Everything You Need to Know About Living on Mars

To melt the Martian core requires the introduction of radioactivity.  A fast breeding atomic pile of plutonium allowed to melt its way into the core should do it.  Once enough radioactive material is generated the heat should melt the core in just a few quick centuries. lol???


Actually I don't believe that Mars core is cooled to where it is solid.  There is still a vestigial magnetic field present, which says that the core is still hot, just not hot enough to generate a full field.