NASA’s James Webb Space Telescope has successfully cleared another critical testing milestone, taking this ambitious observatory one step closer to launch in 2021. The spacecraft has gone through its final thermal vacuum test meant to ensure that its hardware will function electronically in the vacuum of space, and will withstand the extreme temperature variations it will encounter during its mission. 
<p>In its recent major environmental test, technicians and engineers locked the Webb spacecraft element inside a special thermal vacuum chamber. The testing team drained the atmosphere from the room to replicate the vacuum of space, and exposed the Webb spacecraft element to a wide range of hot and cold temperatures, spanning from minus 235 degrees Fahrenheit (minus 148 degrees Celsius) to a sweltering 215 degrees Fahrenheit (102 degrees Celsius). This variation of temperatures ensures the spacecraft will survive the extreme conditions it will actually experience in space.
</p><p>Learn more about this critical testing milestone here: go.nasa.gov/2HKCRi8
</p><p>Image credit: Northrop Grumman 
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James Webb Space Telescope
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