On Jun 28, 7:31 pm, Alain Fournier wrote:

Phobos is still quite deep in the Martian gravity well. Why not go
get it in the main asteroid belt?

Surprisingly, being in Mars' gravity well makes Phobos and Deimos more
accessible, not less.

From LEO, trans Mars insertion is about 3.6 km/sec.

On arrival at a 300 km altitude Martian periapsis, a 1.4 km/sec burn
suffices to change the hyperbola into an ellipse with a 5981 km
altitude apoapsis.

When this ellipse reaches apoapsis, a .6 km/sec burn will circularize
the orbit.

So from LEO to Phobos takes about 5.6 km/sec delta V.

LEO to a main belt asteroid takes in the neighborhood of 8 to 10 km/
sec delta V. Could take a lot more if the orbit has a good inclination
(as a lot of asteroid orbits do).