Mars 2M No.522, also known as Mars M-69 No.522 and sometimes
identified by NASA as Mars 1969B, was a Soviet spacecraft which
was lost in a launch failure in 1969. It consisted of an
orbiter. The spacecraft was intended to image the surface of
Mars using three cameras, with images being encoded for
transmission back to Earth as television signals. It also
carried a radiometer, a series of spectrometers, and an
instrument to detect water vapour in the atmosphere of Mars. It
was one of two Mars 2M spacecraft, along with Mars 2M No.521,
which were launched in 1969 as part of the Mars program. Neither
launch was successful. Mars 2M No.522 was launched at 10:33:00
UTC on 2 April 1969 atop a Proton-K 8K78K carrier rocket with a
Blok D upper stage, flying from Site 81/24 at the Baikonur
Cosmodrome. Two hundredths of a second after launch, one of the
Proton's first stage engines caught fire and exploded. The
rocket continued to fly on its remaining engines for about
twenty five seconds, before it pitched over and bega