Do Mars' Lagrange Points Exist Near Phobos and Deimos? (2024)

FAQs

Do Mars' Lagrange Points Exist Near Phobos and Deimos? ›

Yes, the Martian moons have Lagrange points. They're very close to the surface of the moons, close enough that a tether of just a few kilometers' length is needed to get to the surface. Super easy place to build space elevators (a demo might even fit in a cubesat!).

The five Lagrange points exist in the same relative positions around all major bodies in our Solar System, where one body orbits a more massive body. So, there are Lagrange points in the Earth-Sun system, the Mars-Sun system, the Jupiter-Sun system, and so on.

Both Phobos and Deimos are visible from the martian surface. Phobos is much brighter, as it is both physically larger and orbits much closer to the planet than Deimos.

These five points are mirrored in other pairs of bodies. For example, the Earth-moon system has its own set of Lagrange points.

The L4 and L5 Lagrangian points of the Earth-Moon system are located at ~400 000 km from the Earth, while the L2 point of the Earth-Sun system is at a distance of ~1.5 x 10⁶ km. The baseline is a Lissajous orbit around the L2 Lagrangian point of the Earth-Sun system.

L1 and L2 for the earth/sun is 1.5 million km, L1 and L2 for mars/sun is 2.2 million km. L1 is between the planet and the sun, L2 is on the opposite side of the planet furthest from the sun.

So if you have two galaxis orbiting their common center of mass, there will be five Lagrange points where something significantly less massive can stay in position relative to the galaxies.

It whips around Mars three times a day, while the more distant Deimos takes 30 hours for each orbit. Phobos is gradually spiraling inward, drawing about six feet (1.8 meters) closer to the planet each century.

Phobos is tidally locked to Mars, like Earth's moon is locked to Earth, thus always showing the planet only one side. As a result, the rocks on the near side of Phobos have been bathed for millennia in Martian atoms and molecules.

Phobos orbits closer to Mars, with a semi-major axis of 9,377 km (5,827 mi) and an orbital period of 7.66 hours; while Deimos orbits farther with a semi-major axis of 23,460 km (14,580 mi) and an orbital period of 30.35 hours.

Are there only 5 Lagrange points? ›

There are five special points where a small mass can orbit in a constant pattern with two larger masses. The Lagrange Points are positions where the gravitational pull of two large masses precisely equals the centripetal force required for a small object to move with them.

The James Webb Space Telescope orbits the Sun near Sun-Earth Lagrange point 2 (L2), approximately 1.5 million kilometers (1 million miles) from Earth.

For any combination of two orbital bodies, there are five Lagrange points, L₁ to L₅, all in the orbital plane of the two large bodies. There are five Lagrange points for the Sun–Earth system, and five different Lagrange points for the Earth–Moon system.

Of the five Lagrange points, three are unstable and two are stable. The unstable Lagrange points - labeled L1, L2 and L3 - lie along the line connecting the two large masses. The stable Lagrange points - labeled L4 and L5 - form the apex of two equilateral triangles that have the large masses at their vertices.

L₃ is the Sun–Earth Lagrange point located on the side of the Sun opposite Earth, slightly outside the Earth's orbit. Direct communication with spacecraft in this position is blocked by the sun. There are no known objects in this orbital location.

Hubble is in a very close orbit around the earth, while Webb will be 1.5 million kilometers (km) away at the second Lagrange (L2) point.

Earth and Mars have some surprising similarities. Two plucky NASA spacecraft found that Mars is wobbling in its rotation just like Earth, potentially telling us more about the search for life on the Red Planet.

The absence of these U-shaped valleys means that ice sheets on Mars likely moved and eroded the ground under them at extremely slow rates compared to what occurs on Earth.

Unlike Earth, the obliquity (or tilt) of Mars changes substantially on timescales of hundreds of thousands to millions of years. At present day obliquity of about 25-degree tilt on Mars' rotational axis, ice is present in relatively modest quantities at the north and south poles (top left).