Voyager 1 is a space probe launched by NASA on September 5, 1977. Part of the Voyager program to study the outer Solar System, Voyager 1 was launched 16 days after its twin, Voyager 2. Having operated for 41 years, 7 months and 29 days as of May 4, 2019, the spacecraft still communicates with the Deep Space Network to receive routine commands and to transmit data to Earth. At a distance of 145 AU (21.7 billion km; 13.5 billion mi) from Earth as of February 22, 2019, it is the most distant from Earth of all known man-made objects.