Getting to Mercury

**Getting to Mercury** is one of the hardest missions to do in Spaceflight Simulator because of the following reasons:

* Mercury is very close to the sun
* High delta-v budget that consumes too much fuel

Getting to Mercury may require gravity assists, refueling, orbital maneuvers and more. This guide will tell you the easiest way of going to Mercury and also other methods.

## Rocket

A rocket needs at least 3 stages to go to Mercury with the help of orbital maneuvers. Here's a guide for how to build a rocket that is capable of going to Mercury and back: Building Mercury Rockets

## Mission

This mission will be the most complex mission since it uses a handful of orbital maneuvers such as gravity assists.

Before a launch for a mission to Mercury, a rare planetary alignment of Earth, Venus and Mercury must be needed before getting to Mercury, otherwise, try the procedure described in the Mercury return mission article, which can be performed without specific planets alignment.

### Launch

After launch, the rocket must turn slowly to the side. If the boosters run out of fuel, separate them; if the entire first stage runs out of fuel, separate it and activate the second stage engine, then continue burning prograde (i.e. firing the engine towards the direction of travel with the engine facing away towards it) until the trajectory wraps around the Earth. See more at Getting to orbit

### Mercury transfer

This is the most tricky part: getting to Mercury. It requires a lot of planning and some fuel, unless if you're going for a direct transfer. A direct transfer to Mercury requires too much fuel because a spacecraft must get fast in order to get there. To minimize fuel consumption there is one solution: using gravity to change the orbit until it intersects Mercury's orbit. This type of maneuver requires little to no fuel and uses a planet's gravity to speed up or slow down the spacecraft. In this case, the mission is to get onto Mercury's surface. Mercury is closer to the sun than Earth and Venus, so the spacecraft must slow down in its orbit. For the purposes of this article, it's going to use this method below.

#### Method

The method that the page will use will have 1 Venus slingshot and 3 Mercury slingshots. This requires little fuel. The picture on the right is a space probe trying to get to Mercury. First, do a Venus gravity assist to lower the trajectory to Mercury's orbit. Before doing this the planets Earth, Venus and Mercury must be aligned properly.

##### Venus transfer and slingshot

The first part will be easy: getting to Venus, like any other mission to Venus but it's a flyby. Click on Venus and select *Navigate To*. A transfer window will appear with a dot representing where the engine burn will be conducted and a dotted line showing the nominal trajectory. Just like a Venus mission, fire the engine until the trajectory intersects Venus's orbit. After this burn, time warp until the rocket is near Venus. Make sure the escape trajectory angle must be opposite of the direction where Venus moves.

Usually, the rocket's trajectory won't intersect Mercury's orbit. To achieve this, fire the engine retrograde until the rocket's perihelion is at around 2889000 kilometers. Mercury's orbit in the game is on average 2895000 kilometers away from the sun by the way, which makes the rocket's perihelion 0.3% lower than Mercury's orbit.

Mercury's orbit is eccentric, so the planet comes closer or farther than that distance above. But still: make sure the rocket's perihelion is 0.3% lower than any point at Mercury's orbit.

##### Mercury slingshots

Now for the time-consuming part: decreasing the rocket's perihelion to intersect Mercury's orbit. When reaching the perihelion, burn retrograde until the aphelion gets at approximately 5.4 million kilometers away from the sun or 100 thousand kilometers away from Venus's orbit. Then click on Mercury and select *Navigate To*. Time warp for some time until the rocket get an encounter with Mercury.

Every 2 orbits of the rocket, Mercury will approach the rocket even closer. If it gets an encounter, make sure the escape trajectory angle is opposite Mercury's motion. If not, time warp some more until the rocket hits the transfer window that consumes less than 100 m/s of delta-v. After escaping Mercury's sphere of influence, you should see the rocket's aphelion is closer to the sun and the perihelion is overshooting Mercury's orbit. At the perihelion, set the aphelion to roughly 4634500 kilometers and at the aphelion set the perihelion to the value stated earlier. Wait until it get another encounter or it gets a transfer window that consumes less than 70 m/s of delta-v. Make sure the escape trajectory angle is opposite Mercury's motion just like earlier. The aphelion would have decreased a little after the slingshot. This time, set the aphelion to roughly 3715750 km and the perihelion to roughly 2893100 km (this depends depending upon the distance on the point of Mercury's orbit on the perihelion of the rocket). After a while it should get a Mercury encounter or a transfer window that consumes less than 50 m/s of delta-v.

##### Other methods

There are other methods that you can use to slow down the velocity needed to get to Mercury like what the MESSENGER probe did: 1 Earth slingshot, 2 Venus slingshots, and 3 Mercury slingshots.

### Mercury landing

After all this time waiting to slow down to Mercury orbit, time warp for some time until you achieve a Mercury encounter. When you reach Mercury periapsis fire the engine until the rocket is orbiting Mercury. Orbiting Mercury requires a much slower velocity than orbiting Earth. While at Mercury orbit pick a landing footprint then burn retrograde until the trajectory hits the surface near the landing footprint. When gravity pulls the rocket even more slow down until the velocity is slower than 12 m/s. When nearing Mercury's surface slow down to less than 5 m/s. After years stuck in space the lander is now in Mercury's surface.

### Returning to home (optional)

*Learn more at : Mercury return mission*

Returning to home is less complex than getting to Mercury. Get to Mercury orbit and escape Mercury's sphere of influence. After this the rocket needs to get back to Earth's orbit and get back to its surface. From heliocentric orbit the rocket needs to get some Mercury gravity assists to rise the aphelion to Venus's orbit or by burning prograde. After these steps get to either Venus orbit or raising the orbit to Earth that requires at least 2 slingshots, then getting to Earth orbit that requires at least one slingshot. If in orbit around Venus, select Earth, click *Navigate To* and a transfer window will appear with a dot on it to represent where to burn and a dotted line to represent the nominal trajectory. Time warp until you are at the dot then fire the engine until the trajectory intersects Earth's orbit.

After years stuck in space waiting to return to Earth, the rocket is now finally back on Earth. Before reentry fire the engine to slow down the reentry speed and to increase mission success rates. Separate the capsule. When the capsule enters the atmosphere face the heat shield towards the direction of travel. At 800 meters, deploy the parachute. After many years in space, the rocket is finally back on Earth, and now you are now one of the players that did one of the hardest missions in Spaceflight Simulator: getting to Mercury and back.

## Tips

* If the rocket is low on fuel, dock to a refueling station.
* Create a quick save to save progress. Load them if you make a failure at one point on the mission.
* If going directly from Mercury to Earth, slow down before reentry or else the rocket will burn up.
* Use cheats if you cannot afford the delta-v to get to Mercury and back.
* Build a large rocket in orbit if you don't have the purchases or the rocket is too big to fit in the building space.
* Even if this is not a tip, Mercury is called a ***rocket graveyard*** because of the difficulty to get there.

## Activities

* Landing on landmarks
* Making surface bases
* Refueling stations
* Orbiters
* Landers
* Many more

## See also

* Mercury
* Mercury Return Mission
* Getting to Jupiter