On October 17th, the most recent Cygnus ship (named the S.S. Alan Poindexter) carried 5,000+ pounds of supplies and gear to the International Space Station. For the past month, it’s been attached to the ISS. The crew has been busy carrying supplies off Cygnus and throwing trash and unused gear into it.
At 8:22 am ET, Expedition 50 Commander Shane Kimbrough released Cygnus with an assist from Flight Engineer Thomas Pesquet. Watch the supply ship drift away from the ISS.
The ship’s time with the ISS might be done, but it has two more things to do before it burns up during Earth reentry.
“Now, we get another opportunity to showcase this unique spacecraft’s expanded capabilities beyond its core cargo delivery function,” says Frank Culbertson, President of Orbital ATK’s Space Systems Group, in a statement. “To use Cygnus yet again as a research platform demonstrates a versatility and flexibility that we are proud to offer to our customers.”
First up, NASA will intentionally set nine different material samples on fire. The experiment is called the Spacecraft Fire Experiment-II (Saffire-II) and is the second in a series of planned experiments designed to study how large-scale fires behave in microgravity.
Cygnus represents the perfect testing environment for Saffire. Obviously, NASA doesn’t want to start lighting material on fire aboard the ISS. The chances of something going wrong are too high. But on a supply ship heading for a destructive reentry? It’s the perfect solution.
Saffire I and Saffire III will specifically study how a flame spreads and grows over a piece of material one meter long. Saffire II (the current experiment) will look at a wide range of materials selected by NASA to see their flammability limits. Each piece of material measures 5 cm wide by 25 cm long and is ignited at the bottom using a hot wire. Oxygen concentration inside Cygnus is matched to the ISS at nearly 21%.
Here’s an illustration of what the Saffire experiment module looks like.
Besides setting stuff on fire, the S.S. Alan Poindexter will also deploy four LEMUR CubeSats into orbit to conduct meteorological research. The four tiny satellites are part of a remote sensing satellite constellation that assists global ship tracking and weather monitoring. Here’s one of the CubeSats being loaded into its deployer.
Data gathered from these satellites range from improving weather forecasts for the shipping industry to helping coast guards prevent piracy.
Cygnus’ fiery end
On November 27th (Sunday), the Cygnus spacecraft will fire its engine and send it on a crash course with Earth’s atmosphere over the Pacific Ocean. Every piece of the spacecraft will burn harmlessly over the vast ocean.
The constant train of supply vehicles inbound to the ISS continues on December 1 with the launch of Progress MS-04 from the Baikonur Cosmodrome.