Mercury Activities

In Spaceflight Simulator, Mercury is a challenging planet to visit on, due to its proximity to the sun and the high delta v budget needed to go to Mercury.

## Requirements

Mercury is very close to the Sun. To conduct a flyby, there is a high demand of fuel. To enter orbit, fuel is also needed in larger amounts than in case of other planets. The lack of an atmosphere means that fuel and retrorockets will be needed for landing too. To return from Mercury to Earth, a rocket will require more fuel than in case of any other planet.

In addition, Mercury has a small Sphere of Influence, which requires very good timing in engine burns.

The surface of Mercury is similar to the surface of Moon, but it has deeper craters and they are far apart.

To reach Mercury, a rocket can take advantage of a Venus flyby. However, if Mercury and Venus are not correctly aligned (or while returning if Venus and Earth are not aligned), the flight can take a long time. See also this page for different techniques how to go to Mercury easily.

Unlike in real life; in the simulator, Mercury has a circular orbit.

## Reaching Mercury

The most easy way (but expensive) is to use a transfer window directly towards Mercury. The rocket will require a high amount of fuel. Engine burns will need to be carefully selected, in order to enter Mercury's little sphere of influence. Additional trajectory correction maneuvers may be required.

Sometimes, the tiny transfer window is lost or the engine burns are not correctly done. In this case, if the rocket has enough fuel, there are two options:

1. Wait for a better planetary alignment, then adjust orbit.
2. At perihelion, fire engines backwards, lowering the aphelion. This way, it will be more easy to reach Mercury.

There is also a third option: return home. To achieve this, at aphelion, fire engines forward, to rise perihelion and make an easier return to Earth.

**Gravity assists** can be used. In order to do this, firstly fly towards Venus. Then, upon entering Venus, look on the map to see how close to Mercury your perihelion will get.

There are other, more complex ways to reach Mercury: one or two Moon flybys (to exit Earth's orbit), followed by an Earth flyby (to reach Venus orbit), one or two Venus flybys (to reach Mercury's orbit) and one or two Mercury flybys.

Here's an easy way to get to Mercury: You need to build three rockets, one needs to be the core stage (it doesn't need to be anything special, just some fuel, an engine and a docking port for a Mercury lander), the second one needs to be your Mercury lander (it lands on Mercury and can optionally bring a rover), and the last one needs to be an interplanetary transfer stage. Because of Mercury's close distance from the sun, the Interplanetary transfer stage needs to carry **as much fuel as possible** and use Frontier Engines andor Valiant Engines, or, if you have the time, a LOT of (clipped) Ion Engines. The interplanetary transfer stage gets your core stage and lander from low Earth orbit, then to Mercury, then back to low Earth orbit. The core stage can carry some fuel, its own engine, maybe some solar panels and a docking port for the lander. The lander lands on Mercury and can carry a rover with it.

Launch the parts separately on a large rocket. First the core stage, then the interplanetary transfer stage, then the lander. To make it easier, dock the parts in **high earth orbit or in high moon orbit** (easier), because the velocity is lower. Just remember that you don't think about launching a capable enough interplanetary transfer stage to orbit without draining the fuel first or using cheats.

### Mercury flyby

The first rocket that visited Mercury, Mariner 10 performed 3 flybys. It is possible to conduct a flyby, with or without entering Mercury's sphere of influence. The rocket will have an aphelion reaching Earth orbit and a perigee reaching Mercury's orbit. This way, it is possible at some point to return to Earth.

The flyby is the fastest and cheapest way to reach Mercury, but with limited science findings.

### Hard landing

A hard landing is possible, directly from Earth's orbit or with little trajectory correction maneuvers. However, such an attempt will bring limited science data and will not be feasible.

## Entering orbit on Mercury

Mercury has little gravity, ⅜ the gravity of Earth, about the same as Mars, but its sphere of influence is far smaller.

* If the rocket is approaching Mercury directly from an Earth transfer window, you will need a higher amount of fuel to slow it down to an orbit. This will be more difficult if the apoapsis is within a high altitude with the planet.
* If the rocket is approaching from Venus after a Venus gravity assist or a Venus orbit, then the amount of fuel needed will be much lower. In this case, it is good to perform a deep space trajectory correction maneuver, to get as close to Mercury as possible, for a maximum Oberth effect.
* If the probe approaches from an orbit similar to Mercury (this is very common for new players, who often miss a transfer window and try somehow to reach another planet), the needed amount of fuel will be far smaller.

### Activities

One-way probes will easy make it to Mercury. However, their payloads will be smaller then in case of Venus or Mars.

It is possible to build a **Mercury Space Station**, but with much higher costs than in case of any other planet.

Rockets that plan to return from Mercury may need to refuel.

## Exploring Mercury's surface

Without an atmosphere, a parachute is useless. Rockets will need to use retrorockets in order to land on Mercury. It is a good idea to include landing legs, to avoid damaging some parts in a fast landing.

The **Mercury colony** can be built on the surface. However, construction will require more fuel and more landings than in case of any other planet.

A liftoff can be done relatively as easy as on Mars, without requiring too much fuel.

## Returning to Home

*Main article: [[]]*

A rocket can easily exit Mercury's sphere of influence. However, rising the aphelion to Earth's orbit is a difficult task, but not impossible. It is possible to conduct a complete mission with one rocket. However, many players prefer to use additional rockets to gain thrust. Refueling can be a good option. In either cases, you will need a rocket in orbit.

Some players prefer to use flybys from Venus, while others prefer a direct flight to Earth. Returning to Earth from Mercury is harder than getting to Mercury from Earth, but the fuel needed is much less. Once you leave Mercury, get a transfer window to Venus, and once you get to a transfer window while on Venus, do the trans-terrestrial injection and return safely to Earth. You may need some maneuvers before reentry.

## See Also

What To Do In Spaceflight Simulator

Mercury Return Mission