Spaceflight Simulator Wiki

Phobos is one of Mars's two moons, the other being Deimos. It's the larger one of the two, and it orbits closer to Mars. Its low gravity makes landing on it relatively easy.

Phobos is the key for the exploration of Mars, so many players build bases/colonies on Phobos. They also land a lot of landers on this celestial body.


A section of the surface of Phobos, taken by a lander.

The terrain is irregular, due to its small size. It is covered in some craters and high mountains. The high mountains are a place where the gravity is lowest.

Some areas of the surface are very rough, that's why rockets that landed there after touchdown tip over, due to the low gravity and the irregularity of the surface. Some landers tip over to the side, or land in different directions andor angles, but when they stay on the surface for a long time, the other part that has not touched the surface touches the surface of the moon.

Moving on Phobos

Driving rovers on the surface may be difficult, due to the extremely low gravity and the uneven terrain. Rover Wheels do not have enough grip to stay on the ground and may lift the rocket off of the surface. The gravity may be enough to make the rover orbit Phobos and in some cases escape Phobos's gravity and orbit Mars. Rovers are meant to explore the ground, not to be a satellite with wheels that are useless and drives around nothing but space.

To counteract this, it is recommended to use (clipped) Ion Engines to push the vehicle down while using wheels to move horizontally (though the wheels would have to be manually enabled, and couldn't with RCS Thrusters).

Reaching orbit from Phobos is simple. RCS Thrusters are powerful enough to reach orbit, and adjust, possibly to the extent of leaving the sphere of influence. The ion engine is another option, since it has the same thrust as the thrusters, and has a high specific impulse (Isp) of 1200s.

Around Phobos

Phobos has a small sphere of influence, and low gravity. Engines that have miniscule thrust or operating at a very low throttle is enough for the spacecraft to escape Phobos, then orbit it on Mars. The orbit insertion is easy, because Phobos is small, so short engine burns must be conducted. IN some cases, the rocket comes into a high speed, and long engine burns must be conducted at full throttle.

A Mars space station can be built on Phobos. But due to the small size, docking maneuvers must be done carefully. The other building spaces for a Mars space station are Deimos and in high Mars orbit (usually between the orbits of Phobos and Deimos).

A Phobian base can be built on Phobos. But, bases on Phobos must be small enough, to fit the size of Phobos. The maximum number of bases on Phobos is around 5–8.

A Phobos Space Elevator can be built on Phobos, but in the simulator, it is very complex. First, multiple segments and the main elevator must be built. Then, some support structures must be built around the elevator to keep it stable. Sometimes, the elevator topples even the structures are in place, due to the low gravity.

Phobos is the key of exploring Mars. So, landers would land in the planet, usually in the bases, then they would be refueled, then sent back to Mars or Earth.


  • Phobos is one of the perfect places to experiment on orbital physics due to its low gravity.
  • Due to the low gravity of Mars and its moons, players often extend Mars missions to include landing on the moons of Mars before returning home.
  • Some players practice docking on Phobos, since it is small. Small bodies are easy to dock rockets on.
  • If you jump on Phobos, you would escape the gravity fields of Phobos, then orbit Mars, usually in an orbit that is near to Phobos.
  • In real life, Phobos will drop pass Mars's Roche limit around 40 million years from now and disintegrate, giving Mars a ring. In a few hundred million years, the ring will have fallen to Mars' equator, creating craters on it and heating up the atmosphere.
Sun MercuryVenusEarth (Moon) • Mars (Phobos · Deimos) • Jupiter (Io · Europa · Ganymede · Callisto)
Earth Moon
Mars PhobosDeimos
Jupiter IoEuropaGanymedeCallisto