Mercury

Mercury
Base Data
Radius	122 kilometers
Gravity	3.7 m/s2
Timewarp Height	2500 meters
Color	RGB: 105, 95, 89 HEX: #695F59
Orbit Data
Semi-major axis	2895452.5 kilometers
Eccentricity	0.21
Argument of periapsis	29°
SOI radius	11,710 kilometers

Mercury is the closest and smallest planet to the Sun. It is a mottled gray, airless and moonless world. At 244 kilometers in diameter, it's considerably smaller than the next biggest planet Mars, although its gravity of 3.7 m/s² is very similar to that of Mars.

In-game it orbits the Sun on an ellyptic path at a mean distance of around 2.9 mio. kilometers, which is about 0.39 AE. The excentricity of 0.21 is the highest of any planet in the solar system.

Mercury is also one of the hardest planets to reach due to the proximity to the sun and low gravity.

Surface

Mercury's surface is very rocky, and has a lot of craters most-akin to the Moon or Jupiter's outer-most moon Callisto. In contrast to those moons, Mercury's craters are larger and more spread out on the surface.

Mercurian surface

Landmarks

Mercury has only 2 landmarks which are both plains. It is the planet with the fewest number of landmarks in the solar system.

Borealis Planitia

Borealis Planitia (Latin for Northern Plain) is a plain on Mercury with several craters inside. It can be a landing site for some landers because of its flatness.

Caloris Planitia

Caloris Planitia (Latin for Plain of Heat) is a plain on Mercury and like Borealis Planitia it has several craters and hills. It's marked by a mountain in its very center. At the sides of the basin there are a couple of tall mountains, Caloris Montes (Mountains of Heat).

Atmosphere

Mercury has no atmosphere, therefore aerobraking, aerocapture and parachutes cannot be utilized

Missions to Mercury

Due to the planet's proximity to the Sun and its own weak gravity, missions to Mercury are difficult endeavours and therefore seen as a great accomplishment in the SFS community.

Landing

A successful landing requires the spacecraft first enter into a helio-centric orbit from which the planet can be approached gradually. To help slow down the rocket from its journey to Mercury, one or multiple flybys of Venus or Mercury itself may be done. To get into orbit around Mercury, retrobootsters are required as the planet's absent atmosphere doesn't allow for aerocaptures.

Descending to the surface requires the use of retrorockets to decelerate the spacecraft as aerobraking isn't an option. Hence, parachutes are also useless at slowing the descent. Heat shields aren't needed.

Take Off

Returning from Mercury to Earth is very costly. Escaping the planet's gravitational sphere of influence isn't overly complicated and similar to the take off from Mars, but increasing the orbit around the Sun to reach Earth requires an immense amount ot delta-v and therefore fuel. Venus may also be used as a gravity assist along the way, though it is of limited aid.

Gravity Assist

Utilizing Mercury's gravitational pull to reach another planet is practically useless due to its position in the solar system and small distance to the Sun. The only scenario in which gravity assists may be useful is when trying to land on Mercury itself, to help decelerate the rocket.

Achievements

There are two achievements that can be obtained on on Mercury:

1. Captured into low Mercury orbit
2. Landed on the surface of Mercury

Gallery

A rocket crashed on Mercury's surface because of a failure.

A probe orbiting Mercury

A close fly-by of Mercury showing large craters on its surface

A picture on the surface of Mercury showing the Sun. This is still not implemented yet.

Information

• Mercury, like the moon, has a tiny little exosphere in real life. However, this probably wasn't added into the game because the atmosphere would be too thin to make a difference on the gameplay.
• Mercury's gravity is weaker than in real life. Its real life gravity is 3.7 m/s²

Trivia

• Mercury has a high density because it is mainly composed of iron.
• On the Spaceflight Simulator Forums, Mercury is often referred to as “The Graveyard” due to how difficult it is to orbit and land on.
• In 1.4, Stef Moroyna screwed up Mercury's texture while modifying it to make it more realistic, so it was white until it was fixed in 1.5.
• Mercury in real life has a thin atmosphere (or exosphere), composed of oxygen, hydrogen, helium, sodium and potassium.
• Mercury is also the closest planet of all planets in the solar system.
• In the game, Mercury shares the same size as Callisto, at 120 kilometers; in reality, Mercury is slightly larger than Callisto by 40 kilometers.
• In real life, 3 spacecraft explored Mercury: Mariner 10, MESSENGER and BepiColombo.