A resupply ship from Orbital ATK is ready to launch its largest cargo ever to the International Space Station. The newly redesigned Cygnus craft, first launched in December, is capable of carrying 25 percent more payload than before, and today's weighs nearly four tons. "It's like opening a box of goodies and finding some stuff you've been wanting and some surprises you didn't know about," says Orbital's Dan Tani, a former ISS astronaut. Along with the supplies, Cygnus will carry a 3D printer from Made in Space, two dozen nanosatellites and Saffire, an experiment to test the effects of fire in space.
The Saffire experiments are scheduled to run after all the cargo is unloaded. Fire is obviously a serious hazard in space, so the goal is to safely study how it propagates in zero-gravity. Normally, the crew would just load Cygnus with trash and lets it burn up on re-entry into the atmosphere. This time, however, it will remotely ignite a piece of cloth inside a five-foot-wide module to study how fire behaves in a micro-gravity environment.
If all goes well, Cygnus will launch today at 11:05 PM eastern time, with a 30 minute launch window extension. It will dock with the ISS on March 26th and the Saffire experiment will happen at some point after that, though NASA hasn't said when yet, exactly. Once the experiment is complete, it will remain in orbit seven days while scientists download data from sensors and video cameras. After that, they'll send Cygnus off to burn up on re-entry as usual.