inserted into an elliptical 1755 by 32,555 km, 24 h 53 min orbit with an inclination of 35.3 degrees. Nearly synchronized with the rotation of the planet, its two phototelevision cameras could be commanded to take 12 pictures during each close approach. The Vega camera used a wide area 52mm lens with color filters, the Zulfar camera used a telescopic 350mm lens and long-pass orange filter. Images were transmitted in a rapid 220-line mode, and then selected pictures were retransmitted at 880 or 1760 line resolution. Mars 5 collected data for 22 orbits until a loss of pressurization in the transmitter housing ended the mission. About 60 images were returned over a nine-day period showing swaths of the area south of Valles Marineris, from to . Mars 3MP In 1973 the speed required to place a spacecraft in an interplanetary trajectory had to be increased. Thus the Proton could not deliver spacecraft with an orbiter and an attached lander to the necessary trajectory to reach Mars, as had been possible in 1971. To resolve this problem, four spacecraft were launched. The Mars 4 and 5 orbiters, which had been launched separately, were used to relay communications, and to complete mission objectives which would have been completed by landers. Two landers were launched with orbiter type buses (Mars 6 and 7), but without fuel to enter orbit of the Mars satellite. Mars 6 Mars 6 successfully lifted off on August 5, 1973, into an intermediate Earth orbit on a Proton-K/D booster and then launched into a Mars transfer trajectory. Total fueled launch mass of the lander and bus was 3260 kg. It reached Mars on March 12, 1974. The descent module separated from the bus at a distance of 48,000 km from Mars. The bus continued on into a heliocentric orbit after passing within 1600 km of Mars. The descent module entered the atmosphere at 09:05:53 UT at a speed of 5.6 km/s. The parachute opened at 09:08:32 UT after the module had slowed its speed to 600 m/s by aerobraking. During this time the craft was collecting data and transmitting it directly to the bus for immediate relay to Earth. Contact with the descent module was lost at 09:11:05 UT in "direct proximity to the surface", probably either when the retrorockets fired or when it hit the surface at an estimated 61 m/s. Mars 6 landed at in the Margaritifer