Gotcha: Space Station Grabs Onto NASA's 5,100-Pound Cargo Craft

Astronauts used the International Space Station's robotic arm to grapple the Cygnus cargo spacecraft early Sunday morning, starting the process of bringing more than 5,100 pounds of supplies and research equipment aboard. The cargo's experiments include one thing astronauts normally avoid: fire.

"The new experiments include studies on fire in space, the effect of lighting on sleep and daily rhythms, collection of health-related data, and a new way to measure neutrons," NASA says.

Aboard the station, NASA's Kate Rubins and the Japan Aerospace Exploration Agency's Takuya Onishi snagged the Cygnus craft just before 7:30 a.m. ET; at the time, it was about 250 miles above Kyrgyzstan. The second phase of the rendezvous will begin at 9 a.m., when the cargo craft, built by aerospace company Orbital ATK, will be attached to the bottom of the ISS's Unity module.

It's been a busy weekend for the space station. On Friday, three astronauts — two Russians and one American — docked at the ISS, opened their hatch, and were greeted by the trio that was already aboard, giving the station its normal six-person crew.

Cygnus will stay at the station until mid-November — when it'll be packed full of trash and cut loose so that it can burn up on reentry into Earth's atmosphere. During that final trip, NASA says, a "large-scale fire" will be ignited inside Cygnus, with measurements and images beamed back to Earth.

Here are more details from NASA's description of the scientific projects Cygnus is carrying:

"Low-temperature fires with no visible flames are known as cool flames. In previous combustion experiments aboard the space station, researchers observed cool flame burning behaviors not predicted by models or earlier investigations. The Cool Flames Investigation examines low-temperature combustion of droplets of a variety of fuels and additives in low gravity. Data from this investigation could help scientists develop more efficient advanced engines and new fuels for use in space and on Earth.

"The Lighting Effects investigation tests a new lighting system aboard the station designed to enhance crew health and keep their body clocks in proper sync with a more regular working and resting schedule. The system uses adjustable light-emitting diodes (LEDs) and a dynamic lighting schedule that varies the intensity and spectrum of the LEDs in tune with sleep and wake schedules. Research has shown that enhancing certain types of light can improve alertness and performance while other types can promote better sleep.

"A user-friendly tablet app provides astronauts with a new and faster way to collect a wide variety of personal data. The EveryWear investigation tests use of a French-designed technology to record and transmit data on nutrition, sleep, exercise and medications. EveryWear has potential for use in science experiments, biomedical support and technology demonstrations.

"Astronauts aboard the space station are exposed to space radiation that can reduce immune response, increase cancer risk, and interfere with electronics. The Fast Neutron Spectrometer investigation will help scientists understand high-energy neutrons, part of the radiation exposure experienced by crews during spaceflight, by studying a new technique to measure electrically neutral neutron particles.

"The new experiments will include an investigation that looks at fuels that burn very hot at first, and then appear to go out, but actually continue to burn at a much lower temperature with no visible flames. A second planned large-scale fire inside Cygnus will be ignited after it leaves the space station to help researchers understand how fire grows in microgravity and design safeguards for future space missions. Cygnus also is carrying a new station research facility that will enable a new class of research experiments by allowing precise control of motion in the microgravity environment aboard the station."