Buried sensors are useful only until their batteries fade. That’s why the Pentagon wants to develop nuclear-powered sensors that can last for years.

What’s needed is a radioisotope power source, according to the Department of Defense Small Business Innovation Research (SBIR) solicitation.>

Resource: Read the SBIR Solicitation

The power source should be “suitable for long-lived unattended sensors or network communications nodes, capable of providing a fixed voltage (between 1.5 and 3.3 volts) at 100 microwatt power level for greater than 20 years over military useful temperature ranges,” the proposal said.

Related: Army seeks unified sensor

Apparently acknowledging environmental safety concerns, which have in the past spurred controversy over plutonium-powered satellites, the Pentagon makes clear that “the power source shall be environmentally friendly, with minimal disposal issues. Plans for obtaining a NRC license and for life-cycle management typical of radiation in military materiel are required.”