Final answer:
Satellite sensors for observing cold, dark space must be kept at low temperatures to reduce thermal noise and accurately measure weak signals of space radiation without interference from their own heat.
Step-by-step explanation:
Satellites that are designed to observe the cold, dark space are equipped with sensors that need to be kept at very low temperatures. These sensors are shaded from the Sun, Earth, and Moon to prevent the warming effects of their radiation. The reason the sensors must be at low temperatures is to reduce thermal noise, which can interfere with the detection of the very faint sources of energy at the cold temperatures of space radiation. In short, low temperatures are essential for the sensors in these satellites to accurately measure the weak signals without the interference of their own heat emission.