Researchers at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California are developing gecko grippers to grab space debris which includes the objects like orbital debris or defunct satellites. Gecko gripper is basically an adhesive gripping tool.
The news related to this was published on the website of Jet Propulsion Laboratory on 19 December 2014.
The gripping system has been developed by Aaron Parness who is a JPL robotics researcher and the principal investigator for the grippers.
The system is inspired by geckos, type of lizards belonging to the infraorder Gekkota, found in warm climates throughout the world.
How it works
The Gecko grippers being developed have synthetic hairs like tiny hairs in Geckos' feet. These synthetic hairs also called stalks are wedge-shaped and have a slanted, mushroom-shaped cap.
When the gripping pad lightly touches part of an object, only the very tips of the hairs make contact with that surface. The stickiness of the grippers can be turned on and off, by changing the direction in which you pull the hairs.
The non-permanent stickiness of the gecko gripper is achieved through use of van der Waals force. The force is named after Nobel Prize-winning physicist Johannes Diderik van der Waals.
When the van der Waals force is applied to the adhesive pad material, the synthetic hairs tend to bend. This increases the real area of contact between the hairs and the surface, which corresponds to greater adhesion. When the force is relaxed and the hairs go back to being upright, this process turns off the stickiness.
These temporary adhesive forces happen because electrons orbiting the nuclei of atoms are not evenly spaced, creating a slight electrical charge. Such forces persist even in extreme temperature, pressure and radiation conditions.
The successful experiments
More than 30 spacecraft surfaces tests have been conducted to check the accuracy of the grippers at JPL.
Earlier in August 2014, a test flight was conducted on the gecko gripper project through the Flight Opportunities Program of NASA's Space Technology Mission Directorate. During the test researchers used the grippers in brief periods of weightlessness aboard NASA's C-9B parabolic flight aircraft.
During the test, the grippers were able to grapple a 20-pound cube as it floated. The grippers also were able to grapple a researcher wearing a vest made of spacecraft material panels, representing a 250-pound object.
Grippers have also been tested successfully in a JPL thermal vacuum chamber, with total vacuum conditions and temperatures of minus 76 degrees Fahrenheit (minus 60 degrees Celsius) to simulate the conditions of space.
Also, the grippers were tested separately in more than 30000 cycles of “on" and "off," with the adhesive staying strong. Several prototypes have since been designed.
Uses of Gecko gripper
Besides grappling orbital debris, the grippers could help inspect spacecraft or assist small satellites in docking to the International Space Station.
The system could also grapple objects in space that are spinning or tumbling, and would otherwise be hard to target.
Why there is need of such tool
There are more than 21000 pieces of orbital debris larger than 3.9 inches (10 centimeters) in Earth's orbit. The U.S. Space Surveillance Network routinely tracks these objects. In 2009, an accidental collision occurred between an operational communications satellite and a large piece of debris, destroying the satellite.
When: 19 December 2014
Why: to grab space debris