Encyclopedia of the Solar System 2nd ed

138 Encyclopedia of the Solar System

TABLE 2 MESSENGERInstruments and

Measurements

Instrument Observation

Duel Imaging System (1.5◦

and 10.5◦field of view)

Surface mapping in stereo

(10 color filters)

Gamma-Ray and Neutron

Spectrometer

Surface composition (O, Si,

Fe, H, K)

X-Ray Spectrometer (1– to

10 kKeV)

Surface composition (Mg,

Al, Fe, Si, S, Ca, Ti)

Atmospheric and Surface

Spectrometer

Surface and Exosphere

composition

Magnetometer Magnetic field

Laser Altimeter Topography of northern

hemisphere

Energetic Particles and

Plasma Spectrometer

Energetic particles and

plasma

Radio Science (X-band

transponder)

Gravity field and physical

liberation

necessary to answer most of the questions raised in this
chapter. The Europeans are also planning a Mercury mis-
sion called BepiColombo in the years immediately following
theMESSENGERinvestigations.

Bibliography

Benz, W., Slattery, W., and Cameron, A. G. W. (1988).Icarus
74 , 516–528.
Harmon, J. K., Perillat, P. J., and Slade, M. A. (2001).Icarus
149 , 1–15.
Potter, A. E., and Morgan, T. H. (1988).Science 247 , 675.
Robinson, M. S., and Lucey, P. G. (1997).Science 275 , 197–
200.
Sprague, A., Kozlowski, R. W. H., and Hunten, D. M. (1990).
Science 249 , 1140–1142.

FIGURE 25 This drawing shows the orbit ofMESSENGERin

its 12-hour period. The elliptical orbit is required to maintain an

acceptable operating temperature, and yet still obtain

high-resolution data at and near closest approach. Hp is the

closest approach, Ha is the farthest point in the orbit, and the

orbit is inclined at an angle of 60◦to the equator.

Strom, R. G. (1984). “The Geology of the Terrestrial Planets”

(M. H. Carr, ed.). NASA SP-469, pp. 13–55. NASA, Washington,

D.C.

Strom, R. G. (1987). “Mercury: The Elusive Planet.”

Smithsonian Institution Press, Washington, D.C.

Strom, R. G., and Sprague, A. L. (2003). “Exploring Mercury:

the Iron Planet.” Springer-Praxis, Chichester, England.

Various authors in a special issue on theMariner 10encounter

with Mercury. (1975).J. Geophys. Res. 80.

F. Vilas, F. Chapman, C. R., and Matthews, M. S., eds. (1988).

“Mercury,” Univ. Arizona Press, Tucson.