Mars science and telecommunications orbiter

Figures and tables

Figure 1. A sketch of the structure of the Martian plasma environment, depicting the major boundaries and regions in the equatorial plane. The scales are Mars radii.

Figure 2. (After Mazelle et al., 2002; See also Winterhalter et al, 2001). Magnitude of the magnetic field recorded by Mars Global Surveyor during an early elliptical orbit (October 11, 1997) around periapsis (14:28 UT, altitude 120 km, 17.6 local time) displaying the major plasma boundaries symmetrically on both sides: BS, MPB and CB denote the bow shock, the magnetic pile-up boundary and the magnetic ‘cavity boundary’, respectively. The horizontal axis shows both time and the spacecraft coordinates in the Mars-centered solar orbital (MSO) system (the X-axis points from Mars to the Sun, the Y-axis points anti-parallel to Mars' orbital velocity, and the Z-axis completes the right-handed coordinate system).

Figure 3. Key components of the Mars general circulation.

Figure 4. The solar wind pressure varies over the solar cycle, as does the upper atmosphere and ionosphere-controlling solar EUV flux. The escape rates of heavy atoms and H are expected to be significant at high solar activity. There is no in situ data at present. Thus measurements at solar max are essential (necessary, but not sufficient).

Figure 5. MSTO initial orbit design: Science Phase 1 (red) 150 x 6500 km, duration 1 year. Science Phase 2 (yellow) 400 x 400 km, duration 1 year. Telecom Infrastructure Phase (green) 400 x 2000 km, duration 8 years.

Figure 6. Solar occultation coverage for a 150 x 6500 km orbit over 2 years. Red and blue footprints correspond to 8 and 4 km vertical resolution, respectively.

	Science Objective Description	Applicable MSTO SAG Questions	MEPAG Investigation Addressed
SO-1	Characterize present-day atmospheric escape	Q1, Q3,	II.A.1, II.A.3, II.B.2
SO-2	Determine relative abundances of minor and trace molecular species of lower atmosphere	Q4, Q5, Q7-9	I.C.4, II.A.1, II.B.1
SO-3	Measure zonal and meridional winds	Q1, Q6	II.A.1, II.A.3, II.B.2
SO-4	Map crustal magnetic field w/100km resolution	Q1	II.B.2
SO-5	Use radar or SAR to locate subsurface regions of special interest	Q7	III.A.1, III.A.2, III.A.5

Table 1. Relationship between MSTO Science Questions and Objectives, MEPAG Mars Scientific Goals, (MEPAG 2006) and the recommendations of the Decadal Study, (New Frontiers in the Solar System, NAS 2003).

H, H^+, H2, H2^+, D, D^+, HD, HD^+

^12C, ^12C^+, ^13C

^14N, ^14N^+, ^15N, ^14N2, ^14N2^+, ^14N^15N, ^14N^15N^+

^16O, ^16O^+, ^18O, ^16O2, ^16O2^+, ^16O^18O, ^16O^18O^+

H2O, HDO

CO, CO^+, CO2, CO2^+

NO, NO^+

^36Ar, ^40Ar, ^40Ar^+

.

Table 2. Upper atmosphere atomic and molecular species to be monitored.

Species	Upper limit (mixing ratio)	Type of observation	Reference
C2H2	2x10^-9	IRIS-Mariner 9	Maguire (1977)
C2H4	5x10^-7	"	"
C2H6	4x10^-7	"	"
C2H8	4x10^-7	"	"
N2O	1x10^-7	"	"
NO2	1x10^-8	"	"
NH3	5x10^-9	"	"
PH3	1x10^-7	"	"
SO2	3x10^-8	Ground-based, mm	Encrenaz et al. (1991)
OCS	7x10^-8	"	"
H2S	2x10^-8	Ground-based, IR	"
CH2O	3x10^-9	"	Krasnopolsky et al. (1997)
HCl	2x10^-9	"	"

Table 3. Upper limits for some of the plausible trace molecular constituents of the Martian atmosphere for which spectroscopic searches have been made. (From Ecrenaz et al., 2004.)

Table 4. Relationship between MSTO science objectives, required measurements and proposed instrument types.