Fire, meteor and gecko-gripper experiments en route to Space Station
At this moment, a spacecraft containing the means for astronauts to set fire outside the International Space Station is rocketing into outer space. The spacecraft is an Orbital ATK Cygnus spacecraft, and it was launched courtesy of an Atlas V rocket from Florida's Cape Canaveral Air Force Station on March 22 at 11:05 p.m. EDT. In addition to the materials for the fire-starting experiment, the resupply craft also has 7,500 lb (3,402 kg) of additional supplies aboard including the gear for a total of 250 experiments to be conducted aboard the ISS in the coming months. Here's a look at a few of the highlights.
Understanding how fire spreads in space is key to helping ensure the safety of craft and crew in all space missions going forward. That's the goal of the Saffire experiments, which kick off with this resupply mission. Unlike some of the other experiments heading up there, this one won't actually be conducted aboard the ISS, but rather inside the Cygnus capsule after it has delivered its cargo, been filled with trash from the ISS and detached from the station.
Once the capsule is a safe distance from the ISS, NASA will trigger the experiment from the ground, which consists of burning a piece of SIBAL cloth, made from fiberglass and cotton, inside a box that measures approximately 2 x 3 x 4 feet (about .6 x .9 x 1.2 meters). Contained inside the box is a camera that will observe how the cloth burns in the microgravity environment of space. The experiment will last just a few hours, but the Saffire box will remain in orbit for seven days to make sure all the data it gathers has been transmitted successful back to Earth. The Saffire box will then reenter our atmosphere where it will be destroyed.
The next Saffire experiment will launch in June and will burn up nine different materials commonly used aboard the ISS.
"Saffire is all about gaining a better understanding of how fire behaves in space so NASA can develop better materials, technologies and procedures to reduce crew risk and increase space flight safety," said Gary Ruff, Saffire project manager.
We're no strangers to seeing meteors enter the Earth's atmosphere as shooting stars. While we find them beautiful, Earth-bound scientists wanting to analyze the chunks of dust and rock that burn up in the upper reaches of our atmosphere are hampered because our planet's ozone absorbs some of the emissions the material gives off as it rockets earthward.
As part of Meteor, a visible spectroscopy instrument will be installed at the ISS' Window Observational Research Facility (WORF) rack, a section of the space station reserved for observational experiments. The spectrometer, a device that determines the composition of material based on analyzing the energy it emits, will work during the night phases of ISS orbit, particularly during meteor showers. It has the advantage of being able to analyze meteors without the interference of the Earth's ozone.
NASA hopes the experiment will help us understand how planets develop by better understanding the organic nature of the particles bombarding our own space rock.
Regolith is the material that covers celestial bodies such as our moon, asteroids and the surface of Mars. It is different from soil here on Earth in that it doesn't contain any living material. NASA aims to study regolith in the micogravity of space in order to better understand its properties, including how we might anchor into it and how it might interfere with spacesuits and other materials necessary for humans to explore space.
The Strata-1 experiment is sending multiple tubes of materials that simulate regolith to the ISS in a box with instruments that will record the effects of weightlessness on them.
"Simulant materials for Strata-1 include pulverized meteorite material of known size distribution, glass beads of known size distribution, regolith simulants composed of terrestrial materials, and other similar materials selected to either answer specific scientific questions and/or for their fidelity to regolith that astronauts and/or hardware encounter on upcoming NASA missions," says the space agency.
Strata-1 will remain aboard the ISS for one year, at which time it will be packed up and shipped back to Earth.
Earth-based means of adhesion don't work so well in space — especially for repeated uses. Tape loses its stickiness and Velcro, the current binding material of choice in space, isn't easy to reposition plus it can release fibers into the environment and requires two sides to work.
To achieve stickiness in space, NASA turned to the gecko. Geckos' feet are covered in thousands of tiny hairs. When these hairs meet resistance on a surface, such as the gecko's weight pulling it down while it clings to a vertical surface, van der Waals force comes into play. This force basically operates according to the principle that due to the uneven distribution of electrons in molecules, one side is always positive, while one side is always negative. When materials are pressed together, these positive and negative molecular sides attract and cause a type of stickiness.
Using this idea, NASA created grippers featuring pads with thousands of little hairs a la the gecko. When a shearing force is applied to the pads — that is, when they are forced together, the van der Waals forces come into play and the material stays attached to whatever it is placed upon.
While NASA has already been able to test these grippers out successfully aboard their zero-gravity aircraft nicknamed the "vomit comet," which provides weightlessness for about 20 seconds, now they will be able to conduct longer tests in the zero-g environment of the space station. More information is available in the video below.
The Cygnus spacecraft is scheduled to arrive at the ISS on Saturday, March 26.