The first commercial satellite, the Vanguard I, launched in 1958, was equipped with both silicon solar cells and chemical batteries.[29] By 1965, NASA was using almost a million solar PV cells. Strong government demand and early research support for solar cells paid off in the form of dramatic declines in the cost of the technology and improvements in its performance. From 1956 to 1973, the price of PV cells declined from $300 to $20 per watt.[29] Beginning in the 1970s, as costs were declining, manufacturers began producing solar PV cells for terrestrial applications.