V0.2 - 17-04-2020
Planetary landers
After the safe earth entry (Discoverer 13, august 1960) it was only a matter of time before the first safe landing on another world. Actually, the first landing on the moon was before the first safe earth landing when Luna 2 crashed on the moon on the 14th of September 1959.
Humans to the moon
With every milestone in the space race reached, the finish line was moved. The ultimate goal: landing a human on the moon. This was achieved on the 20th of Juli 1969 at 20:17 UTC when Neil Armstrong and Buzz Aldrin landed their Eagle moon lander at Tranquility Base. The Apollo 11 landing was not just a single mission but was the main goal of the Mercury and Gemini missions before that. Armstrong and Aldrin spent about 21.5 hours on the surface of the moon before rejoining pilot Michel Collins and returning to the earth.
Human lunar flight is interesting from an EDL perspective for two reasons: the entry velocity and thus the mechanical and thermal loading during entry are much higher, and the mission has two landings. The latter was solved by splitting the earth landing system (Apollo capsule) and the moon landing system (LEM) into two parts. The higher heat loads were mitigated by a short skip during the entry phase. Although this skip did not go back into space, it cannot be called an actual skipping entry.
Venus
Venus is one of our sister planets in the sense that it is a rock world. But the air density, pressure and temperature are significantly higher than in our home world. The first hard landing on Venus was the Venera 3 lander in March 1966 followed by the first successful parachute deployment on Venus during the Venera 5 mission in January 1969. It was only Venera 7 in December 1970 which was the first to soft-land on Venus and marked the first landing on another world and the first signals received from another world.
Render of the Venera 3 capsule
Mars
While the Russian focus in the early days was mainly towards Venus, the US seemed to focus more on Mars. That said, it was the Soviet Union that performed the first hard landing on Mars when the Mars 2 mission crashed in November 1971. The first soft landing occurred in December of that year with the Mars 3 lander. Unfortunately, this probe did not live very long and was scientifically not very significant. This honour goes to the US Viking mission. Russia has, besides these two landings, never landed a successful mission on Mars.
The US Viking missions were launched on top of a Titan IIIE rocket in the 1970s. The missions consisted of both a lander and an orbiter. The Viking landers were followed by a large family of very successful US landers including several 1000 kg rovers.
Render of the Mars 3 capsule
Other
Venus and Mars have not been the only targets of landing missions. However, planet wise only Jupiter was visited by the Galileo probe. Other planets have not been landed on. Proposes existed for Mercury on the BePiColumbo mission but it was scraped before the mission flew. Some missions have touched asteroids and comets, often part of sample return missions. One notable planetary lander was ESA's Huygens mission which landed on Titan in 2005 marking the first landing on the moon of an outer world.
