Did you know that Apollo 12 spacecraft – the spacecraft that preceded the Apollo 13 mission made famous by the movie starring Tom Hanks – was struck by lightning? Twice?
According to NASA’s tech brief:
At 36 seconds after launch, lightning struck Apollo 12, causing a massive current to travel down through the outer skin of the spacecraft, to the launch vehicle, and down through the rocket flumes to the ground. Launch controllers immediately lost telemetry contact with the crew. …the lightning strike triggered these overload circuits, which [led to additional failures, including in fuel cells]….
A second lightning strike that occurred at 52 seconds after liftoff tumbled the craft’s Inertial Measurement Unit (IMU) gyroscopes. The high dV/dt (delta voltage/delta time) surge from the lightning strikes also caused minor measurement instrumentation failures, including four helium tank quantity measurements, five thermocouples, and four pressure/temperature transducers. Fortunately, the crew was able to reset critical systems because the craft’s battery-powered emergency bus had continued to operate, which allowed them to continue with their mission safely.
This Smithsonian National Air and Space Museum article tells us that spacecraft are constructed with heat-maintaining materials and metals that cover the spacecraft to protect its inner structure from temperature and micrometeoroids. The Apollo 11 Lunar Module (LM) reveals that “the black materials on parts of the LM are heat-resistant nickel-steel alloy, 0.0021072 millimeters (0.0000833 inches) thick. The black sheets absorb heat when exposed to the Sun and radiate to the blackness of deep space….Not metal foil, these plastic films are thinly coated with aluminum, which reflects the sun’s heat and insulates the spacecraft.”
Certain Metals Protect Aircraft Against Lightning Strikes
Aircraft have also been hit by lightning. CNN reported last August that lightning struck a plane in line for takeoff at the Atlanta international airport. Luckily no one was hurt. Just this past April, two planes were struck by lightning en route to London. In March, the Daily Mail reported that passengers on a North Carolina to New York flight were shaken after their plane was struck by lightning and forced to make an emergency landing. Again, no one was hurt since aircraft are manufactured with suitable metals to withstand a lightning strike, but electrical systems can be disrupted or some minor damage may occur.
According to the Smithsonian’s Air & Space magazine, every airliner is struck by lightning in flight at least once a year, on average. An array of measures – including aluminum and advanced composite materials, strategically placed conductive metals, mesh coverings, and thin films — have improved safety. Careful lightning protection has been engineered into the aircraft and its sensitive components so the strike should not affect passengers or crew.
The NASA sheet metal shop reports that aluminum is the most common metal found on aircraft because it is light in weight and is easy to bend and form into the many shapes common to sleek, high-performance aircraft.
The International Titanium Association reports that for modern spacecraft, in addition to aluminum, titanium is the metal of choice. Selection of titanium for both airframes and engines is based upon its specific properties: weight reduction (due to the high strength-to-weight ratio), coupled with exemplary reliability that is attributable to its outstanding corrosion resistance and mechanical properties.
Luckily, due to using the appropriate metals and alloys, as well as the engineering know-how, passengers are usually safe. However, avionics and flight control systems, if improperly designed, are critically vulnerable to a spike in current from a lightning strike. Avionics – electronic equipment connected with aircraft, artificial satellites, and spacecraft – help keep airplanes in the air. Whether it’s for navigation, communication, or to help fly the plane, the avionics are crucial to the industry, and to human lives. That’s why electronic devices on board are protected by overvoltage arresters and designed as redundant systems, so there are backups.
Protecting Electronics from Lightning
If you are part of the engineering and manufacturing supply chain for commercial, civil and military space, the last thing you want to happen is to ship electronic components that do not meet quality standards, and cannot survive a lightning strike to the plane. With critical electronics, failure is not an option.
Speaking of lightning protection, we will be in booth #2024 at Space Tech Expo, demonstrating a multi-function lightning simulation test platform, which simulates the indirect energy effects of a lightning strike according to the requirements of RTCA DO-160, specifically RTCA DO-160G Section 17 (Voltage Spikes) and Section 22 (Lightning Induced Transient Susceptibility), MIL-STD-461G/CS-117, and the unique requirements of EUROCAE, Boeing, Airbus and others. If you are a manufacturer in the aerospace industry, you need to verify that your products can withstand electrostatic discharge (ESD) events and other threats with comprehensive simulators and test systems that ensure your semiconductors, integrated circuits, and other electronic products are in compliance with national, international, and industry ESD and electromagnetic compatibility (EMC) test standards.
When you are considering a lightning simulation test platform, make sure testing includes pin injection, cable bundle and ground injection with single stroke, multiple stroke and multiple burst modes from the same front panel. In addition, make certain the platform can expand as test requirements evolve or to allow the operator to double his capacity using existing modules without purchasing another system.
Space Tech Expo
Space Tech Expo 2016 is a great place to check out the latest aerospace technology. This three-day conference, being held May 24-26 in Pasadena, California USA, brings together scientists, engineers, C-level executives, government representatives, policy makers, space agencies, military and entrepreneurs to debate the key challenges and opportunities in civil and commercial space. Folks from all sectors of the industry — satellite systems, launch vehicle and spacecraft design, engineering, testing, and all facets of the manufacturing supply chain – will be looking for the latest spacecraft technology.
If you are planning to attend the show, make sure you stop by the Aerospace Testing Zone — an area dedicated to testing and measurement, including materials, components and structural testing, electrical systems, power management, data acquisition, sensors, NDT, EMC/EMI, and ATE. This dedicated exhibition will also include free sessions showcasing different technologies. Here’s a link to the floor plan in case you want to plan your booth visits.
If you are in the area and need an expo pass, just click here to register for a free expo pass. Then stop by our booth to check out ESD, EMC, and TLP test equipment, and our lightning test simulator.