Given the high sensitivity of the detector arrays it is essential that they be operated at very low temperatures and shielded from as much stray light and thermal emission as possible. In order to achieve this, BLAST-TNG uses a Liquid-Helium-cooled cryostat to keep the optics bench with the re-imaging optics near 4 K. The detector arrays are cooled below 300 mK using a closed-cycle 3He refrigerator on the 4 K.
Additional thermal isolation of the 4 K stage from the 300 K exterior is provided by two vapor cooled shields. These use heat exchangers to extract cooling power from the Helium vapor that is boiled off during the normal course of operations.
BLAST-TNG’s flight duration is limited by the quantity of Helium that it can hold so we will have a 250-liter Helium tank that will give us a hold time of about 28 days. This will give us time to observe a rich sample of targets across the southern sky.