Mars flyby and rendezvous with the flyby segment transferring the crew over. (see also Mars Excursion Module (MEM)) Alternately, a flyby-only human mission is also possible, without detaching at Mars, but to slingshot around Mars and back to Earth. In July 1965, Mariner 4 achieved a flyby of Mars with a return of data, providing the public and scientists with dramatically closer images of Mars. During the flyby Mariner 4 took 21 pictures amounting to about 1% of the surface of Mars. Mars was not globally mapped until the Mariner 9 orbiter, which over the course of 1972 to 1973 took thousands
Mars 2 3 had completed their missions by 22 August 1972, after 362 orbits. The probe, combined with Mars 3, sent back a total of 60 pictures. The images and data revealed mountains as high as 22 km, atomic hydrogen and oxygen in the upper atmosphere, surface temperatures ranging from −110 °C to +13 °C, surface pressures of 5.5 to 6 mbar (0.55 to 0.6 kPa), water vapor concentrations 5,000 times less than in the Earth's atmosphere, the base of the ionosphere starting at 80 to 110 km altitude, and grains from dust storms as high as 7 km in the atmosphere.