Buzz
A groundbreaking material infused with microencapsulated healing agents can autonomously repair minor cracks as they appear.
Image credit: University of IllinoisJust as the human body swiftly repairs a cut, scientists are engineering composite materials that mimic this natural healing process for spacecraft. These materials are designed to autonomously fix damage, much like how scars reveal the body's ability to heal itself.
For humanity to venture deep into space and reach distant planets, spacecraft must be constructed from advanced materials. Current composites are prone to developing microscopic cracks, which can lead to significant damage over time. In February 2001, researchers at the University of Illinois at Urbana Champaign unveiled a revolutionary synthetic material capable of self-repairing when damaged.
This innovative smart material, along with similar technologies, could pave the way for spacecraft capable of enduring journeys millions of miles from Earth, where repairs are impractical. In this installment of How Stuff WILL Work, explore the self-healing composite and electronic systems that diagnose and resolve issues before they escalate.
Spaceship, Heal Thyself
This illustration demonstrates how a crack breaks open microcapsules containing a healing agent, which then interacts with a catalyst to seal the crack.
Image credit: University of IllinoisSpaceship hull damage often starts as microscopic surface cracks, invisible to the naked eye. These hairline fractures can also develop beneath the material's surface, remaining undetected. Over time, these cracks expand, weakening the structure until it fails. To combat this, a revolutionary material has been created that detects damage and repairs itself immediately, potentially extending the spacecraft's operational lifespan.
The innovative self-healing material consists of three key components:
- Composite material - The primary component is an epoxy polymer composite. These advanced materials are crafted from carbon, glass, or Kevlar combined with resins like epoxy, vinyl ester, or urethane.
- Microencapsulated healing agent - This adhesive repairs microcracks in the composite. The healing agent, a fluid known as dicyclopentadiene (DCPD), is encased in tiny bubbles dispersed throughout the material. There are approximately 100 to 200 capsules per cubic inch. Image credit: University of Illinois Scanning electron microscope image of a ruptured microcapsule.
- Catalyst - The healing agent requires a catalyst to polymerize. A patented catalyst, Grubbs' catalyst, is used in this self-healing material. It is crucial that the catalyst and healing agent remain separate until needed to repair a crack.
When a microcrack develops in the composite material, it propagates through the structure, rupturing microcapsules and releasing the healing agent. This agent flows into the crack and interacts with Grubbs' catalyst, triggering polymerization. This reaction seals the crack, and in testing, the material regained up to 75 percent of its original strength.
The applications for self-healing materials extend well beyond spacecraft. Annually, around 20 million tons of composite materials are utilized in engineering, defense, offshore oil exploration, electronics, and biomedicine. These materials will soon be found in everyday items like polymer circuit boards, artificial joints, bridge supports, and even tennis rackets.
Over the next two decades, nanotechnology is poised to revolutionize our world. This emerging field focuses on creating machines or robots at the nanoscale, measuring just a few billionths of a meter. These nanomachines will manipulate atoms and construct materials at the atomic level. Their ability to self-replicate will drastically reduce production costs for nearly any product.
One potential application of nanotechnology is the deployment of nanorobots to repair materials by absorbing surrounding molecules to fix cracks. For instance, if a spacecraft's composite shell develops a crack, nanorobots could be deployed to gather nearby molecules and repair the damage.
Before nanotechnology can advance, scientists must master atomic manipulation and program these nanomachines for specific tasks. Learn more in How Nanotechnology Will Work.
Living Wires
For extended space missions, ensuring the functionality of onboard computers and electronics is as critical as maintaining the spacecraft's exterior. NASA is developing an innovative system that equips internal wiring with self-repairing capabilities. This evolvable hardware will monitor and correct electronic systems proactively, preventing malfunctions from escalating into major issues.
Initially, self-repairing flight systems will be implemented in airplanes before transitioning to spacecraft. Researchers at the NASA Aviation Safety Program, located at the Langley Research Center, are developing such a self-healing computer system. In 1999, NASA projected that commercial systems could be available by 2004. The goal is to create a self-repairing computer system utilizing a cluster of low-power processors, connected to spacecraft systems through wireless links.
These health management and control upset management systems are designed to detect, diagnose, and prevent abnormalities before they become irreparable. The health management system will monitor critical functions, mitigate malfunctions, improve the flight crew's response capabilities, and reduce pilot workload during emergencies. Control upset management will incorporate advanced detection algorithms, predictive tools, display formats, pilot guidance, and control methods to prevent accidents during system failures. Both systems are applicable to both aircraft and spacecraft.
In the future, spacecraft may transport us to the farthest reaches of our solar system and beyond. To achieve this, spacecraft must be equipped with built-in safety mechanisms. These intelligent spacecraft will need to detect and respond to potential issues that may go unnoticed by their human occupants.
