- Scientists at NASA’s Jet Propulsion Laboratory in Pasadena, California, are working on adhesive gripping tools that could grapple objects such as orbital debris or defunct satellites
- This debris can cause serious damage to orbiting satellites that would otherwise be hard to handle.
- The gecko gripper project was selected for a test flight through the Flight Opportunities Program of NASA’s Space Technology Mission Directorate.
- As a test, researchers used the grippers in brief periods of weightlessness aboard NASA’s C-9B parabolic flight aircraft in August.
- There are more than 21,000 pieces of orbital debris larger than 3.9 inches (10 centimeters) in Earth’s orbit.
- 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. (Remember Gravity movie!!!, what all a orbiting debris can do..)
What is Gecko Gripper Project?
- Developed by Dr. Parness and his colleagues at JPL
- Inspired from Gecko – lizards which stick to walls
- These have tiny hairs on their feet (thinner than human hair), with which they can easily stick to rough surfaces.
- Although not a perfect replica, still they have put “hair” structures on the adhesive pads of the grippers.
- The 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.
How it works?
- Force is applied to the adhesive pad material in a manner that makes the hairs 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.
- Van der Waals force explains the non permanent stickiness of the grippers.
Van der Waals forces
Van der Waals forces
- Have been tested on more than 30 spacecrafts surfaces at JPL
- Successfully tested 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.
- In the recent tests, the grippers were able to grapple a 20-pound cube as it floated.
- Also able to grapple a researcher wearing a vest made of spacecraft material panels, representing a 250-pound “object.”
- Term is used to describe scenario in which the density of objects in the low earth orbit, is increasing and later becomes high enough that collisions between these objects assume cascading proportions.