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, 8 months and 15 days as of May 20, 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.