmosphere where it will be destroyed. The payload, 1 by 1.3 metres in size, consists of an avionics bay and a flow duct, which contains a one-metre long strip of cotton fibreglass. The cotton fibreglass was ignited by a hot wire.
Until the re-entry, scheduled for 22 June, the experiment will keep transmitting high-resolution images of the fire burning, as well as sensor data about temperature and oxygen and carbon dioxide levels.
Saffire-1 is the first in a planned three-part series of experiments designed to study how flames spread in microgravity.
“Nasa’s objective is to reduce the risk of long-duration exploration missions and a spacecraft fire is one of the biggest concerns for Nasa and the international space exploration community,” said Jason Crusan, Nasa’s Advanced Exploration System director.
Nasa’s Spacecraft Fire Safety Demonstration project manager Gary A. Ruff added: “Gaining a better understanding of how fire behaves in space will help further Nasa’s efforts in developing better materials and technologies to reduce crew risk and increase space flight safety.”
In 1997, a fire aboard Russia’s MIR space station caused by a malfunctioning oxygen generator put the crew’s lives at risk when plumes of toxic smoke filled the station’s interior.
Nasa has previously conducted studies aboard the space shuttle and the ISS, although those have been smaller in scale due to the risks involved. The largest fire deliberately set in space before Saffire-I was approximately the size of an index card.
Fire safety will be a critical element as Nasa progresses on the journey to Mars and begins to investigate deep space habitats for long duration missions.
"We tried for years to find a vehicle and a circumstance where this would work and initially we'd get a 'not on my spacecraft' reaction," said David Urban, Saffire lead researcher.
Fire behaves differently outside of Earth's atmosphere, so scientists want to test whether microgravity will limit flames and what materials will burn.
"One of the big questions is: how big will the flame get?" Urban said.
Nasa plans to carry out two more Saffire experiments aboard future Cygnus spacecraft. Saffire-II, to be conducted later this year, will focus on oxygen flammability limits. The final Saffire-III will involve a similar large-scale microgravity fire as the current Saffire-I.