Figure 2:  Location of Mars bow shocks observed by the Mars Global Surveyor during the first 80 orbits about Mars.  Distance (rho) from the Mars-Sun line (+x direction) is given for all bow shocks identified inbound (+) towards periapsis and outbound (*) from periapsis.
 

Figure 3:  (a) Projection of the MGS spacecraft trajectory and observed magnetic field (B) vectors onto the Mars orbit plane for periapsis pass # 5 on Day 262.  The field observed along the trajectory at 12 second intervals is represented by a scaled vector projection of B originating from the position of the spacecraft at such times.  Distance is given in units of Mars radius (3397 km) and field vectors are scaled to 20 nT = 1 Rm.  (b) Projection of the MGS spacecraft trajectory and observed magnetic field onto a plane perpendicular to the Mars orbit plane and the Mars-Sun line.  The spacectaft trajectory is nearly confined to this plane at this time.
 

Figure 4:  (a) Projection of the MGS spacecraft trajectory and observed magnetic field onto a plane perpendicular to the Mars orbit plane and the Mars-Sun line for periapsis pass # 6 on Day 264.  The field observed along the trajectory at 3 second intervals is represented by a scaled vector projection of B originating from the position of the spacecraft at such times.  Field vectors are scaled to 400 nT = 1 Rm.  (b) Magnitude of the observed magnetic field as a function of time for the interval of time represented in (a).
 

Figure 5:  Electron and magnetic field observations for periapsis 34.  See caption to Fig. 1.  Additional vertical lines indicate the location of the ionopause (IP).