Every once in a while, scientific perfection in the way of hardware design appears. The two Mars rovers, Spirit and Opportunity come to mind along with the Planck, an exquisitely designed space craft developed to measure the microwave background radiation of the universe by cooling its sensors down to 0.1 degrees above absolute zero via liquid Helium.
The detectors of the High Frequency Instrument (HFI) only work properly when cooled to very low temperatures, and for the duration of the mission have been cooled to 0.1 degrees above absolute zero (-273.15 Celsius) – making them the coldest known place in space! The refrigerator that keeps them cold relies on helium gas, and it is this that has finally been exhausted.
Cardiff University researchers, led by Professor Peter Ade, have been heavily involved in the design, build, testing and operation of HFI for over ten years. “We put as much Helium-4 and Helium-3 gas onboard as we could squeeze in and are therefore delighted that the HFI has operated for almost three times its nominal mission lifetime”, explained Professor Ade. “This is a testimony to the expertise of the scientific and technical teams who designed, built and operated Planck and its scientific instruments.”
Originally, the Mars Rovers mission was targeted for 90 days, it's now going on 7 years, a testimony to visionary engineering without question.