Shortly, the Herschel Space Observatory run by the European Space Agency will run out of fuel to continue its mission.

Herschel has been the largest infrared space observatory launched to date. The spacecraft has a 3.5 meter (138 inch)(11.5 ft) diameter reflecting telescope and other instruments.

To view the infrared wavelengths the mirror and instruments are cooled to close to absolute zero using liquid helium.

Unfortunately, the liquid helium stores are running out and Herschel will essentially go blind. The helium evaporates over time, gradually emptying the cryostat tank.  When Herschel was  launched, the tank carried  over 2300 liters (608 gallons) of liquid helium, weighing 335 kg (740lbs.).  Enough cooling for 3.5 years of operations in space.

According to the ESA: “When observing comes to an end, we expect to have performed over 22 000 hours of science observations, 10% more than we had originally planned, so the mission has already exceeded expectations.”

Like many other missions before it Herschel will leave a mountain of data with its passage.  Scientists will spend years reviewing and analyzing the data which may lead to other missions of science and exploration.

The James Webb Space Telescope is the next mission that will also look at the infrared universe along with a variety of other wavelengths.