Editing Mars program (section)

===Mars 4M===
[[File:Mars3 iki.jpg|thumb|[[Mars 2]] and [[Mars 3]] orbiter]]
[[File:FP2A3620 (23497688248) (cropped).jpg|thumb|[[Mars 2]] and [[Mars 3]] lander]]
[[File:PrOP-M.jpg|thumb|[[PrOP-M]] rover]]
[[File:1972 CPA 4113.jpg|thumb|Mars 2 stamp]]
[[Image:1972 CPA 4114.jpg|thumb|right|Mars 3 lander stamp]]
The Mars 4M spacecraft; [[Mars 2]] and [[Mars 3]] missions consisted of identical spacecraft, each with an orbiter and an attached lander, which became the first spacecraft to reach the surface of Mars.

The orbiters' primary scientific objectives were to image the Martian surface and clouds, determine the temperature on Mars, study the topography, composition and physical properties of the surface, measure properties of the atmosphere, monitor the [[solar wind]] and the interplanetary and Martian [[magnetic field]]s, and act as communications relays to send signals from the landers to Earth.

Both landers had a small Mars [[rover (space exploration)|rover]], [[PrOP-M]], on board, which would move across the surface on skis while connected to the lander with a 15-meter umbilical. Two small metal rods were used for autonomous obstacle avoidance, as radio signals from Earth would take too long to drive the rovers using remote control. Each rover had both a densitometer and a dynamic penetrometer, to test the density and the bearing strength of the soil. Because of the demise of the landers, neither rover saw action.

The Mars 2 and 3 orbiters sent back a large volume of data covering the period from December 1971 to March 1972, although transmissions continued through August. It was announced that Mars 2 and 3 had completed their missions by August 22, 1972, after 362 orbits completed by Mars 2 and 20 orbits by Mars 3. The probes sent back a total of 60 pictures. The images and data enabled creation of surface relief maps, and gave information on the Martian [[gravity]] and [[magnetic field]]s.<ref name=Images/>

{| class="wikitable sortable"
! Public name
! Internal name
! Mission
! Launch date
! Carrier rocket
! Outcome
! Remarks
|-
| [[Mars 2]] || 4M No.171 || Orbiter/<br>Lander || 19 May 1971 || [[Proton-K]]/[[Blok D|D]] || {{Partial failure}} || Successfully inserted into a 1,380 x 24,940 km elliptical orbit on 27 November 1971. However, its lander crashed somewhere within [[Hellas Planitia]] ({{Coord|45|S|30|W|globe:Mars}})<ref name=nssdc-m2/>
|-
| [[Mars 3]] || 4M No.172 || Orbiter/<br>Lander || 28 May 1971 || [[Proton-K]]/[[Blok D|D]] || {{Success}} || Successfully inserted into a 1,500 x 211,400 km elliptical orbit on 2 December 1971. Its lander became the first spacecraft to land intact on Mars, however contact lost just 110 seconds after touchdown on [[Ptolemaeus Crater]] ({{Coord|45|S|202|E|globe:Mars}})<ref name=nssdc-m3/>
|}