A Clear View of the Stars
In 1999, NASA launched the Stardust probe. Its five-year mission (well, seven years actually) was not to boldly go. Instead, its job was to collect dust from the tail of a comet and return it safely to Earth for analysis. At the end of the primary mission, the capsule landed in the Utah desert, and scientists were able to get a close look at material left behind after the birth of the solar system.
Stardust, we have a problem...
Despite this scientific success, the mission did not go entirely smoothly. One of the instruments, called the Navigation Camera, experienced a significant loss of resolution. The hope was that this camera could be used to collect detailed images, and create a 3D image of the comet’s nucleus. However, when the images were received back on Earth, it became clear that something had gone wrong. The images did not provide the crystal-clear resolution that had been expected.
This was caused by outgassing. Outgassing is a process in which gas that has become trapped inside another material is released. This is a common problem when materials are exposed to a vacuum or are subject to high temperatures, such as during spaceflight. Under these conditions, the trapped gases escape and can cause problems. In the case of Stardust, the gas that had been released condensed onto the coldest surface available, which turned out to be the optics and sensors of the camera. This in turn severely degraded the resolution of the images that the camera could capture.
The challenges of outgassing
Scientists and engineers have long been familiar with the issues surrounding outgassing, as it creates real challenges when it comes to working with high-vacuum environments. There are several solutions to the problem, including the careful selection of materials that are known to produce little or no outgassing. Alternatively, materials can be purged before use by raising their temperature which drives off the trapped gases in a process known as “baking out”.
As the Stardust example shows, the risk of outgassing remains even after careful preparation. This has become even more relevant as designers embrace the benefits of commercial off-the-shelf (COTS) equipment. Industries that have previously dictated the use of high-performance components have seen the logistical, technical, and financial advantages that the adoption of COTS equipment can provide.
However, in order to use these commercial products, customers need to know they will perform under potentially harsh conditions. In the past, this would have been simple. Choosing a product that conformed to a known standard such as those published by NASA would give the engineer confidence that it had been tested. How can an engineer gain the same level of confidence with COTS equipment?
The testing of COTS components
One manufacturer, Samtec, has understood the challenge and has developed a program to deliver this confidence to customers. Samtec manufactures connectors that are at the leading edge of technology, especially in high-speed data applications. These products are extremely attractive to designers working in the medical, space and scientific markets, who need to combine the latest technology with harsh environment performance.
The Severe Environment Testing (SET) program seeks to test Samtec products beyond typical industry standards, ensuring that they are suitable for use in the most demanding applications. For more information on what outgassing is and how materials are tested, visit Samtec’s guide to outgassing here.
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