Heinlein called the "Moon a Harse Mistress". Bova has explored Mars environment. Mars is not like Earth for this Mission; Moon was just a small step.

Earth and its unique life-support characteristics

One such piece of evidence arose recently from an astronomical mission to Mars. A sensitive magnetometer on board the Mars Global Surveyor reported some unexpected results.1 It found that Mars’s magnetic field is, at best, forty thousand times weaker than Earth’s, ten (or more) times lower than the limits established by previous Mars studies.2 With such a weak, or possibly non-existent, magnetic field, the Martian surface has virtually no protection from deadly solar x-rays.
The Global Surveyor magnetometer also found a few “magnetic anomalies” on the Martian surface, rocks containing “relic” magnetic fields.3 The magnetic characteristics of these rocks suggest that Mars has no internal dynamo now but that such a dynamo probably existed long ago when Mars was young. This electromagnetic and geological history represents a solvable puzzle.
Twenty researchers concurred in the solution. Their published reports show that the magnetometer’s findings make sense if Mars’s core contains a relatively small percentage of sulfur. If a planet’s core contains more than 15% sulfur (by mass), a solid inner core can never form. If the quantity (by mass) of sulfur in the core is considerably less than 15%, a solid inner core can form; however it will grow so rapidly that it soon engulfs and freezes out the liquid layers between it and the planet’s mantle and crust. Without a circulating magnetic fluid between the planet’s solid core and mantle, a strong magnetic field will never develop. Without a magnetic field, the planet has no shield to guard it from the sun’s x-ray radiation.
This discovery about Mars’s lack of such shielding certainly impacts any plans for a manned mission to Mars. The dangers, already known to be grave, now seem graver by far. At the same time, this new understanding about the intricacies of magnetic field formation reveals another wonder of Earth.
Life can exist on Earth because Earth has a strong, stable magnetic field. This field’s strength and stability are determined, in part, by the abundance of sulfur in Earth’s core. Remarkably, this abundance is “just right” for life, as are all the other characteristics that go into formation of a life-protective, magnetic-field-producing dynamo, one that shields life not just for a short time but for a few billion years.

References:
1.
M. H. Acuna, et al, “Magnetic Field and Plasma Observations at Mars: Initial Results of the Mars Global Surveyor Mission,” Science, 279 (1998), pp. 1676-1680.